| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to share an input circuit among a plurality of electric power systems having a different voltage grade in a protection relay.SOLUTION: A protection relay 1 includes: an analog input processing unit that takes in quantity of electricity of an electric power system to output it as a first digital signal; a digital input processing unit that is connected with an external DC power supply E via a switch SW and compares a binary voltage Vdiv input in response to opening/closing of the switch SW with a threshold voltage Vth set according to the voltage Vdc of the external DC power supply E to output comparison results as a second digital signal; and a controller 32 that outputs an interruption command to a circuit breaker by determining the state of the electric power system on the basis of the first and second digital signals. |
