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January/February 2009 Volume 21, No. 1

Drying wettransformersin the field

Examining the low frequencyheating process page 8

Drying wettransformersin the field

Examining the low frequencyheating process page 8

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6 A MULTIBILLION-DOLLAR PUSH IN THE RIGHT DIRECTION

8 LOW FREQUENCY HEATING FIELD DRY-OUT OF A 750 MVA 500 KV AUTOTRANSFORMER

24 TRANSFORMER FIRE CONTAINMENT WALLS INSTALLED IN RECORD TIME

46 NEW YORK’S STRICT NOISE REGULATIONS A PERFECT FIT FOR ABBTRANSFORMERS

12 UTILITY WATER STRAINING: CHOOSING THE CORRECT STRAINER TECHNOLOGY

16 NONDESTRUCTIVE TESTING OF OVERHEAD TRANSMISSION LINES

23 IPPSA 15TH ANNUAL CONFERENCE AND TRADE SHOW - 15 YEARS: 15 QUESTIONS

28 WHAT THE NESC COVERS, WHAT IT DOESN’T

30 PROVIDING OIL SPILL CONTAINMENT IN A REMOTE AREA

32 DISTRIBUTION AUTOMATION AND DEMAND RESPONSE - PART II

44 HAWAIIAN ELECTRIC MAKES AMI CHOICE AFTER TWO YEARS OF TESTING

45 ABB SHARES EMPLOYMENT OPPORTUNITIES WITH UNIVERSITY GRADS

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EDITORIAL

TRANSFORMERS

UTILITIES

OVERHEAD TRANSMISSION

ADVERTISERS INDEX

PRODUCTS AND SERVICES SHOWCASE

CONFERENCES

CODE

TRANSFORMER SAFETY

DEMAND RESPONSE

METERING

TRAINING AND EDUCATION

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Electricity Today4

editorial board

BRUCE CAMPBELL

DAVID O’BRIEN

CHARLIE MACALUSO

SCOTT ROUSE

BRUCE CAMPBELL, LL.B., Independent Electricity System Operator (IESO)Mr. Campbell holds the position of Vice-President, Corporate

Relations & Market Development. In that capacity he is responsible for theevolution of the IESO-administered markets; regulatory affairs; externalrelations and communications; and stakeholder engagement. He hasextensive background within the electricity industry, having acted as legalcounsel in planning, facility approval and rate proceedings throughout his26-year career in private practice. He joined the IESO in June 2000 and isa member of the Executive Committee of the Northeast Power CoordinatingCouncil. He has contributed as a member of several Boards, and was Vice-Chair of the Interim Waste Authority Ltd. He is a graduate of the Universityof Waterloo and Osgoode Hall Law School.

DAVID O’BRIEN, President and Chief Executive Officer, Toronto HydroDavid O'Brien is the President and Chief Executive Officer of TorontoHydro Corporation. In 2005, Mr. O'Brien was the recipient of theOntario Energy Association (OEA) Leader of the Year Award, establish-ing him as one of the most influential leaders in the Ontario electricityindustry. Mr. O'Brien is the Chair of the OEA, a Board Member of theEDA and a Board Member of OMERS.

CHARLIE MACALUSO, Electricity Distributor’s AssociationMr. Macaluso has more than 20 years experience in the electricity

industry. As the CEO of the EDA, Mr. Macaluso spearheaded the reformof the EDA to meet the emerging competitive electricity marketplace, andpositioned the EDA as the voice of Ontario’s local electricity distributors,the publicly and privately owned companies that safely and reliably deliverelectricity to over four million Ontario homes, businesses, and public institutions.

SCOTT ROUSE, Managing Partner, Energy @ WorkScott Rouse is a strong advocate for proactive energy solutions. He

has achieved North American recognition for developing an energy effi-ciency program that won Canadian and US EPA Climate ProtectionAwards through practical and proven solutions. As a published author,Scott has been called to be a keynote speaker across the continent fornumerous organizations including the ACEEE, IEEE, EPRI, and CombustionCanada. Scott is a founding chair of Canada’s Energy Manager networkand is a professional engineer, holds an M.B.A. and is also a CertifiedEnergy Manager.

DAVID W. MONCUR, P.ENG., David Moncur EngineeringDavid W. Moncur has 29 years of electrical maintenance experience

ranging from high voltage installations to CNC computer applications, andhas conducted an analysis of more than 60,000 various electrical failuresinvolving all types and manner of equipment. Mr. Moncur has chaired aCanadian Standards Association committee and the EASA OntarioChapter CSA Liaison Committee, and is a Past President of the WindsorConstruction Association.

DAVID W. MONCUR

Jan Feb ET 1/12/09 3:12 PM

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Electricity Today6

It might have been overlookedamong the hundreds of billions beinghanded out by Washington, but it is cer-tainly going to help make the nation’sgrids a lot smarter.

The $700 billion EmergencyEconomic Stabilization Act, which wassigned into law on October 3, 2008 aftermuch pleading, rejection and eventualacceptance, included provisions foraccelerated depreciation for smart metersand other smart grid equipment.Certainly these funds will stimulategreater utility investment in this much-needed technology.

Basically, the new tax provisionsreduce the depreciation rate for smartgrid technologies from 20 years to 10,bringing smart grid tax treatment in linewith other similar high-technology sys-tems.

The larger deductions will encour-age increased spending on smart metersand related technology.

At the moment, a smart meter isroughly three times the price of an ordi-nary meter – and unfortunately, smarttechnologies are constantly evolving andmaking equipment once leading edgefive years ago quickly obsolete. Whatoccurs, instead of widespread deploy-ment, is a plague of pilot projects – littlebetter than window dressing to show cus-tomers that they are “going green” with-out spending a lot of green.

In Ontario, Canada, smart metering

will be deployed provincewide by 2010.With strong government support, and adetermination through public advertisingcampaigns and concerted pilot projectsthat were a springboard to wider deploy-ment, this goal appears to be withinreach.

Many utilities throughout the UnitedStates have crossed north of the border toexamine Ontario’s smart meter deploy-ment, and it looks like the time is ripe fora nationwide explosion of smart meter-ing, coupled with a smartening up of thevarious grids.

And a general smartening up isneeded now.

Within the next few years, there willbe a growing number of hybrid and all-electric vehicles in driveways acrossNorth America, all looking for a place toplug in. Also, the explosion of personalwind turbines, solar, geothermal andother renewable generation will be look-ing for smarter grids to handle any gen-eration that might be flowing back intothe grid.

This could be the time that NorthAmerica may be looking to electricity asthe liberator from foreign oil – becomingthe primary source of power for every-thing.

The former director of the CIA JimWoolsey spoke recently at the GEOINTSymposium in Nashville, Tennessee,urging Americans to embrace renewablepower (yes, that means nuclear too),

drastically improve the national grids andthrow off the shackles of oil.

He pointed to an historical depen-dence on salt as a trading commodity(think back to your Latin studies, and youwill remember that “salary” is derivedfrom the Roman word for salt, salarium),and how that was ended once the tech-nologies of refrigeration and freezingwere developed.

So too could the development of bat-tery storage and electric vehicles makeoil unimportant in our lives.

This “smartening” of the grids hasbeen going on for several years now,mostly to accommodate the wind andsolar expansion that requires real-timemonitoring to ensure that a steady flow ofpower is available whether the wind isblowing or not, or if the sun decides notto come out that day.

Also, the once proudly independentgrid systems (like ERCOT), are only nowreaching out to neighbours through betterintertie connections – allowing for thisblossoming of renewable development tobear full fruit.

There will be hiccups, trips (punintended) and roadblocks along the way,but it is encouraging that even duringthese tough economic times, firm supportfrom Capitol Hill will be there to rehabil-itate the nation’s aging infrastructure –and maybe even allow us to kick our cen-tury-old addiction to oil.

[email protected]

EDITORIAL

A MULTIBILLION-DOLLAR PUSHIN THE RIGHT DIRECTION

By Don Horne

Keeping the skyline lit in New York will depend on new infrastructure money creating new transmission links to clean power sources northof the border.

Jan Feb ET 1/12/09 3:13 PM

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Electricity Today8

Recently, two 30-year-old EHV 750MVA 500 kV GE autotransformers weredried in the field using the LowFrequency Heating (LFH) process. It isgenerally difficult in the field to achieveacceptable dryness for wet EHV trans-formers using the traditional hot oilcycling method.

The LFH process applies near DCcurrent to the windings allowing uniformwinding temperatures progressively andsafely up to 110°C.

The LFH drying process was com-pleted for both units in two weeks with

significant water removal and the mois-ture in cellulose brought down to belowone percent.

These are the largest field applica-tions of the LFH drying process.

Based on the limited number ofmeasurements, it has already been con-cluded by Hydro One that the LowFrequency Heating (LFH) method issuperior to the methods used previously.The results of less than 1.0 percentremaining moisture allow Hydro One torestore the transformers’ overload capa-bilities without fear of bubble formation.

INTRODUCTIONThe primary purpose of performing

site dry-outs of power transformers is toreduce the moisture content in the cellu-lose. Moisture comes from the agingprocess of the cellulose (it is a byprod-uct) or externally from the transformer(gasket, breather, leak, etc). Moisturedeteriorates the electrical and mechanicalproperties of the transformer and canlimit the allowed overload due to risk ofwater bubble formation.

