115v to 400hz variac to test Polarity brake coil

[angelG]

Hello
We need to test polarity in a brake coil assembly, need provided a 115v to 400Hz signal.
any idea about which Setup & equipment shall we need.

[HalFoster]

Search for "AC Power Source" on epay - many models from Elgar, California Instruments etc.  Be prepared to pay a lot for shipping though - there is a lot of iron in them.

Hal

[mikeselectricstuff]

How much power ?
For up to a few hundred watts, an audio amplifier coupled to a transformer may be a good option.

[angelG]

low power around 45W

[mikeselectricstuff]

Easy enough then, 400hz sinewave into a 100w audio amp, and a  reversed mains transformer on the output

[Psi]

Yep, exactly what Mike said.

The mains transformer wont be super happy with 400hz instead of 50hz but should be fine for the short time needed to test your device.
Just keep an eye on it's temperature, or pick a larger one than necessary power wise.
Transformers can be grossly over-driven if you only need to use them for 20 seconds at a time, or whatever.

If building a more long-term system you can just attach a normally connected thermal switch to the top of the transformer metal core and use that to cut the power if it gets too hot from too much use. 55degC or so.