02 - transformer instruction manual

8/20/2019 02 - Transformer Instruction Manual

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Medium Power Substation Transformers

Document 2.4.06, Reision 2

December 2011

Howard IndustriesSubstation Transformer Diision

InstructionsInstaation, Operation, and Maintenance

of Medium Power Substation Transformers


December 2011


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Document 2.4.06, Reision 2December 2011 Medium Power Substation Transformers

IMPORTANT SAFETY INFORMATION

Read these instructions carefuy before proceeding with instaation, operation, or maintenance of this equipment.

Medium power transformers contain extremey hazardous otages. To preent death, serious persona injury, or property

damage, a information in these instructions shoud be read and obsered. Safe use of this equipment is dependent

on proper instaation, operation, and maintenance procedures.

Certain information in this manua is marked with the words DANGER, WARNING, or CAUTION. DANGER indicates an

imminenty hazardous situation which, if not aoided, wi resut in death, serious persona injury, and property damage.

WARNING indicates a potentiay hazardous situation which, if not aoided, coud resut in death, serious persona

injury, and property damage. CAUTION indicates a potentiay hazardous situation which, if not aoided, may resut in

minor or moderate persona injury, and property damage.

Personne shoud not attempt to serice this equipment unti it has been competey de-energized and a high-otage

and ow-otage bushing terminas hae been propery grounded.

Ony quaied personne shoud insta, maintain, and operate this equipment. Quaied personne are those who are

trained in the instaation, maintenance, and operation of high-otage equipment; trained in the proper use of protectie

equipment (such as rubber goes, safety gasses, protectie cothing, hard hats, etc.); and trained in appropriate rst

aid procedures.

IMPORTANT INFORMATION ABOUT THESE INSTRUCTIONS

The instructions contained herein are intended to be a genera guide for the instaation, operation, and of Howard

Industries medium power transformers, when they are used in typica appications and are operated in norma

enironments. Athough efforts hae been made to ensure accuracy and competeness, these instructions do not

address eery conceiabe appication or circumstance that might be encountered. Features presented herein may

not be present in a transformer designs. Standard and optiona features are subject to change without notice.

Howard Industries makes no representation or warranty with respect to and assumes no responsibiity for the

competeness, accuracy, sufciency, or usefuness of these instructions. Questions regarding instaation, operation,

and maintenance (particuary when encountering unusua or specia circumstances not sufcienty coered by

these instructions) shoud be directed to the Howard Industries Substation Transformer Diision.

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RECEIvINg INSPECTION

These instructions appy to medium power transformers

manufactured by Howard Industries. It is important to

read the safety information on Page 2 before attemptingany instaation, operation, or maintenance actiities.

Athough a transformers, components, and accessories

are carefuy inspected and tested prior to shipment,

a thorough receiing inspection shoud be conducted

to detect any damage or oss that might hae occurred

during shipment. The receiing inspection shoud be

done upon receipt and before unoading from the truck

or rai car. Note any damage or discrepancies on the

bi of ading and e a caim with the carrier, and notify

the Howard Substation Transformer Diision prior to

unoading the transformer.

Impact RecorderImpact recorders are proided on a rai shipments

and on some truck shipments. An impact recorder is

a mechanica recording acceerometer that can record

shock and impact from a directions. The impact

recorder records on pressure sensitie chart paper each

impact that has occurred, its magnitude, direction, and

time of occurrence. These impacts are recorded through

three independenty operating styi in each of three

separate axes: ongitudina, atera, and ertica.

The impact recorder shoud be checked for eidenceof possibe damage to the transformer due to impacts

during shipment. This check shoud be performed prior

to unoading the transformer. A representatie of the

shipper shoud be present when the recorder is checked.

Any eidence of damage shoud be noted on the bi of

ading and signed by the shipper’s representatie before

the transformer is accepted. Consut with the Howard

Substation Transformer Diision if shipping damage is

found or suspected.

Refer to the operating manua accompanying the impact

recorder for instructions expaining how to turn off the

recorder and to interpret the chart. If it appears thechart recorder stopped running before arria at the na

destination, the shutdown time shoud be noted and this

fact shoud be brought to the attention of the shipper

representatie and to the Howard Industries Substation

Transformer Diision.

Impacts in any axis of ess than 4 G’s are considered

acceptabe. Impacts in any axis of 4 G’s or greater

indicate rough handing that coud potentiay hae

caused damage to the equipment. If rough handing

is indicated, this fact shoud be noted on the shipping

documents and brought to the attention of the shipperrepresentatie and the Howard Industries Substation

Transformer Diision before proceeding with inspection

of the transformer.

Drawins and Documentslocate a shipping papers, packing ists, outine

drawings, and other pertinent information. Use these

documents and this instruction manua during the

inspection.

The transformer outine drawing indicates the ocations

of namepates and warning abes, and proides physica

dimensions and weights. The namepate proides

eectrica characteristics, winding connections, and

weights. The wiring diagram proides detais of contro,

fan and aarm wiring.

DO NOT REMOvE OR OBSCURE ANY WARNING lABElS

OR NAMEPlATES.

Externa InspectionThe foowing externa inspections shoud be made at a

minimum.

1. Ensure that a equipment, accessories, and

components isted on the bi of ading are

present.

2. Ensure that there are no signs of externa

damage.

3. Ensure that the paint nish has not been

damaged.

4. Ensure that ttings, conduit, wiring, and other

attachments are tight and undamaged.

5. Check for eidence of uid eakage on the tank,

aes, or cooing assembies.

6. Check for damage to bushings.

7. Check for damage to shipping crates, packages,or other materias shipped separatey from the

transformer.

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December 2011

Tank PressureThe tank acuum/pressure gauge may indicate positie

or negatie when the transformer is receied, depending

on the reatie uid and ambient temperatures. This

indicates that the transformer is seaed effectiey. If the

acuum/pressure gauge reads zero, this may indicate

the possibiity of a tank eak, athough a zero reading can

occur occasionay with changing interna and externa

temperatures. In the case of a zero reading the tank

shoud be pressure tested according to the instructions

on Page 14 (Pre-energization Tests and Checklist).

Report any suspected tank eaks to the Howard

Substation Transformer Diision.

