10.3.2.4 Blocking of the autorecloser
Auto-Reclose attempts are expected to take place only in the event of transient faults
on the own line. The Auto-Recloser must be blocked for the following conditions:
• Tripping from Delayed Distance protection zones
• Tripping from Back-up protection functions
• Tripping from Breaker failure function
• Intertrip received from remote end Breaker failure function
• Busbar protection tripping
Depending of the starting principle (General Trip or only Instantaneous trip) adopted
above the delayed and back-up zones might not be required. Breaker failure local and
remote must however always be connected.
10.3.2.5 Control of the auto-reclosing open time for shot 1
Up to four different time settings can be used for the first shot, and one extension time.
There are separate settings for single- and three-phase auto-reclosing open time, t1
1Ph, t1 3Ph. If no particular input signal is applied, and an autoreclosing program with
single-phase reclosing is selected, the auto-reclosing open time t1 1Ph will be used. If
input signal TR3P is activated in connection with start, the auto-reclosing open time
for three-phase reclosing is used.
An auto-reclosing open time extension delay, tExtended t1, can be added to the normal
shot 1 delay. It is intended to come into use if the communication channel for
permissive line protection is lost. In such a case there can be a significant time
difference in fault clearance at the two ends of the line. A longer “auto-reclosing open
time” can then be useful. This extension time is controlled by setting parameter
Extended t1 = On and the input PLCLOST.
10.3.2.6 Long trip signal
In normal circumstances the trip command resets quickly due to fault clearing. The
user can set a maximum trip pulse duration tTrip. When trip signals are longer, the
auto-reclosing open time is extended by tExtended t1. If Extended t1 = Off, a long trip
signal interrupts the reclosing sequence in the same way as a signal to input INHIBIT.
10.3.2.7 Reclosing programs
The maximum number of reclosing shots in an auto-reclosing cycle is selected by the
setting parameter NoOfShots. The type of reclosing used at the first reclosing shot is
set by parameter FirstShot. The first alternative is three-phase reclosing. The other
alternatives include some single-phase or two-phase reclosing. Usually there is no
two-phase tripping arranged, and then there will be no two-phase reclosing.
Section 10 1MRK 505 291-UEN A
Control
216
Application manual
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