2. Short-circuit current breaking phenomena
2.3 TRVs in power systems
Previous Next Contents


Fig. 2.3 shows a simplified one line diagram of an electric power system around a certain substation. Generally, basic phenomena for TRV can be considered applying such simplified diagram. For three phase circuits, see the following Sub-section.
For considering some typical short-circuit current breakings, fault points F1, F2,---- F4 are introduced.
For F1, applying current injection principle, see Fig. 2.4, the first part of TRV is dominated by the transformer reactance (20mH) and the total surge impedance Z of the lines in parallel, with the time delay ZC (C is the lumped capacitance 0.1 mF). At the very beginning (see the enlargement of Y), small voltage swing due to the line between the circuit-breaker and the main bus-bar ("X") appears.
In case F2, F3 and F4 (line faults), also current injection principle is applicable, and positive and negative polarities of currents are injected from the both side terminals of the circuit-breaker. Both side currents produce both side voltages and the sum of them is the TRV across the terminals of the circuit-breaker. As for the voltage potentials to ground at the terminals, initial condition(s) shall be introduced, and also (a) or (b) in Fig.2.2 is to be considered.

Fig. 2.5 shows a typical TRV in breaking (short) line fault current. The voltage across the terminals corresponds to the shaded part.

This page is based on Prof. E.Haginomori's lectures in Tokyo Institute of Technology, and edited by Japanese ATP User Group. Copyright (C) Eiichi Haginomori and Japanese ATP User Group.