Why is this happening (basic electronics help)

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Can anyone tell me why the lamp in the picture would flicker when the relay is in the off state? Have I wired it wrong?

6mvNH.png
 
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The load isn't big enough, or rather the SSR is incorrectly specified, you don't need a 45A device to control a lamp/boiler. It has a small leakage current in the off state which causes the flickering.

Also, it is incorrectly fused, you need a high speed fuse, not a dead sloth domestic plug type. Your SSR will happily burn to a crisp before that thing ever blows.

You see that RC snubber circuit on the SSR's label? That's why you are getting leakage current when you try to switch AC, the AC goes right through the capacitor.
If you have a 5Kohm 15W resistor handy, connect that in parallel with the driven load to act as a bleeder resistor.

The alternative is to pick a SSR that doesn't use a snubber, or as above, increase the load so the leakage current is irrelevant. Is there any reason why a mechanical relay won't do?



Tsk, lots of random guessing going on in the thread.
 
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Associate
OP
Joined
16 May 2008
Posts
2,358
Location
Bristol
The load isn't big enough, or rather the SSR is incorrectly specified, you don't need a 45A device to control a lamp/boiler. It has a small leakage current in the off state which causes the flickering.

Also, it is incorrectly fused, you need a high speed fuse, not a dead sloth domestic plug type. Your SSR will happily burn to a crisp before that thing ever blows.

You see that RC snubber circuit on the SSR's label? That's why you are getting leakage current when you try to switch AC, the AC goes right through the capacitor.
If you have a 5Kohm 15W resistor handy, connect that in parallel with the driven load to act as a bleeder resistor.

The alternative is to pick a SSR that doesn't use a snubber, or as above, increase the load so the leakage current is irrelevant. Is there any reason why a mechanical relay won't do?



Tsk, lots of random guessing going on in the thread.


Thanks, I should've asked you first :p

I'll try swap it for a lower rated one, it seems quite hard to find them with high speed fuses, maybe I'm searching for the wrong keywords
 
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