Understanding Power Factor Correction

7/26/2019 Understanding Power Factor Correction

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UNDERSTANDING

POWER FACTOR

CORRECTION

Dr. Ir. Mohamed Fuad Faisal

Asset Management Department,

Distribution Division, TNB

Presentation contents

Understanding Electrical Power

Understanding Electrical Energy & Energy Bills

Managing Low Power Factor

Impact of Low Power Factor

Benefits of High Power Factor

Methods to Improve Low Power Factor

Locations to install capacitors Types of Power Factor Capacitors

Sizing of Capacitor

Energy Saving Devices


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Understanding

Electrical Powers

P= kW

Q=kVAr

S= kVA

S=(P2+Q2)

Relationships kW, kVAr, kVA & PF

Power Factor (PF) =kW

kVA


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Types of Loads (Equipment)

Resistive Inductive CapacitiveIncandescent lighting Motors Capacitor

Heating element Transformers

ETC Chokes, ETC

Watt, Kilowatt VAr, KiloVAr VAr, KiloVAr

Equipment Label: kW & Power Factor


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Equipment Label: HP (Horsepower) &

Power Factor (PF)

No label for kW & kVAr

1 hp = 0.746 kW

7.5 hp = 5.5 kW

PF = 0.81 = kW

kVA

kVAr = (kVA2-kW2)

Electrical Energy

& Electricity Bills


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Energy Meter

kiloWatt

kiloVAr

Air conditioner

Energy Meter

kiloWatt

kiloVAr


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Definition of Power & Energy

Energy Meter

kiloWatt

kiloVAr


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P= kW or kWh

Q=kVAr or kVArh

S= kVA or kVAh

S=(P2+Q2)

Average Power Factor (PF) = kWh

kVAh

Relationships kWh, kVArh, kVAh & PF

Power Factor (PF) =kW

kVA

Energy Meter

kiloWatt

kiloVAr

Example for Domestic Customers

Energy cost= RM 0.28/kWh

Cost = RM 0.28/kWh x 330 kWh

= RM 92.40


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Kilang ABC

Energy cost (kWh)Energy cost = kWh (1month) x h

Maximum Demand (kW)Maximum Demand = Highest kW(1month) x Tariff

kVArh

Power FactorPower factor penalty for power factor < 0.85 (0.9)

Charges for Non

Domestic Customers

Managing

Low Power Factors


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Kilang ABC

Energy cost (kWh)Energy cost = kWh (1month) x h

Maximum Demand (kW)Maximum Demand = Highest kW(1month) x Tariff

kVArh

Power FactorPower factor penalty for power factor < 0.85 (0.9)

Charges for Non

Domestic Customers

P= kW or kWh

Q=kVAr or kVArh

S= kVA or kVAh

S=(P2+Q2)

Average Power Factor = kWh

kVAh

DEFINITION OF POWER FACTOR

Power Factor =kW

kVA


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Equipment Causing Low Power Factor

Lightly loaded induction motor. Examples of this type of

equipment and their approximate power factors are:

80% power factor or better: Air conditioners, pumps, center less

grinders, cold headers, up setters, fans or blowers.

60% to 80% power factor: Induction furnaces, standard stamping

machines and weaving machines.

60% power factor and below: Single stroke presses, automated

machine tools, finish grinders, welders.

Example 1Energy recorded by TNB energy meter

kWh = 123,345.24

kVarh=87,453.23

What is the value of average power factor ?


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kWh = 123,345.24

kVarh = 87,453.23

kVAh = (123,345.242 + 87,453.232)

= 151,202

Average PF = kWh / kVAh

= 123,345.24 / 151,202

= 0.815

LIMTS FOR AVERAGE POWER FACTOR

Non Domestic Customers are advise to maintain

power factor at minimum of 0.85 (0.90)

PF = 1.0

PF=0.85 (0.9)Power

Factor

PF=0.75 (0.75)

No Surcharge

Surcharge


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All Tariffs imposed Power Factorlimits except Tariffs A & G

Tarif A Domestic

Tarif B LV Commercial

Tarif C1 MV Commercial

Tarif C2 MV Peak/Off-Peak

Tarif D LV Industry

Tarif E1 MV Industry

Tarif E2 MV Industry Peak/Off

Tarif E3 HV Industry

Tarif F LV Mining

Tarif F1 MV Mining

Tarif F2 MV Mining Peak/OffTarif G Street Lighting

CALCULATION OF AVERAGE

POWER FACTOR PENALTY


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Average Power Factor Charges

