eliminating harmonic neutral current problems
TRANSCRIPT
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Presented by
Michael Z. Lowenstein, Ph.D.
Chief Technology Officer
Harmonics Limited
Eliminating Harmonic Neutral
Current Problems
Powering multiple computer loads createsproblems in electrical distribution systems.
Harmonic current flow generates heat in allparts of the distribution system, whichwastes energy.
Ridding the system of harmonic current flowsaves energy and money.
Basic Premises
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Why there is a problem
Power dist ribut ion in a Wye system
Powering computers
Accommodating harmonic currents
Preventing harmonic currents with theHarmonic Suppression System (HSS)
Saving energy
HSS products Who uses the HSS and the results they
obtain
Outline
When an electric motor is connected to theAC l ine, i t draws i ts power directly from theline. The power is not treated in any way.
The same is true for a resist ive load such asan electr ic heater.
Linear loads
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Voltage & currenthave the samemathematicalrelationship acrossthe entire cycle
PEAKS ZERO CROSSINGS
CURRENTVOLTAGE
0 180 360
AMPLITUDE
WAVE ANGLE
Linear voltage-current relationship
When a computer is connected to theAC line, it draws its power from aninternal DC supply that containsrectifiers and capacitors.
Non-linear loads
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Non-linear voltage-current relationship
Mathematicalrelationshipsbetween voltage& current varyacross the cycle
PEAKS ZERO CROSSINGS
VOLTAGECURRENT
0 180 360
AMPLITUDE
WAVE ANGLE
Linear & non-linear loads (1)
Linear Load Thecurrent looks l ikethe voltage
The more the currentlooks l ike thevoltage, the morelinear is the load
Non-linear LoadThe current doesnot look like thevoltage
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Linear Loads gettheirkW power at60 Hz.
Non-linear loads gettheir kW power at 60Hz and in additiondraw harmoniccurrents
Linear & non-linear loads (2)
What are harmonics?
3rd HARMONIC
5th HARMONIC
FUNDAMENTAL
0 90 180 270 360WAVE ANGLE
AMPLITUDE
Harmonics are continuousintegral mult iples of thefundamental frequency
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FREQUENCYFREQUENCYHARMONIC
1
2
3
5
7
9
11
49
60
120
180
300
420
540
660
2940
400
800
1200
2000
2800
3600
4400
19600
Table of harmonics
Single-phase 2-pulse diode bridge(computer power supply)
+
_
CAPACITIVE LOAD
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Single-phase 2-pulse diode bridge(waveform)
VOLTS
AMPS
0 90 180 270 360 450 540 630 720
WAVE ANGLE IN DEGREES
13
57
911
1315
1719
0
10
20
30
40
50
60
70
80
90
100
C
URRENT%F
UNDAMENTAL
HARMONIC NUMBER
Single-phase harmonic spectrum(typical for personal computers)
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3-phase wye
distribution systems(with phase-to-neutral loads)
Wye distribution system
Serving Linear Loads
TRANSFORMER ENCLOSUREPHASE C
PHASE A
PHASE B
60HzCURRENTS
60Hz CURRENT
60Hz IMBALANCE CURRENT ONLY
PRIMARY CIRCUITBREAKER
TO BUILDING STEEL
X0
HEATER HEATER HEATER
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Standard t ransformer, phase A
linear load
A = 12.4 Amps; B = 0.8 Amps; C = 0.8 Amps; N = 12.2 Amps
Standard t ransformer, phases A + B
linear load
A = 12.4 Amps; B = 11.9 Amps; C = 0.7 Amps ; N = 11.9 Amps
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Standard transformer, phases A + B + C
linear load
A = 12.5 Amps; B = 11.9 Amps; C = 11.8 Amps; N = 0.8 Amps
Harmonics currents do no work, but docontribute to the rms current the system mustcarry
3rd harmonic currents are additive in thesystem neutral
3rd harmonic currents return to thetransformer over the neutral and are dissipatedas heat in the transformer, cables and loaddevices
Reasons to be concerned about
harmonic currents
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PHASE C
PHASE A
60Hz IMBALANCE CURRENT +SUMMED 3rd HARMONIC CURRENT
PHASE B
3rd HARMONIC CURRENTCIRCULATES IN DELTA WINDING
SAFETYGROUND
TRANSFORMER ENCLOSURE
60Hz CURRENT +HARMONIC CURRENT60Hz ANDNON-TRIPLEN
HARMONICCURRENTS
TO BUILDING STEEL
COMPUT ER COMPUT ER COMPUT ER
PRIMARY CIRCUITBREAKER
X0
Wye Distribution System
Serving Non-Linear Loads
Standard Transformer, 10 non-linear loads,