Hydro One recently investigated afailure of an important system autotrans-

TRANSFORMERS

LOW FREQUENCYHEATING FIELD DRY-OUTOF A 750 MVA 500 KV

AUTO TRANSFORMER

By Elisa Figueroa, Tomasz Kalicki - Hydro One & Ed teNyenhuis – ABB

Jan Feb ET 1/12/09 3:13 PM

former which led it to invest in aprogram of site drying its fleet of500/230 kV autotransformers. Thisgroup of autotransformers is thebackbone of the transmission net-work in Ontario. One of these units,a 750 MVA 500/230/28 kV three-phase autotransformer, underwent afailure only hours after a sister unitat that station had been removedfrom service due to a high moisturealarm from an on-line monitor. Theresulting investigation showed thatmoisture was a main contributingfactor to the failure. It was estimat-ed that the moisture level in thefailed unit was approximately 1.5percent. Further analysis indicatedthat similar moisture content exist-ed on other units within that fleet ofinstalled transformers. As a result,many of the units in service werede-rated and an extensive dry outprogram was initiated to reduce therisk of further failures.

Site dry-outs for this drying program were performedusing a Hot Oil Circulation plus Vacuum (HOV) method,which is standard practice for smaller units. Due to the size ofthe units and the deep penetration of the moisture in the cellu-lose, numerous hot oil/vacuum cycles were required. Thisresulted in lengthy transformer outages. To improve moistureremoval effectiveness, a diffusion pump was used to achieve avery deep vacuum - 50 microns. With all this, the final mois-ture results indicated that the effectiveness of HOV was mar-ginal. While the surface moisture dropped, the average mois-ture levels hardly budged. The target level of less than one per-cent moisture content was not achieved. Furthermore, the out-ages lasted over two months due to the large size of the unitsand the consequently large volumes of oil. This effort also tiedup significant resources (staff and equipment) and subsequent-ly other transformer projects were also impacted. The deepvacuums required to extract moisture also caused new leaks tospring up due to aged component stress. At times the processhad to be stopped before reaching target vacuum levels becauseof concerns regarding the structural integrity of the tank. A newmethod had to be found for the large transformers which led tothe application of the Low Frequency Heating (LFH) technol-ogy on two 750 MVA, 500 kV autotransformer with much bet-ter results.

LOW FREQUENCY HEATING OVERVIEWWith the LFH method, current is applied to the windings

in order to heat the transformer more effectively at a highertemperature. The current is applied at 1 - 50 mHz that has twocritical advantages.

First, the impedance voltage is much reduced with low fre-quency meaning the required applied voltage is low. The LFHis applied when the oil is removed from the unit but the appliedvoltage is thus low enough to eliminate any risk of flashover.

Second, the leakage flux is negligible so the temperatureacross the winding is uniform. Under normal AC operation,leakage flux causes uneven winding heating. Thus, the low fre-quency current allows higher temperatures to be safely

achieved across the entire winding during the dry out.The current is applied to the HV winding and is typically

20 - 50 percent of the rated current. The applied current is lim-ited by the temperature of the winding and the induced wind-ings. The frequency can be varied slightly to control the amountof transformation to the LV winding, which is short-circuitedduring the dry-out. Winding temperatures of up to 110°C arepermitted during the LFH dry-out process and are monitored byconstant winding resistance measurement. This peak windingtemperature of 110°C has a negligible effect on the paper agingof the transformer.

The LFH unit has power converters to change the currentfrom 50/60Hz AC to the desired low-frequency current. Thecontrol system monitors the winding temperatures, appliedvoltage & current, frequency, thermocouples (placed inside thetransformer) and vacuum. The safety protocols ensure maxi-mum individual winding temperatures are not exceeded andlow vacuum is not used when LFH voltage is applied.

During the heating of the windings, a hot oil spray isapplied over the core/coils to additionally heat the externalinsulation. Temporary spray nozzles are installed beneath thecover. The hot oil spray allows external insulation temperaturesabove 90°C.

A typical LFH process would be as follows:• Initial heating/circulation of core/coils using hot oil and

with LFH current applied to the windings• Drain the oil and pull vacuum to remove moisture• Break vacuum; apply LFH current and hot oil spray fol-

low this with vacuum. Repeat this process and progressivelyraise the temperature to 110°C

• Pull final vacuum• Break vacuum to remove temporary spray nozzles• Vacuum fill the transformer with dry degassed oilDue to the much higher achieved temperatures compared

to traditional hot oil treatments (110°C versus 80°C) the mois-ture removal with LFH is more effective and is done in areduced amount of time.

9January/February 2009

Jan Feb ET 1/12/09 3:13 PM

HYDRO ONE SITE DRYOUTS WITH LFH PROCESSHydro One performed site dry-outs in 2007 using the LFH

technology on two 750 MVA 500 kV autotransformers. Thefirst dry-out was performed for a unit being repaired in a HydroOne facility. The second unit was dried in the field during anoutage. Both units were 750 MVA 500/230/28 kV three-phaseautotransformers and were 33 years in age. The moisture con-tent in each unit was estimated to be 1.5 percent prior to thedry-out.

Since both units were autotransformers, the LFH unitinjected current into the series/parallel windings and currentwas induced in the tertiary winding. The LFH unit monitoredthe winding temperatures (constant resistance measurement)since the windings did not each heat at the same rate. Whenrequired, the frequency was reduced so that current was notinduced in the tertiary winding (since the tertiary winding heat-ed faster). Thermocouples were placed on the core, windings,lead structure and in the drying tank to closely monitor theprocess. Oil spray nozzles were temporarily installed under thecover via a modified manhole cover.

A total of 11 LFH/vacuum cycles were performed for eachdry out. Hot oil was initially circulated toremove the surface moisture. This hot oilwas heated together with external equip-ment and the LFH, which raised the oiland windings to a temperature of about80°C. This was followed by vacuum. Atthis point the 11 cycles of LFHcurrent/hot oil spray followed by vacuumwere done. The winding temperature wasincreased from 85°C to 110°C over the 11cycles. The oil spray was raised to a tem-perature of 95°C during the LFH cycles.

Thermocouples confirmed that insu-lation external to the windings reached 95°C and that the tem-perature was uniform from the top to bottom. The injected cur-rent for these transformers was limited by the tertiary windingrating. Thus, the tertiary winding current was limited to 70% ofrated current. The frequency of the injected current was 0.05Hzfor when all windings were being heated and 0.0015Hz whenonly the series/common windings were being heated. The firstdry-out took a total of 12 days while the second dry out wasdone in 11 days.

The water removed was calculated to be 150 liters for thefirst dry-out, and 160 liters for the second dry-out. Insulationsamples were also taken from both units after the dry-out,which showed average moisture in cellulose result of 0.7% forthe first unit and 0.3% for the second unit. The 150 liters and160 liters of water removed during the two dry-outs translatesto approximately one percent reduction in moisture content incellulose. With an estimated pre-dry-out moisture in celluloseof 1.5 percent, the one percent reduction implies a final averagemoisture in cellulose of 0.5 percent, which is consistent withthe sample block results.

DISCUSSION OF LFH SITE DRY-OUT PERFORMANCEThe two dry-outs performed showed that the LFH method

of site drying has a number of advantages compared to the tra-ditional HOV method. The primary advantage is the superiordrying effectiveness. As shown above, the final average mois-ture in cellulose result was less than 0.7 percent. Previous HOVdry-outs have not achieved results even less than one percent

and the removed water has been less than 100 liters.The duration of the LFH dry-out was about two weeks

compared to up to eight weeks for the HOV dry-outs. This is ahuge benefit considering the importance of these autotrans-formers for system operation and the severe difficulties inobtaining extended outages. Furthermore, the LFH dry-outstied up fewer resources, as well as being required for a shortertime. The LFH dry-out requires less oil handling equipmentand reduced personnel. Only two operators are required for theoil degasser/vacuum pumps and one LFH operator when LFHcurrent is applied. HOV dry-outs typically require more per-sonnel due to the extra equipment and the numerous hoses,valves and pumps to be operated and monitored during extend-ed hot oil circulations.

Lastly, since the LFH vacuum requirements are not as lowas those required by the HOV method, the stress applied to thetransformer tank is reduced. Even if a transformer tank can sus-tain a deep vacuum (which is questionable for many olderunits), significant effort must be exerted to locate and eliminateall leaks.

A summary of the advantages of LFH compared to HOV isshown in Table 1.

CONCLUSIONAlthough the number of confirmed measurements is limit-

ed, it has already been concluded by Hydro One that the LowFrequency Heating (LFH) method is superior to the previouslyused methods. The results of less than one percent remainingmoisture allow Hydro One to restore the transformers’ overloadcapabilities without fear of bubble formation.

It is believed that future dry-outs will give Hydro Onemore evidence to support the previous statement. More data,combined with the on-line monitoring of the moisture activityinside the transformer returned to service after the dry-out willfurther prove the effectiveness of this method.

ACKNOWLEDGEMENTSThe authors wish to acknowledge Greg Isaacs, Steve Smith

and Joe Manella, all from Hydro One, for providing field dataduring the site dry-outs procedures.

Elisa Figueroa is a Senior Network Management Engineerresponsible for transformer fleet management, Hydro OneNetworks Inc (HONI), Ontario, Canada.Dr. Tomasz Kalicki is Senior Material Management Engineerresponsible for transformer design and engineering at HydroOne Networks Inc (HONI), Ontario, Canada.Ed G. teNyenhuis is the Technical Manager for ABBTransformer Repair and Engineering Services in Brampton,Canada.

Electricity Today10

TABLE 1Comparison of HOV Drying Method versus LFH

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Electricity Today12

Whether used for cooling, or the process itself, the rawwater drawn from lakes, rivers and reservoirs must first bestrained to create acceptable water for use. In many industries,this means continuously straining tens of thousands of gallonsof water per minute to remove dirt and debris that can wreakhavoc on critical process systems and equipment.

