Patent Application
20160099118
1. Field
The disclosed and claimed concept relates generally to electrical distribution equipment and, more particularly, to an electrical interruption apparatus that includes a wear indicator.
2. Related Art
Electrical distribution equipment is well known and includes many components such as electrical switchgear that may contain therein electrical interruption devices such as circuit breakers, vacuum interrupters, and the like without limitation. Such electrical interruption devices typically include a set of separable contacts which, when separated, desirably open a protected portion of a circuit. It is understood, however, that electrical arcing between the contacts can result in vaporization of the material of the contacts and resultant wear of the contacts. Since such electrical interruption devices typically include a mechanism that is spring loaded and that applies a compressive force to maintain the contacts in their closed position, a loss of the material of the contacts due to wear can require the contacts to move a relatively greater distance in order to become electrically engaged with one another. A consequence of having to move the contacts a greater distance is that the spring-loaded mechanism will apply a reduced compressive force to the worn contacts. This is because a compression spring of the spring-loaded mechanism is relatively less compressed as a result of the increased distance. Such reduced compressive force is undesirable, and it is therefore known to provide wear indicators on certain electrical interruption devices. While such indicators have been generally effective for their intended purposes, they have not been without limitation.
In some applications, such as those involving vacuum interrupters for example, the wear indicator can be difficult or impossible to accurately assess since is may be situated at a visually inaccessible location within a switchgear cabinet or may be otherwise unreachable for routine examination. It thus would be desirable to provide a solution that overcomes these and other shortcomings known in the relevant art.
An improved electrical interruption apparatus provides an improved wear indicator that is configured to depict an amount of wear that has been experienced by a set of separable contacts of a vacuum interrupter. At an easily visible location on a drive rod of the circuit interruption apparatus, the wear indicator indicates the extent to which the set of contacts have degraded. The wear indicator is attached to a spring-loaded over-travel mechanism that engages together the set of electrical contacts.
Accordingly, an aspect of the disclosed and claimed concept is to provide an improved electrical interruption apparatus having a wear indicator that can be easily observed and that indicates a state of wear of a pair of contacts of a vacuum interrupter or other circuit interruption device.
Accordingly, an aspect of the disclosed and claimed concept is provided by an improved electrical interruption apparatus, the general nature of which can be stated as including a set of separable contacts comprising a stationary contact and a movable contact, a drive rod comprising an indicator and being movable between an OPEN position wherein the stationary and movable contacts are separated from one another and a CLOSED position wherein the stationary and movable contacts are engaged with one another, a biasing apparatus, and an indication apparatus, the biasing apparatus having a driven portion that is connected with the drive rod and further having a responsive portion that is connected with the movable contact, the biasing apparatus being movable between a first state when the drive rod is in the OPEN position and a second state wherein the drive rod is in the CLOSED position and the movable contact is biased by the biasing apparatus against the stationary contact, at least one of the driven portion and the responsive portion being movable a relative distance with respect to the other of the driven portion and the responsive portion in moving between the first and second states, and the indication apparatus comprising an indication element that is connected with the responsive end and that is structured to provide an indication that is representative of the relative distance, the indication being a relative position of the indication element with respect to the indicator.
A further understanding of the disclosed and claimed concept can be gained from the following Description when read in conjunction with the accompanying drawings in which:
Similar numerals refer to similar parts throughout the specification.
