Application Guide - NP900 Series
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A996A
This type of sequence represents 75-85% of all the faults in the medium voltage overhead
line network.
Figure 3.6.4.8-195 Signal status graph of the transient 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.