In essence, the raw water strainers that accomplish this taskare the first lines of defense for the entire plant’s system.Choosing an inadequate strainer can lead to high maintenanceand operating costs, periods of insufficient water supply, dam-age to process equipment, and expensive downtime. Worse, thestraining media of an overwhelmed water strainer can ruptureor collapse, permitting debris to compromise critical plant oper-ating components. In the power industry, for example, cleanwater is crucial for a variety of tasks including, among others,extending the service life of turbine seals and for the protectionof spray nozzles and heat transfer equipment.

Unfortunately, such failures are not unusual, particularlywhen the strainer design does not allow for sufficient strainingsurface area. In applications using raw water from rivers, forexample, single basket strainers sometimes become over-whelmed and clogged during periods when there were high vol-umes of debris in water due to seasonal conditions such as rain-fall carrying dirt, leaves and other loose particles into the watersupply.

“You never really know what you’re going to experiencewith river water,” says Sang Partington, a Senior Engineer withPennsylvania Power & Light (PPL’s) Generation TechnicalGroup. “It changes from season to season. During autumn andhigh water flow in the river, you may have a lot of debris suchas tree branches, leaves and other solids in the water. Therefore,your water strainer has to be able to handle the solids and stillmaintain a continuous volume of water flow.”

WHICH STRAINER TECHNOLOGY?Water strainers for mass raw water filtration have been

around for decades, and today manufacturers offer a variety ofdesigns, including those that operate automatically. One of themore significant advances in strainer design occurred in the1960s when the first multi-element, automatic self-cleaningstrainer design was developed.

This strainer design was particularly significant because itprovided a durable and reliable alternative to the classic basket-type strainer that — although sometimes carries a lower pricetag — is also limited by its strainer surface area, which canquickly become clogged and force excessive cleaning cycles(backwashing) and reduced water for process requirements.

By replacing the basket with multiple tubular elements, thedesign provides 3-4 times the straining surface area of a typicalbasket strainer. As a result, debris and solids — including fromseasonal peaks — are efficiently removed without downtime.

The increased surface area of the multi-element design allowsfor fewer backwashes, equating to lower operational costs, lessmaintenance and greater overall efficiency.

OPTIMIZING WATER FLOW AT PPLAbout five years ago, Partington noticed that the old, bas-

ket-type water strainers at its Brunner Island plant required highmaintenance and continuously shifted to backwash mode. “Theold system was constantly backwashing,” says Partington.

At PPL’s electric power generation utilities, the priority ismaintaining sufficient volume and pressure, although there iscertainly concern about the debris and other solids that can bein the rivers that feed water to the coal-fired plants.

PPL began to upgrade the raw water strainers at its Brunner

UTILITIES

UTILITY WATER STRAINING: CHOOSING THECORRECT STRAINER TECHNOLOGY

By Ed Sullivan

Bulk raw water users, such as PPL Electric Utilities, protect processand downstream equipment by selecting multi-element water strain-er technology.

Jan Feb ET 1/12/09 2:39 PM

Island and Montour plants, both feed-ing off the Susquehanna River in cen-tral Pennsylvania. Both are large gen-erating facilities with approximately1,500-megawatt capacity, and it iscritical to ensure sufficient cleanwater to keep the plants on line con-tinuously.

According to Partington, the out-flow of clean, filtered water throughthe strainers was also at lower-than-optimal volume when backwashingwas taking place, so he began to lookfor a more advanced and efficientstrainer technology. After reviewingseveral more advanced designs,Partington selected the multi-elementstrainer from R. P. Adams.

Although initially designed forraw water applications, the R. P.Adams multi-element strainer canactually remove solids as small as 25microns. So the multi-element strain-er can be utilized as the “first line ofdefense” in water filtration, or can beinstalled at a point of use for criticalplant operations requiring fine levels


Whether used forcooling, or theprocess itself, theraw water drawnfrom lakes, riversand reservoirs mustfirst be strained tocreate acceptablewater for use. Inmany industries,this means continu-ously straining tensof thousands of gal-lons of water perminute to removedirt and debris thatcan wreak havocon critical processsystems and equip-ment.

Jan Feb ET 1/12/09 2:39 PM

of separation. Another significant feature of the multi-element design is

in the engineering of the backwash mechanism. With basketstrainers, the backwash mechanism comes into direct contactwith the straining media. This can be problematic, as large,suspended solids often encountered with raw water canbecome lodged between the straining media and the backwasharm. The result is straining media damage and/or rupture thatcan compromise plant operations.

The multi-element design utilizes a tube sheet to separatethe straining media from the backwash mechanism. This pre-vents the backwash mechanism from coming into contact withthe media and damaging the elements caused by large solidsbecoming lodged between the media and the backwash arm.

Furthermore, the multi-element design provides three tofour times the surface area of a basket strainer. This translatesdirectly into less frequent backwashing so less water goes towaste, less power is consumed, and there is less maintenancerequired. Partington’s decision was also due to the fact thatthese strainers could provide the necessary plant water require-ments even while in backwash mode.

“The new units will not backwash unless the differentialpressure of the strainer is high enough to activate backwashingautomatically or by the timer, thereby saving us money on thepower consumption,” explains Partington. “We should alsosave significant money on maintenance too, but we don’t knowhow much yet because the units are so new.”

Partington also appreciated the fact that R.P. Adams waswilling to customize the strainers to meet PPL’s design speci-

fications, and also offered an exchange program whereby hecould replace the strainer elements to a different micron size ifhe needed to do so.

“The element exchange program allowed us to go forgreater straining efficiency, which helped us optimize the rawwater system,” Partington says, “We elected to exchange theoriginal elements for a smaller micron size. It has worked verywell, so we’re going to stay with that size for that particularinstallation. But as we continue to upgrade our water strainersat various locations, we can do the same thing - in effect, fine-tune the solid removal and water flow as the situation war-rants.”

To date, PPL has made upgrads to eight R. P. Adamsstrainers at the Brunner Island plant and has installed the firstunit at its Montour site. PPL intends to standardize on the R. P.Adams design, and will phase-in new strainers as opportunitiesarise.

Ed Sullivan is a Hermosa Beach, California-based writer. Hehas researched and written about industrial process equipmentand power systems for over 25 years.

Electricity Today14

A multi-element design provides three to four times the surfacearea of a basket strainer. This translates directly into less frequentbackwashing so less water goes to waste, less power is consumed,and there is less maintenance required.

Jan Feb ET 1/12/09 2:39 PM

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Jan Feb ET 1/12/09 2:39 PM

Electricity Today16

1. INTRODUCTIONMulti-wire cables find wide use in a

number of engineering applications. Forexample, they are used for pre-stressingand post-tensioning in concrete struc-tures; they serve as the load-carryingstructures on cable-stayed and suspen-sion bridges; they are found on elevators;and, they form the transmission lineswhich deliver power to our homes andbusinesses.

Monitoring the integrity of thesecables becomes increasingly important asthe cable ages.

This study focuses in particular onthe structural health monitoring of over-head transmission lines.

Common failures associated withoverhead power line installations includebroken insulators, broken lighteningrods, loose earth conductors, loose spac-ers (spacers are used to separate individ-ual lines), and uncoiled or broken cablewires caused by wind-induced vibrations(Siegert and Brevet, 2005). Power lineinstallations are periodically inspectedusing both on-ground and helicopter-aided visual inspections. Factors includ-ing sun glare, cloud cover, close proxim-ity to power lines, and rapidly changingvisual circumstances make airborneinspection of power lines a particularlyhazardous task. Such factors have led to

a number of fatal helicopter crashes inrecent years. A summary of the heli-copter accidents due to aerial observationis depicted in Table. 1 (U.S. HelicopterSummary Statistics, 1996-2004).

The risk associated with aerialinspection of power line installationscould be substantially reduced throughpartial automation of the inspectionprocess. The power lines themselvescould be automatically monitored. Aerialand ground inspections could then focuson identifying problems associated onlywith the mast structures. Introduction ofsuch an inspection approach not onlyreduces risks to human pilots, but it alsospeeds up the inspection process. Themethodology developed in this study canalso be applied to other cable monitoringapplications, which would otherwise put

human inspectors at risk.The basic idea for defect detection in

a transmission line is illustrated in Fig. 1.As shown, a transducer is used to bothgenerate and detect ultrasonic bursts inthe power line. Initially, longitudinalwaves will be used for diagnostic purpos-es. When the ultrasonic burst interactswith a defect, such as a broken wire, aportion of the incident wave will bereflected. The reflected wave is thensensed by the receiving transducer. If theamplitude of the reflected wave is abovea certain threshold value, then positiveidentification of a defect can be assumed.A wireless transmitter located at thetransducer could be used to relay data toa central communication node or to adefect indicator located on the mast.

2. SURVEY OF RELEVENT WORKMeitzler (1961) studied the propaga-

tion of elastic pulses in wires having acircular cross section. He attributed pulsedistortion to the propagation of severalmodes. His experimental and theoreticalresults suggest that coupling between thevarious modes of propagation wereresponsible for the observed pulse distor-tion. Rizzo and Lanza di Scalea (2002)generated and detected ultrasonic wavesin single wires and seven-wire cablesusing magnetostrictive sensors. A formu-lation based on the Pochhammer-Chree

OVERHEAD TRANSMISSION

NONDESTRUCTIVE TESTING OF OVERHEADTRANSMISSION LINES

By Stephanie L. Branham, Mike S. Wilson, Stefan Hurlebaus Zachry, Department of Civil Engineering,Texas A&M University; Brad M. Beadle, Lothar Gaul, Institute of Applied and Experimental Mechanics,University of Stuttgart

Table 1: Summary of helicopter accidents due to aerial observation.

