Siemens SENTRON 3WL10 - Electronic Trip Unit ETU; Description of Functions

2.9 Electronic trip unit ETU
As a protection device, the circuit breaker has the task of protecting installations and clearing
electrical faults occurring in the system. A trip unit detects whether a fault occurs by comparing
the protection parameters set in it with the measured values. The circuit breaker has
microprocessor-controlled trip units.
The tripping characteristic can be adjusted to the required values with numerous possible
settings.
Selective tripping and instantaneous release
On short-circuits in the medium current range, selective tripping (ST) is ensured. On short-
circuits with a larger current and high arc energy in the arc chute, an instantaneous release
(INST) responds and interrupts the overcurrent immediately (<30ms).
One ETU for two versions of the current-limiting (3VA27) and current-carrying (3WL10)
contact system
The kinematic behavior of the two contact systems (ACB/MCCB) of this platform device only
diverges above the maximum settable operating value of the instantaneous short-circuit
release (INST). For this reason, it is possible to use the identical ETU (ETU of the 3-series and
ETU of the 6-series) for both versions.
2.9.1 Description of functions
Protection Electronic
ETUs of the 3-series
Electronic with display
ETUs of the 6-series
Trip units
ETU320, ETU350, ETU360
Line / generator protection
ETU650, ETU660
Line / generator / motor protection
Parameter assignment Setting parameters with rotary coding
switch
• Setting the parameters with push‐
buttons and reading them o󹪜 the dis‐
play and communication
• Fine adjustment of the parameters
• Reading o󹪜 the measured values
Description
2.9Electronic trip unit ETU
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
Equipment Manual, 10/2023, L1V30499596002-03 43