12615-Energy Efficient Motors

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IS 12615:2004

ENERGY EFFICIENT INDUCTION MOTORS THREE PHASE SQUIRREL CAGE

(First Revision)ICS29.160,30

@ BIS 2004

BUREAU OF IN DIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC

NEW DELHI 110002

November 2004 Price Group 5

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Rotating Machinery Sectional Committee, ET 15

FOREWORD

This Indian Standard (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by theRotating Machinery Sectional Committee had been approved by the Electrotechnical Division Council.

This standard was first published in 1989. The first revision is brought out to take into account the latest technologicaldevelopments primarily to cater the national need for energy conservation by the use of energy efficient motors.Energy efficient motors are categorized with two efficiency levels, that is, Improved efficiency ( eff 2) and Highefficiency ( eff 1) both of which are higher than the nominal values specified in IS 8789: 1996 Values ofperformance characteristics for three phase induction motors (firstrevision).

In preparing this standard, assistance has been derived from the following International Standards:

IEC 60034-1 Rotating electrical machines Part 1: Rating and performance

IEC 60034-2 Rotating electrical machines Part 2: Methods for determining losses and efficiency ofrotating electrical machinery from tests (excluding machines for traction vehicles)

IEC 60038 IEC standards voltages

IEC 60050(411) IEV Chapter411: Rotating machinery

The comprehensive standard revision is prepared with Energy Conservation as the major requirement. The earlierstandard specified efficiency values for only a limited range of 4 pole motors. It has been updated in this revision tobe in line with present international norms in addition to the prevailing environmental and grid conditions in India.

Limited energy resources, scarcity of capital and high interest cost for addition of new generation capacity is leadingto increase in the cost of electrical energy in India. As electric motors consume major portion of electrical power, theusage of energy efficient motors will go a long way in the proper utilization of available resources and help inimproving environment.

Power factor can be improved with the use of capacitors to reduce the line losses. However, inherent motor efficiencycannot be improved further once it is manufactured and installed. Hence efficiency improvement is the main focus inthis revision.

To ensure satisfactory installation and maintenance of induction motors, the recommendations contained inIS 900:1992 Code of practice for installation and maintenance of induction motors (second revision) should befollowed.

For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,observed or calculated, expressing the result of a test, shall be rounded off in accordance with IS 2: 1960 Rules forrounding off numerical values (revised). The number of significant places retained in the rounded off value shouldbe the same as that of the specified value in this standard.

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IS 12615:2004

Indian StandardENERGY EFFICIENT INDUCTION MOTORS

THREE PHASE SQUIRREL CAGE(First Revision)

1 SCOPE

1.1 This standard covers the requirements and performanceof energy efficient, 3 phase squirrel cage inductionmotors in 2, 4, 6 and 8 poles for all frame sizes up to315 L, having output ratings as specified in IS 1231 forcontinuous duty (S1) operation, at rated voltage andfrequency of 415 volts, 50Hz.

1.2 The performance of motors designed for operationon voltage, other than rated voltage of 415 V or up to650 V, shall be in accordance with the relevantperformance Tables 1 to 4 except the full load currentvalues. The full load current will vary in the inverseproportion to the voltage in comparison to the valuesspecified in the above-referred tables.

1.3 To conform to this standard and eligible to beconsidered as energy efficient, the motors shall meet thenorms specified in Tables 1 to 4 when read with 4 relatedto site conditions as applicable. All performance valuesare subjected to tolerance specified in IS 325.

2 REFERENCES

The standards listed in Annex A are necessary adjuncts tothis standard.

3 TERMINOLOGY

For the purpose of this standard, definitions given inIS 1885 (Part 35)/IEC 60050-411 (1993) shall apply.

4 SITE CONDITIONS

The following shall constitute the normal site conditions.

4.1 Altitude and Temperature

Motors shall be designed for the following site conditionsunless otherwise agreed to between the manufacturer andthe purchaser.

4.1.1 Altitude

a) Altitude not exceeding 1000 m.b) For motors intended for service on sites where the

altitude is in excess of 1000 m but below 2000 m,unless otherwise specified, the ambient tempera-

1

ture shall be assumed to be reduced accordingto 6.3 of IS 12802 and same performance values asin Tables 1 to 4 shall be applicable.

c) For even higher altitudes up to 4000 m or for theconditions for altitudes above 1500 m and ambi-ents not reducing enough to compensate for theeffect of reduced cooling to 6.3 of IS 12802, theperformance figures shall in accordance with 4.1.2,of this standard applicable to motors for 55Cambient.

