3 phase 220VAC motor not running properly on 208 3 phase

[team08]

I am having problems at my shop with a new to me clicker press (hydraulic press for die cutting). The seller assures me that the machine worked perfectly at their shop, but it does not seem to work correctly in my shop. Basically, the motor spins up fine (yes in the correct direction), but when I go to activate the press, it is really weak. I can barely punch through paper with a small die. I did keep a meter on the line to see if there is any droop in voltage, but it is rock solid at 208.

This is the second machine we tried with the same symptoms. The plate on the motor reads 220VAC 3 phase 60Hz, 1HP. I thought that there was a magical 10% rule on this type of motor so that they would operate from 200-240VAC? Any suggestions on options? The way I see it, I can either call the power company and see what my options are for getting 220 ($$$$ I am sure), or maybe a transformer setup. I called Grainger about it and they recommended PN 1H271, and two of them. How would this work? Wouldn't I need one on each leg? Thanks for any help!

 

[Scramode]

You could easily install a buck - boost transformer for less than 150.00 from grainger or a local electrical supply house.

NYBTG

 

[jraef]

Before you do anything else, make sure it is not a dual voltage motor, i.e. 220/440V and you have inadvertently connected it in the 440V pattern. If you do that, you will have only about 25% torque, which is going to make it behave exactly the way you are describing. It's a very common mistake.


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[itsmoked]

Very common! I just trouble shot exactly that problem. A hydraulic power unit that could barely get thru its punch routine. If you didn't modulate the controls just right you could watch the motor come to a complete stop.

They'd run it that way for a year but were anticipating increased thru-put demands.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[team08]

It is a dual voltage motor I think. It has only three wires, but there is a diagram on the wiring housing that looks like this (attached photo of my poor drawing). It is wired with one phase from my power panel to one lead coming from the motor. Thanks for the help!

 

[ccjersey]

Sounds like the motor has been rewound and is probably single voltage 460 volt now.

 

[waross]

from the diagram, and the voltage it is possibly a European motor. That would make it a 50Hz motor. A motor rated at 220V, 50Hz would be happiest with 264V, 60Hz.
Yes you can boost with 2 transformers. The circuit is called an "Open delta autotransformer" boost and it is the most economical circuit that I know.
If it is a 50Hz motor read further.
Voltages:
Try a 240:48 volt transformer.
On 208 volts that will develop 41.6V.
When you add the 41.6V to the 208V you will have 249.6V
That's close to 95% of the 264V that you want.
Should work.
If it is a 50 Hz motor let me know and I can walk you trough the transformer connections.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[edison123]

Use the lower voltage connection (The Delta shown in at the top of your sketch).

 

[team08]

The plate on the motor definitely reads 60 Hz (though it looks like it was stamped twice so I am not sure what the original stamp said. I am also sure that the motor is European in origin, there appears to be a another stamping on the casing that reads 380/550 (not sure the exact numbers but somewhere around there).

So I guess I will need help with that transformer circuit!

As for my sketch, I don't have any idea how I would wire it in any of those configurations since there are only three wires coming out of the motor. I guess I should assume that the three wires W2, U2, V2 are tied to U1, V1, W1 respectively, internally (delta config)?

Thanks again for all the help!

 

[LionelHutz]

Honestly, I would not bother trying boost transformers or other such things on a motor when I don't know what voltage it's supposed to be operated with. If it's connected for a voltage higher than 240V then it will just be a waste of time and money. A motor shop should be able to crack it open and give you their best guess as to what voltage it's wound for.

The motor is running on 208V. If the motor is supposed to be 240V, 60hz then it's running at 86% voltage and could produce 75% of rated torque. If it's a 240V, 50hz motor then it's running at 80% of rated voltage and could produce 64% of rated torque. From your description, it sounds like it's almost producing no torque which indicates to me the motor is connected for a voltage greate than 240V.

Finally, call the seller again and find out what their voltage is. If you're not sure about their answer, go visit the site and look for the main voltage as well as any possible step-up or boost transformers they may have been using to run it.

 

[edison123]

Or get it rewound for the right voltage and frequency.

 

[OperaHouse]

"I don't have any idea how I would wire it in any of those configurations since there are only three wires coming out of the motor"

It's where those wires come out of the motor. Remove the cover plate. There will be a terminal block that those three wires connect with. Six screws and metal jumpers just like you pictured. Jumpers can be removed and rotated 90 degrees.

 

[DickDV]

Actually, that's a six lead motor, one on each screw terminal. There are three coils with both ends of each available to connect in wye or delta.

Typically, in the 50hz world, that would be a 190/380V label or today it might be 200/400V.

I would think that, in the delta configuration, you would get good performance even on 60hz at 208V. I suspect you have it connected in wye which would leave the motor starved for voltage and very low in torque.

 

[team08]

I did take off what I thought was the cover plate, and the three power leads came in, and were tied (by wire nuts) to three motor leads. From the small amount I could see it looked like they cam right from coils. The problem with this motor (one of) is that it is cast in a big housing attached to a flywheel so I cannot just take out the motor very easily. I will try to get more pics and info.

I did talk to the supplier again, and he said they have 240 and sometimes as hot as 250.

Thanks again, I am sure we will resolve it!

 

[ScottyUK]

Dick,

Wouldn't that be a 220/380 or 230/400V motor for delta or wye respectively?


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If we learn from our mistakes I'm getting a great education!

 

[ccjersey]

Any chance this thing is (almost) single phasing? Have you checked all 3 phases or have a power monitor on it?

 

[team08]

So here are some pics. Looks like it was permanently wired as delta.

 

[team08]

Motor

 

[Skogsgurra]

To be honest, that's a piece of crap you have got yourself.

From where did you get it? US or non-US. The nameplate has been re-stamped, the connections are sub-standard and there is no cable gland.

If it dsoes not work, just go back to the seller with it. Not worth wasting energy or money on.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[DickDV]

Yes, Scotty, your numbers are correct. But the same principle applies.