question

Hi @fplouffe,

Some loads in particular are quite difficult for inverters to power. Specifically heating elements (heatguns, hairdryers, etc) that use triac or non-linear power controls. They do this so they can run common elements at lower power levels (or adjustable power from the same element).

Here is an extract from Wiring Unlimited.

The inverter is designed (and rated) to supply power from the whole sine wave.

In the case of your inverter, 1200VA.

If only a small part of that total sine wave is used (and the rest chopped), lets say 20%, then only 20% of that 1200VA is available (240VA).

So even though the load is only rated at 300W, it demands that 1500W from only 20% of the sinewave, instead of spreading a continuous 300W load out over the whole cycle, it's a 1500W for 0.2 of the cycle, 0W for 0.8 of the cycle for 300W rating.

Even when the inverter is large enough to run the load, there is additional stress on the inverter and it's capacitors from this load type too, it's likely you can hear that it is unhappy with this type of load as it tries to power it.

It might be possible to find another model appliance that is more compatible, using a linear 300W element, instead of a 1500W element that is running 20% of the cycle, but you would have to test it first to see as this is not commonly available information.

An ever better idea, if possible, is to find a DC appliance that bypasses the inverter all together for this kind of thing. Then it is certain to work.