4.1.2 Temperature

a) The cooling air temperature not exceed~ng 40C.b) Motors intended for service with a cooling air tem-

perature above 40C and up to 55C shall bedeemed to be meeting this standard provided theymeet the following conditions:

1) The break away current values are equal to orbelow 1.1 times of values specified in Tables 1to 4.

2) Efficiency as specified in 17.1.2.4.2 Form and Symmetry of Voltages and Currents

The motor shall be so designed as to be able to operateon virtually sinusoidal and balanced voltage conditionsas defined in 4.2.2 of IS 4722.

4.3 Voltage and Frequency Variation

Motors shall be capable of delivering rated output with:

a) The terminal voltage differing from jts rated valueby not more than *1O percent, or

b) The frequency differing from its rated value by notmore than *5 percent, or

Combined variation The sum of absolute percentvariations of(a) and (b) not exceeding 10 percent.

In the case of continuous operation at extreme voltagelimits, the temperature-rise limits specified in Table 1 ofIS 12802 shall not exceed by more than 10C for motorscovered under this standard. Motors, when operated underthe extreme conditions of voltage and frequencyvariations, may not necessarily have their performancein accordance with this standard.

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IS 12615:2004

4.4 Location, Moisture, Fumes, etc

It shall be assumed that the location and moisture or fumesshall not seriously interfere with the operation of themotor.

5 TYPE OF ENCLOSURES

The motors covered under this standard shall have 1P 44or superior degree of protection provided by theenclosures specified in IS 4691.

6 METHODS OF COOLING

The method of cooling shall be IC 411 in accordancewith IS 6362AEC Pub 60034-6:1991,

7 STANDARD VOLTAGE AND FREQUENCY

7.1 Standard Voltage

The preferred rated voltage shall be415 V (see ah 1.2).

7.2 Standard Frequency

The standard frequency shall be 50 Hz.

8 DUTY AND RATING

The motors shall be rated for duty type S1 (continuousduty) as specified in 9.2 of IS 325.

9 DIMENSIONS, FRAME NUMBER AND OUTPUTRELATIONSHIP

The fixing dimensions and shaft extensions of motorsshall conform to the values specified in IS 1231 andIS 2223 as relevant.

The relationship between output in kW and frame numbershall conform to IS 1231, IS 2223 and IS 2254 as relevant.For additional ratings, preferred frame sizes are listed.

10 EARTHING

The earthing on the motor shall be provided inaccordance with IS 3043.

11 OVERLOAD

11.1 Momentary Excess Torque

The motor shall be capable of withstanding 1.6 times therated torque for 15 s without stalling or abrupt change inspeed (under gradual increase of torque), the voltage andfrequency being maintained at their rated values.

11.2 Pull up Torque

Unless otherwise specified, the minimum pull-up torqueof motors, at rated voltage and frequency shall beminimum 0.70 times the rated full load torque.

11.3 Sustained Overloads

Motor rated in accordance with this standard are notexpected to be capable of carrying sustained overloads.

12 TEMPERATURE RISE

12.1 The determination of the temperature rise of motorsdelivering rated output under rated conditions of voltage,frequency shall be in accordance with IS 12802.

12.1.1 The limits of temperature rise shall be 80C (byresistance method) over an ambient of 40C for motorwith Class B or Class F insulation, however, Class Finsulation is preferred.

12.1.2 For higher ambient up to 55C, the temperaturerise shall be within the permissible limits given inTable 1 of IS 12802 as applicable to the class of insulationused.

13 LIMITS OF VIBRATION

The motors manufactured shall conform to Normalvibration severity according to IS 12075.

14 PERFORMANCE VALUES

14.1 Operating at rated voltage and rated frequency, theperformance of the motor at rated conditions shall be asspecified in Tables 1 to 4. All the performance valuesincluding those for special conditions, for example,specified in 4.1 above, etc, are subject to tolerance asspecified in IS 325.

14.2 The value of full load current shall be taken as theaverage of the currents measured in the three phases.

14.3 For motors having rated voltage other than 415V,the performance of the motor shall be as per the values inthe relevant tables, except that the value of the maximumfull load current would be changed in the inverseproportions of the voltage.

15 NOISE LEVEL

The noise level of motors shall be in accordance withIS 12065.

16 TERMINAL MARKING

The terminal markings shall be in accordance withIS 4728.

