I'm switching on an LED strip power supply using an Arduino, but my relay has just started sticking. The relay switches the mains for a 5V 20A power supply. The relay board is this style.
The relay is apparently rated for 10A @ 250VAC, so I think should be fine for the continuous current, but I guess the inrush current when the power supply is first switched on is what's causing the relay contacts to fuse.
I have another 4 of these relay boards spare, so I'm wondering if I can either a) Somehow limit the inrush current to the power supply so that I can just use one of these boards, or b) Figure out the inrush current so I can use a more suitable relay.
If I go with b) – does anyone know of a relay that would be up to the task? Ideally 5v with the same package as the ones on those boards so I can do a straight swap, but I'm guessing the ones that can handle the higher inrush current are probably a bigger package, right?
Edit:
Here's a quick schematic of the setup:
The reason I'm switching on the AC side instead of the 5V was really just for power saving, so that the power supply isn't on constantly, only when I want it on (when the Arduino signals D5 high).
The relay is sticking in the on position – the output stuck on closed and when the whole thing was unplugged (both USB and AC), I managed to give the relay a few taps and it eventually unstuck and opened up again.
Best Answer
I have faced this issue in past. An easy fix would be to move from relays to solid state switches. Use a standard triac with an optocoupler diac driver and you should be fine. I used BTB16 600BW and FOD420. If FOD420 is difficult to come by, MOC3021 can be used as well.
Since your output power requirements are less than 100 watts, the triac won't be supplying more than 1 A (in case of 110 V. For 220 VAC line, it will be even lower). I have tested the triac and it works comfortably without heat sink for currents up to 1 A.
You can follow this circuit: