Quantcast Automatic Operation

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 


(b) Two major categories of sequence control devices:
o
In the hydraulic type, a pump piston attached to the recloser plunger raises the
trip piston a certain amount by pumping a measured amount of oil under the
trip piston with each operation of the recloser. This changes the sequence from
fast to delayed tripping and eventually locks the recloser out.
o
In the electronic control scheme, minimum phase and ground trip values and
timing of tripping, reclosing, and resetting are established by a
plug-in resistance-capacitance network. Current transformers provide sensing
for overcurrent or faults. The battery-powered electronic control
panel sends signals to a solenoid to open or reclose the contacts.
3.6.6 Automatic Operation. When an overcurrent of sufficient magnitude flows through the
trip coil or current transformers, the tripping action is initiated and the contacts are opened. The
recloser contacts then reclose following a predetermined length of time. By the time the recloser
has reclosed the circuit, the sequence control device has moved to count the trip operation. If the
fault still persists on the circuit when the recloser closes, the tripping and reclosing sequence is
repeated (a predetermined number of times), as established by the sequence control device, until
the recloser goes to lockout. If the fault has cleared from the circuit during any open period, the
recloser closes and remains closed, and the sequence control device resets so that it is in position
for the next sequence of operations.
3.6.7 Manual Operation.
3.6.7.1 Manual Tripping. An automatic circuit recloser can be tripped open manually by
moving the manual operating handle to the trip position by means of a hookstick. If the recloser
is provided with a nonreclosing lever, it should be pulled down as far as possible to cut out the
automatic reclosing before the recloser is manually tripped.
3.6.7.2 Manual Closing. An automatic circuit recloser can be closed manually by moving
the manual operating handle to the close position by means of a hookstick or, if the recloser is
provided with remote control, by moving the control switch to the close position. If the recloser
is provided with a nonreclosing lever, the nonreclosing lever should be pulled down as far as it
will go in order to cut out the automatic reclosing before the recloser is closed manually. After
the automatic circuit recloser has been successfully closed, the automatic reclosing should be
placed in service.
3.6.7.3 Manual Reclosing After Lockout Operation. Reclosers in service are designed to
lock out following a selected sequence of tripping and automatic reclosing operations. When a
recloser appears to be locked out, the operator is always faced with the possibility that the
recloser itself may have failed. The following procedure is recommended for reclosing of
recloser after a lockout operation.
3-45





 


Privacy Statement - Copyright Information. - Contact Us

Integrated Publishing, Inc.