17 EFFICIENCY

17.1 For compliance with the requirements of this standard,the values of efficiency subject to IS 325 tolerance, listedunder appropriate efficiency class (either improvedefficiency eff 2 or high efficiency eff 1) in Tables 1to 4, shall be met as specified below.

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IS 12615:2004

17.1.1 Up to40C Ambient and 1 OOOm Altitude 18.2 Test CertificatesTables 1 to 4.

18.2.1 Unless otherwise specified atthetime of inviting17.1.2 ForAmbientAbove 40C and Up to 55 CAltitude tenders and agreed by the manufacturer, the purchaserUp to 1000 m shall accept manufacturers certificate ~Sevidence of

Efficiency corresponding to 10 percent more losses forcompliance of the motor with the requirements of this

the same rating compared to those in Tables 1 to 4.standard together with a type test certificate (see 22.3.1of IS 325) on a motor identical in essential details with

That is, allowable nominal efficiency in percent: the one purchased, together with routine tests on eachindividual motor.

100 x Nominal efficiency percent from tables110 (O.1 x Nominal efficiency percent) 18.2.2 Certificate of routine tests shall show that the

motor purchased has been run and has been found toHowever, the breakaway current of the motor shall be electrically and mechanically sound workingnot exceed 1.1 times the relevant value specified in Tables 1 condition.to 4.

18.2.3 If so specified when inviting tenders, tests shall17.1.3 For Altitude Above 1000 m be carried out at the manufacturers works in the presence

As specified 4.1.1 (b) and (c)is applicable. of the purchaser or his representative to ensure that themotor complies in every respect with the requirements

17.2 The losses and efficiency of these motors are to of 9, 11, 14, temperature rise of winding, high voltagecalculated according to 4.1 of IS 4889 and 7.5.3.2 of test, insulation resistance test and to ascertain that theIS 4029. efficiency conforms to the guaranteed value.

17.3 To ensure a representative test result for windage and 19 LABELINGfriction losses and in accordance with common practice,the test should be done in a stabilized bearing condition Reference of this standard, that is, IS 12615 shall beand in case of motors with seals without installed seals. prominently displayed. In addition to the data specified

18 TEST AND TEST CERTIFICATESin IS 325, the motor manufacturer shall add theappropriate efficiency class (for example, eff 2) as an

18.1 Tests and Their Classification additional information on the name plate after theefficiency value.

Tests and their classification shall be in accordance 20 COST EFFECTIVENESSwith 22.1 to 22.3 of IS 325. The type and routine tests onmotors shall be performed in accordance with IS 325 in Guidance may be taken from Annex B for working outconjunction with other relevant standards. the cost effectiveness of energy efficient motors.

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IS 12615:2004

Table 1 Values of Performance Characteristic of 2 Pole Energy Eff]cient Induction Motora(Clauses 1.2,1.3,4.1.1,4.1.2, 14.1,17 .1,17.1.1 and 17.1.2)

Rated Frame Full Full Breakaway Breakaway Nominal Efficiencyoutput Designation Load Load Torque in Terms of Current in Terms of full

Speed Current Full Load Torque CurrenL Equal or Below

Min Max Min

For eff 2 For eff 1 For eff 2 For eff 1kW Rev/rnirr Amp Percent Percent Percent Pereent Pereent(1) (2) (3) (4) (5) (6) (7) (8) (9)0.37 71 2790 1.2 170.0 600 650 66.0 70.20.55 71 2760 1.6 170.0 600 650 70.0 74.00.75 80 2780 2.0 170.0 600 650 73.0 77.01.1 80 2790 2.8 170.0 600 650 76,2 82.81,5 90s 2800 3.7 170.0 600 650 78.5 84.12.2 90L 2810 5.0 170.0 650 700 81.0 85.6

