Contactor sizing?

Guys

I'm just doing a single to 3 phase conversion on a lathe and just ordered a 3HP (2.2kw) phase inverter for it. I'm have to redo all the electrics completely and want to add a contactor and mcb fuses (replace the old ceramic bulb type). When i did my mill conversion i changed the motor to a single phase motor and reused the existing contactor without much thought. The question is should i rate the contactor at the fuseable value of the inverter (25amp) or go much higher?

Cheers

Quote:

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Originally Posted by 2e0poz

The question is should i rate the contactor at the fuseable value of the inverter (25amp) or go much higher?

Cheers

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That seems to be too high, i have a rotary inverter 5HP that is rated at 25amps

Phil

Have a look at the manual here.

https://www.inverterdrive.com/group/...W/default.aspx

This is the unit i have ordered

it actually says 22amp on page 108

When you say contactor, do you mean independently of the MCB, which should be 25A. If so the contactor needs to be rated for 25A switching, not carrying..

Yes Irving i do