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Induction motor parameters

Induction motor parameters

Induction motor parameters

(OP)
I am in the process of designing a STATCOM control system for an induction generator.  To do this I must know the parameters of the induction motor that I am using.  Unfortunately I do not have three phase power available to do the testing.  Would the waveforms from a three phase VFD (with single-phase input) be adequate to do this testing?    

RE: Induction motor parameters

That would depend on the VFD allowing single phase without tripping out.

It would also depend on the size of the motor.

It would depend on the load the motor would be put under.  If things can be slowed down and still achieve the testing requirements it could work.

You should provide more info including what STATCOM means if you want more useful responses...

Like motor hp.
VFD make and model number.
What the basic mechanical load is.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Induction motor parameters

(OP)
The motor I am attempting to use is a Baldor M4112T motor.  It is a 20 hp, 870 rpm motor.  Operating voltage is 230/460 and full loads amps are 58/29.

The tests I need to run are no-load, locked rotor, and as you have said, full-load.  I do not have a dyno, I will have to design something to do that test.

The meaning of STATCOM is static compensator.  It's purpose is to provide reactive compensation to the induction motor (in this case it is being used as a generator) to allow it to generate off the grid (self-excited).

To address your first point, I have had some success with using three phase VFDs' in single phase mode.  By de-rating them I have driven small (three phase) motors on the order of two horsepower.  At this point the VFD to drive the larger motor has not been determined.  I am open to all suggestions.

The device I am attempting to test will eventually be used as part of a wind generator.  

Many thanks for your response.



   

RE: Induction motor parameters

I am afraid that you will have a problem finding a single-phase input VFD that can handle locked rotor current of a 20 HP induction motor. That would be my first concern.

Second. If you are going to use capacitors, they will behave a lot differently when fed from a VFD (PWM does not like to see capacitors) than from a stiff grid.

If your static compensator is electronic (injecting leading current to compensate for lagging current) then you will have all sorts of problems with the PWM from the VFD interfereing with your (probaby also PWM) injection current and the control of it.  I would never even think about testing against anything but a grid that the equipment is designed for.

If your static compensator is of any other kind, unknown to me, well - then it might work. But, the locked rotor test needs a lot of current and that will probably be the first problem.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Induction motor parameters

(OP)
Thanks for your reply, Skogsgurra.

This is my first attempt at a professional forum and it would appear that I am not doing a very good job of expressing my needs.

To do the design for the STATCOM I need the parameters of the motor.  To achieve this goal it will be necessary to exercise the motor at no load, full load and locked rotor.  Fortunately for locked rotor, I will limit the current to full load value.  I will then have the parameters I need to do a STATCOM design.  

After the STATCOM is designed, then this device will be used on the motor (generator) which if I am successful, will then generate stand-alone.

The VFD will only be used to obtain the motor parameters, it will not be used in conjunction with the STATCOM.

My main worry with the VFD is will it be good enough for motor testing?  Can I trust the values that I obtain with it?

By the way, Skogsgurra, your information on STATCOMs' is quite accurate.  At this point in time, those are the two principal types of devices in use.  I am attempting to employ the latter.  

Many thanks to those that have responded to my inquiry.

RE: Induction motor parameters

OK. So it is only to get the parameters of the motor that you need the VFD?

I think that there are simpler ways. Already the motor data will tell you a lot. Your main input is, I think, the power factor. And that can be read from the motor manufacturer's data sheet. Not only at full load, but usually at any load between idling and slight overload (SF usually being 115 or so).

Details like leakage inductance and such things usually do not affect the compensator much. At least not to an extent that it influences the basic design.

Or am I missing something?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Induction motor parameters

Two suggestions;
1> Find a location with three phase power where you are able to rent space to do your testing.
2> Rent or buy a diesel generator for a week or so.  

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

RE: Induction motor parameters

Any reason why Baldor tech support can't give you the motor data?
  

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

RE: Induction motor parameters

(OP)
ScottyUK,

I will give them a call tomorrow.  Thanks for the assistance.  If that works out it will save me a lot of time and trouble.

RE: Induction motor parameters

While calling them ask them if they have a test lab.

If they don't have a number you need, or you want specific numbers, it would still be FAR easier to pay them to run the tests to provide the figures you need, than for you to set all that up.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Induction motor parameters

(OP)
Thanks to all that replied to my original request.  Baldor was able to supply the majority of the parameters that I needed.   

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