Patent Application
20130213780
1. Field
The disclosed concept pertains generally to electrical switching apparatus and, more particularly, to circuit interrupters, such as, for example, circuit breakers. The disclosed concept further pertains to jumpers for electrical switching apparatus poles.
2. Background Information
U.S. Pat. No. 6,614,334 discloses a series arrangement of two circuit breaker mechanisms. The interruption performance of the circuit breaker is determined by the “current limitation of series arcs,” which provides two arcs in series, thereby having twice the resistance of a single arc.
It is known to connect multiple poles of circuit breakers in series to provide a high voltage for a low voltage switching and interruption device (e.g., without limitation, 750 VDC; 1000 VDC; 1500 VAC).
Circuit breakers are typically available in one-, two-, three- and four-pole construction, although larger counts of poles are possible.
For a 1000 VDC application, typically multiple circuit breakers are electrically tied together. Most known existing six-pole or eight-pole air circuit breakers are designed such that the poles are electrically connected internally in breaker structures in a predetermined manner.
It is known that to obtain higher interruption and voltage ratings, circuit breaker poles can be wired in series. Normally, cable or bus bars are electrically connected to the circuit breaker terminals, which carry the current and remove a significant amount of the heat that is generated within the breaker. A conventional shorting strap (or jumper) electrically connected between poles can carry the current, but does not remove much heat, resulting in relatively high temperature rises at the circuit breaker terminals.
There is room for improvement in electrical switching apparatus, such as circuit breakers.
These needs and others are met by embodiments of the disclosed concept, which provide both a current carrying function and a heat transfer function within a relatively small available space.
In accordance with one aspect of the disclosed concept, an electrical switching apparatus comprises: a plurality of poles, each of the poles comprising a terminal, the terminal of a first one of the poles being proximate the terminal of a second one of the poles; and a jumper electrically connected between the terminal of the first one of the poles and the terminal of the second one of the poles, the jumper comprising a plurality of heat transfer members, each of the heat transfer members being separated from others of the heat transfer members.
As another aspect of the disclosed concept, an electrical switching apparatus comprises: a plurality of poles; a plurality of pairs of separable contacts; a plurality of terminals electrically connected to the pairs of separable contacts; and a number of jumpers electrically connected to at least some of the plurality of terminals, each of the number of jumpers electrically connecting two of the pairs of separable contacts in series, and each of the number of jumpers comprising a plurality of heat transfer members, each of the heat transfer members being separated from others of the heat transfer members.
As another aspect of the disclosed concept, a jumper is for an electrical switching apparatus comprising a plurality of poles, each of the poles comprising a plurality of terminals, one of the terminals of a first one of the poles being proximate one of the terminals of a second one of the poles. The jumper comprises: a jumper member structured to be electrically connected between the one of the terminals of the first one of the poles and the one of the terminals of the second one of the poles, the jumper member comprising: a plurality of heat transfer members, wherein each of the heat transfer members is separated from others of the heat transfer members.
A full understanding of the disclosed concept can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. Further, as employed herein, the statement that two or more parts are “attached” shall mean that the parts are joined together directly.
The disclosed concept is described in association with a three-pole circuit breaker, although the disclosed concept is applicable to a wide range of electrical switching apparatus having any suitable plurality of poles.
Referring to
In Examples 1-4, the jumpers 2,32,42,52 are bolted to the circuit breaker terminals 4,8. Preferably, portions of these jumpers are threaded to act as nuts, although separate nuts (not shown) could alternatively be employed for the bolts 24,26.
The example jumper 32 of
The three plates 34,36,38 that are positioned on one side of the circuit breaker terminals 4,8 could alternatively be joined to ease assembly onto the circuit breaker terminals 4,8, but such joining is not needed for proper function.
As shown in
The example jumper 42 of
As shown in
The example jumper 52 of
The example jumpers 2,32,42,52 disclosed in connection with Examples 1-4 provide relative ease of manufacturing and use. However, it will be appreciated that these configurations can be modified by persons of ordinary skill in the relevant art to provide relatively greater heat transfer performance.
The disclosed jumpers 2,32,42,52 can be employed to electrically connect adjacent poles on one electrical switching apparatus, such as a circuit breaker.
For example and without limitation, two of the disclosed jumpers 2 electrically connect three poles 58,60,62 of the three-pole circuit breaker 12 in series, in order that a relatively higher voltage can be switched by the circuit breaker 12. For example, the upper (with respect to
Each of the poles 58,60,62 includes a corresponding pair of separable contacts 66,68,70 (as shown in simplified form in the partially cut-away view of
The disclosed jumpers 2,32,42,52 include multiple heat transfer members. Such heat transfer members can be provided by multiple plates (e.g., without limitation, 34,36,38,40 of
The disclosed jumpers 2,32,42,52 are made from a suitably electrically and thermally conductive material, such as copper or aluminum. An electrically insulating material 64 (e.g., without limitation, as partially shown in
The disclosed jumpers 2,32,42,52 preferably maximize the available heat transfer surface area while providing sufficient space for free air convection.
The disclosed phase jumpers 2,32,42,52 may have holes, slots or other suitable openings added to provide relatively more area for free air movement.
While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.
