Oversized Motor Starters

[Pitt123]

I know that NEMA starters are broken into sizes according to motor HP, and a 50HP motor will require a size 3 starter.

My question is weather or not you can use a larger starter such as a size 4 starter on such a motor as long as the breaker and overloads met the the requirements of 430? Can a larger size contactor be used as long as breaker and overloads were sized per the motor?

 

[jim dungar]

Can a larger size contactor be used as long as breaker and overloads were sized per the motor?

Absolutely, yes.

 

[augie47]

As Jim says, no problem. It is not uncommon when motors have numerous jogging or plugging use.

 

[templdl]

You just have to watch the capabilities of the OLR that it is capable of being adjusted low enough to a value that protects the motor.

 

[augie47]

You just have to watch the capabilities of the OLR that it is capable of being adjusted low enough to a value that protects the motor.

good point... I'm still accustomed to the bi-metal OL heaters where that was not much of a problem. Over a wide range, one size fil all.