VFD FEDDING A POWR TRANFORMER
VFD FEDDING A POWR TRANFORMER
(OP)
Dear All ,
We are developping a motor control test center project, and some of our collegues are suggesting to use a VFD to fed a power transformer in order to change the transformer´s voltage output with out change the frecuency, this is intendded for no load test.
Any one with similar experience ? pros and conts??
Thanks for the Inputs
Petronila
We are developping a motor control test center project, and some of our collegues are suggesting to use a VFD to fed a power transformer in order to change the transformer´s voltage output with out change the frecuency, this is intendded for no load test.
Any one with similar experience ? pros and conts??
Thanks for the Inputs
Petronila





RE: VFD FEDDING A POWR TRANFORMER
Did this about nine months ago. But used the output of the transformer to start a synchronous 11 kV 6 MW motor. The inverter was a 500 V 840 A rated inverter.
That application was OK. But, if you want to have a clean sine output from your secondary, you probably need to filter the VFD output heavily.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: VFD FEDDING A POWR TRANFORMER
Apparently you didn't have any problems burning through the transformer winding insulation like you can do with cheap motors. Did you specify special insulation? The distance between the inverter and the transformer was probably very close.
RE: VFD FEDDING A POWR TRANFORMER
The transformer was an existing one and it was oil isolated. So no problems with corona. And no special insulation.
Also, it is only used during start up of the refiner motors and that takes less than two minutes. The refiners then run for typically a week or two. So even if we got some ozone production, it wouldn't accumulate.
I think that PWM and insulation can be a problem with smaller transformers. But larger ones, like those found in a typical motor repair shop, are not exactly "rush wound" and there is plenty of distance between windings and iron, too.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: VFD FEDDING A POWR TRANFORMER
RE: VFD FEDDING A POWR TRANFORMER
If you see the project like you are going to buy the VFD For only voltage variation you are right,is an overkill , but this VFD are intended to powered the low voltage motors up to 660 Volts.The idea is to have the initial VFD`s investment in order to fed one dry type tap transformer and have variable secundary voltage avoiding the use of CTV Transformer.
Attach you will find the design.
Thanks and regards
Petronila
RE: VFD FEDDING A POWR TRANFORMER
The transformer manufacturer should be informed of the PWM characteristics of the drive output.
I had a problem on one site where the step-up transformer was heating up excessively and this was solved by reducing the motor flux parameter in the drive. The application was a 6kV fan and dry type cast resin transformer so the windings were aluminium strip/sheet.