Moisture Test (for units shipped dry)The transformer core and coi assemby was thoroughy

dried before shipping from the factory. Precautionswere taken to ensure that dryness is maintained during

shipment. Since it is possibe that moisture coud

enter the transformer tank due to mishanding or other

causes, perform a dew point test as described beow to

ensure the core and cois are sufcienty dry.

A dew point measurement of the gas inside the

transformer tank can be used to estimate dryness of the

insuation system. Using this technique, it is assumed

that moisture content of the gas is in equiibrium with

the moisture content at the surface of the insuation

materia.

The dew point test shoud be performed as described

beow. The easiest way to ensure reasonabe accuracy

is to take the dew point and temperature measurements

during the eary morning hours, when the ambient

temperature and the insuation temperature are in

equiibrium. The gas in the transformer tank shoud be

at a sight positie pressure (5 PSI max.) when the dew

point measurement is made.

1. Use a dew point tester to measure the dew point

of the gas inside the transformer tank.

2. Using Chart A (Page 6), conert the dew point

measurement to apor pressure.

3. Measure the temperature of the insuating

materia.

4. Using Chart B (Page 6), estimate the moisture

content of the insuating materia.

5. Moisture content aboe the cure is in the

acceptabe range. Moisture content beow the

cure is excessie and shoud be brought to the

attention of the Howard Industries Substation

Transformer Diision before proceeding.

Interna InspectionAn interna inspection of the transformer tank is

rarey necessary and is required ony when there are

indications that the transformer has receied seere

impact damage during transit. If an interna inspection

is necessary, foow the instructions on Page 10 for

opening the transformer tank. Contact the Howard

Substation Transformer Diision before proceeding with

any interna inspection.

It is important to foow a carefu receiing inspection

program to record the condition of the transformer when

receied and to identify the source of any damage that

may hae occurred during shipping and handing. A

compete inspection of the transformer and detached

parts shoud be made as soon as possibe to identify any

such damage.

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vapor Pressure (Micrometers of Mercury)

D e w P o i n t T e m p e r a t u r e ( ° C )

+20

+10

0

-10

-20

-30

-40

-50

-70

-60

10 100 1,000 10,000

6

TABlE A: Conersion of dew point in degrees centigrade to apor pressure in micrometers of mercury

I n s u l a t i o n T e m p e r a t u r e ( ° C )

vapor Pressure (Micrometers of Mercury)

10 100 1,000 10,000

TABlE B: Moisture equiibrium chart showing acceptabe and unacceptabe moisture imits.

+80

+70

+60

+50

+30

+20

+10

0

+40

Acceptabe rane is aboe the cure

Unacceptabe rane is beow the cure `

`


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STORAgE

Transformer StoraeTransformers can be stored if propery prepared. It is

recommended that stored transformers be competeyassembed. Prior to storage, transformers shoud be

pressure tested according to the instructions on Page

14 (Pre-energization Tests and Checklist). The gas

space aboe insuating uid shoud be pressurized with

dry nitrogen to a pressure of between two to three PSIG.

This wi preent a negatie interna pressure which

might draw moisture into the tank. Transformers not

designed for outdoor use must be stored indoors. If

the transformer is not competey assembed, separate

components and accessories shoud be stored in a

cean dry area in their origina shipping containers.

Transformer uid containers or totes shoud be coered

or stored in a protected area to preent exposure to

rain water or other contaminants. Condenser bushings

shoud be stored in an upright position.

Extended StoraeIf the transformer is to be stored for an extended period

of time before being paced into serice, it shoud

be paced on a rm ee surface. The foowing test

procedure shoud be used prior to storage (in addition

to foowing the Receiving Inspection instructions

on Pages 4 and 5 and Transformer Storage

recommendations on this page).

1. Measure and record ambient temperature andbarometric pressure (for correction of test data).

2. Pressure test the tank using the procedure on

Page 14 (Pre-energization Tests and Checklist)

and check for uid eaks. Foowing pressure

test, reduce tank pressure to two (2) PSIG.

3. Test insuating uid for dieectric strength and

moisture content.

4. Test insuation with a 1000-vot or 2500-vot

Megger test set. (Omit if bushings hae not been

instaed.)

5. Measure insuation power factor using Dobe or

simiar test set. (Omit if bushings hae not beeninstaed.)

6. Measure coi ratios in each tap position to

ensure proper operation of the de-energized

tap changer. (Omit if bushings hae not been

instaed.)

7. Obsere uid ee gauge to erify proper uid

ee.

Sidewa-mounted bushings, if exposed and not

contained in a termina chamber or switch encosure,

shoud be protected from moisture and utraioet

damage with an appropriate coering. This coering

shoud be checked periodicay to ensure it is intact.

Coer-mounted bushings which are shipped separatey

from the transformer shoud be stored in a cean,

dry ocation in their origina shipping cartons. These

bushings shoud be carefuy inspected for damage prior

to instaation on the transformer.

A space heaters (if suppied) in termina chambers,

switch cabinets, contro cabinets or other encosures,

must be connected and energized at a times to contro

moisture. Desiccant packets may be used to contro

moisture in contro cabinets ony, if it is not practica to

energize the contro cabinet space heater. Desiccant

packets must be repaced periodicay to maintain

effectieness.

It is recommended that the transformer be inspected

periodicay as described beow whie it is in extended

storage. Resuts shoud be recorded and compared with

preious resuts to ensure that no damage or change in

condition has occurred.

Quartery InspectionThe quartery inspection described beow shoud be

performed after the rst month of storage and then

quartery thereafter.

1. Inspect protectie coering on sidewa-mounted

bushings. Repace coering if damaged.

2. Inspect space heaters to ensure they are

working propery. Inspect desiccant packets (if

any) in contro cabinets; repace if necessary.

3. Record uid-ee and pressure/acuum

gauge readings. Ensure that tank pressure ismaintained at approximatey 2 PSIG.

4. Measure and record ambient temperature and

barometric pressure.

5. If acuum/pressure gauge or uid ee gauge

readings indicate a possibe tank eak, perform

a tank pressure test according to instructions

found on Page 14 (Pre-energization Tests and

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December 2011

9

Checklist). Any eaks found shoud be repaired

immediatey and then rechecked during

subsequent inspections.

6. Transformer uid containers or totes shoud be

isuay inspected for damage and any indication

of water intrusion or other contamination.

Annua InspectionThe annua inspection shoud incude the foowing

checks in addition to the quartery inspection checks

isted aboe.

