1. Field of the Invention
This invention pertains generally to electrical switching apparatus and, more particularly, to such electrical switching apparatus, such as circuit breakers. The invention also relates to locking apparatus for the operating handle of electrical switching apparatus.
2. Background Information
Electrical switching apparatus include, for example, circuit switching devices; circuit interrupters, such as circuit breakers; network protectors; contactors; motor starters; motor controllers; and other load controllers.
Circuit breakers are well known in the art. An example of a circuit breaker is disclosed in U.S. Pat. No. 5,341,191. Circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. Molded case circuit breakers, for example, include at least one pair of separable contacts which are operated either manually by way of an operating handle disposed on the outside of the case or automatically by way of an internal trip unit in response to an overcurrent condition.
Circuit breakers typically have two or three possible operating handle positions, corresponding to the status of the separable contacts. For example, these positions may include an ON position, in which the separable contacts are closed, an OFF position in which the contacts are open, and a tripped position in which the contacts are tripped open. Typically, the handle position corresponding to the tripped position of the contacts is in between the ON and OFF positions.
In circuit breaker installations, for example in a panel board or load center, it is often desirable or essential that the settings of a single circuit breaker, or a group of circuit breakers, remain undisturbed. Unauthorized or inadvertent changing of the position of these breakers could result in annoying interruptions to service or operations, serious damage to an electrical apparatus, or even serious harm to a person. For example, accidental actuation of a circuit breaker might result in electrocution or shock to a person performing electrical work or repair within an office building or home. Therefore, to prevent, for example, another person from inadvertently returning the circuit breaker operating handle to the ON position when a worker is doing electrical work in an area other than the immediate vicinity of the circuit breaker box or electrical panel, safety measures must be taken. One such safety measure is the addition of a locking assembly to prevent displacement of the operating handle.
Although the main purpose of a circuit breaker is to trip during overload or short circuit conditions in order to protect downstream equipment and electrical wiring from damage, it may also be highly desirable to inhibit the circuit interruption function under certain conditions where, for example, the potential fire hazard of a non-opening circuit breaker is deemed to be a lesser hazard than if current flow to downstream devices is interrupted. The decision to accept the risk of fire over some other hazardous consequence may occur during emergencies or other critical situations where loss of life might occur if power is disrupted. Conceivable situations include, for example, circuit breakers employed in connection with combat (e.g., in a battleship under wartime conditions), fire-fighting (e.g., energizing pumps for pumping water to fire hoses in a high-rise building), spacecraft launch (e.g., energizing ground-based circuits critical to a safe launch), mining (e.g., energizing pumps employed to rapidly remove water from a flooded mine shaft), or nuclear power generation (e.g., energizing circuits critical to tripping a nuclear reactor). See, for example, U.S. Pat. No. 5,831,503. Although most circuit breakers can still trip internally even if the operating handle is held in the on position, a handle lock to prevent displacement of the operating handle would preclude manual operation that might inadvertently remove power in a critical situation.
U.S. Pat. Nos. 2,849,552; 3,214,530; 3,408,466; 4,347,412; 5,147,991; 5,219,070; 5,310,969; 5,412,167; 5,500,495; 5,577,599; and 5,732,815 disclose operating handle locking mechanisms consisting of an assembly of at least two parts and each employs a padlock to lock the handle of the circuit breaker in a fixed position. There are several disadvantages associated with known handle locking mechanisms of this type.
Many known locking mechanisms of this type employ a set or Allen screw to engage the operating handle, in order to prohibit its movement. See, for example, U.S. Pat. Nos. 2,849,552; 5,147,991; 5,500,495; and 5,732,815.
There is room for improvement in locking apparatus for electrical switching apparatus.
There is also room for improvement in electrical switching apparatus employing a locking apparatus.
These needs and others are met by embodiments of the invention, which provide a relatively simple and effective locking apparatus for an operating handle of an electrical switching apparatus, which locking apparatus comprises a housing and a spring member interlocked with the housing. The spring member comprises two ends structured to be retained by an electrical switching apparatus enclosure at corresponding apertures of an opening for the electrical switching apparatus operating handle in one of two positions thereof.
