Description
2.8 Electronic trip unit ETU
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
66 Manual, 10/2018, L1V30499596002-01
The settings selected for the trip unit of a circuit breaker depend on the technical
environment (e.g. switchboard and applications) and the type of equipment to be protected.
It is the responsibility of the system planner to calculate and dimension the protection
settings in accordance with the valid rules.
The following diagram shows the tripping characteristics of the circuit breaker.
Setting value of the long-time-delayed protection
Delay time of the long-time-delayed protection
Switchover of the overload characteristic (I
4
Setting value of the short-time-delayed protection
2
t characteristic ON/OFF of the short-time-delayed protection
Delay time of the short-time-delayed protection
Setting value of the instantaneous protection
Setting value of the ground-fault protection
Switchover to the I²t characteristic of the ground-fault protection
Short-time-delayed short-circuit protection range
Instantaneous short-circuit protection range
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