1. Check paint nish and repair any damage.

2. Test insuating uid for dieectric strength and

moisture content.

3. Test insuation with a Megger test set. (Omit if

bushings hae not been instaed.)

4. Check insuation power factor with a Dobe or

simiar test set. (Omit if bushings hae not beeninstaed.)

5. Transformer uid containers or totes shoud be

isuay inspected for damage and any indication

of water intrusion or other contamination.


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location and MountinThe transformer shoud be mounted on a ee concrete

foundation of sufcient strength to support the weightof the competey assembed transformer. If the

transformer is not ee, insuating uid may not circuate

propery through the cooing assemby, possiby causing

oerheating and reduced transformer ife. The mounting

ocation shoud proide for adequate entiation and

easy access for inspection. The transformer shoud be

ocated at east 24 inches from any obstruction. When

instaing transformers designed for indoor operation,

adequate air inets and outets must be proided for

proper cooing. Aoid ocating transformers in corrosie

areas.

Openin Transformer TankTransformers are usuay shipped seaed and shoud not

be opened uness necessary. Opening the transformer

wi be necessary when transformers are shipped without

bushings, when interna ed connections are required,

or when core ground tests are required.

DANgER: SlOWlY RElEASE INTERNAl

PRESSURE PRIOR TO REMOvING TANK

ACCESSORIES. FAIlURE TO DO SO COUlD RESUlT

IN SEvERE PERSONAl INJURY, DEATH, OR PROPERTY

DAMAGE.

DANgER: TO AvOID DEATH FROM

SUFFOCATION NEvER AllOW ANYONE TO

ENTER THE TRANSFORMER TANK UNlESS AN

ANAlYSIS OF THE AIR IN THE TANK SHOWS AT lEAST

19.5% OXYGEN. THE GAS SPACE IN AN OPERATING

TRANSFORMER USUAllY CONSISTS OF NITROGEN

GAS. WHENEvER ANYONE IS IN THE TANK, A

PERSON SHOUlD BE STATIONED AT THE MANHOlE

OUTSIDE THE TANK TO ENSURE SAFETY OF THE

PERSON INSIDE.

Transformer shoud not remain open for more than24 hours at a time. If work is interrupted, the tank

shoud be reseaed, eacuated, and ed with dry air or

nitrogen.

To preent contamination of the transformer tank, do

not open the transformer in an unprotected area during

incement weather or where the air may contain dirt

or other partices. Either of the aboe coud cause

a transformer faiure. The tank opening shoud be

protected against entry of foreign matter.

If it is necessary to remoe some uid from the tank to

aow for inspection or other work, the transformer mustbe reed with uid after work is competed.

Personne shoud not be permitted on top or inside the

transformer whie it is open uness they hae emptied

a pockets and checked for oose objects that might fa

into the tank. A toos shoud be accounted for after

work is competed. It is recommended that any toos

used on top of the transformer or inside the tank be

attached with safety cords to preent them from being

ost inside the transformer.

Personne must not stand directy on any eectrica

insuation. Cean drop coths shoud be used under

working areas in the transformer to preent objects from

dropping into the core/coi assemby.

The foowing procedure shoud be used to remoe the

manhoe coer.

1. Thoroughy cean the manhoe coer.

Remoe a moisture, dirt, and grease to

aoid contaminating the transformer’s uid

compartment.

2. Reiee interna tank pressure by manuay

operating the pressure reief ae.

3. Remoe coer fasteners.

4. Genty pry the coer upward, making sure that

the coer gasket does not fa into the tank. lift

the coer erticay to preent damage to coer,

bots, and gasket.

5. Remoe the gasket sections from the manhoe

ange. Record the ocation and orientation of

each gasket piece, so they can be reinstaed

correcty.

The foowing procedure shoud be used to reinsta the

manhoe coer.

1. Pace gasket sections in their origina positionsand orientations.

2. Reinsta manhoe coer. Reinsta fasteners

and torque to 25 ft-bs. After tightening a

fasteners, re-torque each one to ensure proper

torque.

3. Remoe the pressure reief ae and pressurize

the headspace and check for uid eaks. Do not

exceed 7 PSIG during this test. This pressure

shoud be maintained for at east four hours.

INSTAllATION

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December 2011

11

When interna work is being done on the transformer,

dry air shoud be used to entiate the inside of the tank.

Dry air can be obtained in high-pressure cyinders or

from desiccant-type air-drying equipment. When using

dry air, the foowing precautions shoud be obsered.

1. The temperature of dry air entering thetransformer shoud equa to or greater than the

temperature of the transformer uid and at east

10°F higher than the dew point of the ambient

air.

2. The dry air ow shoud be directed so as to

continuousy purge the transformer gas space.

3. The dew point in the tank gas space shoud

neer exceed 20°F.

Whie the tank is open, the foowing tests shoud be

conducted.

1. A ratio test shoud be made on a windingsand on each tap position. Contact the Howard

Industries Substation Transformer Diision if any

measurement is off-ratio by more than 0.5%.

2. Insuation resistance of each winding to a

other windings and from each winding to ground

shoud be measured. (Coi windings must be

competey coered with uid.) Record the

temperature of the uid. These readings shoud

be comparabe with factory measurements.

3. Disconnect the core ground connection, when

accessibe, on core-form transformers and

measure the resistance from the core to thetank or end frames, using a 1000-vot Megger

test set. The resistance shoud exceed 100

megohms if the core is not coered with uid or

200 megohms if the core is coered with uid.

When the interna inspection is compete, resea the

tank and re with uid (if any was remoed prior to

inspection). The gas space shoud be ed with dry

air or dry nitrogen. Contact the Howard Substation

Transformer Diision if any interna damage is found

during the interna inspection.

Instaation of Detachabe RadiatorsWhen radiators are shipped detached, they shoud be

instaed according to the instructions beow.

1. verify that a aes on the tank are in the

cosed position.

2. Remoe shipping pates from the aes on the

tank and from the radiator anges. Take care

not to damage gaskets.

3. Inspect for moisture and contamination

inside the radiator headers. Contact the

Howard Substation Transformer Diision if any

contamination is found.

4. Cean a mating surfaces on the tank aes

and radiator anges and appy a sma amount

of petroeum jey to the gaskets on the tank

ae anges to hod them in pace during

instaation of the radiators.

5. lift the radiators into position using the ifting

eyes on top of the radiators and aign hoes

in the radiator anges with hoes in the ae

anges. If fans are proided, attach the

radiators haing fans rst, then attach the other

radiators.

6. Insert bots in the top and bottom anges, with

bot heads adjacent to the transformer tank.

7. Tighten bots eeny, aternating across corners,

unti meta-to-meta tightness is achieed at a

four corners of each ange.


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Fiin Instaed Radiators with FuidFoow the steps beow to instaed radiators with

insuating uid.

DANgER: TRANSFORMER OIl SHOUlD

AlWAYS BE HANDlED AS A FlAMMABlE FlUID.

SEAlED TRANSFORMER TANKS MAY UNDER SOME

CONDITIONS ACCUMUlATE EXPlOSIvE GASES, AND

HANDING OF TRANSFORMERS MAY GENERATE

STATIC ElECTRICITY. SAFETY PRECAUTIONS BEFORE

OIl-FIllING OR FIlTERING SHOUlD INClUDE

PURGING All GAS SPACES WITH NITROGEN AND

GROUNDING THE TRANSFORMER, All BUSHINGS,

AND All OIl HANDlING EQUIPMENT. FAIlURE TO DO

SO COUlD RESUlT IN SEvERE PERSONAl INJURY,

DEATH, OR EQUIPMENT DAMAGE.

WARNINg: TRANSFORMERS SHOUlD NOT BE

lEFT UNDER vACUUM EXCEPT DURING THE

vACUUM FIllING OPERATION. THE TANK SHOUlD

BE UNDER POSITIvE PRESSURE DURING PERIODS

OF RAIN OR HIGH HUMIDITY IN ORDER TO PREvENT

MOISTURE FROM BEING DRAWN INTO THE TANK.

FAIlURE TO FOllOW THESE PRECAUTIONS COUlD

RESUlT IN SEvERE PERSONAl INJURY, DEATH, OR

EQUIPMENT DAMAGE.

Eery container or tote of transformer uid used in the

ing process shoud be isuay inspected and tested

for water and other possibe contaminants beforeproceeding with the ing process.

During the process do not aow the uid ee to drop

beow the top of the core and coi assemby. If the

uid ee in the transformer becomes too ow, stop the

radiator ing procedure and add uid to the tank before

competing the ing process.

1. loosen the top header pugs and sowy open

the bottom radiator aes one at a time to start

the ow of uid.

2. Add uid to the tank if necessary during the

process to maintain uid ee in the tank at its

proper ee.

3. After the radiators are ed, open the top

radiator aes.

4. Remoe the top header pugs and reinsta them

using Teon pipe thread tape.

5. Ensure that top and bottom radiator aes on

each radiator are in the fu “OPEN” position.

6. Obsere the uid ee gauge and ensure that

the uid ee is correct. If the ee is ow, add

uid to the tank.

Instaation of Hih-votae BushinsTransformers are usuay furnished with draw-ead or

condenser type high-otage bushings. If bushings

were remoed prior to shipment and shipped separatey

from the transformer, insta them according to the

instructions beow.

WARNINg: DO NOT OvERSTRESS BUSHINGS

WHEN MAKING CONNECTIONS TO AvOID

DAMAGE. DAMAGED BUSHINGS COUlD CAUSE

SEvERE PERSONAl INJURY, DEATH, OR PROPERTY

DAMAGE.

Instaation of Draw-lead BushinsIf draw-ead type bushings are furnished, insta each

bushing as foows.

1. Remoe the bind ange coering the bottom

end of the bushing.

2. locate and uncoi the draw ead.

3. Insta the gasket suppied with the bushing to

the bushing boss. For cork-neoprene gaskets,

appy a uniform coating of gasket cement to

the gasket area of the bushing boss and to the

bottom of the gasket. Aow cement to become

tacky and then position gasket on the bushing

boss. Then appy a thin coating of petroatumto the top surface of the cork-neoprene gasket.

For nitrie or iton gaskets, appy a thin coating

of petroeum jey to the bottom surface of the

gasket and pace the gasket in the center of the

gasket area on the bushing boss.

WARNINg: WHEN APPlYING GASKET

CEMENT, KEEP All SPARKS AND FlAMES

AWAY FROM WORK AREA. AvOID BREATHING lARGE

QUANTITIES OF vAPOR AND AvOID CONTINUOUS OR

EXCESSIvE CONTACT WITH SKIN. FAIlURE TO DO SO

COUlD RESUlT IN SEvERE PERSONAl INJURY OR

DEATH.

4. Insert a sh wire through the bushing porceain

and attach the bottom end of it to the top of the

termina on the end of the draw ead.

5. Straighten the draw ead, so that it is free of

twists and kinks.

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December 2011

13

6. Using the sh wire, carefuy pu the draw-ead

through the bushing, taking care not to damage

the insuation on the ead.

7. Insta the bushing mounting hardware and

fuy tighten by aternatey tightening opposite

corners. For bushings with porceain ange and

camping ange, torque hardware to 8 ft-bs.

For bushings with meta ange, tighten unti the

bushing ange has contacted the bushing boss

and ock washers are attened.

8. Rotate the termina unti the stee pin pressed

in the draw ead seats in the sot inside the

porceain top end. With the pin seated in the

grooe, approximatey 1/2 inch of thread shoud

protrude aboe the porceain top. If the ead

appears to be too short, a probem may exist

that shoud be corrected before proceeding.

9. Appy a thin coating of petroeum jey to the topsurface of the termina cap seaing gasket and

press the coated surface into the gasket recess

in the termina cap.

10. Remoe the sh wire taking care to preent

the draw ead from sipping back inside the

porceain bushing.

11. Insta the termina cap on the draw ead

termina and hand tighten, being carefu to

keep the stee pin seated in the sot inside the

porceain top.

12. verify that the gasket is propery seated and the

termina cap is centered on the porceain.

13. Torque the termina cap to 35 ft-bs.

14. Test for gasket eaks by pressurizing the

transformer with dry air or nitrogen to a

pressure of approximatey 2-3 PSIG and

appying a soap bubbe soution.

Instaation of Condenser BushinsIf condenser type bushings are furnished, insta them

according to the instruction iterature shipped with the

bushings. These instructions wi coer instaation

maintenance, and use of the power factor test termina.

vacuum Oi Fi ProcessThis procedure is for the acuum oi ing of a

transformer. This procedure appies for transformers

which hae been shipped dry air ed. It aso appies

if the oi ee in the transformer has been owered to

a ee that exposes part or a of the cois to air at anytime during the instaation of the transformer.

