On 20/09/2020 11:46, ARW wrote:
On 20/09/2020 11:13, Martin Brown wrote:
On 20/09/2020 09:20, jeff Layman wrote:

Why is a 440v AC capacitor being used with a 230/250V motor?The OP
did say the motor had been replaced, so maybe it was a 440V (3
phase?) motor previously, although that seems a bit strange for a
mini-lathe. Anyway, that capacitor is well past its sell-by date if
the "1966" on it is accurate. I haven't checked, but a 240V capacitor
should be even smaller.

The capacitor has to survive being attached to 240 rms ac mains
voltage which has peaks 1.4x higher and with a margin for the odd glitch.

This site labours the point a bit but shows the difference.

https://www.electronics-tutorials.ws...s-voltage.html

What if the cap is charged up one cycle and power is applied with the
other cycle. That wound mean you need a 750V cap

It doesn't quite work that way. A capacitor put across a voltage
instantaneously looks like a dead short until it starts to charge.

A charged capacitor the wrong way around could double the inrush
*current* but it wouldn't take it out of operating voltage range.

--
Regards,
Martin Brown