# Hello and help please



## JRaef (Mar 23, 2009)

This is what you have, it's a 12 lead motor because it is dual voltage IEC. But for the Europeans, that is not the same as our dual voltage, the low voltage is 58% of the high voltage. So if the motor says it is 380V, the lower voltage will be 220V. Hopefully that is the case, although because you will be giving it 60Hz instead of 50Hz, it will run hot and die young. Click on the image to go to the website that tells you what to connect for Start and Run. 

Had someone asked ahead of time, I would have recommended bagging the phase converter and just using a VFD, they will feed 3 phase to a motor from a single phase source and do so at the design ratings of the motor.


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## micromind (Aug 11, 2007)

What voltages are listed on the motor nameplate? What voltage is being supplied? 

In either case, you'll need 6 wires from the starter to the motor. Each wire needs to be rated at 58% of the motor current. 

And, as noted, a motor designed for 50HZ and operated on 60HZ won't last long. Further, it'll run at 1.2 X the nameplate RPM. 

Does the transformer have 4 terminals on the primary side?


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## KRepairs (Jun 27, 2014)

Supposedly it was previously running here in the US on 480 3 phase...so if that's true then 240 should run it reconfigured when wired for 240.

And it would be wired for starting at 240 vac 3 phase like this (fig 2).

What I need to know is it ok to wire the centers of the wye's together during start phase. Else I don't see how it can be done without another contactor.

And it's always good to work on something after it's been previously worked on but not fixed...but work isn't so easy to come by these days...


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## KRepairs (Jun 27, 2014)

micromind said:


> What voltages are listed on the motor nameplate?
> 
> *None *
> 
> ...


see above


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## KRepairs (Jun 27, 2014)

I looked for and edit but didn't find it... anyway, I'll be supplying 240 vac.


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## micromind (Aug 11, 2007)

Is the motor presently spliced to the 6 wires that go to the starter? And does each of the 6 wires go to a single motor lead? If so, then it is connected for high voltage.

If it is, I'll explain how to re-splice it for low voltage. But if it's just 6 wires hanging out and not spliced to anything, then I'll explain how to splice them to the motor as well as the starter. 

Also, are the 6 wires landed at the starter? 



Looking at the transformer with the 4 primary terminals pointing away from you, (or pointing up) the left one is #1, the next one is #2, next is #3, and the one on the right is #4. The way it is now, power is on #1 and #4. #2 and #3 are jumpered. For low voltage, leave the power on #1 and #4. Remove the jumper from #2 and #3. Install a jumper from #1 to #2. Install another jumper from #3 to #4.


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## JRaef (Mar 23, 2009)

KRepairs said:


> I looked for and edit but didn't find it... anyway, I'll be supplying 240 vac.


Not likely going to work long then. Here's why.

When it was connected to 480V, that was 480V 60Hz and they would have used the connections for 380V 50Hz. A motor is designed to operate at a specific ratio of Volts and Hertz, +- 10%. So the motor was designed for 380/50, that is a ratio of 7.6:1, it was being fed 480/60, a ratio of 8:1, well within 10%, the motor was happy. 20% faster, but happy.

Now you want to reconnect it as 240V 60Hz, a ratio of 4:1, but the low voltage design rating of the motor was 220/*50*, which is 4.4:1. Right on the ragged edge of -10% technically, but in reality because you are running it from a phase converter, you are already using up any "fudge factor" you may have had. Phase converters make a motor LOOK like it is getting full voltage on all three phases, but it really is not, and unbalanced voltages cause a motor to heat up disproportionately to the load on them.


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## KRepairs (Jun 27, 2014)

micromind said:


> Is the motor presently spliced to the 6 wires that go to the starter?
> 
> *Yes*
> 
> ...



Appreciate the help. What I really need to know is if I can connect the center of the wye's together in start mode. This would use the contactor to short W2-U2-V2-W6-U6-V6 vs. 2 contactors and an additional 3 wires to independently short W2-U2-V2 and W6-U6-V6.


As for how long it'll last, all things have a life span. From looking at what his shop does I'm pretty sure the 20 hp won't be stressed. But there's no way to know and the shop owner understands this.

I'll get a pic of the xformer, maybe someone has seen this one before.


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## wendon (Sep 27, 2010)

Another thing to remember with phase converters is to make sure that the manufactured phase isn't connected to the controls.


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## tates1882 (Sep 3, 2010)

Why don't you ditch rpc and go with a vfd. You can set the max freq at 50 hz


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## KRepairs (Jun 27, 2014)

It's what the customer wanted and it's installed. Also typical that RPC's are used on wide table sanders, not vfd's. 

If it was mine, I'd just have paid for electric company 3 phase to building and bought a better sander, cheaper and better in the long run IMO.

But in the customers defense, he's just started his business and available capital sometimes dictates what to purchase (2nd hand and old). I can relate to that sadly.

I'm concerned I'm not communicating my question accurately on the forum...can I connect the 2 center tapped wyes together in start?

edit
Balder has done this before so I think I'm good. Will let you know how it works out as I'll rewire the 3 motors and xformer Monday.

Nice forum btw, will visit often


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## micromind (Aug 11, 2007)

KRepairs said:


> Appreciate the help. What I really need to know is if I can connect the center of the wye's together in start mode. This would use the contactor to short W2-U2-V2-W6-U6-V6 vs. 2 contactors and an additional 3 wires to independently short W2-U2-V2 and W6-U6-V6.


A Y-∆ starter connects the center of the Y during start mode. This is the purpose of the contactor with all 3 contacts shorted. 

There are 3 contactors involved here. #1 (usually on the left) is always closed when the motor is energized. #2 (usually center) is open during starting. #3 (usually on the right, and it has all 3 terminals on one side shorted together) is closed during starting. This causes the motor to be connected Y.

When a certain amount of time has elapsed, #3 drops out and about 1/2 second later, #2 is closed. This disconnects the Y connection and establishes a ∆ connection. 

All you need is 6 wires from the motor to the starter for either high or low voltage. High or low voltage is changed at the motor. 

Are the wires from the starter to the motor labelled? If so, what are the numbers/letters?

P.S. After reading your post a few more times, I think I see what you're getting at. 

W2 is connected to W6 at the motor, as are U2 and U6 as well as V2 and V6. There is no need for additional contactors at the starter. 

Basically the motor windings are connected in series for high voltage and parallel for low. There are still 6 wires from the motor to the starter. The series/parallel is done at the motor.

So yes, the two center of the wyes are connected.


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