momentary switch

What type and size of momentary switch do i need to start a 15 hp 3 phase motor in the construction of a phase converter? The motor draws 28 amps at 240vac. Also ,in wiring the capacitors in parallel ,if the capacitors terminals are not marked positive or negative how do you know which is which? Thanks

You might want to use a latching relay to supply power and use the momentary switch for the coil. We often used a second set of contacts to provide the hold voltage of a normal relay, then put a momentary (NC) switch to turn it off. The arcing when you switch can be quite high.

You would need to use a relay with a "latching circuit". One push of the momentary button would close the relay, and the latching circuit would keep it closed after you release the momentary switch. If you send an email to my profile address, I'll send a diagram of how to do it.