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Pure Sine Wave And Quasi Sine Wave Inverters

1 August 2017  |  Tom


There are two different types of mains power inverter available - a pure sine wave inverter and a quasi or modified sine wave inverter - read on to find out what is the difference and which type you will need.

A mains inverter serves to convert low voltage DC (Direct Current) from a battery/bank of batteries to AC (Alternating Current) mains power which is required for most electrical devices.

There are two main types of inverter - a pure sine wave inverter and modified or quasi sine wave inverter; the main difference is that the former produces a better and cleaner current.

Both types will produce an Alternating Current - positive to negative to positive etc - the difference being how the current changes direction and how long it stays level.

If you look at the diagram, the pure sine waves produces a smooth flowing current, like a wave, while the modified/quasi sine wave has prolonged highs and lows as well as periods at zero voltage.

Quasi sine wave inverters are far cheaper and some appliances will work perfectly well but others may not; as a general rule if you are planning on running basic electrics then a modified sine wave inverter should be fine but for any more sophisticated or sensitive equipment you should use a pure sine wave inverter which produces an output akin to normal AC.

The following types of device should be used with a pure sine wave inverter:

High quality audio/video equipment
Microwave ovens
Printers and copiers
Washing machines
Digital clocks with radios
Bread makers
Lights with dimmer switches
Laptop computers
Any sensitive medical equipment

In terms of size, you need to buy an inverter that has adequate capacity to power all the items you expect to use; here you will have to check the individual items and work out the total power required - and we would suggest that you allow at least 20% more than you think you'll need.

If you are unsure which type of inverter you need then we would always suggest that you check for certain with the manufacturer of your device.