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Sticking relays
A couple of the relays for my interior 12volt lighting get stuck now and again. It’s not a big deal to open the panel and flip it manually, and then it will work fine for another couple of months, but eventually it will stick again. I’m a lazy guy trying to avoid even the minimal work necessary to replace a relay. Can I just give them a shot of WD-40? The relays I’m talking about are the big mechanical ones that make a “thunk” sound when activated and can be switched by hand.
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7 Replies
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I really don’t know exactly what kind of relays you are talking about but I wouldn’t use WD40 on anything electrical.
Clean them with a electrical contact cleaner from say Radio Shack or a auto parts store. Like CRC brand contact cleaner, it is non conductive and want damage circut boards and the such.
Maybe some one knowing exactly what you have will give further advice.
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What Buddy said.
Relays of sufficient size to handle interior lighting don’t have to be big enough to make a clunk so my initial question would be what is the nature of the “sticking”. Typically a relay engages when a magnetic coil is energized and that coil pulls the contacts together. When the source of the power to the coil interrupts the power to the coil the electrical contacts are pulled open by a spring.
When relays stick it could be a mechanical reason, such as the spring is not pulling the contacts open because something is hanging up or the spring has failed. But it could be electrical such as the electrical arc created when the contacts are closed and a heavy load has been applied with the result being a weld. When conditions are right the contacts weld themselves together and the spring lacks sufficient force to pull them back open.
The first thing I would look for is to determine the load the relay handles and make sure the relay is sized to handle the load. If it is too small in terms of rating the result is going to the welding of contacts or heat because the contacts cannot handle the load carried and that heat may cause the relay to bind in the closed position.
But don’t spray relays with anything.
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This is the panel I’m calling “relays”. Is that not what they are? They make a soft “thunk” sound when actuated.
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Can you get a close up shot Bryan? Judging solely by the number of wires going into them they definitely could be. But it would be a guess. would the yellow and red wires be used to denote voltage? Such as 12 or 24?
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Here is a closer picture. When they stick I can just flip the white plastic part manually and then it will be fine for a while.
All of the low voltage lighting my bus is controlled by this panel.
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Those are not relays but are called Micro-Switches. Now that I see how they function you do have some moving parts. I am going to stick my neck out based solely on what I can see and suggest the white parts move the switch levers. Something, possibly a solenoid attached to a rod or lever behind the switch panel is moving the white parts in a gang so in essence you have a “train” in which some device such as a solenoid is moving the white parts all at once and the clunk is likely either the white parts going from “on” to “off” or vice versa. The clunk could also be the device moving the train when it hits the end of its travel.
Yes it might work better if whatever resistance is causing the assembly to drag and bind is loosened up either with lubrication or finding where some parts are too tight together.
If you do opt to lube it, use an oil can that does not spray like the old fashoined kind that will place a drop of oil where needed. I think the risk is slight but I would avoid getting oil on the switches because they are ot sealed and the oil could ruin them or if enough oil is on the entire assembly an internal spark could ve all it takes to start something burning.
Kind of a neat assembly because the entire set of switches can be easily serviced and tested.
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Thanks, Jon. I appreciate the explanation, which helps me understand my bus better. There is what appears to be a separate solenoid behind each micro-switch, but no “train.” They all function independently. I understand the purpose is to simplify the switch controls and lessen the amount of wiring needed, such as for the living room lights for which there are 5 different on/off switches. My system is pretty simple, with mechanical dimmers on just 3 circuits and no Crestron or anything like that, just switch pads throughout the bus. As my knowledge of electronics is weak, I like the simplicity. The downside is that in order to shut off all the lights, I have to separately press the button for each circuit, rather than an “all off” switch. Not a big deal for me, but I can see how convenient a Crestron system could be.
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