Mitigating Arcing in Relays

bitmonkey

Lifetime Supporting Member
Join Date
Oct 2015
Location
Ohio
Posts
94
Hi Guys,
I tried searching the forums but found nothing. I have several instances where I am burning up relay contacts too frequently especially when the relay fires a hydraulic solenoid. I know there are ways of dealing with arcing, such as capacitors, resistors, diodes, etc. But I'm not sure how to pick the right device. Does anyone sell purpose built arc-suppressors for this application?
Thanks,
Brian
 
Hi Guys,
I tried searching the forums but found nothing. I have several instances where I am burning up relay contacts too frequently especially when the relay fires a hydraulic solenoid. I know there are ways of dealing with arcing, such as capacitors, resistors, diodes, etc. But I'm not sure how to pick the right device. Does anyone sell purpose built arc-suppressors for this application?
Thanks,
Brian

Commonly called a snubber, have a read here:

https://www.industrologic.com/mechrela.htm

Depending on the relay you may be able to just change it for one with a built in snubber, otherwise retrofit ones are available similar to these:

https://shop.murrelektronik.com/en/...ressors/OMRON-CONTACTOR-SUPPRESSOR-26401.html
 
Last edited:
The Magnecraft relays we use have suppressor modules as an option. They're nothing more than a diode or MOV inside a little plastic case, but definitely more user friendly than jamming a diode lead under the screw terminal with the wire.

magnecraft.JPG
 
Keeping the physical distance (wire length) between the solenoid coil and the arc suppressor as short as possible will also help to reduce the spike.
 
I think I misunderstood the question, the module I posted is for protecting whatever electronics are driving the relay coil itself and has nothing to do with the relay's contacts. The link posted by BryanG is interesting, I didn't know they made a suppressor that could fit inline with a DIN valve plug.
 
I think I misunderstood the question, the module I posted is for protecting whatever electronics are driving the relay coil itself and has nothing to do with the relay's contacts. The link posted by BryanG is interesting, I didn't know they made a suppressor that could fit inline with a DIN valve plug.

Turck (and others I'm sure) also make them where they are part of the connector itself: For example, VAS 22-F669-xM.
https://pdb2.turck.de/repo/media/_us/Anlagen/777002645 (sheet_1).pdf

They don't cost much more than a standard version. Just have to pay attention to AC and DC valves.
 
The Quencharc's are great. They are basically a resistor/capacitor ina package, some of which are UL approved.

Are the coils AC or DC? It makes a difference what to use depending on the type and voltage. In all cases, it is best to have the snubber device as close as possible to the load.

That App note from AD is very good.
 
I remember having a machine which was constantly burning up relay contracts.
We installed a varistor across the coil device which dramatically slowed down
the carnage.

On an AC solenoid coil, we also went to solid state relays - using the conventional
relay contacts to activate the solid state relay. No contact damage at all for
over a decade.

Poet.
 

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