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View Full Version : Square D Magnetic Starter, 220V coil or transformer and 120v?



cijuanni
05-03-2013, 02:22 AM
I have a RPC supplying power to a 7.5 hp 3 phase motor, so I only have L1, L2, the generated Leg and Ground through the extension cord to the motor.

For the motor I have a Square D Nema Size 2 Magnetic Starter with overloads, but the coil is 480? volts so I need another coil.

Would I be better off getting a 240V coil or a 120V which is far more common and a 240/120 transformer?

outback
05-03-2013, 06:22 AM
I have made three different RPC. Always used motor contactors with 120 V coils. Not sure how important
overloads are in a RPC. I know I have used them but I think my last 10hp RPC build does not have overloads.

My RPC's all have fuses on L1 andL2 comming in.

garagemark
05-03-2013, 06:54 AM
If you can modify and get a neutral easily, go for the 120 volt coil. If a neutral is not easily accessible, I'd buy a 240 volt unit. No extra transformer needed.

Do not use the ground as a neutral conductor.

cijuanni
05-03-2013, 10:01 AM
I have made three different RPC. Always used motor contactors with 120 V coils. Not sure how important
overloads are in a RPC. I know I have used them but I think my last 10hp RPC build does not have overloads.

My RPC's all have fuses on L1 andL2 comming in.

I am not building a RPC, I am powering a motor and starter with a RPC.



If you can modify and get a neutral easily, go for the 120 volt coil. If a neutral is not easily accessible, I'd buy a 240 volt unit. No extra transformer needed.

Do not use the ground as a neutral conductor.

Thanks!

MaxHeadRoom
05-03-2013, 10:01 AM
If you want to save on cost you can go with 240v coil, make sure any other control such as P.B.'s are rated for the higher voltage.
http://static.schneider-electric.us/docs/Machine%20Control/0140CT9201.pdf
Max.

lakeside53
05-03-2013, 10:35 AM
I am not building a RPC, I am powering a motor and starter with a RPC.


Thanks!


Then just go with a 240 volt coil. If not you will be extending neutral from your panel to the rpc, then to the the motor starter, and would need to take great care to to pick one of the two legs where neutral is a valid reference (i.e. not the generated leg T3).