| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a highly reliable digital type protection relay system without incurring a rise in cost. <P>SOLUTION: According to an embodiment, the protection relay system comprises main and sub protection relays connected to a utility grid and an opening unit. The main and sub protection relays include a conversion unit, a main relay arithmetic unit, and a failsafe relay arithmetic unit. The conversion unit converts a voltage level in the utility grid into digital data. The main relay arithmetic unit executes arithmetic operation on the digital data to calculate and output an opening directive. The failsafe relay arithmetic unit executes arithmetic operation on the digital data to calculate and output an opening directive by a different standard than in the main relay arithmetic unit. The opening unit logical ANDs the opening directive output from the main relay arithmetic unit of the main system with the opening directive output from the failsafe relay arithmetic unit of the sub system and logical ORs the opening directive output from the failsafe relay arithmetic unit of the main system with the opening directive output from the main relay arithmetic unit of the sub system, to generate an opening directive control signal for a circuit breaker installed in the utility grid. <P>COPYRIGHT: (C)2013,JPO&INPIT |
