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Description
2.7 Electronic trip unit
3VA molded case circuit breakers with UL and IEC certification
80
Manual, 01/2019, L1V30435333-01
2.7
Electronic trip unit
2.7.1
Electronic trip unit (ETU)
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 summation formation 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