phase A
A = 24.8 Amps; B = 0.8 Amps; C = 0.8 Amps; N = 24.7 Amps
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A = 24.7 Amps; B = 23.4 Amps; C = 0.7 Amps ; N = 33.9 Amps
Standard Transformer, 10 non-linear loads,
phases A + B
A = 24.6 Amps; B = 23.4 Amps; C = 24.5 Amps; N = 41.5 Amps
Standard Transformer, 10 non-linear loads,
phases A + B + C
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k-Rated Transformers
Double Neutrals
Oversized switch gear
De-rated UPSs, and Power DistributionUnits (PDUs)
Zig-zag or phase shifting transformers
Avoiding Harmonic Problems(Accommodation)
PHASE C
PHASE A
60Hz IMBALANCE CURRENT +SUMMED 3rd HARMONIC CURRENT
PHASE B
3rd HARMONIC CURRENTCIRCULATES IN DELTA WINDING
SAFETYGROUND
TRANSFORMER ENCLOSURE
60Hz CURRENT +HARMONIC CURRENT60Hz ANDNON-TRIPLEN
HARMONICCURRENTS
TO BUILDING STEEL
COM PUTER COMPUTER COM PUTER
PRIMARY CIRCUITBREAKER
X0
K-rated transformer to accommodate
harmonic currents
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A = 26.0 Amps; B = 24.9 Amps; C = 25.8 Amps; N = 44.3 Amps
K-rated transformer, 10 non-linear loads, phases
A+B+C
k-Rated Transformers
Double Neutrals
Oversized switch gear
De-rated UPSs, and Power Distribution
Units (PDUs) Zig-zag or phase shifting transformers
Avoiding Harmonic Problems
(Accommodation)
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k-Rated Transformers
Double Neutrals
Oversized switch gear
De-rated UPSs, and Power DistributionUnits (PDUs)
Zig-zag or phase shifting transformers
Avoiding Harmonic Problems(Accommodation)
Zig-zag transformer to accommodate
harmonic currents
PHASE C
PHASE A
PHASE B
3rd HARMONIC CURRENT DISSIPATEDAS HEAT IN SECONDARY WINDING
SAFETYGROUND
TRANSFORMER ENCLOSURE
60Hz CURRENT +HARMONIC CURRENT
TO BUILDING STEEL
COM PUTER COMPUTER COM PUTER
60Hz ANDNON-TRIPLENHARMONICCURRENTS
PRIMARY CIRCUITBREAKER
60Hz IMBALANCE CURRENT +SUMMED 3rd HARMONIC CURRENT
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A = 26.4 Amps; B = 25.2 Amps; C = 26.4 Amps; N = 45.0 Amps
zig-zag transformer, 10 non-linear loads, phases
A+B+C
Introducing the Harmonic SuppressionSystem (HSS)
Blocks 3rd harmonic currents andprevents their flow anywhere in thesystem
Eliminates need for oversized componentsand doubled neutrals.
Minimizes waste heat from the transformerout to the furthest outlet.
Eliminating Harmonic Problems
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3rd
HARMONICFLOW
HSS blocking 3rd harmonic currents
SINCE NO 3rd HARMONICCURRENT CAN RETURN IN THE
NEUTRAL WIRE, NO 3rdHARMONIC CURRENT CAN FLOW
IN THE PHASE WIRES.
60Hz CURRENT and 3rd HARMONICCURRENT FLOWING IN ALL THREEPHASES
60 Hz 3rdHARMONIC
PHASE C
PHASE A
PHASE B
COMPUTER COMPUTER COMPUTER
60Hz IMBALANCE CURRENT PLUS 3RD HARMONICCURRENT, COMBINED FROM ALL THREE PHASES, MUST
RETURN TO THE TRANSFORMER ON THE NEUTRAL WIRE`
NEUTRAL
X0
RLC Parallel-Resonant Tank Circui t HSS)
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TRANSFORMER ENCLOSUREPHASE C
PHASE A
PHASE B
60Hz ANDNON-TRIPLENHARMONICCURRENTS
COMPUTER COMPUTER COMPUTER
HSS
NO 3rd HARMONIC CURRENTSTO CIRCULATE IN DELTA WINDING
60Hz CURRENT & HARMONIC-CURRENTS OTHER THAN 3RD
60Hz IMBALANCE CURRENT ONLYIN COMBINED NEUTRAL
PRIMARY CIRCUITBREAKER
TO BUILDING STEEL
X0
HSS ENCLOSURE
Wye distribution system with HSS
Computer Current (With & Without HSS)
no HSS
HSS
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With HSS Without HSS
1 3 5 7 9 11 13 15 17 19
0102030405060708090
100
1 3 5 7 9 11 13 15 17 19
%o
fFundamental
Phase Harmonic Currents With & WithoutHarmonic Suppression System
Neutral Harmonic Currents With &
Without Harmonic Suppression System
With HSS Without HSS
1 3 5 7 9 11 13 15 17 19
0255075
100125150175200225250
1 3 5 7 9 11 13 15 17 19
Currentinamps
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Reduces neutral currents by more than90% by preventing 3rd harmoniccurrent flow (from the transformer out tothe furthest outlet)
Lowers rms phase currents, leading tomore useable capacity without the needto install a larger system.
Reduces energy losses throughout thesystem
What the HSS Does (for your system)
Proper Sizing of the Distribution System
System over-sizing to handleharmonic currents is eliminated.
Useable system capacity isincreased (single phase power factoris improved.)
