Contactor Type 1

[mfotouhi]

Folks,

I am using a 40A motor contactor to energize a circuit with the following components:

4 motors each rated for 208V, ¾ HP, 5.2 FLA (manufacturer’s info)
1 motor rated for 208 V, 1/3 HP, 2.3 FLA (manufacturer’s info)
and a total of 14 A non-motor load (mini-fan, ballast, horn, indicating lights, ...)

Isn’t it a misapplication to use a motor contactor to energize non-motor loads? I am using a Square D contactor SC02 type. Many thanks for your comments, -Mort

 

[peebee]

A quick look at the data sheet (

http://164.109.40.74/huggy_pdf/en/SD/8502sec1.pdf)

indicates that your contactor is only rated for either 27 or 36 amps, not the 40 amps that you state. Those lower ratings could be a problem.

Otherwise, it's OK to use a motor contactor for the loads you indicate. Motors are, generally speaking, a "difficult" load to start due to their inductive nature, compared to other resistive loads such as lights, heaters, etc. You can use a motor contactor to control resistive loads, but you cannot use a general purpose contactor to start a motor, at least not without proper derating.

Make sure you have provided overload and short circuit protection for all loads per code requirements. And double check the rating of your contactor as I mentioned above.

 

[Crowbar1]

To my way of thinking I would have individual motor starters for each motor or at least a single properly rated contactor with individual overload relays for each motor and a seperate contactor for the non motor load. That would provide the proper overload protection for the motors.

 

[Crowbar1]

P.S. The above installation would also easily facilitate troubleshooting of an overload trip condition. The tripped motor(s) would be obvious.