11-8. 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

11-9. 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

OM-4423 Page 51

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Image 57
Miller Electric Big Blue 400 KX manual Power Required To Start Motor, How Much Power Can Generator Supply?