| 摘要 |
<p>PURPOSE:To prevent dielectric breakdown fault by connecting the outputs of current transformers having excellent high frequency characteristics, provided for respective wirings of three adjacent ground coils, through a common ground wire connected with a pulse current detecting circuit. CONSTITUTION:When wirings 2 of three phases R, S, T are sound, current transformers 3a, 3b, 3c having excellent high frequency characteristics provided for that wirings 2 are connected, at the output thereof, with a common ground wire 4 and power supply pulses are offset each other through superposition of the phases. Upon occurrence of partial discharge due to defect, e.g. deterioration of insulation, of any one of ground coils 1a, 1b, 1c for three phases R, S, T, the partial discharge can not be offset through superposition on the ground wires 4 of two other phases but detected through a pulse current detecting circuit 5. According to the constitution, dielectric breakdown can be prevented.</p> |