3.7 100L 2820 8.0 160.0 650 700 84.0 87.5

5.5 132S 2830 11.0 160.0 650 700 85.7 88.67.5 132S 2840 15.0 160.0 650 700 87.0 89.5

9.3 160M 2840 18.5 160.0 650 700 87.7 90.0

11,0 160M 2860 21.5 160.0 650 700 88.4 90.5

15.0 160M 2870 29.0 160.0 650 700 89.4 91.318.5 160L 2880 35.0 160.0 650 700 90.0 91.8

22.0 180M 2890 41.5 160.0 650 700 90.5 92.2

30.0 200L 2900 54.0 160.0 650 700 91.4 92.9

37.0 200L 2900 67.0 160.0 650 700 92.0 93.3

45,0 225M 2955 80.0 160.0 650 700 92.5 93.7

55.0 250M 2960 95.0 160.0 650 700 93.0 94.0

75.0 280S 2970 130.0 160.0 650 700 93.6 94.6

90.0 280M 2970 150.0 160.0 650 700 93.9 95.0

110.0 315s 2980 185.0 160.0 650 700 94.0 95.0

125.0 315M 2980 209.0 160.0 650 700 94.5 95,3

132,01 315M 2980 220.0 160.0 650 700 94.5 95.3

160.0) 315L 2980 265.0 160.0 650 700 94.8 95.5

NOTE Output to frame size relation is maintained in accordance with IS 1231 for all motors, except those marked as ],wherein the frame size indicated is preferred frame size.

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IS 12615:2004

Table 2 Values of Performance Characteristic of 4 Pole Eneqgy Efficient Induction Motors(Clauses 1.2,1.3,4.1.1,4.1.2, 14.1,17 .1,17.1.1 and 17.1.2)

Rated Frame Full Full Breakaway Breakaway Nominal Efficiencyoutput Desi~ation Load Load Torque in Terms Current in Terms of Full

Speed Current of Full Load Curren~ Equal or BelowTorque

Min Max Min

For eff 2 For eff 1 For eff 2 For eff 1

kW I Rev/rein Amp Percent Percent Percent Percent Percent(1) (2) (3) (4) (5) (6) (7) (8) (9)

0.37 71 1330 1.4 170.0 550 600 66.0 73.00.55 I 80 1 340 1.7 170.0 550 600 70.0 78.00.75 80 1 360 2.2 170.0 550 600 73.0 82.51.1 90s 1 370 2.9 170,0 550 600 76.2 83.81.5 I 90L 1 380 3.8 170.0 550 600 78.5 85.02.2 100L 1 390 5.1 170.0 600 700 81.0 86.4

3.7 112M 1 410 8.1 160.0 600 700 84.0 88.35.5 132S 1420 11.4 160.0 600 700 85.7 89.27.5 132M 1430 15.4 160.0 600 700 87.0 90.19.3 160M 1430 18.5 160.0 600 700 87.7 90.5

11.0 160M 1 440 22.0 160.0 600 700 88.4 91.015.0 160L 1 440 30.0 160.0 600 700 89.4 91.818.5 180M 1 440 36.0 160.0 600 700 90.0 92.222.0 180L 1 440 43.0 160.0 600 700 90.5 92.610.0 200L 1 450 56.0 160.0 600 700 91.4 93.2)7.0 225S 1 450 69.0 160.0 650 700 92.0 93.615.0 225M 1460 84.0 160.0 600 700 92.5 93.9\5. O 250M 1460 99.0 160.0 600 700 93.0 94.215,0 280S 1470 134.0 160.0 600 700 93.6 94.7)0.0 280M 1 470 164.0 160.0 600 700 93.9 95.0I10.0 315s 1 480 204.0 160.0 600 700 94.4 95.2125.0 315M 1 480 234.0 160.0 600 700 94.7 95.5132.01J 315M 1 480 247.0 160.0 600 700 94.7 95.5160.01) 315L 1480 288.0 160.0 600 700 95.0 95.8

NOTE Output to frame sire relation is maintained in accordance with IS 1231 for all motors, except those marked as 1),wherein the frame size indicated is preferred frame size.

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IS 12615:2004

Table 3 Values of Performance Characteristic of 6 Pole Energy Efficient Induction Motors(Clauses 1.2,1.3,4.1.1,4.1.2, 14.1,17 .1,17.1.1 and17.1.2)

Rated Frame Fulloutput Designation Load

Speed

-1--+I I

0.55 80 .1 870

0.75 I 90s I 8901.1 90L 900

EEEE7.5 I 160M I 930

9.3 160L 930

30.0 I 225M i 945

55.0 I 280M I 960

75.0 I 315.S I 970

Full I Breakaway BreakawayLoad Torque in Terms Current in Terms-of Full

Current of Full Load Curren~ Equal or BelowTorque

Max Min

For eff 2 I For eff 1Amp ! Percent Percent I Percent(4) (5) (6) (7)1.4 160.0 550 I 6001.9 160.0 550 6002.3 160.0 550 6003.2 160.0 550 6004.0 160.0 550 6005.5 150.0 600 7008.8 150.0 600 700