Power Factor Description

PF > 0.85 No charge

PF = 0.85 No charge

0.75 < PF < 0.85 For every different of 0.01,

additional charge of 1.5 %

from monthly bill

PF < 0.75

For every different of 0.01,

additional charge of 3.0%from monthly bill

(0.75 < PF < 0.90)

(0.90)

(0.90)

EXAMPLE 2One 11 kV LPC has monthly power factor of 0.60 & the monthlyelectricity bill is

RM 4,800.

What is the actual monthly electricity bill?

Charge1 = (0.85 - 0.75)/0.01 x1.5 % = 15 %

Charge 2 = (0.75 - 0.60)/0.01 x 3.0 % = 45 %

Overall charge = (15 % + 45 %) = 60 %

Power factor penalty = 60% x RM 4,800.00 = RM 2,880.00.

Monthly ElectricBill = Energy Bil (kWh) + power factor penalty

Actual electricity bill = RM 4,800 + RM 2,880 = RM 7,680.00


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Impact of Low

Power Factors

Reactive Power Problem (1)

Condition 1

Power Factor = 1.0, Load = 50 kW,

Load kVA = kW / PF = 50 kVA

Load Current = kVA / (3 x 480 Volt) = 60 Amp

Condition 2

Power Factor = 0.7, Load kW = 50 kW,

Load kVA = kW / PF = 50 kW / 0.7 = 72 kVA

Load Current = kVA / (3 x 480 Volt) = 86 Amp


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60 Amp

86 Amp

Load = 50 kW

PF =1.0

Load = 50 kW

PF =0.7

100kW

100kW

100kW

100kW

100kW

48.43kVar

75kVar

102kVar

133.33kVar

100 kVApf=1.00

111.11 kVApf=0.90

125 kVApf=0.80

142.8 kVApf=0.70

166.7 kVApf=0.60



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100kW

90kW

80kW 60

kW

70kW

43.59kVar

60kVar 71.41

kVar80kVar

100 kVApf=1.00

100 kVApf=0.90

100 kVApf=0.80

100 kVApf=0.70

100 kVApf=0.60


Transformer size

100 kVA


Condition 1

Power Factor = 0.45

Tx Size = 1000 kVA

Load kVA = 1,777 kVA

% TX Load = 177 %

Condition 2 Power Factor = 0.9

Tx Size = 1000 kVA

Load kVA = 888 kVA

% TX Load = 88 %


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Condition 1

Power Factor = 1.0

Load kVA = 50 kVA

Current = 50 kVA/ (3x480) =60 Amp

Cable resistance = 5 ohm

Losses = I2 x R = 602 x 5 = 18,000 Watt

Condition 2

Power Factor = 0.7

Load kVA = 72 kVA

Current = 72 kVA/ (3x480) =86 Amp

Cable resistance = 5 ohm

Losses = I2 x R = 862 x 5 = 36,980 Watt

Losses = Watt

In 1 hour (h), the losses

value will be kW x h

Summary of Impacts of Low Power Factors

a low power factor will inflict power factorpenalty to customers

a lower power factor can cause increase inline current and cause technical losses (I2R)for both customers and TNB.

a low power factor can increase the kVA loadfor TNB transmission/distribution systems(use more of system capacity kVA).


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Benefits of High

Power Factors

Benefits of High Power Factor Correction

No power factor penalty to customers

Reduce line current and minimize technicallosses (I2R) for both customers and TNB.

Reduce use of system capacity kVA for bothcustomers and TNB.


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Methods to Improve

Low Power Factors

Methods to Improve Low PF

Install power factor correction capacitorsFixed or Switch Capacitors

Synchronous Condenser When a Synchronous motor operates at No-Load and

over-exited then its called a synchronous Condenser.

Whenever a Synchronous motor is over-exited then it

provides leading current and works like a capacitor

Adjust power factor settings (COGEN)


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Locations to

Install Capacitors

Locations to Install Capacitors

Capacitors connected at a distribution board and

controlled independently from the individual

starters is known as Capacitor Bulk Correction".

