3WL air circuit breakers
3.4 Functions and parameters
3WL/3VL circuit breakers with communication capability - PROFIBUS
System Manual, 03/2011, A5E01051353-02
55
Threshold "load shedding"
If the current exceeds the set load shedding parameter in one phase, a "load shedding
alarm" is generated. Only when this lower threshold is violated by all three phases is the
"load shedding alarm" reset. These alarm messages are displayed direct as alarms in
Switch ES Power and they result in a yellow background in the status screen in the main
overview. However, they are also channeled into the event log and are provided with a time
stamp there.
Note
The event log is only available with COM15!
Threshold "load pick up"
The opposite applies for the load pick up threshold. If all three phases fall below the set
parameters, a "load pick up alarm" is generated. If only one of the three currents exceeds
the value of the parameter, the "load pick up alarm" is reset.
Delay time t
x
To prevent these messages being generated by brief current peaks and troughs, they can be
delayed by the delay time t
x
from 1 s to 15 s.
Where can the parameters be set?
The parameters for load management can be found in the parameter tree of
Switch ES Power under "Device parameters – Switch – Protection function – Supplement".
Local switching signals
The signals load shedding/load pick up are available as outputs on the digital output module
with rotary coding switch for automatically shutting down and connecting loads. The
configurable output module can also be set in such a way as to output the load shedding and
load pick up status.
3.4.3
Extended protection function
The extended protection function metering function PLUS adds further tripping criteria to
those of the trip unit. If an additional tripping condition from the extended protection function
is activated (e.g. phase unbalance voltage > 8%), this always results in a tripping operation
that the metering function initiates via the trip unit.
The options specified in the table "Protection function of the metering function PLUS" in
Chapter Voltage transformer (Page 48) are available as additional monitoring criteria.