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Working of SF6 Circuit breaker
In general, the circuit breakers consist of two main parts, the poles and the mechanism. The
poles consist of contact and arc-extinguishing devices. The mechanism is the part to open or
close the contacts in the poles at the same time instantaneously (with max. 5 millisec.
Tolerance). The closing and opening procedures are performed through springs which are
charged by a servomotor and a driving lever. In the system, the closing springs are first
charged. If "close" button is pressed, the opening springs get charged while the contacts get
closed. Thus, circuit breaker will be ready for opening. The mechanical operating cycle of the
circuit breaker is (OPEN-3 Min CLOSE/OPEN-3 Min- CLOSE/OPEN) or (OPEN-0.3 sec-
CLOSE/OPEN-3 Min CLOSE/OPEN). The second cycle is valid when the circuit breaker is
used with re-closing relay. In that case, after the closing operation, the closing springs are
charged by the driving lever or by driving motor (if equipped). Thus, the circuit breaker will
be ready for opening and re-closing.
When manual or motor-drive is used, the circuit breaker will be ready to close. The closure
can be actuated by pressing the closing button located on the circuit breaker. It is
recommended to close it using remote control system for secure operations. The opening can
be performed either by opening button or remote controlled opening coil. In case of a fault,
the relay signal actuates the opening coil and circuit breaker opens. (This is mechanically a
primary protection system). In addition, there is an anti-pumping relay for preventing the reclosing
and opening of the circuit breaker more than one cycle (O - C - O) and for preventing
possible troubles created by remote closing button.
gregorymasila answered the question on February 22, 2018 at 16:40
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