Earth Fault Protection; Functionality; Principle Of Operation - ABB REF601 Applications Manual

Section 4
Protection and Control Function
4.2
4.2.1
4.2.2
14
Table 5: Setting ranges Non-directional overcurrent protection, High stage 3I>>, 50-1
Description
Setting range of pick-up current I>>
Operation mode
Operate time delay (DMT) t >>
Reset ratio
Reset time
Table 6: Setting ranges Non-directional overcurrent protection, Instantaneous stage 3I>>>, 50-2
Description
Setting range of pick-up current I>>>
Operation mode
Operate time delay (DMT) t >>>
Reset ratio
Reset time

Earth Fault Protection

Functionality

The earth-fault protection function is used as non-directional earth-fault protection
for feeders.
The earth current can be calculated internally (IEC variant only, respective not
available in CEI variant) or measured externally by core balance current
transformer of 1A or 5A secondary current.
The operate time characteristics for low stage can be selected to be either definite
time (DT) or inverse definite minimum time (IDMT). The instantaneous stage
always operates with the definite time (DT) characteristics.

Principle of Operation

The earth fault protection function continuously measures the neutral current of the
protected object. The current is evaluated by the low stage (I0> / 51N) and
instantaneous stage (I0>> / 50N) of earth fault over current functions.
On occurrence of fault, fulfilling the trip condition of respective stage, the LED
"Trip" and "Trip Io" will be activated. Additional the output relays (Trip and
signalization) will be activated according the binary output configuration.
Each of the stages could be blocked by settings or via binary input of the relay.
Value
0.5...25 x In in steps 0.001, infinite
Definite time
0.04...64 sec in steps of 0.01
0.98
40 sec
Value
0.5...25 x In in steps 0.001, infinite
Definite time
0.03...64 sec in steps of 0.01
0.98
40 msec
1MDU07212-YN Rev. A
REF601 / REJ601
Application Manual