Selecting Adaptive Sequence Length; If One Or Several Phase Currents - ABB REF610 Technical Reference Manual

1MRS755535
6.1.3.
Feeder Protection Relay
Technical Reference Manual - ANSI Version
At the factory default delay of 300 s for AR 51P pickup Delay and
AR 51N pickup Delay, the pickup signals will, in practise, not be
used for shot initiation. However, if elements 51P or 51N have been
given an IDMT characteristic, the factory default delay of 300 s will
function as a trip time limiter. With small currents, the operate time at
IDMT characteristic may be relatively long. However, since the pickup
signals are always routed to the AR function, the circuit breaker will be
tripped and a shot initiated (provided that the signal Open CB
Command has been routed to the trip output contact) on expiration of
the factory default delay.
When using AR 51P pickup Delay and AR 51N pickup Delay
for shot initiation and the signal Open CB Command has been routed
to the trip output contact, elements 51P and 51N should not be used for
blocking of shot 1.

Selecting adaptive sequence length

The auto-reclose sequence can be set to adapt to the fault current, either through
blocking of shot initiation or disable of the AR function.
In the examples below, three overcurrent elements (51P, 50P-1 and 50P-2) are used
and the number of shots of the AR sequence vary depending on which elements
trips.
Example:
Start by checking that the switches have been properly set:
Settings
SG1/1=1
SG3/1=1
Number of shots = 3

If one or several phase currents

exceed the set pickup value of element 51P but not of elements 50P-1 and
*
50P-2, the AR sequence will include shot 1, 2 and 3.
exceed the set pickup value of elements 51P and 50P-1 but not of element
*
50P-2, the AR sequence will include shot 2 and 3.
exceed the set pickup value of elements 51P, 50P-1 and 50P-2, no shots
*
will be performed (AR function disabled).
Function
Blocking of initiation of shot 1 by the trip signal from
element 50P-1
Disable of the AR function by the trip signal from element
50P-2
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