Search This Blog

Friday, September 2, 2011

Generator School

Generators (Portable) Wattage Requirements & Calculator

There are different categories to consider when choosing a generator for your needs: recreation, home standby and construction. You may also want to consider using an inverter generator for sensitive electronic devices. Inverter generators are smaller and lighter as power is created electronically and not through a conventional alternator. Inverter power offers the cleanest power output.

If you want a generator for home standby, say to run your refrigerator, you'll need at least 2500 watts or more. And if you want to use a transfer switch so that power can go directly into your home, you'll want a generator with at least 3000 watts.

You'll also need to consider the maximum and rated power of the generator. This is important depending on what items you want to run off of your generator. Items such as toaster, lamps, and coffee makers are resistive , or constant loads and their total load can be calculated at amps x 1. Items such as saws and drills are reactive loads and while the running load may be small, the starting load should be calculated at running amps x 3. Remember, after the intial start less power is required for actual operation.

Always remember that simple power management will allow a smaller generator to do a big job. Very seldom are all tools or appliances operating simultaneously. When calculating power requirements, consider the starting requirements are only for the initial start and then additional tools may be operated in addition.

Remember Ohm's Law
Watts = Volts x Amps
Amps = Watts/Volts

So, if you have two of the numbers (e.g. volts, amps) then you can find out the other (e.g. watts). This can help you to determine the rated power that you'll need from your generator.
AVERAGE WATTAGE REQUIREMENT GUIDE
(AMPS X VOLTS = WATTS)
Household
Running
Wattage
Requirements
Additional
Wattage Required
For Starting
Coffee Maker
1750
0
Dishwasher
Cool Dry
700
1400
Electric Fry Pan
1300
0
Electric Range
8-inch element
2100
0
Microwave Oven 625 watts
625
800
Refrigerator or Freezer
700
2200
Automatic Washer
1150
2300
Clothes Dryer
Electric
5750
1800
Furnace Fan, gas or fuel oil
1/8 Horsepower
300
500
1/6 Horsepower
500
750
1/4 Horsepower
600
1000
1/3 Horsepower
700
1400
1/2 Horsepower
875
2350
Lights
as indicated on bulb
0
Radio
50 to 200
0
Sump Pump
1/3 Horsepower
800
1300
1/2 Horsepower
1050
2150
Television - Color
300
0
Central Air Conditioner
10,000 BTU
1500
2200
Contractor
Running
Wattage
Requirements
Additional
Wattage Required
For Starting
Air Compressor
1 Horsepower
1500
4500
Bench Grinder
8 inches
1400
2500
Hand Drill
1/2 inch
600
0
High-pressure Washer
1 Horsepower
1200
3600
Circular Saw, Heavy Duty
71/4 inches
1400
2300
Electric Chain Saw
14 inches, 2 Horsepower
1100
0
Table Saw
10 inches
1800
4500
Drills
3/8 inch 4 amps
440
600
1/2 inch 5.4 amps
600
900
Industrial Motors
Running
Wattage
Requirements
Additional
Wattage Required
For Starting
Split Phase
1/4 Horsepower
600
1000
1/2 Horsepower
875
2300
Capacitor Start Induction Run
1/3 Horsepower
720
1300
1 Horsepower
1600
4500
Capacitor Start Capacitor Run
11/2 Horsepower
2000
6100
Fan Duty
1/4 Horsepower
650
1200
Farm Equipment
Running
Wattage
Requirements
Additional
Wattage Required
For Starting
Electric Fence, 25 miles
250
0
Milk Cooler
1100
1800
Milker (vacuum pump),
2 Horsepower
1000
2300
Portable Heater (kerosene, diesel fuel)
50,000 BTU
400
600
90,000 BTU
500
725
150,000 BTU
625
1000
Battery Charger

No comments: