TDR9000
™
Circuit Breaker Test System User’s Guide
72A-1898 Rev. A 11/01 A-21
Monday, November 26, 2001 1:09 pm
Both the blade and the interrupter are closed, carrying current. When
activated, the interrupter opens, breaking the current, while the blade is
still closed. The blade then opens for full visual confirmation of circuit
isolation. On closing, the blade is rotated closed, while the interrupter is
still open. The final closing of the blade activates the mechanism, closing
the interrupter.
Some circuit breakers have isolators (#6, Figure A.21) in conjunction
with their main interrupting contacts (#1,Figure A.21) as well as arcing
contacts (#2, Figure A.21) and auxiliary arcing chambers. The BBC DR
36 is such a circuit breaker. Because the main, arcing and resistor
chamber contacts all have distinct timing characteristics, it is necessary
to use a timing device which allows for several different sets of contact
timing specifications.
Figure A.21 Circuit Breaker with Isolating Contacts
6
5
1
443
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