Siemens SENTRON 3WL10 Series Manual page 47

Additional functions
Pre-alarms response thresholds - PAL (function trigger)
This function permits definition of four independent current setting thresholds that can be
configured and switched when freely definable outputs are crossed (e.g. via the IOM040/
IOM300 input and output modules). In this way, the logic functions can be defined and
corrective action taken that, for example, triggers cooling systems in the plant, or sheds
loads to prevent the overload release from tripping the circuit breaker.
Two thresholds are defined as a selectable multiple of the overload current I
thresholds as a selectable multiple of the circuit breaker current rating I
It is also possible to choose the direction in which the threshold is crossed. For example,
a signal can be set if a current falls and the threshold is crossed in the downward direction.
2nd parameter set (set A/B)
The ETUs of the 6-series can store and manage a complete second set of alternative
parameters for the protection functions. It is possible to switch to this second set of
protection parameters (set B) with an external command or input. It then replaces the default
parameter set A.
The command to switch over can be issued if the circumstances of the power system
change, for example, when an emergency generator kicks in with the resulting load currents
or protection requirements.
Note
The second parameter set exists for all protection functions and thus also for DAS mode,
which provides reduced, alternative protection settings just for the instantaneous short circuit
protection (INST).
There are various ways of switching between parameter sets A and B:
● Locally, on the display of the ETU of the 6-series
● Via communication
● By input at the digital I/O module IOM040 or IOM300, which was triggered by an external
signal
● By input at the digital I/O module IOM040 or IOM300, which was triggered by an internal
signal, for example, the pre-alarm response thresholds (PAL)
● Automatically after a defined delay time, after the circuit breaker has been closed
Air circuit breaker 3WL10
Manual, 11/2017, L1V30499596002-01
Description
2.4 Electronic trip unit ETU
and two
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