Bit off topic but there seems to be a vast array of random knowledge here so figured I'd see if any of you have any ideas on this!
I have a 3/4hp (as in, 0.75) hermetic refrigeration compressor that started tripping a breaker intermittently on startup. Now it trips every time.
It has a start and a run capacitor. I've tried another start capacitor that I robbed from another unit (same rating), no change. The potential relay contacts are closed, so the start cap is in circuit at startup. I then noticed the run cap appears to have gone open circuit, but I'm not sure if that is the cause or a symptom - I have a replacement that is meant to arrive today. I'm not convinced its going to solve it though - from what I gather, it should attempt to run if not particularly well without it. Or sit and hum until the overload protection cuts it off.
The breaker to the circuit is a B type 32amp, suggesting its pulling silly amps for some reason or has gone dead short. Checking the windings, I'm getting 3.3 ohms on the run, and 9.5 on the start. Specs call for 3.3 on run and 12 on start, so start seems a bit low but isn't a dead short. Prior to it tripping constantly, when it would run, it never made any odd noises either while running or on startup, so I don't think its seized up. It isn't short to earth either. Checked the wiring throughout the rest of the unit and its fine - disconnecting the feed to the compressor results in the breaker not tripping when its contactor pulls in, so I'm sure its at fault.