Description
2.8 Electronic trip unit
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
87
An electronic trip unit is based on the following concepts:
● Complete measurement of the current in the phases L1, L2 and L3, with N and currents
to ground optional
● Rogowski coil
– Very precise measurement of the current
– Better ground-fault protection because the vectorial sum is more exact
● Evaluation of the current measurement values and constant comparison with the tripping
limits
● Tripping by means of a maglatch
Electronic trip unit (ETU)
Maglatch
Current sensor
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