HARMONIC FILTER ACROSS DC DRIVE

[deeveeyes]

wE PLAN TO CONNECT A HARMONIC FILTER TUNED TO 4.7TH ACROSS OUR DC DRIVE 250 KW. WILL THERE BE ANY EFFECT ON THE WORKING OF DC DRIVE ? THE DRIVE HAS A DEDICATED TRANSFORMER AND THE FILTER IS PROPOSED TO BE INSTALLED PARALLEL TO THE DRIVE ?

 

[electricpete]

I think this could be a problem for the drive. Let's say your drive supplies PWM voltage with relatively little internal filtering (within the power supply) to an inductive/resistive motor - the motor inductance acts to "filter" the harmonics in the voltage and the current is relatively free of higher harmonics.

But let's say you conduct capacitive filter across the pwm output of the drive. The caps will draw huge current due to the high dv/dt... causing possible overheating of your drive and your filter.

I would think you would want to check with the manufacturers of the drive and the filter before proceeeding.

 

[electricpete]

My discussion related to a variable speed ac drive with filter on the output.

When I reread your message, I see you refer to a dc drive. Is that simply a dc power supply? Are you hooking the filter in parallel to the input or the output? What do you mean by "TUNED TO 4.7TH"?

I guess I don't know exactly what your situation is. But there are likely to be harmonics on both the input and output of any solid state device. (on the input due to nonsinusoidal current which causes non-sinusoidal voltage drop across supply impedance). If hooked in parallel to the input of the drive, then you only need to worry about whether the filter can handle the harmonics it'll be exposed to. If hooked to the output you also have to consider the possible increase in current drawn from drive. Forgive me if I'm stating the obvious.

 

[jbartos]

Suggestion: Reference:
1. Ashmore S., Manager, Harmonic Filter Systems, High Voltage Capacitor Division,, "Capacitor Banks and Harmonics," 1997 ABB Electric Utility Conference, Subject VII-3
Essentially, there are tuned and untuned capacitor filter banks. Tuned shunt capacitor banks or harmonic filters eliminate the risk of harmonic amplification due to resonance when applying VAR compensation. The components of tuned capacitor bank, capacitors, and tuning reactors (sometimes resistors) shall be sufficiently rated to withstand the harmonic content.

 

[deeveeyes]

Thanks jbartos. where can I access the reference article of Ashmore s.

 

[SPI]

DEAR DEEVEEYES, BASICALLY HARMONICS GENRATED DUE TO AC TO DC CONVERSION & DUE TO DC OFF SET COMPENENT. MEASURE HARMONICS LEVEL ON AC SIDE MUST BELOW < 2% THD ( VOLTAGE & CURRENT). FOR STUDY CALCULATE OVER ALL NETWORK CKT & EFFECT
WITH DIFFERENT LOAD. I WANT TO KNOW WITH OUT HARMONICS FILTER ANY EFFECT ON DC DRIVES WITH DIFFERENT LOAD.
VISIT

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