Application Guide - NP900 Series
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A996A
Figure 3.6.4.7-193 Signal status graph of the semi-permanent overcurrent autoreclosing
cycle.
1.
Overcurrent is found in the protected line which causes overcurrent protection I> to
pick up and activate REQ1 which causes the starting time calculating for the Shot 1.
Shot 1 signal is activated simultaneously with corresponding starting time even the
autorecloser is still in not running mode.
2.
Start time 500 ms for Shot 1 is elapsed and the autorecloser enters to running mode
and sends open command to the breaker.
3.
Circuit breaker is opened and I> Start signal is released and simultaneously REQ1
signal for autorecloser is released. Recloser starts to calculate the Shot1 Dead Time
for closing the breaker.
4.
Dead Time for Shot1 is exceeded and autorecloser sends close request for the Object
breaker, the close conditions are met and the breaker close command is sent to
breaker close coil.
5.
Circuit breaker is closed and since fault is not cleared by the Shot1 given non-
energized time, pick-up of I> is detected. Close command is drop off after the breaker
