How to control 3phase motor starter

Other Hardware Motors, Mechanics, Power and CNC
1

How to control direct on line 3 phase motor starter (for 3hp motor) with arduino,can L1,L2,L3 controlled by relays.If yes what should be the specification of relay

2

Yes.. but..

to switch the 3-phase motor current you need a special high power relay called a contactor.

These generally have a 240vac ( 110ac in the states) coil, which you can drive with either an ordinary relay or a solid-state-relay (SSR) whose coil/opto input is driven via a transistor from the arduino output.

regards

Allan