User Manual

Description
2.3 Protection system
3WA Air Circuit Breakers
60 Equipment Manual, 05/2021, 92310000002-03
Ground fault interruption
The ground fault on the outgoing side can be interrupted with the circuit breaker.
When a ground fault is detected on the infeed side, the ETU600 LSIG Hi-Z electronic trip
unit issues a signal to open the medium-voltage circuit breaker. In this case, the ETC600
external trip controller can be integrated in the intertripping circuit of the medium-voltage
circuit breaker and can also open the low-voltage 3WA circuit breaker by means of the second
tripping solenoid F6.
The tripping solenoid F6 operates independently of the ETU600 electronic trip unit and
prevents reclosing after the circuit breaker has been opened. The circuit breaker can only be
closed after resetting the reclosing lockout locally, marked EXT TRIP in the figure below. The
3WA is the only circuit breaker capable of this functionality.
(1)
ETU TRIP, reclosing lockout not active
(2)
EXT TRIP, reclosing lockout active
(3)
ETC600 external trip controller
2.3.5.9 Directional short time dST
With the directional short time dST, the power distribution system is protected against power
system faults such as:
• Phase-phase short-circuit
• Phase-neutral conductor short-circuit
• Phase-ground short-circuit
The circuit breaker trips when the rms value of a phase current exceeds the set directional
short-time-delayed tripping current for the duration of the set directional delay.
This function requires an internal voltage tap or external voltage transformers and a voltage
tap module VTM. For this protective function, the direction of energy flow must also be
defined and parameterized on the ETU600 electronic trip unit: