Relay contacts sticking

[Kelly E Jones]

I've got a relay that controls the submersible pump which supplies
water to my house. (For reasons I won't go into, the pressure switch
and the pump power circuit are separated by a great distance, so the
pressure switch supplies a 30V signal to the relay which actually
switches the 240V to the pump). Yesterday, I noticed water coming out
of my overpressure relief valve, and after some frantic
troubleshooting discovered that the relay had stuck 'on' (the contacts
were in the 'on' position despite no juice to the coil). The relay is
being used within the current/voltage for which it is rated. A gentle
push with a screwdriver separated the contacts, and after that they
seemed to work fine.

Any idea what caused this, and how to prevent it in the future?

Thanks,

Kelly

 

[Cornelius J Rat]

"Kelly E Jones" wrote

discovered that the relay had stuck 'on' (the contacts
were in the 'on' position despite no juice to the coil). The relay is
being used within the current/voltage for which it is rated. A gentle
push with a screwdriver separated the contacts, and after that they
seemed to work fine.

Any idea what caused this, and how to prevent it in the future?

Any kind of ring/arc supression circuit on those contacts ? I did once come

across a case where the contacts welded lightly shut when the supression
failed.