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By B.G. Shankar Managing Director

AGS-Energy Conservation Pvt. Ltd. Hyderabad, AP

ELECTRICAL ENERGY AUDIT FOR POWER OPTIMISATION

CII 9th ENERGY EFFICIENCY SUMMIT 2010ENCON IN ELECTRICAL SYSTEMS

4th Sep’10

Energy Audit is an effective control device for supervision and guidance of energy utilization.

Comprehensive Energy Audit

Electrical Energy Audit

Power Optimisation

Process Optimisation

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Detailed Electrical Energy Audit

Zero Cost Low Cost Med. Cost Capital Cost

Saving Potential by Various Methods Based on Payback Periods

Power Optimisation

Uniform Power Factor

Power Factor Improvement

Energy Eff. Equipment

Saving 5-7% Saving 0.2-0.5% Saving 0.2-0.3% Saving 0.2-1.0%

Payback Immediate

Payback <2 Months

Payback <12 Months

Payback >12 Months

Detailed Electrical Energy Audit is the first step for Power Optimization.

Measurements:

• Operational load parameters of all the individual drive motors from 2.2 KW to the highest range available.

• HT & LT incomer & distribution Network branch loads.

• Incoming & outgoing of Power Transformer load parameters.

• Study of Capacitor distribution for Uniform Power Factor.

Estimation of Savings:

• Based on Data Collected and real-time Measurements

• Based on various experiments and studies carried out at different plants

Power Consumption: Detailed Electrical Energy Audit helps to Identify the reasons for the increased power consumption, if any, and the remedial measures to minimise the wastage.

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Every time the energy audit is carried out it rekindles the interest in Energy Conservation as an important function.

Energy Auditors sharing their experience and knowledge with the plant personnel, helps in fueling the innovative ideas for further action of reduction in Specific Power consumption (SPC)

Any loose connections or heating of cables come to timely vision.

Inform any irregularities in Energy meter CT connections for rectification.

For an external agency due to unbiased vision, a few points for energy conservation may be visible each time they perform the audit and this would help in achieving further saving.

MMCC

Before connecting Capacitor across the motor 37.6 Amps @ 0.64 PF

After connecting Capacitor across the motor 25.6 Amps @ 0.94 PF

MMCC

55 KW Motor

55 KW Motor

15 KVAR

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CM-1RM-2 CM-2RM-1CR-1 CR-2 P/P-1 P/P-2

41489.6A

38.00.59

422115A

58.90.70

416105A

50.60.67

405 V67.2 A35.2 KW0.75 PF

405117A60.90.74

421243A

1470.84

400381A

2310.87

402384A

2240.84

409 V57.1A39.0 KW0.98 PF

41481.4A

57.30.99

424186A

1340.99

404328A

2270.99

41867.5A

47.30.97

399328A

2210.98

42481.7A

58.00.97

41760.2A42.80.99

50 KVAR100 KVAR50 KVAR50 KVAR 50 KVAR 100 KVAR 50 KVAR100 KVAR

BEFORE

AFTER

These Capacitors were connected to improve Power Factor that reduced current flow

1990-91 ACC Research and Consultancy Directorate

1998 ESG / AGS-EC

2004 Dr. K.K. Sasi, and Dr. T.B. Isha … Research material published in Electrical India April’04

Powerboss - An electronic device assessing the load on the motor every cycle of the supply and adjusting the voltage proportionately to the load

All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted

as being self evident. --- Arthur Schopenhauer

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IMPROVING EFFICIENCY OF PARTIALLY LOADED INDUCTION MOTORS

Considering Frequency to be constant; Core loss is proportional to the square of voltage.

Also magnetising component of the stator current decreases due to decreased voltage and hence power factor improves even at partial loads.

Copper

Core

Motor Electrical Losses:1) Copper Loss

2) Core Losses

75

80

85

90

70

95

1005025

Losses in Ind. Motors

Copper Loss – Proportional to Sq. of Load Current. (Variable with Load)

Core Loss – Proportional to Square of Voltage (Constant)

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VOLTAGE

K W

460

380340

440

415

400

VOLTAGE VS KILOWATTS OF A PARTIALLY LOADED INDUCTION MOTOR

In this case 380 volts is the optimum voltage at which the powerconsumption is minimum.

This is not true for all motors as they are loaded differently.

