HV AC generation:
(1) A high voltage testing laboratory is required to test apparatus with a capacitance of the order of 2000pF which is used in a 230kV system. If the test voltage requirement is 2.2 times the system rated voltage, determine the power rating of the test transformer at 50 Hz operation.
(2) A 100kVA, 250V/200kV testing transformer has 5% leakage reactance and 1% resistance on 100kVA base. A cable has to be tested at 400kV using the above transformer as a resonant transformer at 50Hz. If the charging current of the cable at 400kV is 0.5A, find the series inductance required. Assume 1% resistance for the inductor to be used and the connecting leads. Neglect losses for the cable. What will be the input source voltage to the primary of the transformer?
(3) A simple series resonance power supply is used for testing a high voltage bushing, which can be treated as a pure capacitive load of 2000pF. The required test voltage is 15kV at 5kHz, when the system operates under resonance, using an inductor of high-quality factor, Q = 14. Calculate the output voltage rating of the power supply (excitation voltage), and the value of the inductance at 5kHz.