1. Check a radiators to be sure the radiator aes

are in the open positions and to erify that a

the radiator anges are tightened.

2. Check a high otage bushing bot anges and

a ow otage bushing bot anges and be sure

a are propery tightened.

3. If the manhoe access coer has been remoed

for any reason erify that the bots securing the

manhoe coer(s) are propery tightened.

4. Connect the acuum pump suction ine to the

tank coer tting. If the transformer has an OlTC

then acuum must be appied to the OlTC tank

at the same time as the main tank is acuumed.

Connect acuum ines and pu a acuum on the

OlTC tank.

5. Connect the oi ine to the tank at the bottom

drain ae connection.

6. Start the acuum pump.

7. When the acuum ee inside the tank reaches

500 microns (500 miiTorr) start timing and

when this acuum ee has been maintained for

24 hours the oiing may be started. Oiing

rate to be 30 – 40 gpm.

8. Continue to unti the oi gauge registers

sighty aboe the 25 C oi ee.

9. After the oi ing has been competed continue

to hod the acuum ee for 1 additiona hour.

10. The acuum pump may now be stopped. Use

dry nitrogen to ent the transformer tank.

11. After the transformer has been ed with oi

it shoud be aowed to sit for 24 hours before

energizing in order to aow bubbes of gas

(which hae been pued out of soution by the

acuum ing process) to be reabsorbed by the

oi.

12. At any time during the instaation of the

transformer if the oi ee in the transformer

has been owered to a ee that exposes part or

a of the cois to air, the oi must be competey

remoed and the aboe procedure foowed.


14/24


14

Instaation of Sure ArrestersSurge arresters shoud be instaed according to the

foowing instructions and the outine drawing.

WARNINg: FAIlURE TO FOllOW THESE

INSTRUCTIONS COUlD RESUlT IN SEvEREPERSONAl INJURY, DEATH, OR EQUIPMENT DAMAGE.

1. Carefuy unpack and inspect surge arresters for

damage.

2. When instaing arresters, a mounting feet

must be ush with the mounting surface before

tightening bots. Use shims if necessary.

3. Do not cimb or stand on arrester. Do not pace

undue mechanica stress on arrester.

4. Use ony the ifting deices proided on the

arrester for ifting.

5. Arrester exhaust ports (if suppied) must be

oriented so that exhaust wi be directed away

from other arresters and other equipment.

Instaation of Air Termina Chamber and

15 Kv and 5 Kv Switchear AdaptersAir termina chambers are designed to protect

personne from high otages and to proide a cean, dry

enironment for bushings. Air termina chambers must

be instaed according to instructions on the drawing.

Refer to transformer outine drawing, detai drawing, and

station pan drawing.

WARNINg: IMPROPER INSTAllATION OF

CONNECTING CHAMBERS AND ADAPTERS

MAY AllOW WATER OR OTHER CONTAMINANTS

TO CONTACT lIvE PARTS, POSSIBlY RESUlTING IN


DAMAGE.

Securey attach the exibe connectors to the switchgear

bus bars (The number of exibe connectors suppied

is determined by the transformer current and not

by the current rating of the bus bar.). Check theength of exibe connectors and ensure that there is

approximatey 0.375 inch (10 mm) of sack. This wi

permit some moement of the bus bars to aow for

expansion and contraction and possibe setting of the

transformer. Securey attach the ground bus connection

between the transformer and switchgear. Before

reinstaing the adapter housing, check for adequate

eectrica cearances as indicated on the outine drawing

and check tightness of connections and supports.

Compete the instaation by assembing the housing.

Insta the adjustabe pate and ensure proper gasket

seaing of the switchgear throat.

Pre-enerization Tests and CheckistThe foowing tests and checks shoud be performed at

a minimum to ensure that the transformer is ready to

be energized. Do not energize the transformer without

performing these tests and checks.

1. Insuating Fuid Test. Draw a uid sampe and

test its dieectric strength. Dieectric strength of

new uid shoud be 26 kv or greater.

2. Pressure Test. Check the transformer tank for

eaks by pressurizing the tank with dry air or

dry nitrogen through the pressure test tting toa pressure of 3 to 4 PSIG. let the tank stand

under pressure for one to two hours, then

examine the tank and ttings for eaks. leaks

aboe the uid ee can be detected by appying

soap soution to a weds, joints, pipe ttings,

and cabe connections. Upon competion of this

test, reduce the interna pressure to 1 or 2 PSIG.

3. Insuation Megger Test. Perform a 1000-vot

Megger test and a power factor test to ensure

that none of the windings is grounded.

4. Ratio Test. Perform a ratio test at each tap

position to ensure that transformer coi ratios

and tap changer connections are correct.

5. Continuity Test and Resistance Test. Perform

a continuity check on each winding. Measure

the winding resistance of each winding and

compare resuts to factory test aues. An

increase of more than 10% coud indicate a

oose interna connection.


15/24



December 2011

15

6. line Connections. In preparation for making

ine connections, check to make sure that

a mating connector surfaces are cean and

smooth. Connections must be tightened

appropriatey to preent oerheating and

possibe subsequent faiure of the connection.Connections to shoud be made with care to

aoid pacing undue stress on the bushings.

Refer to bushing connection information on

Pages 12 and 13.

7. Tap Changer Setting. Check the tap changer

setting to ensure it is set to the proper position

for the required otage.

8. Deta/Wye and Series/Mutipe Switch Settings.

Check deta/wye and series/mutipe switch

settings to make sure they are set correcty. If

these connections are made using an interna

termina board, check to ensure that theseconnections are made propery according to

the chart on the transformer namepate. If

the transformer is equipped with an interna

termina board, refer to Page 10 for instructions

and warnings prior to opening tank.

9. Grounding. Check to ensure that the

transformer tank is permanenty and effectiey

grounded. The transformer tank ground pad is

ocated near the bottom of the tank.

10. Wiring. Check wiring of contro and aarm

circuits (if proided) to make sure there are no

oose connections and no damage to insuation.11. Fuid lee. Check to make sure the uid

ee as indicated by the uid ee gauge is as

indicated on Page 17.

