A 2400/240-V two-winding transformer has the following parameters,
Req = (0.62) Ohm
Xeq = (0.25 Ohm
Both Req and Xeq are referred to the primary. The core resistance and the magnetization reactance are neglected.
Three of the above single phase transformers are connected as a 3-phase transformer bank. The high voltage side of the transformer bank is connected in Y and the power is supplied to the transformer bank through a transmission line with an impedance equal to ZTL = j 2 Ohm.
The transformer bank is supplying two different three-phase loads connected to the 240 V side of the transformer bank as follows,
Load 1: 100 kVA, 0.85 p.f lagging.
Load 2: 80 kW, 0.9 p.f leading.
a) Determine the rating of the transformer bank (KVA) to supply the above load.
b) Calculate the voltage and current of the sending end of the transmission line.
c) Calculate the p.f. at the sending end of the transmission lines.
d) Based on your calculation in (c), what is the kVAR rating of a three-phase capacitance (or inductance) load to be connected to the secondary side of the transformer to improve the p.f. in (c) to 0.95 lagging.