Active filter and cable sizing

[Alex68]

Dear Collegues,

I must size the cable of an active filter.

This cable has to carry a little 50 Hz harmonic but lots of harmonics in the range 150 Hz to 2.5 kHz.
So I can't apply the usual sizing criteria based on the fondamental harmonic and the de-rating factors as indicated in the Red Book and the IEEE 519.

I could apply the heating criteria described in IEC 60287 standard for each harmonic. But it could be a very long job.

Is there a standard (ANSI, IEEE, IEC, BS, ...) concerning this matter?
What criteria do you apply? How do you approach this problem?

Thank you
Alex68

 

[electricuwe]

It would be helpful, if you provide information on the rating of the active filter unit.

The neccessary derating for a cable varies signifcantly with cross section.

 

[sammydog]

The Active Filter will remove the fundamental current by way of a notch filter, so other than the switching losses (approximately 2% of the filter frame size) the only line current will be the harmonic current plus the 2% swiching losses.
From experience, I would suggest derating the input cable harmonic current by at least 15%, plus the 2%, assuming the the distance to the supply is within 5m.

 

[Alex68]

Thank you for your answers.
Some data:

Filter:
Connection voltage is 600V. Rating is 4*900A rms. Harmonic current is mainly 5th but this can change and what we need is a general purpose rating method that can be adjusted to almost what ever combination of harmonic loads the operators dial up on the controller. 50Hz is only on a "what left" basis so if heavy drilling load no 50Hz.

Cable:
3x(1x500) sqmm on cable tray indoors 40degC max temp.
Tinned annealed copper conductor, singlo core, taped, 0.6/1kV R-HF-90 insultaed, HF-90-R inner sheath, tape TN/Copper braid, taped, HF-90-R sheaths. To AS/NZS 4193 W/A.

Any suggestion would be appreciated.
Cheers
Alex68