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Power factor is defined as activepower divided by apparent power
Power factor can be described as ameasure of the effective util ization ofelectrical system capacity
Single-phase power factor
System Capacity
Unloaded system
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System Capacity
kW Power
Harmonics
Low power factor
System Capacity
kW Power
Harmonics
Slightly improved power factor
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System CapacitykW Power
Harmonics
High power factor
*Single-phase power factor, is a measure of
the efficiency of system capacity utilization.
TEST VOLTAGE
(rms volts)
CURRENT
(rms amps)
WATTS VOLT-
AMPS
POWER
FACTOR*
No HSS 116.7 4.972 360.4 580.4 0.62
With HSS 117.2 3.173 355.9 371.8 0.96
Single-phase power factor(with and wi thout the HSS)
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System-wide I2R energy losses
Losses due to system-wide heating showup on the energy bi ll as increased kWHusage
The HSS reduces system-wide heatingand provides real energy savings.
This savings can be measured byexamining a system with and without anHSS installed
Measurements both in the laboratory andin the field conf irm system-wide energysavings.
Power saved by removing harmonic currents
varies with system loading and wiring method
% kW REDUCTION WITH VARYING WIRING OPTIONS
AND LOADING, STANDARD TRANSFORMER
0
1
2
3
4
5
6
7
8
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
% TRANSFORMER LOADING
%
kW
REDUCTION
50' 50'+100' SN 50'+ 100'CN 50'+100' SN+100'CN
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The Energy Savings Estimator
The energy savings estimator
(I2R waste heat savings)
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The energy savings estimator(avoided air conditioning)
Secondary currents (by transformer type)
0
5
10
15
20
25
30
35
40
45
CURRENTINAMP
std xfmr k-rated xfmr Zig-zag xfmr
TRANSFORMER TYPE
SECONDARY CURRENT BY PHASE AND TRANSFORMER TYPE (WITH
HARMONICS) 50' + 100' COMMON NEUTRAL
p has e a pha se b p has e c neutral
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0
5
10
15
20
25
30
35
40
45
CURRENTINAMP
std xfmr k-rated xfmr Zig-zag xfmr
TRANSFORMER
SECONDARY CURRENT BY PHAS E AND TRANSFORMER TYPE (HARMONICS
SUPPRESSED) 50' +
100' COMMON NEUTRAL
phas e a phas e b phas e c neutral
Secondary currents (by transformer type)with HSS
6.20
6.30
6.40
6.50
6.60
6.70
6.80
6.90
7.00
7.10
POWERINk
st d x fmr k -r at ed x fmr z ig- zag x fmr
TRANSFORMER TYPE
POWER BY TRANSFORMER TYPE (WITH AND WITHOUT
HARMONICS) 50' + 100' COMMON NEUTRAL
SOLID = WITH CHECKERED = WITHOUT
Power with and without HSS
(by transformer type)
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-8.00%
-7.00%
-6.00%
-5.00%
-4.00%
-3.00%-2.00%
-1.00%
0.00%
1.00%
2.00%
3.00%
PERCENTCHANGEIN
POWERUSED
std x fmr k-rated x fmr zig-zag xfmr
TRANSFORMER TYPE
COMPARISON OF POWER USED, BY TRANSFORMER TYPE
(PERCENT INCREASE OR DECREASE) 50' + 100' COMMON
NEUTRAL (PAGE 2)
CHANGE IN POWER USE COMPARED TO STANDARD TRANSFORMER
CHANGE IN POWER USE WITH HARMONIC REMOVAL
Power used with and without HSS, change(by transformer type)
Harmonic Suppression Products
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The SysteMax
is an add-on
Harmonic
Suppression
System That can be
added to your
present transformer
to remove harmonic
currents
The TransMaxcombines a high
quality TP-1 (formerly
energy star)
transformer with the
Harmonic
Suppression Systemin a single easy-to-
install enclosure.
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500 kVA TransMax(installed in a basement vault)
Who uses the HSS and why?
Data Centers
Financial institutions
Government institutions
Casinos
Educational institutions
Hospitals
Research laboratories
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Stock exchange trading room floor
Transformers2- 112 kVA & 1-75 kVA, K-20 TransformersAvg. transformer loading 64% of Rated
Capacity
Combined Neutral Current reduced by75%, from 750 amps., to 186 amps..
3rd Harmonic Neutral Current reduced by98%, from 712 amps., to 15 amps.,
RMS Phase Current reduced by 9% Using energy savings estimator-- ROI, 19
months 3 Portable A/C units removed ($54,000.00
per yr.)
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Software development center(before and after HSS)
Every electrical distribution system poweringmultiple single-phase non-linear loads, issusceptib le to harmonic neutral currentproblems
Installing a Harmonic Suppression Systemincreases electrical system reliabili ty
Installing a Harmonic Suppression Systemreduces heat and wasted energy system-wide
Using the HSS saves you energy and money
Conclusions
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CONTACT INFORMATION
Michael Z. Lowenstein
Harmonics Limited
2400 Ardmore Blvd., Suite 302
Pittsburgh, PA 15221
Phone: 412-636-9600 ext 3
Cell: 970-216-4515