Power optimisation of the entire plant means studying all the equipment and finding out the common acceptable voltage for minimum consumption.

By observing the running load parameters.

By Studying KW verses Voltage at different loads.

By Analyzing various Short Term Tests for the best to achieve optimum voltages.

Past experience from various tests / trials conducted at different plants.

By monitoring critical loads that are more than 90% of the rated capacity.

By observing the current in the network distribution.

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ADDITIONAL BENEFITS OF POWER OPTIMIZATION

a) A cleaning tool for electrical equipment and machinery.

b) Reduces peak demand on Captive Power Plants.

c) Improves Overall Performance of Electrical System.

d) A vision of the entire plant.

e) Exposes any weak and hidden points in the electrical system for corrective measures.

Saving Potential In Process Plants Through Power Optimisation

With the existing facilities of the process plant, just by fine-tuning the operational load parameters, energy consumption can be reduced by about 5-7%

As power optimisation does not require any investment for achieving the saving, it is called a Zero Cost method.

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CONCLUSIONSElectrical Energy Audit is an effective control device for supervision and guidance of energy utilisation. Also helps to identify wastage of energy and necessary conservation steps by Zero, Low, Medium and Capital cost methods.

Detailed Electrical Energy Audit is very essential for Power optimisation that can be done with out any investment where automatic OLTC is provided on the incoming main transformer.

Power Optimisation reduces energy consumption of the overall plant by about 5%. Due to reduction in energy wastage, the machinery life increases.

Effective utilisation of capacitors by uniform distribution according to the load and at load end reduces cable losses

Power factor improvement at LT distribution network improves cable life due to reduced flow of current.

Power factor improvement through capacitors and through power optimisation improves equipment reliability apart from saving.

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The following slides with Bar Graph is made

with the similar conditions for

comparing the Kwh/Ton of Material

Before and After Power Optimisation.

i.e.,

Same Production

• Same Rate of Production

• Same Running Hours

22

23

24

25

26

27

28

29

30

18-Jan 19-Jan 21-Jan 3-Mar 5-Mar

Running HourskWh/MT Mat erialProduct ion/ 400TPH/15

s

Before Power Optimisation After Power Optimisation

PYRO PROCESS

10

0

5

10

15

20

25

30

3-Jan 17-Jan 21-Jan 23-Jan 12-Feb 21-Feb 28-Feb 2-Mar

Runni ng Hour skWh/ MT Mater ialPr oducti on/ 1000TPH/ 40

Before After RAW GRINDING (24 Hr Basis)

VARIATION IN ENERGY CONSUMPTION - RAW MILL NO.1

20.66

20.1

19.46

18.5618.85

24.38

20.09 20.1

21.62

20.16

18.5518.29

18.24

15

16

17

18

19

20

21

22

23

24

25

8/30/2005 9/1/2005 9/3/2005 9/5/2005 9/7/2005 9/9/2005 9/11/2005 9/13/2005 9/15/2005

DATE

Ener

gy C

onsu

mpt

ion

(Kwh

/Ton

)

Before After

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VARIATION IN ENERGY CONSUMPTION - RAW MILL 2

20.04

20.92

19.5219.29

20.01

18.7518.76

18.62

18.918.76

19.12

19.48

17

17.5

18

18.5

19

19.5

20

20.5

21

21.5

9/2/2005 9/3/2005 9/4/2005 9/5/2005 9/6/2005 9/7/2005 9/8/2005 9/9/2005 9/10/2005 9/11/2005 9/12/2005 9/13/2005 9/14/ 2005 9/ 15/2005

DATE

Energ

y con

sump

tion (

Kwh/T

on)

Before After

10500

11000

11500

12000

12500

13000

13500

1 2 3 4 5 6 7

KWh/HV*2

DISTRIBUTION NETWORK

12

0

20

40

60

80

100

120

140

Earlier Consumption (1999-00)

Power Optimisation (1999-00)

Process Improvement (2000-01)

Power Optimisation (2002-03)

Coromandel Cements Ltd.

Specific Electrical Energy Consumption in Units / Ton of Cement

128122

98 95

82

83

84

85

86

87

88

89

Present Consumption Zero Cost Method Low Cost Method (RS 260,000)

Medium Cost Method (RS 750,000)

Estimated Cost for Implementation

Specific Electrical Energy Consumption in Units / Ton of Cement

88.0

84.5

84.083.8

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