B-Electrical Energy Audit.ppt

8/22/2019 B-Electrical Energy Audit.ppt

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GERIAP-NPC 13 1

13. Audit of Electrical Systems


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GERIAP-NPC 13 2

FANS & BLOWERS PUMPS R & AC COMPRESSORS LIGHTING, HEATING

M M M M C

M

M

DG SET

EB POWER

Metering

TransformerEffi.95-98%

Feeders,

Capacitors

Distribution

Panels

Motors

Effi.85-96%

MECHANICAL

ELECTRICAL

TRIVEATOR METER

11 KV/440V

ELECTRICAL DISTRIBUTION SYSTEM -- SINGLE LINE DIAGRAM

C

C

Dist

. loss

4 - 8%


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GERIAP-NPC 13 3

Typical Range of Losses in Common

Electrically Operated EquipmentEquipment % Energy Loss at Full Load

Outdoor circuit breaker (15 to 230 KV) 0.002 - 0.015

Medium voltage switchgears (5 to 15 KV) 0.005 - 0.02

Transformers 0.40 - 1.90

Load break switches 0.003 - 0.025

Medium voltage starters 0.02 - 0.15

Bus ways less than 430 V 0.05 - 0.50

Low voltage switchgear 0.13 - 0.34

Motor control centers 0.01 - 0.40

Cables 1.00 - 4.00

Motors (1-10 HP) 14.0 - 35.0

10 200 HP motors 6.0 - 20.0

200 1500 HP motors 4.0 - 7.0

Capacitors (Watts / KVAR) 0.50 - 6.0


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GERIAP-NPC 13 4

How to reduce Electricity Bill in

an Industry ?

0

200

400

600

800

1000

12001400

1600

1800

2000

2200

May'01

Jun'0

1Jul'01

Aug'01

Sep'0

1Oc

t'01

Nov'0

1

Dec'01

Jan'0

2

Feb'0

2

Mar'0

2

Apr'0

2

Month

kVA

Minimum billable demand1683 kVA

Contracted demand 2250 kVA

Maximum Demand

By reducing

MD (KVA)

Energy ( KWH)


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GERIAP-NPC 13 5

How to reduce MD charge?

Electrical Load Management

Power Factor Improvement

Tariff Management


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Install MD controllers (Automatic load shedding)

ELECTRICAL LOAD

MANAGEMENT OPTIONS

Shift the load to non peak hours


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0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

May'01

Jun'01

Jul'01

Aug'01

Sep'01

Oct'01

Nov'01

Dec'01

Jan'02

Feb'02

Mar'02

Apr'02

Month

kVA

Minimum billable demand 1683 kVA

Contracted demand 2250 kVA

Maximum Demand


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GERIAP-NPC 13 8

0

200

400

600

800

1000

1200

7:00

8:30

10:0

0

11:3

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13:0

0

14:3

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16:0

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17:3

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19:0

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20:3

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22:0

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23:3

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1:00

2:30

4:00

5:30

Time (Hrs)

De

mand,Kva

Maximum Demand curve


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Reducing MD by Power Factor

Improvement

KW = KVA x P.F

100 = 142 x 0.7KW or active power is what is required by the plant. Suppose

if we increase the P.F. to 0.95, then

KVA= 100 / 0.95

KVA= 105So increasing power factor reduces the Maximum Demand


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GERIAP-NPC 13 12

How to improve power factor ?


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What does the capacitor do to

improve P.F. ?


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Other benefits of power factor

correction

Improve voltage to

equipment

Increase Current-

carrying capacity

% Voltage rise = Capacitor kVAR x (Transforemr % Impedence)

Transformer kVA

Reduce power losses (Power Loss =I2R)


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GERIAP-NPC 13 15

Where to reduce Kwh in

electrical systems ?

Transformers

Distribution systems

Motors


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GERIAP-NPC 13 16

Energy savings in Transformers

Optimise loading of transformers

Switch off the primary side of transformer if

it is not serving any loads Maintain balanced voltage with polyphase

transformers by maintaining equal tap

settings. Balance single-phase loads amongphases to keep voltages within 1% of theaverage.