12. Tank Finish. Check a painted surfaces to

make sure that there is no damage or corrosion.

13. Boted Connections. Check a boted

connections for tightness.

14. Toos. Check to make sure that a toos and

equipment are accounted for and hae been

remoed from the transformer.

15. Fuid Temperature. Read the uid temperature

gauge and make sure the temperature is noower than minus 20°C before the unit is

energized.


16/24


Refer to the outine drawing for a ist of accessories

furnished with the transformer.

Transformer NamepateA namepate is suppied on each transformer according

to ANSI standard C57.12.00. The namepate proides

certain physica and eectrica information about the

transformer.

Contro CabinetRefer to the wiring diagram for a description of eectrica

circuits inside the contro cabinet. Use caution when

testing aarm switches to preent damage to the switch.

DANgER: THE CONTROl CABINET

CONTAINS DANGEROUS vOlTAGES. DE-

ENERIGZE THE CONTROl CABINET vOlTAGE

SUPPlY PRIOR TO PERFORMING WORK INSIDE THE

CONTROl CABINET OR ON EXTERNAl ACCESSORIES

CONNECTED TO EQUIPMENT WITHIN THE CONTROl

CABINET. FAIlURE TO DO SO COUlD RESUlT IN


DAMAGE.

Aarm Switch Ratins

When contro wiring or aarm contacts are proided, referto the contro wiring diagram, or the outine drawing for

contact type, contact ratings, and termina ocations.

Current TransformersCurrent transformers (if proided) are mounted inside

the transformer tank around the transformer ine eads.

For coer-mounted bushings, current transformers are

ocated underneath the transformer coer. For tank-wa

mounted bushings, current transformers are usuay

ocated on top of the core and coi assemby. Current

transformer eads are aways terminated inside a

junction box. Refer to the transformer wiring diagram toidentify the wire markings. Current transformer eads

are aways shorted and grounded to the tank at the

factory before shipment.

WARNINg: CURRENT TRANSFORMER

SECONDARIES MUST BE CONNECTED TO A

lOAD OR SHORT CIRCUITED TO AvOID DAMAGING

vOlTAGES AT THE TERMINAlS. FAIlURE TO MAKE

THESE CONNECTIONS COUlD RESUlT IN SEvERE

PERSONAl INJURY, DEATH, OR PROPERTY DAMAGE.

Pressure/vacuum gaueThe pressure/acuum gauge indicates the pressure in

the tank gas space reatie to atmospheric pressure.

The pressure wi normay ary as a function of

transformer temperature. If the transformer is ighty

oaded or de-energized during times of ow ambient

temperature, the gauge may indicate a negatie

pressure.

Pressure/vacuum gauges can be suppied with an

optiona aarm/signa switch. Refer to the schematic

wiring diagram furnished with the transformer.

WARNINg: IF THE PRESSURE/vACUUM

GAUGE CONSTANTlY READS ZERO UNDERvARYING lOAD AND AMBIENT CONDITIONS,

THE TRANSFORMER SHOUlD BE CHECKED FOR

A POSSIBlE TANK lEAK. A lEAK WIll AllOW

MOISTURE AND AIR TO ENTER THE TRANSFORMER,

WHICH COUlD DEGRADE THE INSUlATION AND

FlUID. lEFT UNREPAIRED, lEAKS COUlD lIMIT

TRANSFORMER lIFE OR CAUSE A vIOlENT FAIlURE

THAT COUlD RESUlT IN SEvERE PERSONAl INJURY,

DEATH, OR EQUIPMENT DAMAGE.

Automatic Pressure Reief DeiceMedium power transformers are usuay furnished with

a weatherproof, coer-mounted automatic pressure

reief deice (PRD) to reiee excessie tank pressures

that might occur during operation of the transformer.

The deice consists of a sef-resetting, spring-oaded

diaphragm and a isua indicating ag. When gas

pressure in the tank exceeds the PRD’s specied imit,

the gas pressure wi open the diaphragm, ent the

excess pressure, and trip the isua indicating ag.

After the interna pressure decreases beow the PRD

resea rating, the ae wi automaticay cose and

resea the transformer. The isua indicating ag mustbe manuay reset. The cause of PRD actiation shoud

aways be inestigated, since pressure enting indicates

a potentia probem inside the transformer.

COMPONENTS AND ACCESSORIES

16


17/24



December 2011

17

Winding temperature gauges can be suppied with an

aarm/signa switch. Refer to the schematic wiring

diagram furnished with the transformer.

Therma Oeroad ReayTransformers may be suppied with a therma oeroad

reay, which is simiar in operation to the winding

temperature gauge described aboe. The reay proides

aarm/signa contacts that cose at approximatey 100%

and 110% rated oad.

Rapid Pressure Rise ReayThe optiona Rapid Pressure Rise Reay (RPRR) monitors

the rate of pressure rise in the transformer’s gas space

and signas when the rate exceeds a safe threshod.

This signa can trigger circuit breaker operation to de-

energize the transformer and can send an aarm. The

RPRR wi not be actuated by norma pressure ariationsduring operation of the transformer. A sea-in reay

atches the output reay and iuminates an indicator

amp unti the unit is manuay reset. The sea-in reay

and associated circuitry is mounted in a separate contro

cabinet.

If the RPRR has actiated, interna arcing has ikey

occurred in the transformer tank, and the cause of such

arcing must be inestigated. The foowing steps are

suggested to determine the extent of damage to the

transformer, in any.

1. Using a combustibe gas detector, check for

combustibe gas products of decompositionin the gas space. Refer to the operating

instructions that came with the gas detector.

2. Test the RPRR and sea-in reay pane to make

sure they are operating propery. Refer to

instructions furnished with RPRR and sea-in

reay pane.

3. Test for insuation power factor, insuation

resistance tests, and transformer turns ratio.

4. Remoe the manhoe coer and inspect the tank

interior for appearance and sme. (A burning

odor may be present.)

5. Make any other tests which may be appropriate

considering resuts of the tests isted aboe.

WARNINg: DO NOT ATTEMPT TO

DISASSEMBlE A PRESSURE RElIEF DEvICE.

TO DO SO COUlD RESUlT IN EQUIPMENT DAMAGE

AND SEvERE PERSONAl INJURY.

PRD’s can be suppied with an optiona aarm/signaswitch. Refer to the schematic wiring diagram furnished

with the transformer.

