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Operating Electric Motors

Find the horsepower rating on the nameplate of the motor. Multiply kilowatts (kW) of corresponding horsepower on the chart by the total number of hours the motor is used. This figure – kilowatt-hours (kWh) – multiplied by the applicable rate, will give you the cost of operation.

Example:

How much would it cost to operate a 10 h.p. motor 24 hours per day for three weeks?

10 H.P. 230V 1Ø, 24 hours/day for 3 weeks.

ANSWER: (assuming the electric rate is $.08)

8.625 kW x 24 hours x 21 days = 4,347 kWh
4,347 kWh x $.08 = $347.76

Note: No capacity charge included.

Squirrel cage motors with average efficiency and power factor for each size 1Ø = Single-Phase; 3Ø= Three-Phase
H.P.	115 V 10 kW @ Full Load	230 V 10 kW @ Full Load	230 V 30 kW @ Full Load
1/6	.329	.329
¼	.447	.447
1/3	.571	.571
½	.800	.800	.568
¾	1.159	1.159	.774
1	1.380	1.380	.999
1 ½	1.794	1.794	1.335
2	2.180	2.180	1.893
3	3.167	3.167	2.868
5		4.701	4.478
7 ½		6.808	6.310
10		8.625	8.724
15			12.269
20			16.679
25			20.197
30			24.858
40			33.044
50			38.752
60			48.078
75			60.105
100			82.253

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