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 3.6.5.3 Operating Mechanism. The operating mechanism of an automatic circuit recloser
provides the power to open, close, or lock out the main contacts.
(a) The tripping mechanism releases the holding means and permits the contacts to
open. In most cases the opening force is furnished by springs that are charged by the closing
action.
(b) The closing mechanism is normally a solenoid coil or a motor and gear
arrangement. The closing force serves to close the main contacts and at the same time to charge
the spring providing the opening force. The lockout mechanism locks the main contacts in the
open position following the completion of a predetermined sequence of operation; i.e., when the
fault is not cleared after a predetermined number of reclosures.
3.6.5.4 Interrupter. The interrupter contains separable contacts that operate within an oil
or vacuum chamber. Low-energy arc interruption in a vacuum results in quiet and reliable
operation.
3.6.5.5 Control. Reclosers are provided with sequence control devices and an operation
integrator to change the recloser from instantaneous operations to time-delay operations, and to
lock out the recloser after a prescribed number of operations. Individual tripping operations of a
recloser can be made to follow instantaneous or time-delay time-current characteristics.
(a) Examples of operational sequences:
o
Four time-delay operations. This consists of three open-close operations and a
final open operation. All operations are preceded by a fixed time delay to
allow the fault to clear. After three open-close operations, it is assumed that the
fault is permanent and the fourth operation is a lockout trip.
o
One instantaneous operation followed by three time-delay operations. This
consists of three open-close operations and a final open operation.
The first operation is instantaneous, and the subsequent three operations are
preceded by a fixed time delay. The fault may be intermittent, so that
the first operation, which is instantaneous, often clears the fault in a shorter time
than if a time delay were used for the first operation.
o
Two instantaneous operations followed by two time-delay operations. These are
similar to the above, in that the first two operations are made with no intentional
time delay. This is based on the assumption that most faults are transient in
nature, and that possibly the fault did not clear on the first try, but no intentional
time delay is needed for the second operation.
3-42
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