9 – 45
Replacing rating plug
9.1.9 Ground-fault protection modules
Various trip units can be optionally equipped with ground-fault protection modules. The following ground-fault protection modules cannot be
removed once they have been installed.
Depending on the ground-fault protection module version, the set value being exceeded will cause either an alarm only or an alarm and a
trip at the same time.
(page 9-13)
The following device combinations are possible:
The following options exist for ground-fault detection:
- vectorial summation of the phase currents or vectorial summation of the phase currents and the neutral conductor current if a
neutral sensor is used
- Direct measurement of the ground-fault current using a separate 1200 A : 1 A ground-fault sensor
Input current carrying capacity of the ground-fault protection module:
-max. 1 A continuous
-max. 5 A for 0.5 sec.
Alarm and tripped signals can be transmitted via the c, PROFIBUS-DP and MODBUS.
Module GFM A 745
- Alarm only, circuit breaker does not trip
- The changeover switch for ground-fault detection is only accessible when the control panel or the trip unit itself is removed.
NOTICE
Circuit breaker may trip.
If the trip settings are changed while the breaker is closed (and under load) the breaker may trip.
Adjust parameters only when the circuit breaker is in the open position.
Trip unit Ground-fault protection module
ETU745 - 748
GFM A 745-748
GFM AT 745-748
ETU776
GFM A 776
GFM AT 776
Rotary coding switch for ground-fault
alarm setting value
Ground-fault alarm indicator
Rotary coding switch for ground-fault
delay setting t
g
/ I
2
t
g
Changeover switch for ground-fault
detection
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