# Solid-State Relay Precharge Resistor ASSR-5211



## PStechPaul (May 1, 2012)

It looks OK to me. As long as the fuse is properly rated and the PC board is laid out with enough spacing and good connectors for the voltage, I don't see a problem. It might be a good idea to monitor the difference voltage across the main contactor and inhibit closing if it is more than a few volts. I'm trying to think of a simple means to do this. Perhaps an optoisolator and resistor that will keep it turned on from 300V to about 5-10V, and when it turns off, it enables the main contactor. Something like a PS2561 can handle 30 mA so a 10k 10W resistor will work. It will work down to 1 mA which is about 10V, which might be OK.

I would feel more comfortable with an industrial relay rated for DC output. Here is one for about $15:
http://www.mpja.com/20A-480VDC-Solid-State-Relay/productinfo/17288 RL/


----------

