snappy wrote:My PIC will be controlling a 1HP pool pump motor. I have two 50A solid state relays (optically isolated), and a large mechanial relay. My question is will the Solid state relays (Potter-Brumfield) pose any operational problems with the motor? Will leakage current in the shutdown state cause any problems other than safety? I was thinking of having both solid states controlling each "hot" line since it is a 220VAC pump...or have one solid state relay actuate the DPST mechanical relay. any suggestions?
Greetings snappy,
Good to see a swimming pool question on this forum! (I don't play a pool boy on TV, but I do look after our backyard pool in real life).
A solid-state relay would be ideal, and any leakage current trivial for a motor circuit. Our main pump is on a clockwork timer (relay) and our booster pump is on a second timer, but also connected through the solar panel controller (to kill the boost pump for three minutes when the panels engage).
Sounds as if your pump is configured for 220V, so you need to break both lines (L1, L2) to turn it on and off. Most if not all pool pumps use capacitor-start, single-phase, induction motors, which can be strapped for 120V or 240V operation.
The solid-state relay (even if you use two single poles) will last longer than a mechanical DPDT relay. It would be easy to set it up for testing.
Final note, try to keep the pump running as long as possible, instead of turning it on and off frequently. Most pumps are happy when run up to temperature with a steady load.
Comments Welcome!