NGT Calculation

CALCULATION FOR NEUTRAL GROUNDING TRANSFORMER PROJECT : 11KV, 40MW CONDENSING TYPE TURBO GENERATOR SET A/C. BHUSHAN LIMITED Generator MW Rating Generator KV Rating Generator Capacitance/Ph (U (M (Micro Farad) Connected Capacitance(assumed)/Ph (Micro Farad) Trafo. Capacitance (assumed)/Ph (Micro Farad) Net Capacitance/Ph LAPT Capacitance/Ph (Micro Farad) Total Capacitance (Micro Farad) 3 X Capacitance Xc Capacitor Current/Amps Field Forcing Allowance ( a) NGT Vk (KV) ( b) Insulation (KV) (Vp) NGT KVA Rounded off KVA

57 11 0.286 0.0572 0.006 0.3492 0.3 0.6492 1.9476 1634.16 3.88643 5.828888 11 11

( a x b)

Equ. Primary Resistance

KVA Rs

0.7779 240 ** 0.05708 Rs

=

0.720838 288.487 I Sq = 65117.768 0.720838

I Rounded Off Current Rating NGT Rating

:

NGR Rating (LR):

**

65 KVA KVA for for 30 Sec Sec 0.720838 + 10% Ohms

Values to be entered

** **

1634.16

c x ( Vs/Vp) Sq.

Secondary Voltage Selected (Vs) Trafo. Resistance (assumed)/Ohms External Resistance/Ohms(Total Resistance/Ohms(Total Resis. - Trafo. Resistance) Resistance) Current Rating/Amps

**

64.117768 65

(c)

Secondary Resistance

** ** ** ** **

= 301

300.559765