220/ 380 vac 3 phase motor

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Red Wiggler

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I need to test a 220/380 VAC 3 phase 50 hertz motor and I was wondering how I generate that type of test voltage? Is there a variable voltage drive unit that will provide adequate voltage for testing?

Do you have any ideas what I could use to supply the correct voltage? Is transformers the only way of getting necessary voltage?
 
Red Wiggler said:
I need to test a 220/380 VAC 3 phase 50 hertz motor and I was wondering how I generate that type of test voltage? Is there a variable voltage drive unit that will provide adequate voltage for testing?

Do you have any ideas what I could use to supply the correct voltage? Is transformers the only way of getting necessary voltage?
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If you have a 220V, 3-phase supply available, you can do the test without having to "generate that type of voltage"! Re-connect the motor leads into wye and you're good to go. Your motor phase winding is rated 220V if it is wired in delta and is rated 380V if wired wye.
 
topgone said:
Re-connect the motor leads into wye and you're good to go. Your motor phase winding is rated 220V if it is wired in delta and is rated 380V if wired wye.
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Wouldn't he want to use the Delta connection for "220" volts?
 
topgone said:
If you have a 220V, 3-phase supply available, you can do the test without having to "generate that type of voltage"! Re-connect the motor leads into wye and you're good to go. Your motor phase winding is rated 220V if it is wired in delta and is rated 380V if wired wye.
Click to expand...

how would that give him 50 hz ?
 
Red Wiggler said:
I need to test a 220/380 VAC 3 phase 50 hertz motor and I was wondering how I generate that type of test voltage? Is there a variable voltage drive unit that will provide adequate voltage for testing?

Do you have any ideas what I could use to supply the correct voltage? Is transformers the only way of getting necessary voltage?
Click to expand...
What is it you want to test? That it works? HP output? Torque output? Power consumtion?

A 380V 50Hz motor will run fine on 480V, but it will run 20% faster and put out 20% more HP.

If connected for 220V 50Hz and you give it 220V 60Hz, it will 20% run faster, and it will put out the same HP, therefore less torque. So if it has the same load it will probably overload; if it's a centrifugal load like a pump, the load requirements will INCREASE so it will almost definitely overload. Plus it will burn up because you will be over-exciting* the windings.



*In spite of my personal experience, some things can indeed be over excited.
 
The motor that I need to test is just one component on a skid assembly that will eventually end up at a water treatment plant. The motor is part of a pump assembly on the skid.

We have been asked to test the components of the skid to ensure the functionality of the entire assembly. The customer has a set of testing requirements as part of the specifications, but I have not received a copy as of yet. The company we are dealing with designed the skid is asking for us to provide a quote to build and test the unit. I will have more information as soon as I receive the specifications.
 
One solution is to use a transformer to get the proper voltage, then hook up a VFD to get 50 Hz. Side benefit is that you start at 5 Hz or so to check rotation first, then ramp up to 50 Hz if needed. Depending on motor HP and test procedure, you may be able to get by with an undersized transformer and VFD. If you have a big motor, a demanding full load test, and a small budget, this may not be feasible. Most VFDs put out the same voltage they are fed.

I had to test a few 2 HP 480V, 3 ph motors with only 120/240 1 phase power available. I used a small 500VA transformer to get 480, and used that to run a small 480 V VFD (only fed single phase). But all I had to do was prove that the motor rotated and that the direction of rotation was correct with respect to another 3 phase motor. Obviously this would not run at full speed and full load, but it was sufficient for my limited test.
 
A computer mfg once told me that he had a MG set that had a 5/6 ratio on one shaft, and it would output 50 cycles if you ran it on 60 cycles, or work just as well in reverse. He used this MG set to test export equipment that was freq sensitive. Or you could buy or rent a generator for the purpose. Mine has a simple throttle lever to change governor speed, therefore frequency.
 
If you get a VFD of the proper current capacity (i.e. motor FLA at 380V) and feed it with 480V, you can program the VFD to only put out 380V at 50Hz. No problem at all.
 
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