Capacitors connected at each load is known as

Capacitor Load Correction".


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Capacitor Bulk Correction

Capacitor bulk correction will minimize

average power factor penalties

If the customers want to minimize the average power factor

penalty, they must install suitably sized capacitor banks exactly

after the energy meter.

Energy Meter Capacitor

Load


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Locations to install capacitor for

minimizing power factor penalties

OPEN

INCOMER

1.5MVA

DY11

X

X 11 kV

X

1.5 MVADY1

X415 Volt

1MVADY11

M

M

ProductionEquipment

Compressors

Chillers

208 Volt

UTILITY

M

Servo Drives

M

Cooling Tower

M

ASD

Locations to install capacitor for

minimizing power factor penalties


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Capacitor load correction will minimize

line current, losses and improve average

power factor.


line current, losses and improve averagepower factor.


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line current, losses and improve average

power factor.

Types of Power Factor

Correction Capacitors


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Delta 415 Volt Capacitor for

Schools & Shops

Delta 415 Volt Capacitor


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11 kV Pole Mounted Capacitor

Y-Y Ungrounded 11 kV


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Sizing of Power

Correction Capacitors

Methods to Size Capacitors

Use the power factor correction reference

(PFCR) table

Perform load profiling at selected sites.


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57

Power Factor Correction Reference Table80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

50 0.982 1.008 1.034 1.06 1.086 1.112 1.139 1.165 1.192 1.22 1.248 1.276 1.306 1.337 1.369 1.403 1.442 1.481 1.529 1.59 1.732

51 0.937 0.962 0.989 1.015 1.041 1.067 1.094 1.12 1.147 1.175 1.23 1.231 1.261 1.292 1.324 1.358 1.395 1.436 1.484 1.544 1.687

52 0.893 0.919 0.945 0.971 0.997 1.023 1.05 1.076 1.103 1.131 1.159 1.187 1.217 1.248 1.28 1.314 1.351 1.392 1.44 1.5 1.643

53 0.85 0.876 0.902 0.928 0.954 0.98 1.007 1.033 1.06 1.088 1.116 1.144 1.174 1.295 1.237 1.271 1.308 1.349 1.397 1.457 1.654 0.809 0.835 0.861 0.887 0.913 0.939 0.966 0.992 1.019 1.047 1.075 1.103 1.133 1.164 1.196 1.23 1.267 1.308 1.356 1.416 1.559

55 0.769 0.795 0.821 0.847 0.873 0.899 0.926 0.952 0.979 1.007 1.033 1.063 1.09 1.124 1.156 1.19 1.228 1.268 1.316 1.377 1.519

56 0.73 0.756 0.782 0.808 0.834 0.86 0.887 0.913 0.94 0.968 0.996 1.024 1.051 1.085 1.117 1.151 1.189 1.229 1.277 1.338 1.4857 0.692 0.718 0.744 0.77 0.796 0.822 0.849 0.875 0.902 0.93 0.958 0.986 1.013 1.047 1.079 1.113 1.151 1.191 1.239 1.3 1.442

58 0.655 0.681 0.707 0.733 0.759 0.785 0.812 0.838 0.865 0.893 0.921 0.949 0.976 1.01 1.042 1.076 1.114 1.154 1.202 1.263 1.405

59 0.618 0.644 0.67 0.696 0.722 0.748 0.775 0.801 0.828 0.856 0.884 0.912 0.939 0.973 1.005 1.039 1.077 1.117 1.165 1.226 1.368

60 0.584 0.61 0.636 0.662 0.688 0.714 0.741 0.767 0.794 0.822 0.85 0.878 0.905 0.939 0.971 1.005 1.043 1.083 1.131 1.192 1.334

61 0.549 0.575 0.601 0.627 0.653 0.679 0.706 0.732 0.759 0.787 0.815 0.843 0.87 0.904 0.936 0.97 1.008 1.014 1.096 1.157 1.299

62 0.515 0.541 0.567 0.593 0.619 0.645 0.672 0.698 0.725 0.753 0.781 0.809 0.836 0.87 0.902 0.936 0.974 0.982 1.062 1.123 1.265

63 0.483 0.509 0.535 0.561 0.587 0.613 0.66 0.666 0.693 0.721 0.749 0.777 0.804 0.838 0.87 0.904 0.942 0.949 1.03 1.091 1.233

