Three legged component

MartinTT

New Member
Hello here, i have a problem identifying three legged component on automatic PIR light switch, it’s capacitor or something exotic? many thanks
 

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Solution
Looks like a PolySwitch, a positive temperature coefficient resistor that acts as a self-resetting fuse.

Or, could be two back-to-back Y capacitors as part of a power line filter (although I've not seen one).

ak
I dont see 3 legs on the yellow disc ? Which seems to be marked as a 430
pf ceramic capacitor.


Regards, Dana.
 
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Looks like a PolySwitch, a positive temperature coefficient resistor that acts as a self-resetting fuse.

Or, could be two back-to-back Y capacitors as part of a power line filter (although I've not seen one).

ak
 
Solution
strangely it has three legs
As it has V1 printed next to it, that makes it look more like a VDR - however, while it has three legs it has two obvious separate components inside, one large, one small. This is 'similar' to a posistor, which was used to degauass CRT's back in the day, and consisted of two thermistors, one positive coefficient, and one negative.

But you're still only giving us a tiny picture, so we've no idea what it might be doing - or what it's in - there's no context.
 
apologize here the bigger view, maybe helps with identification, it’s legrand motion sensor light switch
 

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Presumably the three terminals are live in, live out, and neutral?. Probably the component is some kind of protection, possibly against lightning pulses?. Why do you want to know?.
 
Presumably the three terminals are live in, live out, and neutral?. Probably the component is some kind of protection, possibly against lightning pulses?. Why do you want to know?.
because on the other switch this component blew, new switch is expensive and they don’t do this design anymore, in house we have six more….
 
because on the other switch this component blew, new switch is expensive and they don’t do this design anymore, in house we have six more….

OK, can you draw that part of the circuit out, so we can see how it's connected - the component, the three pin terminal connector, and where it goes to.
 
It's double sided, and you can't see the traces on the top, nor do we know what the terminal connections are.
Some people are just incapable of compliance with a simple request. It would require some amount of effort and industry on their part which they are unwilling to expend to get to a solution. Easier to ask someone else to do it by -- magic perhaps?
 
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