Detune filter harmonic

Hi, I want to know how many kind of the filter harmonics.
In many datasheet I seems that if there is 5th harmonics in the system then they tune the filter in the 4.7 not in 5th, why?

Parallel Resonance

Hi, What does the Parallel Resonance in the filter harmonics term mean, and how to detect them.

transformator

How to analysis the transformator that in the attachment file,
I want to know the Short circuit ampere and everything about analysis the transformator

LV capacitor bank

Hi, I have LV capacitor bank with L= 0.767 mH and C= 3*20 kvar and 8.33 kvar in Delta connection. This Panel is 12 step with 50 kvar per step. I have some problem with this panel, because the contactor always burn. whereas the size of contactor is for 80 kvar. The capacitor is tune for 189 hz. I had been measure the harmonics with fluke 43B and this the result:


1. Before capacitor switch on the V Amplitude at incoming LVS is :
49.87 Hz = 376.90 Vac
149.61 Hz = 0.44 Vac
249.35 Hz = 4.5 Vac
946.77 Hz = 0.26 Vac
and the kvar measurement is 640 kvar, 820 Kw, 1040 Kva.

2. After capacitor switch on the V Amplitude at incoming LVS is :
49.9 Hz = 383.1 Vac
149.7 Hz = 0.62Vac
249.5 Hz = 3.62Vac
948.1 Hz = 0.09 Vac

And the L measurement is 0.450 mH ( 63 % ) from Nameplate

And at this time I don't know what's happened with my capacitor. I hope anyone can help me......

Thank's