Hitachi Relion 650 Series Technical Manual page 44

Section 4
Binary inputs and outputs
The PIO module provides 6 fast static outputs that are rated for making and carrying high currents.
The switching instants of these precision binary outputs can be controlled at 100 microseconds'
accuracy, which makes them ideal for controlled switching of circuit breakers.
Binary outputs rated for making and carrying high currents allow connection directly to breaker
tripping and closing coils. If breaking capability is required to manage failure of the breaker auxiliary
contacts normally breaking the coil current, parallel reinforcement by an external relay is required.
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Trip circuit supervision generates a current of approximately 1.0 mA through the
supervised circuit. It must be ensured that this current will not cause a latch up of the
controlled object.
To protect the trip circuit supervision circuits in the IED, the output contacts are
provided with parallel transient voltage suppressors. The breakdown voltage of these
suppressors is 400 ± 20 V DC.
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1MRK 511 557-UEN Rev. A
Technical Manual