Your motor sounds very similarly sized to my pool pump, which is a 240V single phase 1.5HP motor. Mine typically draws about 1100W when everything is running normally. The capacitor you refer to is probably the starting cap. When that starts to fail, as mine did recently, you’ll find the motor intermittently stalls on start-up… it just sits there and hums and draws a lot of current for a worrying number of seconds and then eventually starts.
If I’m near it at the time, I can give it a flick and it starts right up. Experiments on a salvaged motor from a previous pump reveal it’ll happily run in either direction from that state, depending on which direction I flick it, so you really want to make sure you flick it in the right direction once it’s installed in the system.
All that lends itself nicely to early failure detection and reporting. My monitor now reports things like:
-------- Forwarded Message --------
Subject: Check pool pump
Date: Fri, 14 Oct 2016 16:00:11 +1000
From: xxx
To: xxx
Possible pool rotor lock event detected (3266W), timer 1 stopped
Regards,
Primary Server.
It no doubt varies from pump to pump and application to application, but to give you some idea of the startup current when everything is working normally, I initially assumed a 20A CT would be fine for a pump that uses about 5A once running, but it turns out it was clipping badly on startup. I replaced that with a 50A CT and you can see in the attached capture from my energy monitor that the first peak exceeds 40A. My CTs and energy monitor are not OEM based, so not directly translatable to what you’ll need, but I’ve included them to give you a feel for what my similarly sized pump looks like on start-up.
