Miller Electric Big 40 CAT Power Required To Start Motor, How Much Power Can Generator Supply?

12-8. Power Required To Start Motor

4
		AC MOTOR			2
1
	VOLTS	230	AMPS	2.5
3	CODE	M	Hz	60
	HP	1/4	PHASE 1

Single-Phase Induction Motor Starting Requirements

Motor Start	G		H	J	K	L	M	N	P
Code
KVA/HP	6.3		7.1	8.0	9.0	10.0	11.2	12.5	14.0
kVA/HP x HP x 1000 = STARTING AMPERAGE
	VOLTS
EXAMPLE: Calculate the starting amperage required for a 230 V, 1/4
HP motor with a motor start code of M.
Volts = 230	HP = 1/4 Using Table, Code M results in kVA/HP = 11.2
11.2 x 1/4 x 1000		= 12.2 A		Starting the motor requires 12.2 amperes.
230

1Motor Start Code

2Running Amperage

3Motor HP

4Motor Voltage

To find starting amperage:

Step 1: Find code and use table to find kVA/HP. If code is not listed, multiply running amperage by six to find starting amperage.

Step 2: Find Motor HP and Volts.

Step 3: Determine starting amper- age (see example).

Welding generator amperage out- put must be at least twice the motor’s running amperage.

S-0624

12-9. How Much Power Can Generator Supply?

1

2

1Limit Load To 90% Of Generator Output

Always start non-resistive (motor) loads in order from largest to small- est, and add resistive loads last.

2 5 Second Rule

If motor does not start within 5 seconds, turn off power to prevent motor damage. Motor requires more power than generator can supply.

Ref. ST-800 396-A / S-0625

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