Multiple Motor Loads on Single Contactor

[ee.van]

Hi,

I am attempting to drive a 240V 3HP 1PH 17FLA Motor on a Manual Motor Starter and L1 and L2 on a 3 pole 18A Contactor.
Can I run a 120V (taken from L1 5A Fused) Positive Displacement Pump on L3 of the contactor?

Both Pumps Run at the same time.

It is my understanding that each pole is isolated therefore I can drive 2 separate loads using the same contactor.

 

[petersonra]

You will need some kind of overload protection suitable for each motor.

What would shut off the contactor if the 120 V motor overloaded?

 

[texie]

I'm not sure I fully understand the OP. But, off the top of my head, it would seem to me that the easiest way to do this would be to just use 2 magnetic motor starters and then you can do any operation you want with the control circuit.

 

[tom baker]

Is the 120 v pump thermally protected?

 

[ptonsparky]

I wonder where the neutral for that 120v motor is coming from.
That and the interlock that doesn't appear to be included in the rough draft.

but, Yes you could run the 120v motor off the third pole of the contactor.

 

[Jraef]

That situation exists in a lot of HVAC control panels already.

 

[mbednarik]

Yes you can, you don't need separate contactors. Make sure both motors have some fashion of overload protection.

 

[kwired]

OP does say "manual motor starter". Unless he means something else that is likely a manually operated contactor and overload protection is incorporated. If it is a field selectable thermal element type overload it probably can work as requested. If it is bimetal with adjustment dial for setting then the setting selected applies to all three poles and unless each motor had same full load current one or the other will not be protected properly. On top of that if it is designed to detect phase loss it probably won't work so well anyhow as it will be looking for reasonably equal current on all three lines to prove there is no phase loss.