DC coupling for A.C. systems of dissimilar frequency - is fitted with DC poles connected to earth through RC circuits

摘要

The object is to minimise the risk of heavy fault currents and high voltage peaks on the power components in a circuit coupling two a.c. power systems of dissimilar frequency. Rectifier (5) and inverter (6) are in a d.c. loop (7) and are connected to their respective a.c. systems (1, 2) through appropriate rectifier transformers (3, 4). The poles of the d.c. circuit are indirectly connected to earth (9) through RC elements (10), typically arranged symmetrically with respect to the poles. As there is no direct earth connection a single breakdown in insulation does not give rise to heavy fault currents, and the RC elements also act as voltage surge suppressors. The chances of a double earth fault on opposite poles is considered so extremely remote that it can be ignored.