Fuid lee gaueThe uid ee gauge indicates the uid ee inside the

tank. The transformer tank is ed with uid at the

factory to the norma ee at a reference temperature of

25°C.

Fuid Temperature gaueThe uid temperature gauge indicates the uid

temperature at the top of the uid coumn. Thetemperature gauge is mounted in a dry, eak proof

we, permitting remoa of the gauge without owering

the uid ee in the tank. The gauge is furnished with

a resettabe drag-hand pointer which indicates the

maximum temperature reached since it was ast reset.

The drag-hand can be reset by rotating the magnet at

the center of the dia or, on some modes, by pressing a

reset button.

During norma operation the uid temperature

gauge shoud read ess than the sum of the ambient

temperature and the rated temperature rise. For

exampe, a 50°C gauge reading at an ambient

temperature of 25°C yieds a top oi temperature of

75°C, which is beow the transformer’s 85°C rated

temperature rise.

Windin Temperature gaueTransformers may be furnished with a gauge that

dispays estimated winding hot-spot temperature. The

gauge uses a probe that measures the temperature of

the transformer uid pus auxiiary heat from a heating

eement that is energized by a current transformer

mounted inside the transformer tank.

The gauge’s temperature probe is mounted in a dry we,

permitting remoa of the gauge without owering the

uid ee. The gauge is furnished with a resettabe drag-

hand pointer that indicates the maximum temperature

reached since it was ast reset. The drag-hand can be

reset by rotating the magnet at the center of the dia, or

on some modes, by means of a pushbutton.


18/24


18

Transformer Cooin FansOptiona cooing fans may be proided to increase

the transformer oad capabiity without oerheating

the transformer windings. Operation of the fans is

controed by a contact in the uid temperature gauge

or winding temperature gauge (when furnished) andby an “auto/manua” contro switch. Contros for the

fans are contained in a contro cabinet mounted on the

transformer.

DANgER: AlWAYS DE-ENERGIZE THE FAN

CIRCUIT WHEN INSTAllING OR PERFORMING

MAINTENANCE ON FANS. IN ADDITION, DE-ENERGIZE

THE TRANSFORMER WHEN IT IS POSSIBlE TO COME

ClOSE TO ElECTRICAllY CHARGED/lIvE PARTS.

FAIlURE TO DO SO COUlD RESUlT IN SEvERE

PERSONAl INJURY OR DEATH. FAN GUARDS ARE

FURNISHED AND INSTAllED AT THE FACTORY TO

PREvENT ACCIDENTAl CONTACT WITH ROTATING FAN

BlADES. DO NOT REMOvE FAN GUARDS OR AllOW

PERSONNEl TO REACH INSIDE A GUARD. DOING SO

CAN RESUlT IN SERIOUS PERSONAl INJURY AND

EQUIPMENT DAMAGE.

The auto/manua switch determines the mode of

operation for the fan motors. When the switch is in

the “manua” position, fans wi operate continuousy.

When the switch is in the “auto” position, fans wi

be automaticay controed by contacts in the uid

temperature gauge or winding temperature gauge.Refer to the schematic wiring diagram proided with the

transformer.

Fan motors are proided with therma oeroad

protection. The oeroad protection is usuay contained

within the motor. Howeer, if the motors are ocated in a

hazardous ocation, the oeroad protection deice may

be ocated in the contro box. Refer to the wiring diagram

proided with the transformer.

Fan motors hae permanenty seaed ba bearings

and do not normay require maintenance, except as

expained on Page 20.

When fan assembies are instaed by the user, it

is important to permanenty remoe the drain pug

from the motor housing of each motor. This wi aow

condensation to drain from the motor housing.

De-Enerized Tap ChanerThe de-energized tap changer may be used to adjust the

otage ratio of a transformer whie it is de-energized.

It is intended to aow adjustment of the output

(secondary) otage to the rated aue. Do not use the

tap changer to raise or ower the output otage to anyotage other than that indicated on the transformer

namepate. If the tap changer is set to proide an output

otage different from rated otage, a high noise ee,

high core oss, and core saturation may resut.

DANgER: DO NOT OPERATE A DE-ENERGIZED

TAP CHANGER UNlESS THE TRANSFORMER IS

TOTAllY DE-ENERGIZED. FAIlURE TO DO SO WIll

RESUlT IN DAMAGE TO THE TRANSFORMER AND

COUlD RESUlT IN SEvERE PERSONAl INJURY OR

DEATH. DO NOT RE-ENERGIZE THE TRANSFORMER

UNlESS THE TAP CHANGER IS FIRMlY lOCKED INTO

POSITION.

The tap changer is operated by use of a rotating

hande ocated on the outside of the transformer tank.

Neer operate a de-energized tap changer whie the

transformer is energized. Tap changers normay hae

e or seen tap positions as indicated on the tap

changer dia pate and the transformer namepate. A

ocking mechanism is proided to ock the tap changer

in position and preent accidenta operation. Do not

re-energize the transformer unti the tap changer is rmy

ocked into a tap position.

The transformer is shipped from the factory with the tap

changer in the rated otage position, uness otherwise

specied by the customer.

Dua-votae or Deta/Wye SwitchTransformers designed with dua-otage windings or

reconnectabe deta/wye windings as indicated on the

namepate are proided with a de-energized two-position

dua-otage or deta/wye switch. The transformer must

be competey de-energized before operating the switch.

If the transformer is not de-energized before operating

the switch, permanent damage wi resut.

WARNINg: DO NOT OPERATE DUAl-vOlTAGE OR

DElTA/WYE SWITCH UNlESS THE

TRANSFORMER IS TOTAllY DE-ENERGIZED.

FAIlURE TO DO SO WIll RESUlT IN DAMAGE TO THE

TRANSFORMER AND COUlD RESUlT IN SEvERE

PERSONAl INJURY OR DEATH. DO NOT RE-ENERGIZE

THE TRANSFORMER UNlESS THE DUAl-vOlTAGE

OR DElTA/WYE SWITCH IS FIRMlY lOCKED INTO

POSITION.


19/24



December 2011

On-load Tap ChanerSome transformers are proided with an on-oad tap

changer that can change taps whie under oad, thereby

reguating the output otage. A user-programmabe

contro unit automaticay operates the on-oad tap

changer to maintain the seected output otage. Referto the manua proided with the on-oad tap changer for

warnings and for operating and maintenance

instructions.

