Miller Bobcat 250 Application Manual - Page 11

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8. Power Required To Start A Motor

VOLTS

CODE

Single-Phase Induction Motor Starting Requirements

Motor Start

Code

KVA/HP

EXAMPLE: Calculate the starting amperage required for a 230 V, 1/4 HP

motor with a motor start code of M.

Volts = 230

11.2 x 1/4 x 1000

230

9. How Much Power Can The Generator Supply?

AC MOTOR

230

AMPS

1/4

PHASE

6.3

7.1

kVA/HP x HP x 1000

VOLTS

HP = 1/4

Using Table, Code M results in kVA/HP = 11.2

= 12.2 A

Starting the motor requires 12.2 amperes.

2.5

8.0

9.0

10.0

= STARTING AMPERAGE

1 Motor Start Code

2 Running Amperage

3 Motor HP

4 Motor 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 start-

ing amperage.

Step 2: Find Motor HP and

Volts.

Step 3: Determine starting

amperage (see example).

Welding generator amper-

age output must be at least

twice the motor's running

amperage.

11.2

12.5

14.0

1 Limit Load To 90% Of

Generator Output

Always start non-resistive

(motor) loads in order from

largest to smallest, and add

resistive loads last.

2 5 Second Rule

If motor does not start within

5 seconds, turn off power to

prevent motor damage. Mo-

tor requires more power than

generator can supply.

803 636 / S-0625

S-0624

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