# Motor leads question???



## McClary’s Electrical (Feb 21, 2009)

ruthunter said:


> Okay guys i have a 3ph motor that was wired 480v and the guy has moved and the only power he has now is 120/208. The motor was wired like the lower left diagram shows which looks to be on a delta high voltage. I am dealing with low voltage and believe i should be wiring it to the upper right diagram? Also the 3 sets of wires that are suppose to be lettered z1-w2 x1-u2 and Y1-v2 are not labeled like the diagram. They are numbered 24-25 26-27 28-29. Is there a way i can determine which # corresponds with the proper letter/number? The only 6 wires that are labeled like the diagram are u1-v1-w1-z2-x2-y2 Please advise!


 
Is this a Wye/delta starter, or accross the line? And did the motor have any voltage ratings on it?


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## Aussielec (Apr 1, 2012)

You need to bell the windings out with a multimetre. It looks to me like the windings are tapped in the centre to allow for a higher or lower voltages.

Z2-X2-Y2 should be shorted out.
Z1-X1-Y1 should be shorted out.

So out of 24, 25, 26, 27, 28 and 29 only three of wires need to be shorted out.
You then connect the remaining 3 wires with u1-v1-w1

Once you have done that put a multimtre u1-z1, v1-x1, w1-y1 and check for continuity of the windings. Also check from u2-z2, v2-x2, w2,y2..
This is how I see the motor should be wired but I could be way off...
Hope this helps...


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## don_resqcapt19 (Jul 18, 2010)

In should be wired for delta low voltage, but the winding coils are for 240 volts not 208 and that may not be enough voltage for the motor to work properly.
If you wire in a low voltage wye and connect it to 208 volts the windings that are looking for 240 volts will see 120 volts.


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## ruthunter (Feb 18, 2011)

don_resqcapt19 said:


> In should be wired for delta low voltage, but the winding coils are for 240 volts not 208 and that may not be enough voltage for the motor to work properly.
> If you wire in a low voltage wye and connect it to 208 volts the windings that are looking for 240 volts will see 120 volts.


 So are you saying it wont work with the voltage i have? Is there a way for me to determine what leads are what?


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## micromind (Aug 11, 2007)

There are 6 coils in this motor. Each coil is designed to operate on 240 volts. 

Since you know one end of each coil, finding the other end is easy. All you need is a simple continuity tester or an Ω meter.

First, separate all leads so none are touching each other. Next, place one lead of the meter on U1. Find the only other lead that has continuity. This will be U2. Do the same for V1, the other lead will be V2. Do W1 too, the other end will be W2. 

Now, do X2. The other end will be X1. Same with Y2.....Y1. Then Z2.....Z1. 

Get rid of the 24 - 29 numbers and label the leads properly. 

Now, if the motor starts across the lines, connect the leads per the drawing in the upper left corner. If it's some other type of reduced-voltage starting, post back what type it is, and we'll walk you through it.


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## ruthunter (Feb 18, 2011)

micromind said:


> There are 6 coils in this motor. Each coil is designed to operate on 240 volts.
> 
> Since you know one end of each coil, finding the other end is easy. All you need is a simple continuity tester or an Ω meter.
> 
> ...


 Not sure what you mean about across the line? Will this motor work with 208 3ph?


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## Aussielec (Apr 1, 2012)

Alright looking at the motoring diagram again, it actually looks like this motor is meant to be used in conjuction with a star/delta starter, hence why the two diagrams are labeled "start" and "Run". 

In this case if your not using a motor starter of any description go with the diagram in the upper left corner.

As we have already told you, you need to find out which terminals go to which coil and label them correctly, using a multimetre will accomplish this.

That said the motor should work regardless of which diagram you use. The only difference is when connected in star you will have reduced power and your line and phase voltages will be different.

Connecting it in delta will give you full motor power since your line and phase voltages will now be the same.

And one more thing what is the voltage range of this motor? You haven't told us that yet so really we don't if it will actually work on 208 volts like you say.


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## micromind (Aug 11, 2007)

ruthunter said:


> Not sure what you mean about across the line? Will this motor work with 208 3ph?


