Description
2.8 Electronic trip unit
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
103
If the current in one phase exceeds the parameter setting for "load shedding" for longer than
delay time t
x
, an incoming alarm "load shedding" is generated. Only when the current in all
three phases drops below this threshold is an outgoing alarm "load shedding" generated.
The incoming and outgoing alarms can be output via an optional EFB module and
transferred via the communication link.
The opposite applies for the load acceptance threshold. If the current in all three phases
drops below the parameter setting, an incoming alarm "load acceptance" is generated. If
only one of the three currents exceeds the parameter setting, an outgoing alarm "load
acceptance" is generated.
To prevent these alarms being generated by brief current peaks and troughs, they can be
delayed by the time t
x
from 1 s to 15 s.
powerconfig is used for parameterization.
Measuring with a Rogowski coil
The Rogowski coil is a toroidal coil without a ferromagnetic core. It is used as a component
in electronic measuring devices to measure alternating current.
Advantages of the current sensor:
● Each transformer can be optimized for its task and operating points
– Transformers for power generation
– Transformers for measurement
● Higher accuracy of current measurement and therefore higher accuracy for ground-fault
currents
A power measurement is made possible by the more exact and more linear measurement of
the current together with the integrated voltage tap in the molded case circuit breaker.
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