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Regenerative Drives - Effect of Power Factor

Former Community Member
Former Community Member

I am working on a small 16kW hydro system which is experiencing about 15% loss in the Regenerative VSD. To maximise efficiency the turbine operates at variable speed. The VSD controls a synchronous generator and supplies the grid.

The VSD is a Siemens G120. The datasheet states that the efficiency should be around 96%, whilst also stating that the Power Factor is 0.9. I am looking to replace this drive for an ABB ACS 880-11 which has similar efficiency but a unity power factor.

Firstly can I trust these datasheets since, I assume, they relate to the VSD delivering electrical energy to a motor rather receiving it from a generator? Is there an efficiency penalty for regenerative generation?

Secondly, with all else being equal, will the drive with a unity power factor equate to more electrical energy on the meter than the drive with a 0.9 power factor? 

Thanks

 

 

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  • Former Community Member
    0 Former Community Member

    I have taken some time to consider the concerns about the meter which are valid and I will look to get the scope on to check the waveforms. I have however had a look through some data taken from the drive itself and this seems to confirm the values from the meter are correct. 

    So I would like to ask if there are any other reasons our Siemens G120 PM250 drive could be operating at such a low efficiency when operating in a regenerative mode. Could this be a power factor issue or is this particular drive not the best option for our application?  

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  • Former Community Member
    0 Former Community Member

    I have taken some time to consider the concerns about the meter which are valid and I will look to get the scope on to check the waveforms. I have however had a look through some data taken from the drive itself and this seems to confirm the values from the meter are correct. 

    So I would like to ask if there are any other reasons our Siemens G120 PM250 drive could be operating at such a low efficiency when operating in a regenerative mode. Could this be a power factor issue or is this particular drive not the best option for our application?  

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