KD relay problems

[cm47]

In some of my company's substations, some of the KD relays have experience issue in which white powder or green goop has formed inside the relay case. Anyone has any information on this issue? What cause this? What's the speed for this white or green material to form? How to prevent this? Any information or lead would be helpful and appreciated. Thanks

 

[itsmoked]

This has been discussed at length recently.

See: thread248-129440

 

[subtech]

Green Goop?
I'd look very carefully at any capacitors in the relay assembly. We've recently had some relays with oil filled capacitors from another maker which began leaking and coated alot of the relay components with green sticky oil.
Depending on the vintage of your relay, I'd also consider carefully if these capacitors may contain oil with some pcb content.

 

[mikey70]

When there is a standing positive DC on a wire, elctrolysis is a posibility. I'm not sure of the physics involved but thats why you always see control circuits with the contacts on the positive bus and the relay coils tied to negative.

The other possibility is the heat generated by the restraint coils of elctromechanical distance relays. Over time a small amount of the insulation on the coils vaporizes and condenses elsewhere on the relay. You will see it on the relay glass, especially when it has not been cleaned in several years.

Add high ambient temperature and high humidity and the inside of the relay case feels like its coated with crazy glue.

We never found a cure except to maintain the relays more often. We had some that had to be cleaned up with chlorothane, which I am sure by now is on the EPA list to cause every possible disease known to man.