Fig. 1: Interrogation of a transmission line using ultrasonic pulses

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orders 0 and 1 respectively; and, p and q are given by

where w is the circular frequency, k is the circularwavenumber, cB is the bulk wave speed in an unboundedmedium, and cS is the shear wave speed. The radial and axialdisplacements for the longitudinal modes are, respectively

A similar analysis yields frequency equations and dis-placement mode shapes for torsional and flexural waves. Thisstudy however uses the fundamental longitudinal mode fordefect identification. In the case of pulse-echo detection inwhich the ultrasonic source is also used as the receiver, as usedin this study, the fundamental longitudinal mode is the fastestmoving mode and can therefore be used for clear identificationof defects. Fig. 3 depicts the group velocity-frequency charac-teristic for the first two longitudinal modes (L(0,1) and L(0,2))and the first two flexural modes (F(1,1) and F(1,2)). The dis-persion characteristic was calculated for the rods considered inthis study (4.45 mm diameter, aluminum). At low frequencies,the group velocity of the fundamental longitudinal mode

theory is used to predict the change in the velocity of longitu-dinal waves as a function of applied stress (acoustoelasticeffect). Results from acoustoelastic experiments are presentedand compared to the theoretical predictions. Ways to enhancethe sensitivity of the acoustoelastic measurements were inves-tigated. The different behavior exhibited by the seven-wirecables when compared to single wires suggests the need forwidening the theory to include acoustoelastic phenomenon inmulti-wire cables. Additionally, the suitability of the guidedwave method for the detection of defects in the critical anchor-age zones is considered. Washer et al. (2002) also utilized theacoustoelastic effect for measuring the stress levels in post-ten-sioning rods and seven-wire cables. In a later study, Rizzo andLanza di Scalea (2004) examined the wave propagation prob-lem in seven-wire cables at the level of the individual wires.They used a broadband ultrasonic setup and a time-frequencyanalysis based on the wavelet transform for characterizing thedispersion and attenuation of longitudinal and flexural waves.They identified the vibration modes that propagate with mini-mal losses.

Such modes are particularly useful for long-range inspec-tion of the wires. Furthermore they found that since the dis-persion curves are sensitive to the load level, the elastic wavescould be used for continuous load monitoring. In a recentpaper, Rizzo and Lanza di Scalea (2005) employed a time-fre-quency analysis based on the discrete wavelet transform(DWT) for analyzing the ultrasonic signals. They found the de-noising property of the DWT to be particularly useful in theiranalyses.

3. THEORYUltrasonic waves are used for material characterization in

many structural health monitoring and nondestructive evalua-tion applications. Guided ultrasonic waves are particularlyeffective for interrogating large structural components, sincethey propagate far distances when compared to body waves.

Guided waves appear in a medium that constrains internaldisturbances to move between the lateral bounding surfaces. Inessence, standing waves are established in the lateral (short)direction whereas propagating waves are manifested in thenormal (long) direction. For the case of a multi-wire cable,there exists no closed-form analytical solution that describeswave propagation. The following development therefore focus-es on the simpler case of a single wire.

For the case of a solid, homogenous cylindrical rod withradius a (see Fig. 2), the substitution of the stress-free bound-ary conditions trr = trq = trz = 0 at the rod surface r = a intothe Lamé-Navier equations leads to the so-called Pochhammerfrequency equation for the longitudinal modes (Graff, 1991),

Here, J0 and J1 are Bessel functions of the first kind of


Fig. 2: Cylindrical rod with coordinates.

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approaches the bar wave velocityand at high frequencies, the group veloc-ity approaches the Rayleigh wave veloci-ty.

The radial variation of axial stress asa function of frequency for the funda-mental longitudinal mode is depicted inFig. 4. The stress curves were computedusing the displacement functions in Eqn.(3). The curves were normalized by set-

ting the largest values of radial distanceand stress to one. At high frequencies, theelastic energy becomes concentrated nearthe surface. This skin effect is found inplates and in the case of Rayleigh wavepropagation in a half-space.

The equation describing the longitu-dinal wave motion (Eqn. 3) does notaccount for attenuation due to material or

geometrical effects. Introducing the com-plex wave number

k* = k1 + k2i, the axial motion at afixed radial distance can be expressed as

It is clear from Eqn. (4) that the k1contribution is associated with propaga-tion of the wave, and the k2 contributionis associated with spatial attenuation ofthe wave. It follows immediately that

where Dz is the separation distancebetween two measurement points.

4. EXPERIMENTAL CHARACTERIZA-TION OF THE 1ST LONGITUDINAL MODE

A cross-sectional view of the trans-mission line considered in this study isdepicted in Figure 5. The transmissionline is comprised of thirty-three steel andaluminum wires that are tightly wound

Electricity Today18

Fig. 3: Group velocity-frequency dispersioncharacteristic for a 4.45 mm diameter alu-minum rod.

Fig. 4: Radial variation of axial stress forthe 1st longitudinal rod mode.

Continued on Page 20

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together. There are seven load-bearing steel wires in the middleof the transmission line, which are surrounded by twenty-sixcurrent-carrying aluminum wires. The diameter of each steelwire is 3.5 mm, and the diameter of each aluminum wire is 4.45mm.

The diameter of the entire transmission line is 28.3 mm,and the length is 910 mm. In section 4.1, the experimental char-acterization of longitudinal waves in a single aluminum wire ispresented. Specifically, the attenuation and dispersion behaviorof the first longitudinal mode are determined. In section 4.2,the wave phenomenon in the transmission line as a whole ischaracterized. Cross-sectional measurements of the axial dis-placement are made in addition to attenuation and dispersionmeasurements.

4.1. SINGLE WIREMEASUREMENTS

The experimental setup forcharacterizing longitudinal modepropagation in a single wire isdepicted in Fig. 6. A single sineburst from the function generator isamplified with the radio frequency(RF) amplifier, and this signal isused to drive a piezoelectric disctransducer. The transducer, in turn,generates an elastic wave in thealuminum wire (4.45 mm diameter, 820 mm length). The elas-tic wave propagates through the aluminum wire and is detect-ed by a laser Doppler vibrometer (LDV). The LDV is a power-ful measurement tool that allows non-contact, high fidelity,point-like measurements over a wide frequency range. Asshown, the LDV is used to measure the axial particle velocityat the left end of the wire. The output from the LDV is capturedby an oscilloscope and is then transferred to a PC for process-ing. Figure 7 depicts the measured axial particle velocity at thewire end for different frequencies. The existence of three dis-crete signal bursts (as seen in the 500 kHz trace) is evidence ofthe dispersive nature of the fundamental longitudinal mode.

The frequencies of the bursts themselves coincide with the nat-ural frequencies of the disc transducer.

The LDV is particularly well suited to making attenuationmeasurements since it is noncontact and therefore does notinfluence wave propagation. The attenuation coefficient is esti-mated according to Eqn. (5), where the maximum amplitudesof the end reflections have been used in computations. Depictedin Fig. 8 is the LDV-measured axial velocity for a 100 kHzdrive frequency. The attenuation coefficient of the first longitu-dinal mode at this excitation frequency is estimated to be k2 =0.15 m-1. Thus, the elastic wave will propagate approximately30m before the signal level falls below a measurable level,specifically when the signal-to-noise ratio (SNR) < 2.Obviously, this material damping estimate is somewhat highsince the driving transducer partially absorbs the elastic energy.

4.2. TRANSMISSION LINE MEASUREMENTSThe experimental setup for measuring the longitudinal

modes in a transmission line (28.3 mm diameter, 910 mmlength) is depicted in Fig. 9. The transmission line setup isidentical to the single wire setup, with the exception that a

Electricity Today20

Nondestructive testingContinued from Page 18

Fig. 5: Cross-section-al view of the trans-mission line.

Fig. 6: Experimental setup for characterizing longitudinal waves ina single wire.

Fig. 7: LDV-measured axial particle velocity as a function of fre-quency.

Fig. 8: Multiple reflections of a longitudinal wave in a single wire(100 kHz excitation).

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tudinal mode in the surface aluminum wire is estimated to bek2 = 0.27 m-1, meaning that the elastic wave will propagateapproximately 12 m before the signal level falls below a mea-surable level (SNR < 2).

5. DEFECT DETECTIONThe main goal of this research is the monitoring of over-

head transmission lines using elastic waves. In this section,two detection methodologies are considered. In section 5.1, a“global” scheme is described which uses a ring transducer tosend elastic energy into every single wire in the transmissionline. In section 5.2, a “local” scheme is described which uti-lizes smaller transducers for sending elastic energy into aselect few surface wires.

5.1. GLOBAL DETECTIONThe experimental setup for global defect detection in a

transmission line is shown in Fig. 12. As shown, a pulser-receiver drives the piezoelectric ring with an electrical spikeinput which, in turn, generates an elastic wave in the trans-mission line. The piezoelectric ring, as it is attached to thetransmission line, is illustrated in Fig. 13. The pulser-receiverthen switches automatically from “send” to “receive” mode.The elastic wave is reflected from discontinuities in the trans-mission line, and the reflected wave is sensed by the piezo-electric ring. The signal from the ring is received and ampli-fied by the pulser-receiver. Artificial damage in the form of atransverse cut is made using a handsaw. The cuts are made ata distance of 700 mm from the piezoelectric ring, and they

piezoelectric ring is used as the driving transducer. Fig. 10depicts the measured axial particle velocity for a surface wireat different drive frequencies. There exists two discrete signals(as seen in the 500 kHz trace). The first signal corresponds tothe fast-moving longitudinal mode, and the second signal cor-responds to a slower-moving flexural mode. The dispersion ofthe second signal at low frequencies (as seen in the 100 kHztrace) is evidence that this signal is indeed the flexural mode.A second feature worth noting is the prominent ringing of thetransducer, as evidenced by the multiburst nature of the firstsignal (as seen in the 100 kHz trace).

