Synchronous Generator Input Data

Answer: Make sure to use manufacturer data. Below is an example of generator input data from manufacturer.

Rated Voltage : 480 V

Rated Size : 1875 kVA

Power Factor : 0.8

Poles : 4

Z_b = [(kV_b) ² x 1000]/ kVA_b = [(0.48 kV) ² x 1000]/ 1875kVA = 230.4kV²/1875kVA = 0.12288 ohms

R_a =0.0023 ohms ; R_apu = R_a/Z_b = (0.0023 ohms)/ (0.12288 ohms) = s0.01872 pu

X"_pos = 0.1831 pu X/R_pos = X"_pos/ R_apu = 0.1831/0.01872 = 9.781

X_neg = 0.1750 pu X/R_neg = X_neg/ R_apu = 0.1750/0.01872 = 9.348

X_zero = 0.0098 pu X/R_zero = X_zero/ R_apu = 0.0098/0.01872 = 0.524

X_d' = 0.2694 pu

X_d = 3.3008 pu

T_d" = 0.0074 seconds = 7.4 ms

T_d' = 0.4800 seconds = 480 ms

T_dc = X_d" / (2pf * R_a) where X_d" = X"_pos, f is frequency.

T_dc = 0.1831/ (2pi *60Hz * 0.01872) = 0.1831/ 7.061 = 0.0259 seconds = 25.9 ms