Need help wiring a motor starter

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Old 06-29-08, 10:20 AM
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Need help wiring a motor starter

Hello all, I'm new to this sort of forum so I'm not sure I'm in the right place to ask this question but here goes.

I am converting a piece of woodworking machinery from 3ph to single and need help wiring a 3ph magnetic contactor to work on single phase.
I am fairly competent as I have worked as a residential/commercial electrician for a short while but this is a little beyond my experience.
Can anyone help or point me in the right direction?
Thanks in advance!

Jonathan
 
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Old 06-29-08, 11:20 AM
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Originally Posted by JonathanJoseph View Post
Hello all, I'm new to this sort of forum so I'm not sure I'm in the right place to ask this question but here goes.

I am converting a piece of woodworking machinery from 3ph to single and need help wiring a 3ph magnetic contactor to work on single phase.
I am fairly competent as I have worked as a residential/commercial electrician for a short while but this is a little beyond my experience.
Can anyone help or point me in the right direction?
Thanks in advance!

Jonathan
Your going to either have to replace the motor with single phase or use a phase converter.
 
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Old 06-29-08, 01:19 PM
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I'm sorry I wasn't very clear. I am installing a new 5hp single phase motor in place of the old 3ph motor. I also have a new three phase starter. 240v
I know there is a way to wire the starter to use single phase. It involves running at least one jumper "somewhere" I've been scouring the web but can't find anything. The old starter actually had instructions inside the cover to wire it for single phase but it is very different from the new one.
I found one source that said to connect power to L1 and L2 and run a jumper from T2 to L3 and go from T1 and T3 to the motor. The theory there was that some contactors need power on all three legs for some reason for the coil to operate. That doesn't work though.

Thanks for any help anyone can provide. I can of course provide more info if needed.

Jonathan
 
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Old 06-29-08, 01:53 PM
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Can you tell us what manufacter name of that starter you are working on it ??

The reason why due I can able pinpoint the safe way to do it by using the Three phase starter on single phase source myself I know few ways it can be done but need name of the starter manufacter and model number if possible and the starter size as well.

Merci,Marc
 
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Old 06-29-08, 02:52 PM
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Originally Posted by JonathanJoseph View Post
I found one source that said to connect power to L1 and L2 and run a jumper from T2 to L3 and go from T1 and T3 to the motor. The theory there was that some contactors need power on all three legs for some reason for the coil to operate. That doesn't work though.

Jonathan
Connecting T2 to L3 will not give L3 voltage until the coil is activated anyway. That's probably why that did not work.

If you need voltage on all three legs supply side, then Jump L2 to L3.

Did you say the control was also 240V? Is it separate or common?

KC
 
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Old 06-29-08, 03:29 PM
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Thanks for the responses. It is a Square D size 1 starter.

We think we may have sort of figured it out, but I still want to understand it a little better.

With power applied to L1 and L2 and the motor on T1 and T2 and the heaters on 1 and 2 (heres the problem I think....do I need three heaters?) and the thermal reset on 3 pushed back manually( because I don't have a heater to hold it back) it now works. Hooray! Seems strange to have to buy a heater for something with no load on it? Is this the right thing to do?

Thanks again guys.

Jonathan
 
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Old 06-29-08, 08:25 PM
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I'm sure Marc will get you going but FYI your question is a common one at the OLD WOODWORKING MACHINE forums. There is a good chance that one of the members has done the conversion and restored a similar machine.

Click on link then 'discussion', select Shop forum.

http://www.owwm.com/


Steve
 
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Old 06-29-08, 10:34 PM
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You need all three heaters in place to order to get the O/L {OverLoad} section working it don't matter if single or tri phase running if you take out one heater the O/L relay will not function it will stay locked out.

But i am little condersing the size of starter it is a mite small for 5 HP single phase useage due the motor is rated about 28 amp full load

If started unloaded it is not too bad senice you mention woodworking machine so genrally they are started unloaded that should be ok. But for like air compressor or hard start loading units then you have to upside the starter next size bigger due they have larger contacts to handle the current.


Just make sure you check the heater rating to match the motor size.
Majorty of the heater the info numbers will useally stamped on the heater itself so you can check it to make sure you got the right one.

The SqD have quite few diffrent style of heater element for your starter if need more info let me know myself or other members can help you with it.

Merci,Marc
 
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