The LDV was used to measure the axial particle velocityfor three distinct wires in the transmission line, specifically anouter aluminum wire, an inner aluminum wire, and an outersteel wire (locations a, b, and c in Fig. 5, respectively). Resultsfor a 100 kHz excitation frequency are shown in Fig. 11.Clearly, elastic waves are also present in the inner wires, andhence, it is possible to detect breaks in these wires. The ampli-tude of the elastic waves becomes smaller at increasing dis-tance from the surface due to the weak coupling of energy tothe inner wires. The attenuation coefficient for the first longi-


Fig. 9: Experimental setup for characterizing longitudinal wavesin a transmission line.

Fig. 10: LDV-measured axial particle velocity for a surface wire asa function of frequency.

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range from 2 mm in depth to a complete cut.The received signal for a 7 mm cut is compared to the

undamaged case in Fig. 14. The two signals are nearly identi-cal until ~ 0.3 ms. The reflection of the fundamental longitu-dinal wave from the cut is responsible for the difference in thetwo signals. The presence of a signal before the arrival of thisreflection is caused by the ringing of the piezoelectric ring.

That is, the ring continues to vibrate, thereby generating a

voltage signal,even after theexcitation hasbeen removed.The maximumamplitude ofthe reflectedwave as a func-tion of cutdepth is illus-trated in Fig.15. A linearr e l a t i o n s h i pbetween thedegree of dam-age and them a x i m u mreflected wave amplitude has been observed. This relationcould be used for monitoring purposes in order to identify thestate of damage in a cable.

Electricity Today22

See the March issue of Electricity Today for the conclusion ofthis article

Fig. 11: LDV-measured axial particle velocity for an outer aluminum wire (left), an inner aluminum wire (middle), and an outer steel wire(right).

Fig. 12: Experimental setup for defect detection in the transmis-sion line.

Fig. 13: Piezoelectric ring transducer attached to the transmissionline.

Fig. 14: Transducer output for a damagedand an undamaged transmission line.

Fig. 15: Maximum amplitude of the reflected wave at variousdamage levels.

Jan Feb ET 1/19/09 9:40 AM


IPPSA’s milestone 15th Anniversary Conference - “15Years: 15 Questions” - reviews how far the Alberta electricitymarket has come and seeks to answer 15 residual questions fac-ing the industry.

These questions include: “Is electricity a commodity?”“How do we get transmission built?” “Is it time to lift the pricecap?” and “what can we learn from other markets?” among oth-ers. IPPSA invites you to join them for this special event March8-10, 2009!

About Independent Power Producers Society ofAlberta (IPPSA)

Founded in 1993, IPPSA represent Alberta’s power suppli-ers, power marketers and their supporting industries in theprovince’s competitive power market. IPPSA’s vision is to pro-mote an open, fair market for power suppliers in Alberta’s com-petitive electricity industry.

CONFERENCES

IPPSA 15TH ANNUAL CONFERENCE ANDTRADE SHOW - 15 YEARS: 15 QUESTIONS

IPPSA Trade Show Floor Plan and Exhibitors

If you would like information about purchasing a booth at the IPPSA Conference and Trade Show please call (403) 210 0596or email [email protected].

Booth - Exhibitor

3- Alberta Electric System Operator

12- AltaGas19- Canadian Hydro Developers

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2- GE Energy10- Golder Associates Ltd1- NRGSTREAM9- TransCanada5- Victaulic

15- Wellons Canada Corp.13- ZE PowerGROUP INC

For further information about IPPSA, the conference and the trade show please visit www.ippsa.com.

BANFF, ALBERTA - MARCH 8-10, 2009

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Electricity Today24

In less than twenty-four hours, a six-man crew at Imperial Irrigation District(IID) retrofitted three large transformerfirewalls at a critical transmission substa-tion. The firewalls are needed to containtransformer oil fires from spreadingbetween three 230 kV transformers, acontrol house, and other equipment at theCoachella Valley Substation. This substa-tion is a vital power hub for power trans-fers between Arizona, California andMexico; hence, outage time must be min-imized. The key to such a constructionsuccess lies in IID management’s selec-tion of TruFireWalls.

Each firewall measures 40 by 24feet. The walls were quickly assembledin the field from fireresistant precastcolumns and panels.First, the columns werebolted to the existingfoundation and aligned.Next, the panels wereslid down the groovedcolumns and assemblywas then complete.Disassembly of theseremovable mainte-nance-free firewalls isequally simple andquick.

SUBSTATION FIREHAZARD CONDITIONS

AND POTENTIALCONSEQUENCES

A power substation by its naturecontains all the right ingredients to gen-erate the perfect firestorm. A typicaltransmission transformer bank consistsof three or more transformer tanks, eachcontaining 10,000 to 45,000 gallons ofmineral oil. The initial spark is likely tocome from electrical arcing inside thetank, which also generates heat and pres-sure high enough to rupture the tank.Oxygen immediately rushes into thetank. The oil violently explodes accom-panied by a blast of intense radiation, fly-ing shrapnel, and flaming oil. The radia-tion’s effect is instantaneous and has

been document-ed to ignite othert r a n s f o r m e r smore than 60 feetfrom the initialfire.

The temper-ature of an oilfire is in therange of 960°Cto 1,200°C. Apower trans-former’s fireduration ranges from 4 to 28 hours,which is, in most cases, the time it takes

the fire to burn itself out. As larger sub-stations are often located in outlying

TRANSFORMERS

TRANSFORMER FIRE CONTAINMENT WALLSINSTALLED IN RECORD TIME

Simple and Quick Installation: OneDay - One Wall (above)

Step One - Position, align, andsecure the columns (left).

Step Two - Slide in the panels(below) and…

Jan Feb ET 1/12/09 2:45 PM

areas, the fire department’s response timeis long. In addition, fire trucks are rarelyequipped to suppress these supersized oilfires.

Firewalls are only a third of the totalsolution to effectively protect a substa-tion against fire. The other two compo-nents needed are an early detection andalert system and the correct fire suppres-sion system. Hence, the installation ofeffective firewalls is the bare minimumto protect a transformer bank and neigh-boring equipment.

In general, existing standards andcodes do not realistically address theactual conditions of large hydrocarbonpool fires in open air. Therefore, perfor-mance-based criteria need to be appliedto ensure effective fire protection in sub-stations. To replicate real-world require-ments, a transformer firewall must beexposed to a four-hour fire followedimmediately by a high-pressure water jetblast on the same test sample.

The replacement cost of a largetransformer is about $1.5 million to $2.5million per phase. However, the highercost by far is the replacement energy,which must be purchased from the spotmarket at premium prices. During peakhours, rates could spike up to $200,000per hour.

Compounding the problem, thedelivery time on a rush basis for thesetransformers is about 18 months.Insurance premium increases may beimposed (conversely, insurance compa-nies have reduced rates when fire wallsare installed), and long-lasting unfavor-able public relations with the communi-ty, regulators, and investors can result.

EFFECTIVE CONTAINMENT OFTRANSFORMER FIRES

Effective transformer firewalls mustbe:

(1) made from materials that canwithstand the intense high temperatureand long duration of these fires;

(2) designed such that both thermaland mechanical requirements are metbefore, during, and after the fire.

Traditionally, transformer “firewalls” have been built from reinforcedconcrete and/or concrete blocks. The ini-tial cost of these walls is deceptively low,because these materials do not performas needed under high temperature. At650°C, concrete retains only about 35%of its room temperature strength, andsteel has practically no strength left atthat same temperature, which is about350°C lower than the oil fire’s ‘working’

temperature as shown below.Hence, concrete walls fail under the

actual conditions of a transformer fire.Furthermore, concrete walls are largeand heavy, requiring deep reinforcedfoundations, and they must be torn downand rebuilt when major transformermaintenance is performed.

The firewall must also have suffi-cient impact resistance to survive shrap-nel impingement because it is quite pos-sible that the fire will initiate a trans-

former explosion. As there is yet no stan-dard for firewall impact loading, ballisticand explosion experts have recommend-ed applying UL Standard 752. This isequivalent to a firewall panel stopping a44 Magnum projectile with no through-penetration, as the IID wall panels arecapable of doing.

Refractories, as used in the IID fire-walls, are water-based and totally inor-ganic with nothing to burn. The relative-ly lightweight thermal panels and


Jan Feb ET 1/12/09 2:45 PM

columns are cast from time-tested refractory concrete. Refractories emit no volatileorganic compounds or hazardous material when manufactured, during the fire, or whendisposed. The time-proven refractory cements that have been used for centuries to han-dle molten metal in foundries and smelters clearly meet the thermal and mechanicalrequirements over the service life of the substation.

Field-proven refractories and the well-established manufacturing process byOldcastle Precast, with 80 plants throughout the United States, ensure that the requiredthermal and mechanical performance is achieved at a competitive cost. TruFireWallsby ThermaLimits are designed and certified to meet thermal, wind loading, seismic,and substation layout requirements. The modular design reduces manufacturing andinstallation costs.

Electricity Today26

The installation is COMPLETE!

An IID firewall panel stops a 44 Magnum bullet.

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Electricity Today28

A culture of safety has gathered across the electrical com-munity, and the ongoing refinement of the National ElectricalSafety Code (NESC) — outlining thebasic provisions necessary for thesafety of employees and the publicunder specified conditions — hasproven to be an indisputable driverin the trend.

An Edison Electric Institute(EEI) survey of investor-ownedutilities, for example, showedover 765 million hours workedamong respondents in 2007;those respondents reported 19deaths related to work that iscovered by the NESC.

Injuries must never beconceded in our industry.But, given the terrific num-ber of hours worked, thesurvey does reveal thesuccess of the NESC inworking within its scopeto create work rules thatcontribute to protectingthe electrical industryand users.

Defining andredefining that scopehas been an ongo-ing effort since theNESC was firstpublished in1914.

