Siemens SENTRON 3VL System Manual page 43

2. Overcurrent trip unit of the SENTRON VL160 to VL1600 circuit breakers, electronic, ETU / LCD-
ETU
The electronic overcurrent tripping system consists of:
● current transformers
● Evaluation electronics with microprocessor
● Tripping solenoid
No auxiliary power supply is necessary for the tripping system.
Activation of the microprocessor trip unit requires a minimum load current of approximately
20% of the relevant rated current I
At the output of the electronic overcurrent trip unit, there is a tripping solenoid that releases
the circuit breaker in the event of an overload or short-circuit.
3VL molded-case circuit breakers
System Manual, 03/2009, 110 0110 - 02 DS 01
of the circuit breaker.
n
Functions
5.1 Current protection
43