GE MLP1000 Manual page 25

3 - Fault inside the zone 3 reach or overreach.
4 - Remote open detector.
5 - Line pick up.
Since it is a three phase trip protection, the type of fault detected (single phase, two
phase, or three phase) is irrelevant at the time of the tap decision. therefore the type of
fault is not mentioned.
When setting the different timers you must take into account the operating time of
the measuring units (1 network cycle). So when setting the zone I timer to 0 ms
(instantaneous trip) the relay takes 1 network cycle to detect a fault and 8 ms to close the
trip contact.
1 - Fault inside the zone 1 reach
In the case of a fault inside the zone 1 reach, any of the 6 distance measurable
units in zone 3 or overreach as well as the 6 distance measuring units in zone 1 will
detect the fault
Once the protection trip is produced, the process is identical to that of the previous
fault.
3 - Fault inside the zone 3 reach and outside the zone 2 reach
In the case of a fault inside the zone 3 reach, zone 1 distance measuring units will
not detect the fault, ho•ever zone 3 distance measuring units will detect the fault.
After activating the "DMUZ3 ACTIVE" signal the protection is activated and the
zone 2 and zone 3 timers are started.
The zone 2 timer will be the first to finishing counting and will deactivate the zone 1
distance measuring units and activate those of zone 2. At this moment the zone 2
measuring units will continue without detecting the fault and will have to wait until
the end of the zone 3 timer count to allow a protection trip in zone 3 provided that
the block trip in zone 3 is not set, in which case the protection is returned to
standby.
Once the protection trip is produced, the process is identical to those of the
previous fault.
4 - Remote open detector
Activation of the remote open detector unit directly authorizes a protection trip.
provided that the block trip by remote open detector is not set, in which case the
protection is returned to standby.
Once the protection trip is produced, the process is identical to those of the
previous fault.
5 - Line pick up
Activation of the line pick up unit directly authorizes a protection trip.
GEK-98846A
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