KEEPINGTHE CODE

VIABLE ANDREALISTICIn most

cases, utili-ties andtheir employees, con-tractors and manufacturers canfall back on a simple rule as to whether theNESC applies to the work they are doing: The NESCcovers everything up to the service point — the point of demar-cation between where power is handed off from utility to enduser. On the other hand, the NESC does not cover premiseswiring or utilization equipment, which are addressed in theNational Electrical Code (NEC).

But there do exist numerous andvaried instances where no meter existsto provide a well-defined service point.For example, area lighting might beinstalled in the parking lot of a retailbusiness or in the backyard of a resi-dence. In some cases, the connection is made directly off the

distribution line, and, in others, on the load side of a meter. Or,the entry point for power might be a locked vault or closetinside a building or a weatherhead on the roof of a home.

The service point in instances such as these might be apoint of debate. Utilities follow local jurisdictions’ regulations,

contracts or authorized agreements with regard to suchinstallations, in order to understand how the

NESC applies in relation to theNEC or other specifi-

cations.Shapers

of theN E S C

c o n s i d e rthese gray

areas inworking to

keep the 94-year-old Code

realistic, practi-cal and useful.

They also mustaddress innova-

tions in the trans-formers, breakers,

conductors, fiberoptics and the other

tools used to providepower.

A PROVEN PROCESSOF ENHANCEMENT

The NESC is regularlyupdated via a five-year

process that ensures theCode remains the safety

authority for power, tele-phone, cable TV and rail-

road signal systems. Change proposals for the

2012 Code are under consid-eration now. NESC subcom-

mittees are reviewing thesechange proposals and making

preliminary recommendations.This effort will yield the NESC

Preprint, scheduled to be availableon September 1, 2009. A period of

comment will then continuethrough May 2010, with a proposed revised Code to be made

available for public review in January2011. The next, completed NESC willbe published August 1, 2011.The U.S. Department of LaborOccupational Safety & HealthAdministration (OSHA) considers theNESC in writing its regulations. Also,

public service/utility commissions or other bodies that oversee

CODE

WHAT THE NESC COVERS,WHAT IT DOESN’T

By Michael Hyland, Chair, and Jim Tomaseski, Vice Chair,IEEE National Electrical Safety Code

View the survey online at:http://standards.ieee.org/nesc/

Jan Feb ET 1/12/09 2:46 PM

utility operation in48 states and morethan 100 countriesother than the UnitedStates mandateadherence to theCode in part orwhole.

In these ways,the NESC providesthe foundation forthe holistic safetyprograms of utilitiesaround the world —informing the manu-als, “tailboard dis-cussions,” weeklyand monthly meet-ings, etc., that allcombine to helpkeep electrical work-ers and users safe.By design, theNESC leverages theongoing lessonslearned across theelectrical communi-ty and works hand-in-hand with utili-ties’ mandated bestpractices.

CONCLUSIONThe electrical community has been doing work on facili-

ties and equipment in an energized state since Thomas Edisoninvented the light bulb in 1879. The U.S. Congress in 1913asked the Bureau of Standards to investigate the hazards ofelectrical practice, resulting in the first publication of theNESC one year later.

Although working de-energized may pose less of a risk tothe worker, it may not be possible or practical. Today, we arein an age when shutting off the power in order to do electricalwork is sometimes not even an option. Public safety and glob-al commerce require electricity 24 hours a day, seven days aweek. In turn, energized work must be performed around theclock every day.

The NESC has successfully contributed to the trendtoward safety in the electrical industry, and the commitment tocraft and refine a strong Code has never been stronger.

Michael Hyland, PE, is chair of IEEE NESC and vice presidentof engineering services with the American Public PowerAssociation (APPA), the service organization for the nation’smore than 2,000 community-owned electric utilities that servemore than 45 million Americans.

Jim Tomaseski is vice chair of IEEE NESC and director, safe-ty and health department, with the International Brotherhoodof Electrical Workers (IBEW), which represents approximately750,000 members who work in a wide variety of fields includ-ing utilities, construction, telecommunications, broadcasting,manufacturing, railroads and government.


2012 National Electrical Safety Code (NESC) Schedule

Jan Feb ET 1/12/09 2:46 PM

Electricity Today30

An environmental assessment wascarried out on a utility’s substation builtin the early 1980s in northern Alberta.This substation consists of two trans-formers each containing approximately70,000 liters of mineral oil.

This substation is in a remote area,unmanned and on the banks of a river.

The site was deemed to be at highrisk due to the fact that the transformerson site contain a very large amount of oiland, second, the site is very near a river.

Due to the possibility of damage to theenvironment and monetary penalties thatthis could bring, the utility came to theconclusion that it was in their best inter-est to determine a preventive solutionthat would be most compatible with thesite.

This substation supplies a vastamount of electricity in the northernAlberta area and it was not possible totake the two transformers off line toinstall a secondary oil spill containmentsystem.

Any secondary oil spill containmentsystem had to effectively work in allweather conditions, given the remotenessof the location.

Given that utilities everywhere haveless manpower than in the past, little orno maintenance of any secondary oil spillcontainment system was also a criterion.

Research by the utility was done onvarious types of secondary oil contain-ment systems. Given that the transform-ers had to remain energized and that thesystem had to function in all weatherconditions down to –50 C, the utilitycame to the conclusion that the

SorbwebPlus secondary oil containmentsystem offered by Albarrie CanadaLimited was the only choice. The utility’sinsurance company also examined theSorbwebPlus system and deemed that theSorbwebPlus system was a viable optionfor not just this particular substation butall of their substations for secondary oilcontainment.

SorbwebPlus is a no maintenancepassive system, which can be installedaround existing energized transformersand will function in all-severe weatherconditions. It is designed to contain110% of the volume of oil within thetransformers along with a historical 24-hour rainfall over the past 25 years.

Albarrie was the general contractorfor the complete job, including the instal-lation of a firewall between the two trans-formers.

The installation of the SorbwebPlussecondary oil system required thatAlbarrie take into consideration all cabletrays within the perimeter of the contain-ment system, including a concrete sub-surface cable tray (trewna). We also,given the area that was available to the

TRANSFORMER SAFETY

PROVIDING OIL SPILL CONTAINMENTIN A REMOTE AREA

Jan Feb ET 1/12/09 2:46 PM

The high risk for this substation was eliminated with theaddition of a no-maintenance, passive, secondary oil contain-ment system which operates in any severe weather conditions.


SorbwebPlus system had to lower thegrounding grid from 0.5 meters to onemeter. All this had to be accomplishedwhile the transformers were live.

Inasmuch as there was to be installeda firewall between the two transformers,two containment systems had to be builtone for each of the transformers.

The substation sloped towards theriver at a three-degree angle, requiring theexcavation of the containment system forleveling; this eliminated the contour of theland causing the oil to spill out of oneside.

The soils were determined through anindependent laboratory to be permeable,therefore no special drainage system hadto be designed. SorbwebPlus is designedto allow the permeation of water in theform of precipitation or melted snow intothe subsoil.

If the soil had been impermeable, adrainage system can be built underneaththe SorbwebPlus to move the water awayfrom the containment system.

Upon excavation, the cable trays (which ran along the sur-face of the containment) had to be supported with woodenplanks. Upon reaching the 0.5-meter depth the grounding gridhad to be exposed so that there would be no damage to thegrid. The grid was made visible so that further excavationcould be made down to the 1-meter depth.

Further excavation was necessary between the two sec-ondary oil containments for the two transformers to allow fora foundation that would support the firewall. The two contain-ment systems would abut to the foundation of the firewall.

A surface cable tray ran through the foundation for thefirewall, so allowance was made for passage of the cable traythrough the foundation. This would later be sealed preventingany seepage of oil from one containment system to the other.

Slings lifted the cables in the trewna and the trewna waslined with the oil mat to prevent any seepage of oil into theground as the bottom of the trewna was earth. Once lined, thecables were then replaced and the top of the trewna was sealedwith concrete lids.

Once excavation was completed, the grounding grid wasdropped to the 1-meter depth. As the substation was built in theearly 1980s, upgrades to the grounding grid were done at thesame time.

All the excavated areas were installed with theSorbwebPlus system. This includes the impermeable lineraround the perimeter and the special oil mat at the bottom ofthe containment which will seal upon contact with oil, yet if nooil is present, will allow the passage of water into the subsoil.

Once the SorbwebPlus system was installed, rock wasadded to the system. The rock was 19 mm to 38 mm in diam-eter, which typically gives a void area of 40 to 45%. It is thisvoid area that the 110% of oil within the transformer and the25-year, 24-hour rainfall event will be contained in the event ofa catastrophe. The layer of rock serves as an effective retardantin the event of fire.

The firewall completed the entire installation.

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Electricity Today32

CONTINUED FROM ANARTICLE IN OUR OCTOBER

ISSUE

The results are moreexpressed when DR is applied tothe load in the end of the feeder.The increase of voltage isgreater in this case, whichreduces the effect of the loadreduction, but the reduction oflosses is greater, and, therefore,the reduction of generation isabout at the same level. Thechanges of voltages for the cor-responding conditions are seenin Figure 8. The model of thisexample assumes that the volt-age change at the substation busdue to DR applied in distribu-tion does not typically exceedthe bandwidth of the voltagecontroller, and therefore thischange does not result in LTCoperations. In some cases, whenthe voltage is initially close tothe boundary of the bandwidth,the voltage controller can move one stepof the LTC. To account for these cases,the example model includes simulationof continuous line-drop compensation.

Typically, the line-drop compensa-tion does not fully compensate forchanges of voltage caused by the change

of load in a portion of the distributionsystem, especially in the secondaries. Ifthere were no line-drop compensation,the load reduction due to DR would beeven smaller (as can be seen in Figure 9).

