Digital forma electric current differential conservation relay device

摘要

PURPOSE:To detect so-called blind point fault, occurring between current transformers and disconnectors at each terminal of a multi-terminal transmission line having a pi branch, positively. CONSTITUTION:Digital current differential relays 11, 21, 31 are provided for each terminal of a multi-terminal transmission line including pi branch terminals. The current differential relay takes in current value information and open/close information of disconnector at its terminal. The information is then transmitted/ received mutually and decision is made between fault section and interrupted section based on the current value information and open/close information of disconnector at all terminals thus protecting a system. The current differential relay 31 corresponding to the pi branch terminal is provided with a transmission selecting means 51 for transmitting current value information only of the closed one of the disconnectors 33A, 33B. The current differential relays 11, 21, 31 corresponding to respective terminals are provided with reception processing means 52 for processing the open circuit command of circuit breaker at its terminal while considering that there is no current value information at the other terminal of an opened circuit breaker being inserted.