Description
2.8 Electronic trip unit
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
87
2.8
Electronic trip unit
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
①
Electronic trip unit (ETU)
②
Maglatch
③
Current sensor