64 0.45 0.476 0.502 0.528 0.554 0.58 0.607 0.633 0.66 0.688 0.716 0.744 0.771 0.805 0.837 0.871 0.909 0.918 0.997 1.058 1.2

65 0.419 0.445 0.471 0.497 0.523 0.549 0.576 0.602 0.629 0.657 0.685 0.713 0.74 0.774 0.806 0.84 0.878 0.887 0.966 1.027 1.169

66 0.388 0.414 0.44 0.466 0.492 0.518 0.545 0.571 0.598 0.626 0.554 0.682 0.709 0.743 0.775 0.809 0.847 0.857 0.935 0.996 1.138

67 0.358 0.384 0.41 0.436 0.462 0.488 0.515 0.541 0.568 0.596 0.624 0.652 0.679 0.713 0.746 0.779 0.817 0.828 0.905 0.966 1.108

68 0.329 0.355 0.381 0.407 0.433 0.459 0.486 0.512 0.539 0.567 0.595 0.623 0.65 0.684 0.716 0.75 0.788 0.798 0.876 0.937 1.079

69 0.299 0.325 0.351 0.377 0.403 0.429 0.456 0.482 0.509 0.537 0.565 0.593 0.62 0.654 0.686 0.72 0.758 0.769 0.84 0.907 1.049

70 0.27 0.296 0.322 0.348 0.374 0.4 0.427 0.453 0.48 0.508 0.536 0.564 0.591 0.625 0.657 0.691 0.729 0.741 0.811 0.878 1.02

71 0.242 0.268 0.294 0.32 0.346 0.372 0.399 0.425 0.452 0.48 0.508 0.536 0.563 0.597 0.629 0.663 0.701 0.712 0.783 0.85 0.992

72 0.213 0.239 0.265 0.291 0.317 0.343 0.37 0.396 0.423 0.451 0.479 0.507 0.534 0.568 0.6 0.634 0.672 0.685 0.754 0.821 0.963

73 0.186 0.212 0.238 0.264 0.29 0.316 0.343 0.369 0.396 0.424 0.452 0.48 0.507 0.541 0.573 0.607 0.645 0.658 0.727 0.794 0.936

74 0.159 0.185 0.211 0.237 0.263 0.289 0.316 0.342 0.369 0.397 0.425 0.453 0.48 0.514 0.546 0.58 0.618 0.631 0.7 0.767 0.909

75 0.132 0.158 0.184 0.21 0.236 0.262 0.289 0.315 0.342 0.37 0.398 0.426 0.453 0.487 0.519 0.553 0.591 0.604 0.673 0.74 0.882

76 0.105 0.131 0.157 0.183 0.209 0.235 0.262 0.288 0.315 0.343 0.371 0.399 0.426 0.46 0.492 0.526 0.564 0.578 0.652 0.713 0.855

77 0.079 0.105 0.131 0.157 0.183 0.209 0.236 0.262 0.289 0.317 0.345 0.373 0.4 0.434 0.466 0.5 0.538 0.552 0.62 0.687 0.829

78 0.053 0.079 0.105 0.131 0.157 0.183 0.21 0.236 0.263 0.291 0.319 0.347 0.374 0.408 0.44 0.474 0.512 0.525 0.594 0.661 0.803

79 0.026 0.052 0.078 0.104 0.13 0.156 0.183 0.209 0.236 0.264 0.292 0.32 0.347 0.381 0.413 0.447 0.485 0.499 0.567 0.634 0.776

8 0 0 0 .0 26 0 .0 52 0 .0 78 0 .1 04 0 .1 3 0 .1 57 0 .1 83 0 .2 1 0 .2 38 0 .2 66 0 .2 94 0 .3 21 0 .3 55 0 .3 87 0 .4 21 0 .4 59 0 .4 73 0 .5 41 0 .6 08 0 .7 5

8 1 0 0 .02 6 0 .0 52 0 .0 78 0 .10 4 0 .1 3 0 .1 57 0 .1 84 0 .2 12 0 .2 4 0 .2 68 0 .29 5 0 .3 29 0 .36 1 0 .3 95 0 .43 3 0 .4 47 0 .51 5 0 .5 82 0 .72 4

8 2 0 0 .0 26 0 .0 52 0 .0 78 0 .1 05 0 .1 31 0 .1 58 0 .1 86 0 .2 14 0 .2 42 0 .2 69 0 .3 03 0 .3 35 0 .3 69 0 .4 07 0 .4 21 0 .4 89 0 .5 56 0 .69 8

83 0 0. 026 0. 05 2 0. 07 9 0 .105 0. 132 0 .1 6 0. 18 8 0 .21 6 0. 243 0. 277 0. 30 9 0 .34 3 0 .38 1 0. 395 0. 463 0.5 3 0 .67 2

84 0 0 .02 6 0. 05 3 0 .079 0. 106 0. 13 4 0. 16 2 0 .1 9 0. 217 0. 251 0. 28 3 0 .31 7 0 .35 5 0. 369 0. 437 0 .50 4 0 .64 5

85 0 0.027 0.053 0 .08 0.108 0.136 0.164 0.191 0.225 0.257 0.291 0.329 0.343 0.417 0.478 0.62

86 0 0.026 0.053 0.081 0.109 0.137 0.167 0.198 0.23 0.265 0.301 0.317 0.39 0.451 0.593

87 0.027 0.055 0.082 0.111 0.141 0.172 0.204 0.238 0.275 0.29 0.364 0.425 0.56788 0 0.028 0.056 0.084 0.114 0.145 0.177 0.211 0.248 0.262 0.237 0.398 0.54

89 0.028 0.056 0.086 0.117 0.149 0.183 0.22 0.234 0.309 0.37 0.512

90 0.028 0.058 0.089 0.121 0.155 0.192 0.206 0.281 0.342 0.484

91 0.03 0.061 0.093 0.127 0.164 0.176 0.253 0.314 0.456

92 0.031 0.063 0.097 0.134 0.143 0.223 0.284 0.426

93 0 0.032 0.066 0.103 0.113 0.192 0.253 0.395

94 0.034 0.071 0.079 0.16 0.221 0.363

95 0.037 0.042 0.126 0.187 0.328

96 0 0.089 0.15 0.292

97 0 0.047 0.108 0.251

98 0 0.061 0.203

99 0 0.142

O

ri

g

in

a

l

P

ow

e

r

F

a

c

t

o

r

i

n

%

Desired Power Factor in %

58

Performing a Load Profiling

OPEN

INCOMER

X 11 kV

X

1.5 MVA

DY1

X415 Volt

1MVA

DY11

M

M

Production

Equipment

Compressors

Chillers

208 Volt

UTILITY

M

Servo Drives

M

Cooling Tower

M

ASD

PQ recorder

No.1

PQ recorder

No.2


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59

Event #1 at 11/09/2006 12:08:58.000

BVrms, CVrms, BVrms, CV rms Voltage Journal Trigger Normal To Low

Timeplot

Max At Min At

AQFnd(kVAR) AVG 1764 11/13/2006 21:10 917.6 11/13/2006 21:10

BQFnd(kVAR) AVG 1916 11/09/2006 19:30 1041 11/09/2006 19:30

CQFnd(kVAR) AVG 1775 11/09/2006 19:50 935.4 11/09/2006 19:50

TOTQFnd(kVAR) AVG 5442 11/09/2006 19:30 2894 11/09/2006 19:30

11/10/2006

Friday

11/11/2006

Saturday

11/12/2006

Sunday

11/13/2006

Monday

11/14/2006

Tuesday

11/15/2006

Wednesday

1000

2000

3000

4000

5000

kVAR

A Q Fn d( kVA R) (a vg ) B Q Fn d( kV AR ) ( av g) C Q Fn d( kV AR ) ( av g) T OT QF nd (k VA R) (a vg )

Created with DranView 6.0.23

Base kVAR

Maximum kVAr

Summary of Capacitor

Sizing & Placement


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Overall Procedures for Capacitor Sizing

& Placement

Start

Capacitor sizing

Identify location

Technical

assessment

Design &

specificationsInstallation Asset Mgmt

Objectives

Energy Saving Devices

(ESD)


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Energy Saving

Device (ESD) ?

Brand XXXSmartKit

?

Does A Energy Saving Card (ESC)Exist to achieve Energy Efficiency ?


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Energy Saving Card (ESC) ?

ABC


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Thank You

[email protected]

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Understanding Power Factor Correction

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