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GERIAP-NPC 13 17

Energy loss in Transformers

Transformer kVA No load loss

(Watts)

Full load copper loss

(Watts)

100 kVA 260 1760

160 kVA 330 2200

200 kVA 540 3300250 kVA 600 3600

315 kVA 700 4200

500 kVA 840 5700

630 kVA 1000 6400750 kVA 1100 7500

1000 kVA 1300 9800


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GERIAP-NPC 13 18

Typical Losses in Induction Motor

Loss component % of total loss

Iron Losses 25

Stator I2r loss 45

Rotor I2r loss 25

Stray load loss 2

Friction & windage loss 3


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Load vs P.F. and Eff.


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Energy savings in motors

Motor Load Survey

of all identified key equipments

measurement of electrical parameters, V, A, PF, kW

compare with the design load and calculate %

loading

Opportunities would include reshuffling of motors,

replacing with energy efficient motors, Rewindingvs new motor


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GERIAP-NPC 13 21

Typical worksheet for Motor load analysis

Sl. Motor Location HP RPM Amp Volt Amps KW PF KVAr KVA HZ Load

No. %

1 Dust collector fan 30 1470 38 397 29.3 15.9 0.82 11.1 20.1 48.0 712 100 ton EPN Press 10 1440 14.7 413 7.34 2.11 0.4 4.77 5.21 48.1 28

3 Circulation Pump 30 1460 41 408 17.3 2.64 0.21 12.0 12.2 48.1 12

4 A/C Plant No.4 50 1460 65 398 37 17.2 0.09 18.7 26.1 48.1 46

5 A/C Plant No.1 50 1460 65 408 22.3 10 0.63 12.5 19.9 48.2 27

Motor load survey


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Energy efficient motors


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GERIAP-NPC 13 23

Benefits of Energy Efficient

Motors: Example

Case-1 Existing

standard motor

Input kW

47.2

Eff. 55%Eff. 90%

Delivered kW

23.37Output - kW

42.5

PumpMotor

Input kW

44.7

Eff. 55%Eff. 95%

Delivered kW

23.37Output - kW

42.5PumpMotor

Case-2 Replaced

with Energy

Eff icient moto r


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GERIAP-NPC 13 24

Analysis of Electrical Power SystemsSystem Problem Common Causes Possible Effects Solutions

Voltage imbalancesor differencesbetween relative

oltage levels amongthe three phases in allor part of a facility.

Improper transformer tapsettings, one single-phase

transformer on a polyphasesystem, single-phase loadsnot balanced amongphases, poor connections,bad conductors,transformer grounds orfaults.

Motor vibration,premature motor failure,energy waste. A 5%imbalance causes a 40%increase in motor losses.

Balance loadsamong phases.

Voltage deviationsrefer to voltagesbeing too low orhigh.

Improper transformersettings, incorrect selectionof motors, e.g., a 230/208motor (which is actually230 rated) on a 208 circuit.

Over-voltages in motorsreduce efficiency, powerfactor, and equipmentlife, and increasetemperature.

Checkandcorrectransformersettings, motorratingsand motorinput voltages

Poor connectionsmay be in distributionor at connected loads.

Loose bus bar connections,loose cable connections,corroded connections, poorcrimps, loose or worncontactors, corrosion ordirt in disconnects.

Wastes energy,produces heat, causesfailure at connectionsite, leads to voltagedrops and voltageimbalances.

Use IR camerato locate hot-spots andcorrect.


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GERIAP-NPC 13 25

Analysis of Electrical Power Systems (Contd.)System Problem Common Causes Possible Effects Solutions

Undersized

conductors.

Facilities expandingbeyond original designs,poor power factors

Voltage drop and energy

waste.

Reduce the loadby conservationload scheduling.

Insulation leakage

Degradation over time due

to extreme temperatures,abrasion, moisture,

chemicals, conductorinsulation inappropriate for

conditions.

May not cause breaker

to trip, and may leak toground or to another

phase. Variable energywaste.

Replaceconductors,

insulators

Low Power Factor

Inductive loads such as

motors, transformers, andlighting ballasts; non-linear

loads, such as mostelectronic loads.

Reduces current-carrying capacity of

wiring, voltageregulation effectiveness,and equipment life. May

increase utility costs.

Add capacitorsto counteract

reactive loads.

Harmonics (non-sinusoidal voltageand/or current wave

forms)

Office-electronics,PBXs,

UPSs, variable frequencydrives, high intensitydischarge lighting, and

electronic and core-coilballasts.

Over-heating of neutral

conductors, motors,transformers, switchgear. Voltage drop, low

power factors, reducedcapacity.

Take care with

equipmentselection andisolate sensitive

electronics fromnoisy circuits.

Documents

B-Electrical Energy Audit.ppt