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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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GERIAP-NPC 13 6
Install MD controllers (Automatic load shedding)
ELECTRICAL LOAD
MANAGEMENT OPTIONS
Shift the load to non peak hours
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GERIAP-NPC 13 7
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
0
13:0
0
14:3
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16:0
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17:3
0
19:0
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20:3
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22:0
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23:3
0
1:00
2:30
4:00
5:30
Time (Hrs)
De
mand,Kva
Maximum Demand curve
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GERIAP-NPC 13 9
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GERIAP-NPC 13 10
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GERIAP-NPC 13 11
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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GERIAP-NPC 13 13
What does the capacitor do to
improve P.F. ?
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GERIAP-NPC 13 14
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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GERIAP-NPC 13 19
Load vs P.F. and Eff.
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GERIAP-NPC 13 20
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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GERIAP-NPC 13 22
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.
Recommended