Electrical power is measured in Watts - a bright
light bulb uses 100 watts and the maximum that can be drawn from a home power point is 2400 watts - also known as 2.4 kilowatts or kW.
You may see output as kVA, and for many appliances this is the same kW, but for those appliances with motors in them, the kVA needed can be up to 50% more than the kW needed.
If the generator has a rating like 2400 watts and 1800 watts at 0.8 PF (Power Factor), this is just another way of showing the kW and kVA rating. When the PF is 1.0 then kVA equals the KW rating.
Two numbers are used to describe the output of a Generator - Peak and Continuous.
- Peak describes the output deliverable for several minutes - the generator’s components won’t blow up at that amount of load, but they will heat up quickly.
- Continuous ratings are usually limited by the heat that needs to be removed when running continuously.
Since the Peak is always more than Continuous, not surprisingly most Generators are described by their Peak output (Inverters
are the opposite !).
So you may find that an 850 Watt generator can really only run a 600 watt load continuously. Ideally you would find out the Peak and the Instantaneous ratings of your appliances and check that they were less than the Generator output. But you can’t rely on this because most appliances don’t state the start-up or peak power needed and the length of the peak really needs to be known too.
Unfortunately the only way to be sure, is to test the appliance with the generator. Tables of power needs for appliances and compatibility with Generators (and Inverters
) are available, but again, they’re only a guide.