If the rise of voltage is eliminated bya coordinated Voltage and Var control

function, so that after the DR is applied,the voltage in the lowest point of the cir-cuit is returned to low standard limit,then the overall load and losses in distri-bution are additionally reduced, and thegeneration is also reduced by an amountgreater than the initial DR value (See

DEMAND RESPONSE

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Figure 8. Changes of voltages at load sides for different locations of DR with and withoutcoordinated VVO.

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high demand to low demand times, commercial loads with sig-nificant demand response capabilities, and a small group of

point “DR in remote withVolt adjustment). If thesame amount of DR isapplied uniformly to allloads along the feeder, theeffect of the voltageadjustment to the resultsof DR is smaller.

If the transmissionlosses are taken into con-sideration, the effect ofdemand response inreduction of the genera-tion needed to cover thedistribution demand isgreater (see Figure 10). Itdepends on the connectiv-ity and loading of thetransmission system andon the location of theincrementing generation.

When more than onefeeder is connected to thesame substation bus, theeffect of DR applied in thesame manner as above tothe load in one feeder onlyis smaller (see Figure 11). This is caused by the increase ofvoltage at the substation bus due to reduction of the voltagedrop in the substation transformer. But, in this case, the volt-age increase is applied to a greater load of more than one feed-er.

If the bus voltage is adjusted to compensate for theincrease of voltage in this case, the effect of the combined DRand voltage control is greater than in the case with one feeder.

A similar analysis was performed for cases where thedemand response is applied to the primary of distribution feed-ers. Our example assumes that a Distributed Energy Resource(DER) is connected to the primary distribution either in themiddle of the feeder, or close to the end. The size of the DERis assumed to be 1 MW. The results are presented in Figure 12through Figure 14. As seen in the figures, if the voltages arenot adjusted, the remote location of the DER results is a slight-ly smaller effect of the DER contribution to the reduction ofdistribution demand and generation. If the voltages are adjust-ed, the remote location of the DER produces greater benefits.The increase of the benefits due to bus voltage adjustment issmaller than it was with the Demand Response applied to thesecondaries, because the voltage rise from the injection of thereal power in the primary circuits is smaller. For the same rea-son, the increase of voltage at the substation bus in negligible,because the impedance of large substation transformers is pre-dominantly reactive.

Examples of applying DA applications, which include thesimulation of DR, to a realistic distribution system are pre-sented below. The selected distribution system is fed from onebus with an LTC and consists of two 12.5 kV feeders withabout 1,200 distribution transformers and 3,850 customers.Different DR means are allocated at 114 distribution trans-former loads. The load is represented in four load categories:residential load with a small amount of direct load control,industrial load with significant DR capabilities, includingembedded DER devices and the ability to shift the load from


Figure 9. Impact of Line-Drop Compensation on results of DR

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loads with demand response and energy storage.In these examples, it is assumed that the demand response

reacts on a price signal proportional to the real-time LMPs. Thesignal in p.u. is presented in Figure 15.

It is also assumed that the DR of industrial customers istriggered when the signal exceeds 1.4 p.u., and the DR of othercustomers, when the signal exceeds 2.2 p.u. The energy storageand load shifts to the minimum-demand times starts, when theprice signal is below 0.6 p.u.

The Distribution Operation Model and Analysis applica-tion [5-8] shows the following simulation results for the casewithout DR and with DR:

As seen in the table on the previous page, DR at peak timereduces the kW and Amps and increases the voltage.

At the low-price times, the load is increased due to theshifts of load or due to the energy storage.

As seen in Figure 15, the triggers for DR exist not only atpeak time. If there is no limit on the number of times per daywhen DR can be activated, the demand response would changeduring the day as presented in Figure 16.

The coordinated Volt/Var Optimization application [8-12]was applied in this example with an energy conservation objec-tive during the daytime, firstly, without DR and, secondly, withDR.

The results are presented in the table to the right. As seenin the table, when VVO adjusted the bus voltage to reducedvoltage drops along the feeders due to DR, the VVO-relatedreduction increased by 14%.

In this example, the load in the voltage-critical points in the

secondary distribution did not have DR. This means that thevoltage drop was reduced by DR in the primary feeders only. Ifthe DR means were implemented in the voltage-critical pointsin the secondaries, the amplifying effect of DR on load reduc-tion by VVO would be significantly greater.

Electricity Today34

Figure 10. Changes of operational parameters for distribution sys-tem due to DR with and without coordinated Volt/VarOptimization, for one feeder, taking into account transmission loss-es.


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Another example relates to using DR during a partial ser-vice restoration [13-14] after a fault in distribution is cleared.The example represents a case, when not all the load connect-ed to healthy sections of the faulted feeder can be restored dueto an overload of the backup feeder. When the demand

response is applied to the loads of the backup feeder and to theloads of the healthy sections of the faulted feeder, all healthysections can be restored (see Figures 17 through Figure 20). Asseen in Figure 19, without applying the DR, section S16-T21with 1173 kW should be de-energized. With DR, the sectioncan be restored without the overload of feeder 3 (Figure 20).

The amount of load reduced by DR is 841 kW, which issmaller than the load of the de-energized section and, in addi-tion, reducing load by DR is less intrusive than shedding load.

The difference in applying the demand response for ser-vice restoration is that the recommendations, which become aportion of the switching order, should be made for future time,for when the restoration problem is solved, and for the loads ofa disconnected feeder, from which the real-time measurementsmay not be available.

Similarly, the Demand Response can amplify the effect ofFeeder Reconfiguration application [14], for instance when theobjective is elimination of overloads in distribution and trans-

Electricity Today36

Figure 12. Changes of operational parameters for distribution sys-tem due to DER with and without coordinated Volt/VarOptimization, for one feeder.

Figure 13. Changes of operational parameters for distribution sys-tem due to DER with and without coordinated Volt/VarOptimization, for one feeder, taking into account transmissionlosses.

Demand ResponseContinued from Page 34

Figure 11. Changes of operational parameters for distribution sys-tem due to DR with and without coordinated Volt/VarOptimization, for two feeders, taking into account transmissionlosses.


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mission systems. When the reconfiguration is limited by a volt-age violation or by an overload, DR can expand the operationaltolerance, and more load can be transferred from the over-loaded element to other feeding buses.

CONCLUSIONS1. The significant penetration of Demand Response means

Electricity Today

Figure 14. Changes of operational parameters for distribution sys-tem due to DER with and without coordinated Volt/VarOptimization, for two feeders, taking into account transmissionlosses.

Figure 15. Daily price signal for DR in p.u., where the averagevalue is = 1.



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in distribution increases the uncertainty of the nodal load mod-els. Additional sources of information for adequate load mod-

eling are needed.2. In order to be adequate for the near real-time monitor-

ing and control of distribution operations, the simulation mod-els and optimization procedures used in DistributionAutomation applications should take into account the behaviorof the variety of Demand Response means.

Electricity Today40

Figure 18. Topologically possible solution with an overload offeeder 3

Figure 16. Change of load due to demand responseFigure 17. The example distribution circuits for illustrating the ser-vice restoration scenario.



Figure 19. The solution with de-energized section S16-T21

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3. Distribution Automation applications coordinated withDemand Response may provide additional benefits, e.g. theVolt/var optimization in load reduction mode may utilize theadditional room for voltage reduction created by DemandResponse.

4. If the Demand Response can be triggered by a DAapplication, when and where it is needed, it would also signif-icantly increase the efficiency of the DA applications, as inService Restoration or Feeder Reconfiguration cases.

5. Taking into account the impact of the integrated appli-cation of DA and DR, the location of the Demand Responsemeans should be planned and encouraged first in areas whereit can maximize the efficiency of both the DR and the DA.

REFERENCES.1. Studies of Distribution Operations to Aid in

Determining Object Models for Distributed Energy Resources(Phase 1), EPRI, Palo Alto, CA, 2004, EPRI Project ManagerF. Goodman. Principal Investigator: N. Markushevich, UCI

2. Integration Of Distribution Automation into PowerSystem Operation, Edward H.P. Chan, Nokhum S.Markushevich; DA/DSM Conference, January 1994, Florida

3. Impact Of Automated Voltage/Var Control InDistribution On Power System Operations, Nokhum S.Markushevich, R.E. Nielsen, A.K. Nakamura, J.M. Hall, R.L.

Nuelk; DA/DSM Conference January 1996, Tampa, Florida.4. Load to Voltage Dependency Tests at B.C. Hydro, Alf

Dwyer, Ron Nielsen, Joerg Stangl, Nokhum S. Markushevich;IEEE/PES 1994 Summer Meeting, July 1994

5. Guidelines for Assisting Understanding and Use ofIntelliGrid Architecture

Recommendations: Distribution Operations, Use Case forDistribution Operation Model and Analysis, EPRI Palo Alto,CA: 2006. 1013612. EPRI Project Manager: J. Hughes.Principal Investigator: N. Markushevich

6. http://intelligrid.info/IntelliGrid_Architecture/Use_Cases/DO_DOMA_Use_Case.htm

7. Modeling Distribution Automation, Nokhum S.Markushevich; DA/DSM Conference, January 1994, Florida

8. Implementation of Advanced Distribution AutomationIn US Utilities, Nokhum S. Markushevich and Aleksandr P.Berman (Utility Consulting International), Charles J. Jensen(JEA), James C. Clemmer (OG&E), USA, CIREDConference, Amsterdam, 2001

9. Voltage and VAR Control in Automated DistributionSystems, Nokhum S. Markushevich; DA/DSM Conference,January 1993, Palm Springs, California

10. The Specifics of Coordinated Real-Time Voltage andVar Control in Distribution, Nokhum S. Markushevich, UtilityConsulting International (UCI), Distributech 2002 Conference

11. Distribution Volt and Var Control in EmergingBusiness Environment, Nokhum Markushevich (UCI) and RonNielsen (B.C. Hydro), CEA Technologies DistributionAutomation Seminar, Halifax, Nova Scotia, Canada. June,2003

12. Dynamic System Load Control through Use ofOptimal Voltage and Var Control, Nokhum Markushevich, RonE. Nelson, 1998 Dynamic Modeling Control Applications forIndustry Workshop, IEEE Industry Application Society, 1998,Vancouver, Canada

13. Optimizing Feeder Sectionalizing Points forDistribution Automation, Charles Jensen, NokhumMarkushevich, Alex Berman, Distributech Conference,January 1998, Tampa, Florida.