12.7 150.0 600 70016.7 I 150.0 600 I 70020.5 140.0 I 600 700

23.0. 140.0 600 I 70030.5 140.0 600 700

1 1 1

37.5 140.0 600 700r 1 1

44.0 140.0 600 700

Nominal Eftlciency

For eff 2 Fur eff 1Percent Percent

-+--R-68.0 I 72.071.0 ] 74.6

+%-R+%--%

84.5 / 86.886.0 I 88.187.0 89.3

=+=

87.5 89.788.5 90.589.5 91.390.0 91.8

59.0 140.0 600 700 91.0 1- 92.672.0 I 140.0 600 I 700 I 91.5 93.087.0 140.0 600 700 92.0 93.4

107.0 140.0 600 700 92.5 93.8145.0 140.0 600 700 93.0 94.2175.0 140.0 600 700 93.3 94.5214.0 140.0 600 700 93.5 94.6257.0 140.0 600 700 93.8 94.9

NOTE Output to frame size relation is maintained in accordance with [S 1231 for all motors, except those marked as ),wherein the frame size indicated is preferred frame size.

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IS 12615:2004

Table 4 Values of Performance Characteristic of 8 Pole Ewrgy Efficient Induction Motors(Clauses 1.2,1.3,4.1.1,4.1.2, 14.1,17 .1,17.1.1 and 17.1.2)

Rated Frame Full Full Breakaway Breakaway Nominal E~lciencyoutput Designation Load Load Torque in Terms Current in Terms of Full

Speed Current of Full Load Curren$ Equal or BelowTorque

Min Mux Min

For eff 2 For cff 1 For eff 2 For eff 1kW Revlmin Amp Percent Percent Percent Percent Percent(1) (2) (3) (4) (5) (6) (7) (8) (9)

0.37 90s 640 1.5 150.0 550 600 62.0 66.80.55 90L 640 2.1 150.0 550 600 67.0 71.10.75 100L 650 2.7 150.0 550 600 70.0 73.81.1 100L 660 3.5 150.0 550 600 72.0 76.21.5 I12M 670 4,5 150.0 550 600 74.0 77.92.2 132S 680 6.1 140.0 600 700 77.0 80.53.7 160M 690 9.8 140.0 600 700 80.0 83,05.5 160M 690 14.2 140.0 600 700 82.5 85. I7.5 160L 695 19.0 140,0 600 700 84.0 86.49.3 180L 700 23.0 140.0 600 700 85.0 87.3

11.0 180L 700 26.0 140.0 600 700 86.0 88.115,0 200L 705 35.0 130.0 600 600 87.0 89.018.5 225S 705 45.0 130.0 600 700 88.0 89.822.0 225M 710 52.0 130.0 600 700 88.5 90.230.0 250M 710 70.0 130.0 600 700 90.0 91.537.0 280S 710 86.0 130,0 600 700 90.5 91.945,0 280M 720 99.0 130.0 600 700 91.0 92.455.0 315s 720 118.0 130.0 600 700 91.5 92.875,0 315M 730 153.0 I 30.0 600 700 92.3 93.590.0) 315L 730 182.0 130.0 600 700 92.8 93.9110.0) 315L 730 218.0 130.0 600 700 93.3 94.3

NOTE Output to frame size relation is maintained in accordance with IS 1231 for all motors, except those marked as II, whereinthe frame size indicated is preferred frame size.

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IS 12615:2004

IS No.

325:1996

900:1992

1231:1974

1885 (Part 35) :1993

2223:1983

2254:1985

3043:1987

4029:1967

4691:1985

ANNEX A(C/ause 2)

LIST OF REFERRED INDIAN STANDARDS

Title

Three-phase induction motors(jirst revision)

Code of practice for installationand maintenance of inductionmotors (second revision)

Dimension of three-phase foot-mounted induction motors (thirdrevision)

Electrotechnical vocabulary:Part 35 Rotating machines (firstrevision)

Dimensions of flange mounted acinduction motors (@t revision)

Dimensions of vertical shaftmotors for pumps (secondrevision)

Code of practice for earthing (firstrevision)

Guide for testing three-phaseinduction motors

Degrees of protection provided byenclosure for rotating electricalmachinery fjlrst revision)

IS No.

