PURPOSE: To realize delicate protection coordination by providing an element being set or reset instantaneously with a current lower or higher than a value being set by the tap of a relay and outputting the logical product of the outputs from a time limit element and the instantaneous element.

CONSTITUTION: Logical product of the output from a reverse time characteristic element provided from contacts 31, 32 through disc operation and the output from an instantaneous set/reset element provided from a contact 6 is delivered, as an output from a time limit element (interruption signal) to a circuit breaker. When the secondary current of a current transformer CT exceeds the current value at a set tap, the plunger of a coil 5 is set instantaneously to turn the contact 6 ON thus completing the selective interruption at a downstream interrupter. When the secondary current of a current transformer CT drops below the current value at a set tap, the plunger of the coil 5 is reset instantaneously to turn a contact 6 OFF. Since the contact 6 is turned OFF, no output is delivered from the time limit element even if the relay is set by the inertial force. Since error due to inertial force is eliminated, multistage protective coordination can be realized.