14. What Can Distribution Automation Do for PowerSystem Reliability?, N. Markushevich, A. Berman , J.Handley, DistribuTech, 2005.

Electricity Today42

Figure 20. Solution with DR applied to the loads of faulted andbackup feeders


Jan Feb ET 1/19/09 9:41 AM

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Officials of Hawaiian Electric Company and SensusMetering Systems announced a 15-year definitive agreementfor mass deployment of Sensus Metering Systems’ FlexNetwireless smart grid solution. The decision comes after twoyears of rigorous field testing of the FlexNet system, wherethousands of smart electric meters were tested in a variety ofsettings, terrains and environments on Oahu.

Subject to Hawaii Public Utilities Commission approvalof Hawaiian Electric’s AMI plan, approximately 430,000 resi-dential and commercial electric customers will be transitionedto the Sensus FlexNet smart meters between 2009 and 2015.Just 19 tower network sites throughout Oahu, Maui, andHawaii Island will provide the advanced, two-way radio fre-quency (“RF”) network coverage.

The FlexNet system provides Hawaiian Electric with two- way communications to Sensus’ iCon smart electric meters,which enables on-demand reads, remote connect/disconnectservices, notifications of outages and restoration, and remotefirmware upgrades. FlexNet also establishes the platform foradditional customer and utility system related benefits in thefuture.

These features will support new pricing and demand-response initiatives to help Hawaiian Electric customers man-age their own electricity use by taking advantage of variouspricing options, and programs designed to enhance energyconservation efforts.

“We have carefully evaluated the FlexNet AMI systemover a series of pilot tests including meter deployment and per-formance, customer billing and outage management,” said Dr.Karl E. Stahlkopf, Hawaiian Electric Senior Vice PresidentEnergy Solutions & Chief Technology Officer. “The resultsdemonstrate that Sensus clearly delivers the technology solu-tion we require for urban and rural coverage, with the powerand flexibility for future advanced applications that will bene-fit our customers and our operations.”

Stahlkopf further noted the deployment of the smartmeters is a key action to help achieve the goals of the recentlyannounced Hawaii Clean Energy Initiative agreement betweenHawaiian Electric and the State of Hawaii to expand Hawaii’srenewable energy portfolio and move towards a sustainable,clean energy future.

Peter Mainz, Sensus’ Chief Executive Officer, noted thatthe Hawaiian Electric field test was accomplished amid somechallenging areas. “But as a technology leader, Sensus pro-duced reliable results. Therefore, Hawaiian Electric’s decisionto select FlexNet for company-wide deployment reaffirms ourposition as a leader in two-way AMI systems. Our partnershipwith the utility has also proven valuable in shaping the productand business direction for Sensus.”

Electricity Today44

METERING

HAWAIIAN ELECTRICMAKES AMI CHOICE

AFTER TWO YEARSOF TESTING

Pictured from left to right: Karl Stahlkopf – Sr VP EnergySolutions and CTO, John Stafford - Sensus Director of SalesWestern Region, and Dave Waller – VP Customer Service.

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Representatives from all five ofABB Inc’s U.S. divisions met on August26 with students who have graduatedfrom universities across the country toprofile the trove of engineering opportu-nities within the host of Local BusinessUnits that comprise the five divisions.

The students, recently hired byABB, were handpicked for ABB’s“Engineering Leaders for the Future”program, and ABB division business pro-fessionals met with them at ABB’s divi-sion headquarters for Power Products onCampus Drive in Raleigh, NorthCarolina.

“It was exhilarating to be able tointroduce a global company with somuch reach, and a deep product line thatis evergreen, to a room of college stu-dents genuinely interested in the futureof electrical energy and a rewardingwork opportunity,” said KathleenWatson, who presented on behalf ofABB’s Automation Products division.“Employment opportunities exist allalong the ABB electrical chain — fromgeneration through to how electricity isdeployed and used inside buildings andprocessing facilities.”

Watson is the product manager forcomponent and machinery drives lines atthe company’s New Berlin, Wisconsin,drives headquarters.

“We started the program this sum-mer to give students with an expressedinterest in engineering a very concretetrack from study/graduation to employ-ment,” said Noelle Heinrich, who admin-isters the program. Over an 18-monthperiod, graduates with mechanical, elec-trical or industrial engineering degreesgo through three rotations across ABB’sfive divisions, and visit businesses locat-ed in the U.S., Canada and/or Mexico.

At the end of the program rotation,the graduates are sought by, and placedinto, the divisions and countries thatgraduates identify as a high point ofinterest – and where ABB managers haveidentified the opportunities they want toplace graduates into.

“ABB and this program are part ofsomething larger than our individual

businesses and divisions,” said Heinrich.“Like all technology driven, and automa-tion-based companies, ours needs toidentify, attract and retain engineers whowant to work in electrical, mechanicaland/or industrial applications; this needis growing exponentially, right alongsidethe tremendous success and growth ofthis company!”

Watson joined fellow presentersfrom all ABB divisions; these presentersincluded: Kathy Doherty, vice president,Human Resources, Robotics and PowerSystems; Connie Nigro, director, HumanResources, Power Products; JonathanBretzius, P.E., East Regional channelmanager, Process Automation; andErwin DiMalanta, business developmentmanager, Robotics. Allen Burchett, vice

president Strategic Initiatives, presentedthe Divisional business overview.

The global nature of ABB’s businessis attractive to students, according to theteam of presenters.

“We try hard to communicate thatthe opportunities are virtually limitless,”said Heinrich, “because ABB is far flungin its geographic reach, with deep local-market service to customers; so newemployees can choose among opportuni-ties that span from the oil-sand fields ofCalgary, to pursuing work in one of themost deeply funded R&D centers —among all automation suppliers — inZurich, Switzerland.”

The early success of “EngineeringLeaders for the Future” is creatingmomentum and interest, as it continues.


TRAINING AND EDUCATION

ABB SHARES EMPLOYMENT OPPORTUNITIESWITH UNIVERSITY GRADS

Jan Feb ET 1/12/09 2:47 PM

Electricity Today46

ABB has developed the technology for ultra-low-noise power transformers to help Consolidated Edison(ConEd) meet the newly enforced noise regulations ofNew York City, considered by many to be the toughest inthe world.

The transformers are the successful result of an inten-sive research and development effort over a number ofyears by a team of ABB engineers and scientists in theUnited States, Sweden, and Germany. Included in theteam were experts in the fields of vibrations as well assound generation, transmission, and radiation.

The project also involved the development of appro-priate measuring methods of ultra-low-noise levels at dis-crete frequency components, as well as appropriate trans-NOW HIRING

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An ABB ultra-low-noise transformer en route to ConEd for use in New York City. These technologically-advanced transformers do not needSound Enclosures or Sound Panels, and satisfy New York’s stringent noise regulations.


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former mounting. The newly developed technology has set newindustry benchmarks for transformer noise emissions.

Dr. Ramsis Girgis, the leader of the development effortwith ABB, said, “This achievement is a testimony that truetechnology advancements can only be achieved through vision,hard work, persistence andphysics.”

The noise require-ments of these ConEdtransformers are not only20-25 decibels lower thanis typical for this size oftransformers, but limitswere also set on the noiselevel of each frequencytone when the transformersare operating at full loadand over-excitation.

In addition to meeting ConEd’s stringent standards fornoise, ABB had to ensure that the transformers meet tight lim-its on weight, width, and height to permit transportation inManhattan and other areas of New York City. The transformersmust also comply with technical requirements like significant

overload and extremely tight limits on the range of transformerimpedance.

ABB delivered the first ultra-low-noise transformer toConEd in 2005. This transformer had to be provided with asound enclosure. As the ABB team developed the technologyfurther, subsequent transformers delivered to ConEd did notneed a sound enclosure and, in fact, were much smaller in bothsize and weight. Several of these transformers have been deliv-ered to ConEd and a number of them are already in operation.Additional transformers of even lower noise levels are sched-

uled for delivery late 2008,early 2009.

The ultra-low-noise trans-former technology resultingfrom this intensive develop-ment effort is now being usedto produce optimum designsfor low and ultra-low-noisetransformers for other noise-sensitive metropolitan areasaround the world.

These accomplishmentswould not have been possible without the support that the ABBtechnical team received from many in the ABB St. Louis facil-ity and globally. The challenge and cooperation received fromthe ConEd technical team, headed by Donald Chu and HaroldMoore, provided exceptional commitments throughout thetechnology development process that were pivotal.

Electricity Today48

Noise RegulatioonsContinued from Page 46

Dr. Ramsis Girgis, the leader of thedevelopment effort with ABB, said,“This achievement is a testimony thattrue technology advancements canonly be achieved through vision, hardwork, persistence and physics.”

Jan Feb ET 1/12/09 2:47 PM

Jan Feb ET 1/19/09 9:46 AM

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www.electricityforum.com/careers/lineal.htmLineman’s Testing Laboratories 1, 2 www.ltl.ca

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www.electricityforum.com/products/lizco.htmMaracle Press Limited 53 www.maraclepress.caMetering America 49 www.meteringamerica.comMetering China 27 www.meteringchina.comMIDAS Metering Services 36 www.midasmetering.comNesco 25 www.nescosales.com

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