We bought an inverter to power some toys at camp, and when we opened the box, the directions warned about some applications not liking the inverter. Naturally I had to put a scope on it for a look see. EEwwwww. Now I guess I'll have to take a look at the generators...

 

Yup! Doesn't look sinusoidal to me.

 

It costs more to generate a power sinewave efficiently so most inexpensive inverters use a switched step type of drive with no output filter. In your inverter it's a three step design, stopping at 0V between the plus and minus excursions. More expensive inverters use more steps and/or output filtering to more closely approximate a sinewave.

 

Believe it or not that wave puts most of it's energy out at the fundamental line frequency.

I've heard several anecdotal stories of devices such as microwave ovens failing almost immediately after being given such power.

 

I'm thinking my flourescent lights didn't like the taste either. I'm going to research the generators outputs as some of the loads could possibly be shaded pole, like my pellet stove motors. Probably not as bad as the inverter, but worth a look.

 

A question to fit this thread.. Are the inverters in an uninterruptable power supply ( say an APC 750) a true or modified sine wave? They look 100 times more advanced just by looking at one.

 

It's called a "modified sine wave" inverter. Almost all economy inverters make this wave. They are good for lights and other resistive loads, but not for much of anything else. My inverter fails to operate my little compressor, but does work well when I connect a fan. Go figure.