| 摘要 |
PURPOSE:To shorten the power failure section and time by setting the individual delay time of a high voltage switch, which is installed in each section point of a plurality of power distribution sections of the time limit forward transmission type power distribution line, shorter than the operating time of the ground-failure protection relay in the power substation and longer than the operating time of the short-circuit protection relay having the anti-limit time characteristic. CONSTITUTION:An automatic section switch provided at each section point of the power distribution line of the time-limit forward transmission system is composed of a high voltage switch S and a control box T. The switch S is provided with a zero-phase current transformer ZCT, a zero-phase transformer ZPD, a switch M and a delay circuit 3 consisting of a resistor R and 6 a diode D1. The control box T is provided with a ground-fault direction relay E operating with outputs of ZCT, ZPD, relay G and F sequentially interlocking with the relay E and an automatic sectional apparatus H. The delay time of relay circuit 3 is shorter than the operating time of the ground-fault protection relay in the substation and longer than the operating time of the short-circuit protection relay of the anti-limit time characteristic and is usually set to about 0.6 second. Thereby, the power failure section and time when a fault occurs can be shortened. |
