Thread: Will this work as a straight razor polisher?

Originally Posted by Lemur

One other thing to consider is that some cheap speed controllers may mess up the local electric grid.

Yes, that is another thing wort considering. The motor won't really notice, but frequency convertors work by taking 60Hz, converting it to DC and then reconstructing a sinewave of the correct frequency. But it is an imperfect reconstruction. It will be more or less stepped in little increments so that the whole resembles a sinewave.

A good frequency drive will have a close match to a sinewave, while a cheap one will havbe bigger steps, and more importantly: they will also have interference or spikes in the output. None of this has a big influence on the motor, because the motor coils combined with the inertia of the motor smooth out things as far as shaft speed is concerned. But there will be a lot of noise and garbage going down the grid. As a result, you might damage or at least influence other electronics in your home.

That's why it is worth going for reliable brand names, such as danfoss or siemens (to name 2 popular ones) instead of buying cheaper ones at half the price, even though the seem to do the same thing.