VAMP VAMP 59, Инструкции по установке, эксплуатации и настройке

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2.3 General features of
protection stages
2 Protection functions Technical description
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Output matrix
Using the output matrix the user connects the internal start
and trip signals to the output relays and indicators. For more
details see chapter 5.4.
Blocking
Any protection function can be blocked with internal and
external signals using the block matrix (chapter 5.6). Internal
signals are for example logic outputs and start and trip signals
from other stages and external signals are for example digital
and virtual inputs.
When a protection stage is blocked, it won't pick-up in case of a
fault condition is detected. If blocking is activated during the
operation delay, the delay counting is frozen until the blocking
goes off or the pick-up reason, i.e. the fault condition,
disappears. If the stage is already tripping, the blocking has no
effect.
Retardation time
Retardation time is the time a protection relay needs to notice,
that a fault has been cleared during the operation time delay.
This parameter is important when grading the operation time
delay settings between relays.
Figure 2-1 Definition for retardation time. If the delay setting would be
slightly shorter, an unselective trip might occur (the dash line pulse).
For example when there is a big fault in an outgoing feeder, it
might start i.e. pick-up both the incoming and outgoing feeder
relay. However the fault must be cleared by the outgoing feeder
relay and the incoming feeder relay must not trip. Although the
operating delay setting of the incoming feeder is more than at
the outgoing feeder, the incoming feeder might still trip, if the
operation time difference is not big enough. The difference
must be more than the retardation time of the incoming feeder