Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – With housing or support means
Reexamination Certificate
2000-05-09
2001-12-04
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
With housing or support means
C218S155000, C218S139000
Reexamination Certificate
active
06326872
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to power circuit breakers and particularly to a compact power circuit breaker having a molded insulative casing with a ground plane barrier between the pole mechanisms and the operating mechanisms and an air gap between the casing and the barrier on the side of the barrier facing the pole mechanisms.
2. Background Information
Power circuit breakers for systems operating above about 1,000 volts typically utilize vacuum interrupters as the switching devices. The vacuum interrupters for each phase must be adequately electrically isolated from each other for the operating voltage. Where sufficient space is available, the vacuum interrupters and associated conductors can be spaced apart sufficiently to achieve the required isolation. For the higher voltages, or for a more compact arrangement, each vacuum interrupter is housed in a separate pod molded of an electrically insulative material such as a polyglass. These molded pods in turn are bolted to a metal box containing the operating mechanism. The metal box is grounded to isolate the operating mechanism from the line voltage of the power circuit. Manual controls for the operating mechanism are accessible at the front face of the metal box. The metal box provides structural support for the separately housed vacuum interrupters and the operating mechanism. As the metal box is grounded, it also provides a “dead front” for the breaker which increases protection of the human operator from the high voltage of the power circuit. This is particularly important if there is a fault within the power section of the breaker. The metal box also provides electromagnetic shielding where the operating mechanism includes sensitive electronics such as an electronic trip unit.
There are some circuit breakers at the lower end of the power breaker voltage range which house the phase vacuum interrupters in bays within a single piece molded insulative casing. However, these circuit breakers also use a metal box to house the operating mechanism, and to provide a dead front and electromagnetic shielding.
A need has been identified for reducing the size of power circuit breakers in the above 1,000 volt range. However, this also requires reducing the size of the operating mechanism. A smaller operating mechanism delivers less energy which presents a challenge. A considerable amount of energy is required to close a power breaker into the sizable current in a distribution system in which loads are turned on. The ductile steel boxes in which the operating mechanisms are currently supported absorb a substantial amount of energy in deflection and distortion, but the mechanism is sufficiently robust to accommodate such losses. The smaller operating mechanisms required for the compact power circuit breaker cannot afford such losses. Consideration must also be given to protecting molded insulative structures from destructive arcing.
Our commonly owned, concurrently filed application Ser. No. 09/567,313 entitled “Power Circuit Breaker Having Molded Insulative Casing With A Dead Front”, is directed to a compact power circuit breaker which utilizes a molded insulative casing to provide structural support and electrical isolation for the pole mechanisms. A grounded barrier sandwiched between two sections of the molded insulative casing also electrically isolates the operating mechanism from the pole mechanisms and provides shielding for any electronics of the operating mechanism.
There is a need in such a power circuit breaker for providing the molded insulative casing with protection against erosion by arcing which could occur at the pole mechanisms.
SUMMARY OF THE INVENTION
This need and others are satisfied by the invention which is directed to a power circuit breaker which utilizes a molded insulative casing to provide structural support for the pole and operating mechanisms. A grounded barrier between the pole mechanisms and the operating mechanism improves protection of the user from electrical shock and the electronics in an operating mechanism with an electronic trip from electric magnetic interference. An air gap is provided between the molded insulative casing and the grounded barrier to minimize erosion of the molded insulative casing in the event of arcing in a pole mechanism.
More particularly, the invention is directed to a power circuit breaker which comprises a plurality of pole mechanisms each with separable contacts, an operating mechanism coupled to the pole mechanisms to open and close the separable contacts, a grounded barrier between the pole mechanisms and the operating mechanism and a molded insulative casing at least between the grounded barrier and the pole mechanisms. This molded insulative casing forms with the grounded barrier an air gap which is interposed, along with the molded insulative casing and the grounded barrier, between the pole mechanisms and the operating mechanism. Preferably, the molded insulative casing has a recess facing the grounded plane member at each pole mechanism forming the air gap. In a preferred embodiment, the recess is a common recess extending across all of the pole mechanisms. This recess is vented to allow any ionized gases that could be formed by an arc to escape and be replaced with fresh air. Also, preferably, the recess in the molded insulative casing is formed by edge walls and the vents are formed by slots extending outward through these edge walls. These slots can be open slots facing a planar grounded barrier.
Preferably, the molded insulative casing has pole cavities housing each of the pole mechanisms. These pole cavities have a wall spaced from the pole mechanism to interpose an additional air gap between the pole mechanism and the operating mechanism. In its most preferred form, the molded insulative casing has a rear section in which the pole cavities and the recess are formed and a forward section between the grounded barrier and the operating mechanism.
REFERENCES:
patent: 3895199 (1975-07-01), Frewe et al.
patent: 4025883 (1977-05-01), Slade et al.
patent: 5521567 (1996-05-01), Devonald, III et al.
patent: 5668361 (1997-09-01), Moncke et al.
patent: 5927482 (1999-07-01), Davies
patent: 5931290 (1999-08-01), Wehrli, III et al.
Calhoon Glenn A.
Davies Norman
Jenkins Walter O.
Marchand Francois J.
Rinefierd, Jr. Robert J.
Donovan Lincoln
Eaton Corporation
Moran Martin J.
LandOfFree
Power circuit breaker with air gap between molded insulative... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power circuit breaker with air gap between molded insulative..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power circuit breaker with air gap between molded insulative... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2574610