King Jonah Electrical Engineering

n the past French Transmission System Operator RTE installed 30 Mvar capacitor banks connected to the 63 kV and 90 kV networks. 30 Mvar rated power corresponds to the optimal value to limit the voltage changes when the capacitor bank is switched in, when the short-circuit current (Scc) of the substation is low.
These capacitor banks have an isolated neutral. Indeed, for a 63 kV network, grounded neutral can not be used since the impedance of a 30 Mvar capacitor bank (about 130 ohms capacitive) is rather close to the equivalent zero impedance of a typical 63 kV substation of the South Brittany network (50 ohms inductive).

Now-a-days electrical energy is generated, transmitted and distributed in the form of alternating current. One important reason for the widespread use of alternating current in preference to direct current is the fact that alternating voltage can be conveniently changed in magnitude by means of a transformer.
Transformer has made it possible to transmit a.c. power at high voltage and utilize it at a safe potential. High transmission and distribution voltages have greatly reduced the current in the conductors and the resulting line losses.