Hih-votae BushinsTransformers are normay suppied with draw-ead

or condenser type high-otage bushings. If bushings

were remoed for shipment, insta draw-ead bushings

according to instructions found on Pages 12 and 13,

and insta condenser-type bushings according to

instructions furnished with the transformer.

WARNINg: DO NOT EXCEED THE CANTIlEvER

lOAD RATING OF THE BUSHING. GREATER

lOADS MAY CAUSE BUSHING DAMAGE THAT COUlD


PROPERTY DAMAGE.

Draw-ead bushings usuay require no maintenance

except as described on Page 20. Maintenance

instructions for condenser-type bushings are furnished

with the bushings.

low-votae BushinsTransformers are normay suppied with cast resin or

porceain draw-ead bushings. These bushings usuay

require no maintenance except as recommended on

Page 20.

Sure ArrestersTransformers may be furnished with optiona distribution

cass, intermediate cass, or station cass surge

arresters. Arresters are shipped separatey from the

transformer to preent damage. Upon deiery, unpack

the arresters and carefuy inspect them for damage,especiay the porceain components. Insta surge

arresters according to instruction found on Page 14.

19

RadiatorsTransformers are furnished with radiator assembies

(usuay pane type) to dissipate heat from the

transformer. Cooing fans may aso be furnished to

proide additiona oading capabiity without oerheating

the transformer. Radiator assembies may be shippedseparatey from the transformer to reduce the shipping

size of the transformer and to preent damage. When

radiators are shipped unattached, they shoud be

instaed in the ed according to the instructions on

Pages 11 and 12.


20/24


DANgER: THE TRANSFORMER MUST BE

DE-ENERGIZED BEFORE BEGINNING ANY

MAINTENANCE WORK. FAIlURE TO DO SO COUlD


PROPERTY DAMAGE.

It is the responsibiity of the owner to inspect, maintain,

and keep the transformer in proper operating condition.

Report a faiures during the warranty period to the

Howard Substation Transformer Diision. A warranty

repairs must be made or approed by the Howard

Substation Transformer Diision.

WARNINg: TANK lEAKS MUST BE REPAIREDIMMEDIATElY UPON DISCOvERY. FAIlURE TO

DO SO COUlD RESUlT IN SEvERE PERSONAl INJURY,

DEATH, OR PROPERTY DAMAGE.

Periodic Tests and InspectionsThe foowing periodic tests and inspections are

recommended for routine maintenance of the

transformer.

1. Gauge readings (one month after initia

energization and annuay thereafter). Gauge

readings, ambient temperature, and kvA

oad shoud be measured and recorded. Anyabnorma reading suggests that further

diagnostic testing or inspection shoud be

done. If pressure/acuum gauge and/or

uid ee gauge readings suggest a possibe

tank eak, perform a pressure test according

to instructions found on Page 14 (Pre-

energization Tests and Checklist). Tank eaks

must be repaired immediatey to preent serious

damage to the transformer and danger to ife.

2. Cooing fans (annua). Check the cooing fans

(if any) by setting the fan “auto/manua” contro

switch to the “manua” position. The fansshoud rotate at fu speed within approximatey

e seconds. The fans shoud rotate smoothy

with minima ibration.

3. Contro wiring (annua). Contro wiring shoud be

checked to insure that wire insuation is in good

condition. The contro cabinet and associated

conduit shoud be inspected to ensure that

weather seas are intact. Contro power suppy

otage shoud be checked and compared to the

otage stated on the wiring diagram.

4. Paint nish (annua). Inspect the paint nish for

damage or weathering that exposes the primer

coat or bare meta. Repair any paint damage

that might be found.

5. Fuid dieectric test (annua). Sampe the

insuating uid as described beow. The

dieectric strength of the insuating uid shoud

measure at east 26 kv.

6. Bushing and surge arrester insuators (annua).

Bushing and surge arrester insuators shoud be

cean. If the surfaces are excessiey dirty, they

shoud be ceaned whie the transformer is not

energized.

7. Bushing terminas (one month after initia

energization and annuay thereafter). If the

transformer is energized and under oad,

measure bushing termina temperatures

using an infrared scanner. Excessie bushing

termina temperature indicates a oose or dirty

connection. If the transformer is not energized,

use a torque measuring deice to make sure

termina connections are tight.

Sampin of Insuatin FuidTransformers are ed with insuating uid, which

proides eectrica insuation within the transformer

tank and transfers heat generated in the cois to thetank wa and radiators. The uid is either conentiona

transformer oi (minera oi), Enirotemp® FR3 uid, or

siicone uid.

Periodicay check the transformer for proper uid ee

by reading the uid ee gauge. Add uid if necessary.

When adding uid, add ony the same type uid that is in

the transformer.

It is aso recommended that a uid sampe be drawn

annuay and tested for dieectric strength. Sampes

shoud be drawn from the bottom of the tank. Use

proper samping procedures to preent erroneous test

resuts. Dieectric strength shoud measure 26 kv

minimum.

MAINTENANCE

20


21/24



December 2011

21

gasketsvisuay check a gaskets for cracking or other signs of

deterioration. Repace as necessary. When repacing

a gasket carefuy cean mating surfaces to remoe any

rust, dirt, transformer uid, od gasket materia, or other

contamination that might preent a good sea. Use anappropriate gasket cement when instaing new gaskets.

Do not reuse od gaskets. Six months after repacing a

gasket, check and retighten if necessary.

Additiona Maintenance InstructionsContact the Howard Substation Transformer Diision for

additiona maintenance instructions.

Repair PartsRepair parts can be ordered from the Howard Substation

Transformer Diision. A description of the part and the

transformer seria number wi be required to ensure thatthe correct part has been ordered.

Warranty CaimsThe Howard Substation Transformer Diision shoud

be notied immediatey when probems are discoered

during the warranty period. A warranty repairs must be

made or approed by the Howard Substation Transformer

Diision.


22/24


23/24



December 2011

23

NOTES


24/24


Instructions for Instaation, Operation, and Maintenanceof Medium Power Substation Transformers

Document 2.4.06, Reision 2 (December 2011)

Copyright © 2011, Howard Industries, Inc.

laure, Mississippi

Teephone: 601-425-3151

Fax: 601-649-8090

Web: howardtransformers.com