The auto-recloser is sometimes used in time-coordinated, IDMT-protected networks that have old
mechanical relays with current-dependent release times. In these cases the operation of the protection
selectivity must be guaranteed by allowing all relay timing devices to completely reset during dead time
to maintain the correct time discrimination after reclosing to the fault. Some mechanical IDMT relays
can require up to ten seconds (10 s) to reset. When short dead times are required, the relays should
reset almost immediately for the current-dependent time grading to operate as expected, and set
the discrimination time (instead of the arcing time) to start simultaneously with the reclaim time. If new
reclosing requests are made during this discrimination time, the function halts and lets the protection
devices operate based on their own settings, and does not interfere with the protection functions' or the
breaker's operation. However, this means that the auto-recloser has to be manually reset and the
breaker manually closed before further reclosing requests can be made.
Auto-recloser I/O
The main outputs of the auto-recloser function are the control signals OBJECT OPEN and OBJECT
CLOSE. The function also reports the recloser status information which is used in the logics, LED
indications, and applied operations.
The inputs of the function are the following:
• binary recloser request signals
• blockings
• controlling signals
• the controlled object's monitoring and status signals.
The function generates general time-stamped ON/OFF events to the common event buffer from each
of the two (2) output signal as well as from several operational event signals. The time stamp resolution
is 1 ms. The function also a resettable cumulative counter for each of the applied reclosing events and
requests.
The auto-recloser function can be divided into the starter, shot selector state machine, sorter and shot
blocks which operate dynamically during the recloser sequences according to the given settings and
input signal monitoring. The behavior of the function can be changed even during sequences that are
based on programmed reclosing schemes and on active requests.
The following figure presents a simplified function block diagram of the auto-recloser function.
A
AQ
Q-F205
-F205
Instruction manual
Version: 2.04
274
© Arcteq Relays Ltd
IM00013
Summary of Contents for AQ F205
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