Frequency Converters to change 400hz to 60hz

Posted in General at 8:34 pm by Dennis Brown

First a warning: I am not an expert at frequency conversion. It is only that I know nothing about them in practice that I had to do some research on them, and present it here. You should do your own research before making life and death decisions based on this data. Now, with that said…

A frequency converter is a device that will change the hertz (cycles per second) of electricity to incoming power. Why would you want one? To convert the power from your 400hz aircraft style diesel generator to 60hz, for use to power your home or other equipment. Without a frequency converter, the 400hz output is useless (and will do damage) to electronics and most electrical equipment in your home. Certain electrical devices, such as analog heaters or light bulbs don’t really care what the frequency is, but anything that is electronic, digital or has any moving parts does. This included DVD players, refrigerators and air conditioners, as well as everything else in your home that isn’t a light bulb or passive heat strip.

They are rated according to kva (kilowatt capacity) and by the incoming/outgoing hertz desired. You can calculate what your needs are by using a simple formula: VA / V = A where VA = Volt-ampere (or watts), V = volts and A = amps. For instance, if you want something that will carry a single phase of power at 10 amps, then:

10 amp requirement = voltage (120v) x ($x unknown rating)
$x / 120 = 10
$x = 1200

So you need a unit that is rated at least 1200VA or 1.2kVA.

Inversely, something that is rated for 1kVA (which equals 1000VA) for 240VAC would give you variables:

VA=1000, V=240, A is unknown

So using VA / V = A, you get: 1000 / 240 = 4.166

The result is that a 1kVA unit running at 240VAC can handle a maximum amp load of 4.166. Keep in mind, this is a bit of oversimplification and the actual needs can vary from this formula, but for most simple devices (like a generator, heater or other resistive device) this gives pretty good results. You can read more about it at Wikipedia’s KVA page. Or get a better explanation (but much more technical) at this website.

Companies that sell frequency converters: (these are not sponsors of this site)


As most require a formal request for information before giving you a price, I have no info on the prices of the units for “normal” applications, whatever that means. Make sure whatever you get that it matches the INPUT hertz of your source, the OUTPUT hertz for your needs (likely 60hz) and the VA rating that is equal or greater than your generator, so you don’t melt it.


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