I am using a relay wth a 50V dc/ac coil and i would like to suppress the coil using a verister. How do a determain the size and type of verister?

 

Hi,

I moved your post to a more appropriate location.

An AC-rated relay coil always has a diode in series with it. It's really DC activated. Rather than using a varistor, which will break over and short voltages over a certain rating, another diode across the coil is tha way to go. The realy should have polarity marks on the body by the coil contacts. The suppressor diode needs to go across just the coil so it is reverse-biased by current through the rectifying diode. Something like a 1N4006 should do the job.