LV capacitor bank

[hadi]

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

[Guest]

My friend, did u check for loose connections on the contactors? This will generate heat and maybe the cause for your contactors to burn-out.

[hadi]

Yes, I had been checked all connection between contactor to reactor (L). And last time I has check the connection between reactor to capacitor, and I found the insulation of cable shoe was burn but the connection still OK ( there is no fault in the connection). and I stiil confused for this problem, until now I don't change the contactor because I'm affraid this problem appear again. so what's can I do for the next time