Is a Mag starter needed?

[930dreamer]

Happy Easter to all. I have a Champion 5 hp 3 phase compressor. Using a RPC and a disconnect I can run the compressor just fine. Do I need a Mag starter? Thank You 930.

 

[Charles (in GA)]

Does the motor have a thermal overload reset button on it, usually on the end opposite the pulley? If not, the motor does not have any overload protection and for that reason alone, you probably should have a starter, as they, when set up with the proper overload heat element in them, provide that protection. Beyond that, 5 hp is alot for the pressure switch, much easier on the pressure switch contacts to have a starter.

Charles

 

[s_ontario]

I don't have a Mag starter on my champion 5 hp compressor

 

[GeorgiaHybrid]

Most people use a starter when the HP gets to 5 or more. like Charles mentioned, it is easier on the pressure switch contacts. Also read his comment about thermal overload protection. If your motor does not have an overload reset, you should have a starter with the correct heater installed.

 

[Norcal]

Some type of overload protection is required for 1 HP & larger cont. duty motors per 430.32 (NEC 2005), this can be debated if compressor is cont. duty though...

That being said, I would have a starter on a compressor.

 

[930dreamer]

Thanks for the comments. Earlier this year I tried to install a mag starter but failed, I posted my questions here but wasn't in town enough to mess with it. I have some time now and will post a picture of the mag starter. Thanks

 

[930dreamer]

This is the Furnas motor control, I'm trying to wire the pressure switch also.
It shows LINE to L1, MOTOR,MOTOR and LINE L2. The motor control box only has a reset on the cover, do I need a on/off switch also. Thanks 930

 

[W-Cummins]

That motor starter will work BUT, as far as I know it's no longer allowed under the later NEC codes as it only has the overloads on 2 of the three phases.....

William....

 

[JBurgess]

I circled the parts of the label that apply to what you want to do. I also circled teminals 1 and 3 on the drawing.

If you want a on off switch wire it in series with the pressure switch.

I circled the directions for single phase in case you are using a RPC. The manufactured phase would go in the middle on L2 but you don't want to use it to power the coil. This change will correct that. It may cause the coil to chatter on start up if it is powered by the manufactured phase.

 

[Charles (in GA)]

You need a manual disconnect within view of and within 50 ft of the compressor. If you cannot meet those requirements using the circuit breaker, you need a disconnect of some sort. It will need to break all three hot legs.

Charles

 

[Norcal]

In the 1st post it was said the compressor was 3Ø , & that starter has been prohibited for a 3 Ø applications since the 1971 NEC was adopted, one overload per phase is required.

 

[930dreamer]

I have a 30 amp disconnect next to the compressor,with 3 -30 amp fuses. I'm running 3 phase from a RPC.

One question is, does the wiring from the motor go into the pressure switch. From there out to the disconnect and then to the starter?

 

[Norcal]

I have a 30 amp disconnect next to the compressor,with 3 -30 amp fuses. I'm running 3 phase from a RPC.

One question is, does the wiring from the motor go into the pressure switch. From there out to the disconnect and then to the starter?

No, the pressure switch leads go to the mag starter.

 

[JBurgess]

The presure switch goes where I circled where it says "remote 2 wire control". From terminals 1 to 3.

 

[930dreamer]

The wiring diagram shows a wire going from "W" to terminal "2". I don't have a wire there. Does that wire power the coil?

 

[JBurgess]

The wiring diagram shows a wire going from "W" to terminal "2". I don't have a wire there. Does that wire power the coil?

No. That wire would be used with start/stop buttons instead of the pressure switch.

 

[rwhite692]

IMHO, You should spend the $70 or so, and buy a new mag starter. The one you have looks to be 50 years old.

 

[930dreamer]

No. That wire would be used with start/stop buttons instead of the pressure switch.

Thank You for the help, Wired it all up and runs great cut in @ 95 out @ 155.

 

[JBurgess]

If I remember right you still need to change the heaters to the correct ones for your motor.

You might want to trim the ends on those wires ties before the wire tie police catch up with you.

 

[930dreamer]

You are correct