Surge suppression... might be on topic... sorta

[realolman]

Could someone tell me or direct me toward some info re: making a surge suppressor for 120vac coils, such as would be in a general purpose 8 pin relay or a solenoid?

Or if there's something to buy, and some way of determining what size to get for what coil.

 

[Roy Matson]

Metal Oxide Varistors (MOVs) work very well for that. You can connect them across the solenoid at your panel terminal strip. I think in your case 130 V MOVs would be applicable.
Regards
Roy

 

[jseavers]

Try these,
R-K Electronics P/N RCS1A-6

 

[realolman]

Metal Oxide Varistors (MOVs) work very well for that. You can connect them across the solenoid at your panel terminal strip. I think in your case 130 V MOVs would be applicable.
Regards
Roy

That was my first thought to use.

I have read that these develop a "favorite" current path with every surge and eventually short out, and should be in series with a fuse.

Is the amount of energy passed with the spike associated with the collapse of the electrical field around an 8 pin relay enough to do this or are they talking about something larger?

The relay cycles several times a minute.


thanks

 

[keithkyll]

They are reliable and extremely popular. You have at least one in every switch mode power supply. If the "favorite" current path story is true, I expect it to be extremely rare.
You could use a R/C network. They make modules. Inside is a .05 cap with a 47 ohm resistor, or .1 with 100 ohm. Series connected. I think that's old school. An MOV is the standard today.

 

[panic mode]

they do short out when excessively high voltage is applied from source that is able to provide large fault current. that's normal (and this is how every surge protection works in power bars for my home PCs). having overcurrent protection for branch (load with or without surge protection) is common practice. having fuse in series with just MOV is complete nonsense.

 

[realolman]

The older I get, the more reluctant I am to be that sure of anything.

This article pretty much describes what I was talking about MOV's.

http://www.extremetech.com/article2/0,2845,1155237,00.asp

I found some Releco brand relays that are manufactured with RC surge suppression already incorporated... I'm gonna use them. It'll be easy... just swap out the relays

Thanks to all who replied