Across the lines means that the motor is started at full voltage, not with any type of reduced voltage, soft start, VFD, or anything other than full voltage applied.

Whether it'll work on 208 depends on what it's driving. 

It'll certainly run on 208, but the locked-rotor (starting) torque will be less, and it won't produce its full rated HP. 

Most of the time, a 230 volt motor will work just fine on 208; I've installed hundreds of them. 

Sometimes though, if the driven machine is hard to start or the motor is loaded to the gills, 208 is not enough. In this case, two (and only two) buck-boost transformers will solve the problem.


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## ruthunter (Feb 18, 2011)

micromind said:


> Across the lines means that the motor is started at full voltage, not with any type of reduced voltage, soft start, VFD, or anything other than full voltage applied.
> 
> Whether it'll work on 208 depends on what it's driving.
> 
> ...


Okay i will check the nameplate again as i cant seem to find my notes. The motor is being controlled with a momentary foot pedal and has a magnetic switch.


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## ruthunter (Feb 18, 2011)

Here is the contactor..........


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## micromind (Aug 11, 2007)

If there are 3 wires (not counting the ground) from the starter (magnetic switch) to the motor, use the upper left diagram. If there are 6 wires, use the upper right diagram.

What type of machine does the motor run?

Edit; the starter shown is across the lines. 

All starters are rated in HP or KW or both. The rating of most starters is higher for 480 than it is for 240 or 208. Make sure the starter can handle the motor when it's operated at 208. Also, you'll need to adjust the overload relay for higher current since the motor is being run at 208 now.


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## ruthunter (Feb 18, 2011)

micromind said:


> If there are 3 wires (not counting the ground) from the starter (magnetic switch) to the motor, use the upper left diagram. If there are 6 wires, use the upper right diagram.
> 
> What type of machine does the motor run?
> 
> ...


 The motor runs a vertical band saw. The starter has 3 in on the line and 3 out the load.


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## JRaef (Mar 23, 2009)

The only thing that starter info provides is that they are starting it Across-the-Line and that the starter coil is for whatever their line voltage was. That MAY indicate it was set up for 230V control, but without knowing the actual coil voltage shown on the label, it's not for sure.

We ask you to provide the motor nameplate data and say what your voltage is, but and you post a picture of the starter. I have to say here that your posts indicate that you dont understand what we are asking, so you are not likely an electrician with any kind of industrial / commercial experience. That's ok, we can help, but you have to provide the information.


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## ruthunter (Feb 18, 2011)

JRaef said:


> The only thing that starter info provides is that they are starting it Across-the-Line and that the starter coil is for whatever their line voltage was. That MAY indicate it was set up for 230V control, but without knowing the actual coil voltage shown on the label, it's not for sure.
> 
> We ask you to provide the motor nameplate data and say what your voltage is, but and you post a picture of the starter. I have to say here that your posts indicate that you dont understand what we are asking, so you are not likely an electrician with any kind of industrial / commercial experience. That's ok, we can help, but you have to provide the information.


Pretty sure i indicated earlier in the post that i had not found my notes with the motor nameplate info? The voltage for the coil says 24vac-440vac. I will be getting that info today and will post up later today. I appreciate all your guys help.


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## Wirenuting (Sep 12, 2010)

ruthunter said:


> The motor runs a vertical band saw. The starter has 3 in on the line and 3 out the load.


You have it labeled 
B - R - W? Is that W meaning white? And if so is it a neutral?


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## micromind (Aug 11, 2007)

Wirenuting said:


> You have it labeled
> B - R - W? Is that W meaning white? And if so is it a neutral?


Most likely a 4 wire cord. Black, Red, White.


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## ruthunter (Feb 18, 2011)

micromind said:


> Most likely a 4 wire cord. Black, Red, White.


The existing Contactor was wired using an SO cord. They just used the white for C phase. I believe this is the last piece of the puzzle, here is a pic of the nameplate. So it looks like the motor is 7.5 hp and the contactor is rated at 5.5 hp 4kw at 220 volts. I suppose i will need to supply a new contactor rated for the hp? Based on everything you see is the top left diagram my go to for getting this machine running? Again i appreciate all the info on this site and hope i can help someone in the near future.


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