MCB SELECTION CHART FOR MOTOR APPLICATIONS
MCB RATING ( AMPS )
DOL STARTING STAR DELTA
MOTOR HP STARTING
SINGLE PHASE THREE PHASE THREE PHASE
LIGHT DUTY HEAVEY DUTY LIGHT DUTY HEAVEY DUTY
0.05 0.5 1 - - -
0.10 1 2 - - -
0.13 2 2 - - -
0.15 2 3 - - -
0.20 2 3 - - -
0.25 3 4 - - -
0.33 3 5 - - -
0.50 4 6 1 2 -
0.75 5 10 - - -
1.00 6 10 2 3 -
1.25 10 16 - - -
1.50 10 16 3 4 -
2.00 16 20 4 6 -
3.00 16 25 5 10 -
4.00 25 32 - - -
5.00 32 40 10 16 16
6.00 40 50 - - 16
7.50 40 63 16 20 20
10.00 50 63 20 32 25
12.50 63 - 25 40 32
15.00 63 - 32 50 40
20.00 - - 40 63 50
25.00 - - - - 63
Page 1
MCB SELECTION CHART FOR HOUSEHOLD
APPLICATIONS OFFICE REQUIREMENTS
SL.NO APPLIANCE CAPACITY MCB RATING (AMPS)
1 TON 16
1.5 TON 20
1 Air Conditioner
2 TON 20
3 TON 25
165 ltrs 2
2 Refrigerator
285 ltrs 2
1KW 6
3 Water Heater
3KW 16
4 KW 20
4 Geyser
6 KW 32
5 Electric Kettle 1.5 KW 10
6 Mixie ( 50% load ) 200 W 1
7 Vacume cleaner 50 W 0.5
8 Toaster 1.2 KW 6
750 W 4
9 Cooking Range 2W 10
4.5 W 25
1KW 6
10 Room Heater
2KW 10
300 W 2
11 Washing machine
1.3 KW 10
750 W 6
12 Electric Iron
1.25 KW 6
13 Photocopier 1.5 KW 10
14 Mini water cooler (10 lts) 500 W 3
15 Electronic type writer 65 W 0.5
16 EPABX 50 W 0.5
Page 2
CIRCUIT BREAKERS
1.Monthly
1.1Bushings
1.2.Oil level
1.3.Gas preasure
1.4.Space heater
2.Quarterly
1.Finger contacts
2.Clamp connections
3.Replacement of oil in MOCB
4.Breaker operation Local and remote
3.Yearly
3.1 Auxiliary Switches
3.2 Cotacts
3.3 Foundation Bolts
3.4 Limits switchs
3.5 Spring charger
3.6 Locking elements
3.7 Speed of opening
3.8 Relay caliberation
3.9 Sliding part tightness
Page 3
MOTER CURRENT TABLE FOR ALTERNATING CURRENT
B.H.P OF SINGLE PHASE TWO PHASE THREE PHASE
MOTOR 230 volts 400 volts 230 volts 400 volts 346 volts 400 volts 440 volts 500 volts
1/8 1.0 0.6 0.3 0.6 0.4 0.3 0.3 0.3
½ 1.8 1.1 7.0 1.1 0.8 0.7 0.6 0.6
½ 3.5 2.0 1.2 2.0 1.5 1.2 1.0 1.0
¾ 4.8 3.0 1.5 3.0 1.9 1.7 1.4 1.3
1 6.2 4.0 2.0 4.0 2.2 2.0 1.7 1.5
1½ 7.4 4.8 2.5 4.8 2.7 2.5 2.2 1.9
1½ 8.7 5.7 3.0 5.7 3.0 2.8 2.5 2.2
1½ 10.0 6.3 3.2 6.3 3.5 3.2 2.8 2.5
2 11.8 7.0 3.5 7.0 4.0 3.5 3.2 2.8
2½ 14.0 8.2 4.3 8.2 5.0 4.3 4.0 3.6
3 17.5 9.5 5.0 9.5 6.0 5.0 4.5 4.2
4 20.0 12.0 6.5 12.0 7.5 6.5 6.0 5.5
5 24.0 14.0 7.0 14.0 9.0 8.0 7.5 7.0
7½ 36.0 21.0 10.0 21.0 13.0 12.0 11.0 10.0
10 47.0 27.0 13.0 27.0 17.0 15.0 14.0 13.0
12 ½ 59.0 34.0 15.0 34.0 21.0 19.0 18.0 16.0
15 70.0 40.0 19.0 40.0 25.0 22.0 21.0 25.0
20 91.0 53.0 25.0 53.0 33.0 29.0 28.0 36.0
30 135.0 78.0 38.0 78.0 48.0 42.0 39.0 47.0
40 183.0 106.0 50.0 105.6 63.0 56.0 53.0 58.0
50 227.0 130.0 60.0 130.0 79.0 71.0 66.0 58.0
Note: approx.amps.per phase taken by morden induction motor allowing resonable efficiencys
and power factors
Page 4
MAINTANCE SCHEDULE FOR BATTERIES
SL.NO ITEM OF MAINTANCE PERIODICITY
1 Talking Sp.Gr and voltage of pilot cell Daily
2 Checking Sp.Gr and Voltage of each cell Weekly
Cleaning of terminals applying Vaseline and
3 Weekly
topping up with distilled water
4 Leakge test by lamp or voltmeter method Each shift
Checking all connections of charger and
5 Each shift
battery for tightness quality
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