Protection Engineering Basics and Schemes Protection Engineering | страница 257

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pg. 257
digital form for metering and fault current
calculation in auto reclosure
When line current or ground increases from
preset pick up value(as per TCC), then through
CPU and RIF the trip solenoid of auto reclosure
energized, and auto reclosure operation initiate
means 1 st shot occur, after delay when reclosure
attempt to close, again CPU and RIF check the
current and if current remains above minimum
pick up value then auto reclosure attempt second
shot, this cycle continue till block stage.
Block stage is the value of number of shots after
which auto reclosure stop any attempt to closed
the circuit and remains in open position
At distribution system of 33KV and 11KV ,
recommended shots are 3 to 5 but again I want to
said it all depend on client requirement
At Transmission system of 132KV and more,
recommended shot is one