An improved wear indicator 4 is depicted in
The circuit interrupter apparatus 6 can be described as including the a vacuum interrupter 16 and as further including a drive mechanism 18 that includes the wear indicator 4. The vacuum interrupter 16 is a conventional type of vacuum interrupter having an evacuated vacuum bottle 20 within which a fixed contact 24 and a movable contact 28 are disposed. The fixed and movable contacts 24 and 28 are movable between an OPEN position spaced apart as is depicted generally in
The drive mechanism 18 can be said to include a drive rod 32, an over-travel mechanism 36, and a bellcrank 40 that are cooperable together to move the fixed and movable contacts 24 and 28 between the OPEN and CLOSED positions. The drive rod 32 includes an elongated shank 44 having a set of graduations 52 that are situated generally at one end of the shank 44. A flange 48 is situated generally at the other end of the shank 44. In the depicted exemplary embodiment, the graduations 52 are a set of markings that are marked on the shank 44 of the drive rod 32 and that serve as indicators of wear of the contacts 24 and 28. In other embodiments the graduations 52 could be stamped markings or virtually any other type of indicia which, when used in cooperation with the wear indicator 4, provide an indication of a degree of wear of the fixed and movable contacts 24 and 28. The shank 44 has an elongated slot 56 formed therein whose use will be described in greater detail below. The drive rod 32 can be said to be in an OPEN position when the contacts 24 and 28 are in their OPEN position, and the drive rod 32 can further be said to be in a CLOSED position when the contacts 24 and 28 are in their CLOSED position.
The over-travel mechanism 36 is a spring-loaded biasing apparatus that applies a compressive force to the movable contact 28 to bias it into engagement and electrical contact with the fixed contact 24. The over-travel mechanism 36 can be said to include a support 60 that is attached to the shank 44 with a pair of nuts 64 or other fasteners, a compression spring 68, a follower rod 72 that is cooperable with the compression spring 68, and a pin 76 that is movably received in the slot 56. The support 60 can be said to movably support thereon the compression spring 68 and the follower rod 72. The follower rod 72 extends through the central axial region of the compression spring 68 and includes a flared retainer 80 that engages the compression spring 68 and that retains the compression spring 68 interposed between the retainer 80 and the flange 48. The pin 76 is mounted on the follower rod 72 opposite the retainer 80 and, as suggested above, is movably received in the slot 56.
The pin 76 and the retainer 80 are situated generally at opposite ends of the follower rod 72, and the reception of the pin 76 against the rightmost (from the perspective of
The over-travel mechanism 36 can be said to be movable between a first state when the drive rod 32 is in its OPEN position and a second state when the drive rod 32 is in its CLOSED position. The over-travel mechanism 36 can additionally be said to include a driven portion 74 that is connected with the drive rod 32 and a responsive portion 78 that is connected with the bellcrank 40. The driven portion 74 can be said to include the flange 48 and the support 60, which are understood to move with the drive rod 32. The responsive portion 78 can be said to include the follower rod 72 and the pin 76, which are operatively situated at the opposite end of the compression spring 68 from the flange 48. As will be understood from the teachings presented herein, the responsive portion 78 is movable with respect to the driven portion 74 upon compression of the compression spring 68.
As can be understood from
When the drive mechanism 18 is in the position depicted generally in
The wear indicator 4 is depicted in
More particularly,
When the drive mechanism 18 has been moved from its OPEN position in
When the fixed and movable contacts 24 and 28 are in a zero wear condition, such as is depicted generally in
As the fixed and movable contacts 24 and 28 experience wear over time, however, the compression spring 68 is loaded with a lower level of compressive force since the bellcrank 40 must pivot relatively farther than in
Furthermore, the technician can be aware of the various locations of the indication element 88, i.e., adjacent the graduations 52A, 52B, 52C, by way of example, when the drive rod 32 is in its leftmost and/or rightmost positions. If the indication element 88 is seem to have suddenly become moved from its anticipated location, this can signal the need for other attention being required for other portions of the circuit interruption apparatus 6.
It thus can be seen that the elongated legs 84A and 84B are connected directly with the over-travel mechanism 36, particularly the responsive portion 78, and communicate the degree of compressive loading on the compression spring 68 to a location on the drive rod 32, which is connected with the driven portion 74 of the over-travel mechanism 36. This location is at the end of the shank 44 adjacent one of the graduations 52 of the set of graduations 52, which is a location that can easily be observed by a technician. The ease with which the degree of wear on the fixed and movable contacts 24 and 28 can be ascertained by the technician thus saves time and effort and provides for better maintenance of the circuit interruption apparatus 6.
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.