4722:2001

4728:1975

4889:1968

6362:1995

8789:1996

12065:1987

12075:1987

12615:1989

12802:1989

Zitle

Rotating electrical(second revision)

machines

Terminal marking and direction ofrotation for rotating electricalmachinery (/7rst revision)Method of determination ofefficiency of rotating electricalmachines

Designation of methods of coolingof rotating electrical machines(@ revision)VaIues of performancecharacteristics for three-phaseinduction motors @rst revision)Permissible limits of noise levelfor rotating electrical machines

Mechanical vibration of rotatingelectrical machines with shaftheights 56 mm and higher-measurement, evaluation andlimits of vibration severity(superseding IS 4729)Energy efficient, three-phase,squirrel cage induction motors

Temperature-rise measurement ofrotating electrical machine

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IS 12615:2004

ANNEX B(Clause 20)

CALCULATIONS FORASSESSING COST EFFECTIVENESS OF ENERGY EFFICIENT MOTORS

B-1 CALCULATION

The formulae given below illustrate the calculations ofsavings in the operation of energy efficient motors:

a)

b)

c)

d)

Extra investment on energy efficient motors:

Let X = Cost of standard motor, in Rs.

x, = Cost of energy efficient motor, in Rs.

1 = Interest rate on investment inpercentage per annum.

Interest on extra investment per annum:

= (X, -x)+(x, -x)xuloo

Savings on account of using energy efficientmotors:

Let E = Efficiency of standard motor, inpercent.

E, = Efficiency of energy efficient motorin percent.

P = Power output of motor, in kV.

H = Number of hours of operation of motorper year.

Energy saved per annum:

=P [(l/E) -(l/E,)] xlfloxlfin kWhLet Tbe the energy tariff (cost of power per kWh)Savings per annum in Rs = Energy saved x T.

Payback period of months:= Extra investment (A)/Savings per annum x 12months

Payback period is less than one year Net savings in first year= Saving per annum extra investment for first year (A)NOTE If the payback period is more than one year,the interest on extra investment for subsequent periodshould be considered.

B-2 TYPICAL EXAMPLE : M~OR RATING 11 kW,4 POLE

According to the formula given in B-1 the example maybe worked out as follows for eff 1 and eff 2 motors:

Let X = Rs. 12500 price for motor conforming toIS 8789.

xl

x,

I

a)

b)

c)

d)

e)

= Rs. 18000 price for eff 1 energy efficientmotor.

= Rs. 14500 price of eff 2 energy efficientmotor.

= 15 percent interest per annum.

The extra investment on energy efficient motorfor first year=Rs. (X,-w+ (X,-X)X1 100Foreffl = Rs. (18000-12500)+(18000-2

500) X 15/100=Rs.6325Foreff 2= Rs. (14500-12500)+(14500-2

500) x 15/100=Rs.2300

Let E = 85.5 percent efficiency according toIS 8789 of Standard motorE, = 91 percent efficiency eff 1 as per Table 2;Ez = 88.4 percent efficiency eff 2 as per the

Table 2;P = 1lkW, rated power of motor; and

H = 2400 h, working hours per year.Energy saved (eff 1) = 11(1/85.5 1/91) x 100x2400 =1866kWhEnergy saved (eff 2 ) = 11(1/85.5 - 1/88.4) x 100X 2 400= 1013 kWh

Tariff = Rs. 4 per kWh (rate per unit energy)

Savings per annum (eff 1) = Rs. 1866 x 4.0=Rs. 7464.

Savings per annum (eff 2) = Rs. 1013x 4.00=Rs. 4052.

Payback period (eff 1) = 6 325/7 464 x 12 = 10.2months

Payback period (eff2)=2300/4 052 x 12= 6.8months

Net saving in first year (eff 1) = Rs. 7464-6325 =Rs. 113

Net saving in first year(eff2)=Rs.4052 -2300 = Rs. 1752Saving in subsequent years (eff 1) = Rs. 7464per year

Saving in subsequent years (eff2)=Rs.4052per year

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Title Page Foreword1. Scope2. References3. Terminology4. Site Conditions5. Type of Enclosures6. Methods of Cooling7. Standard Voltage and Frequency8. Duty and Rating9. Dimensions, Frame Number and Output Relationship 10. Earthing11. Overload12. Temperature Rise 13. Limits of Vibration14. Performance Values15. Noise Level16. Terminal Marking17. Efficiency18. Test and Test Certificates 19. Labeling20. Cost EffectivenessTable 1Table 2Table 3Table 4

Annex AList of Referred Indian Standards

Annex B