STARTING ELECTRIC MOTORS

multiplying nameplate voltage by nameplate amperage.

VOLTS

X AMPS

= WATTS

Example: 120V

X 5A

= 600W

When connecting a resistive load such as incandescent lights, heaters or common electric power tools, a capacity of up to the generator full rated wattage output can be used.

When connecting a resistive-inductive load such as a fluorescent or mercury light, transformers or inductive coils, a capacity of up to 0.6 times the generator’s full rated output can be used.

Always allow the generator to reach operating speed before a load is applied.

STARTING ELECTRIC MOTORS

Electric motors require much more current (amps) to start than to run. Some motors, particularly low cost split-phase motors, are very hard to start and require 5 to 7 times more current to start than to run. Capacitor motors are easier to start and usually require 2 to 4 times as much current to start than to run. Repulsion Induction motors are the easiest to start and require 1.5 to 2.5 times as much to start than to run.

Most fractional motors take about the same amount of current to run them whether they are of Repulsion-Induction (RI), Capacitor (Cap), or Split- Phase (SP) type. The following chart shows the approximate current required to start and run various types and sizes of 120 volt 60 cycle electric motors under various conditions.

120V, 60 Hz Motors

Starting Amps

Hp motor

Running

RI type

Cap type

SP type

 

Watts

 

 

 

the engine. If allowed to operate at very low speeds, the electric motor starting winding will burn out in a short time. The generator head winding might also be damaged.

Running the generator under these conditions may result in damage to the generator stator as well as the motor windings. Because the heavy surge of current is required for only an instant, the generator will not be damaged if it can bring the motor up to speed in a few seconds. If difficulties in starting a motor are experienced, turn off all other electrical loads and if possible reduce the load on the electric motor.

EXTENSION CORDS

When electric power is to be provided to various loads at some distance from the generator, extension cords can be used. These cords should be sized to allow for distance in length and amperage so that the voltage drop between the set and point of use is held to a minimum.

Current/Power

Maximum Extension Cord Length

Amps

Load

#10

#12

#14

#16

at

(watts)

Ga.

Ga.

Ga.

Ga.

240V

 

Cord

Cord

Cord

Cord

10

2400

250’

150’

100’

75’

20

4800

125’

75’

50’

25’

30

7200

60’

35’

25’

10’

40

9600

30’

15’

10’

*

50

12000

15’

*

*

*

 

 

 

*Not

recommended

CAUTION: Equipment damage can result from the low voltage caused by using an extension cord with a small wire size.

Use this chart to estimate the total load on your generator.

For Determining Generator Load Requirements

1/6

1/4

1/3

1/2

1

11/2

2

3

5

525

700

875

1175

1925

2400

2900

4075

6750

7-11

9-15

11-18

15-25

24-40

30-50

36-60

51-85

84-140

9-18

12-23

14-29

20-40

32-64

40-80

48-96

68-136

112-224

16-22

22-32

26-35

NA NA NA NA NA NA

 

Dev ice

Running Watts

 

Air Conditioner (12,000 Btu)

1700 (b)

 

 

Battery Charger (20 Amp)

500

 

 

Belt Sander (3”)

1000

 

 

Chain Saw

1200

 

 

 

 

 

 

Circular Saw (6-1/2”)

900

 

 

Coffee Maker

1000

 

 

Compressor (1 HP)

2000 (b)

 

 

Compressor (3/4 HP)

1800 (b)

 

 

Compressor (1/2 HP)

1400 (b)

 

The figures given above are for an average load such as a blower or fan. If the electric motor is connected to a hard starting load such as an air compressor, it will require more starting current. If it is connected to a light load or no load such as a power saw, it will require less starting current. The exact requirement will also vary with the brand or design of the motor.

Generators respond to severe overloading differently than the power line. When overloaded, the engine is not able to supply enough power to bring the electric motor up to operating speed. The generator responds to the high initial starting current, but the engine speed drops sharply. The overload may stall

Curling Iron

700

Dishwasher

1200

Edge Trimmer

500

Electric Nail Gun

1200

Electric Range (one element)

1500

Electric Skillet

1250

Furnace Fan (1/3 HP)

1200 (b)

 

 

Freezer

800 (c)

Hair Dryer

1200

Hand Drill (1”)

1100

Hand Drill (1/2”)

875

Hand Drill (3/8”)

500

Hand Drill (1/4”)

250

6

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Image 7
North Star 5500 owner manual Starting Electric Motors, Extension Cords