Inverter – Electrical Equipment Needing Pure Sine Wave Inverter


I am planning to purchase a good inverter, and pure sine wave inverters cost about 3 times as much as modified sine wave ones of the same power. I am thinking about a 2000W continuous/4000W peak inverter 12/24VDC -> 230VAC.

Which commonly used equipment requires a pure sine wave, and what kind of equipment will be equally fine with a modified sine wave?

I am especially wondering about compressor and absorption refrigerators, dehumidifiers, electric drills, fans, microwave ovens, common power tools and kitchen tools. Purely electronic, computer and lighting equipment will not be used through this inverter, as these will have dedicated low-voltage DC-DC converters straight from the battery.

Are pure sine wave inverters any more efficient then much cheaper modified sine wave ones, in terms of input battery consumption per 230VAC output power?

Do there exist inverters which can accept a wide range of input DC voltage, for example will work on all of: 12V, 24V and 48V DC?

Best Answer

Some people claim that certain loads "may" not work as well, or "may" be damaged, with anything other than a pure sine wave.

Since the power coming out of my wall sockets is significantly different from a pure sinewave, I suspect these sincere and well-meaning people are merely repeating propaganda from the manufacturer of a pure sinewave inverter, much like people repeat urban legends.

There is only one kind of device that I know doesn't work as well with a non-sine-wave inverter: devices that use a "capacitive power supply" -- see How efficient is a capacitive power supply? for details.

Since a "capacitive power supply" has a power factor near 0, it is questionable whether any "capacitive power supply" meets EU-mandated power factor laws, such as EN61000-3-2.

I suspect that all products -- as long as they were designed after EU-mandated power factor laws went into effect -- should work just as well on "modified sine wave" as with "pure sine wave" inverters.

Of course, I can't possibly know about every product ever designed -- if there is any specific product (that was designed after those EU-mandated power factor laws went into effect) that can't work or doesn't work as well with "modified sine wave" power, I would be interested. If anyone can explain why it doesn't work, in enough detail that I can try to avoid that kind of failure, I would be fascinated and grateful.