In accordance with one aspect of the invention, a locking apparatus is for an electrical switching apparatus comprising an enclosure including an opening having a first side, an opposite second side, a first end, and an opposite second end, the enclosure also including a first aperture on the first side and proximate the first end, a second aperture on the first side and proximate the opposite second end, a third aperture on the opposite second side and proximate the first end, and a fourth aperture on the opposite second side and proximate the opposite second end; separable contacts; an operating mechanism structured to open and close the separable contacts, the operating mechanism including an operating handle pivotally mounted with respect to the enclosure and disposed through the opening of the enclosure, the operating handle including a first position proximate the first end of the opening of the enclosure and a second position proximate the opposite second end of the opening of the enclosure, the locking apparatus being disposable proximate the first end of the opening of the enclosure when the operating handle is in the second position or being disposable proximate the opposite second end of the opening of the enclosure when the operating handle is in the first position. The locking apparatus comprises: a housing; and a spring member interlocked with the housing, the spring member comprising a first end and an opposite second end structured to be retained by the enclosure at the third aperture and the first aperture, respectively, proximate the first end of the opening of the enclosure when the operating handle is in the second position, or structured to be retained by the enclosure at the second aperture and the fourth aperture, respectively, proximate the opposite second end of the opening of the enclosure when the operating handle is in the first position.
The housing may comprise a first recess and a second recess; each of the first and second recesses may be structured to receive a hand tool; and the spring member may be structured to cooperate with the hand tool to move one of the first end and the opposite second end of the spring member away from one of the first, second, third and fourth apertures.
As another aspect of the invention, an electrical switching apparatus comprises: an enclosure comprising an opening having a first side, an opposite second side, a first end, and an opposite second end, the enclosure also comprising a first aperture on the first side and proximate the first end, a second aperture on the first side and proximate the opposite second end, a third aperture on the opposite second side and proximate the first end, and a fourth aperture on the opposite second side and proximate the opposite second end; separable contacts; an operating mechanism structured to open and close the separable contacts, the operating mechanism including an operating handle pivotally mounted with respect to the enclosure and disposed through the opening of the enclosure, the operating handle including a first position proximate the first end of the opening of the enclosure and a second position proximate the opposite second end of the opening of the enclosure; and a locking apparatus disposed proximate the first end of the opening of the enclosure when the operating handle is in the second position or disposed proximate the opposite second end of the opening of the enclosure when the operating handle is in the first position, the locking apparatus comprising: a housing, and a spring member interlocked with the housing of the locking apparatus, the spring member comprising a first end and an opposite second end retained by the enclosure at the third aperture and the first aperture, respectively, proximate the first end of the opening of the enclosure when the operating handle is in the second position, or retained by the enclosure at the second aperture and the fourth aperture, respectively, proximate the opposite second end of the opening of the enclosure when the operating handle is in the first position.
The enclosure may further comprise a first surface including the opening thereon; the operating handle may comprise a second surface proximate the opening and a third surface extending away from the second surface and the opening; the housing of the locking apparatus may comprise fourth surface engaging the first surface, a fifth surface proximate the second surface, and a sixth surface engaging the third surface; and the housing may block the operating handle from moving from one of: (a) the first position to the second position when the first end and the opposite second end of the spring member are retained by the enclosure at the second aperture and the fourth aperture, respectively; and (b) the second position to the first position when the first end and the opposite second end of the spring member are retained by the enclosure at the third aperture and the first aperture, respectively.
A full understanding of the invention 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 term “hand tool” means an insertion hand tool and/or a removal hand tool, such as, for example and without limitation, a flat blade, flathead or slotted screwdriver.
The invention is described in association with a circuit breaker, although the invention is applicable to a wide range of electrical switching apparatus.
Referring to
The example molded housing 6 includes a first side 30 (also shown in
Referring to
As shown in
The locking device 2 is disposed proximate the first end 72 of the enclosure opening 58 when the operating handle 64 is in the second, open position (
As best shown in
As shown in
The housing 6 of the locking device 2 advantageously blocks the operating handle 64 of
The locking device housing 6 includes the first side 30, the opposite second side 32, the first end 38 and the opposite second end 40. The housing cavity 42 houses the U-shaped portion 14 of the spring 8 including the base 16, the first leg 22, the second leg 24, a portion of the first foot 26, and a portion of the second foot 28. The cavity 42 is disposed between the first end 38 and the opposite second end 40, and between the first side 30 and the opposite second side 32 of the housing 6.
In the position of
As best shown in
Still referring to
When one of the two ends 10,12 of the spring 8 (e.g., end 10 of
Although
The circuit breaker molded enclosure 56 captures the example quick release spring 8 of the locking device 2, which is easy to install for either one of the “ON” (
The example locking device 2 can easily be removed by simply inserting a hand tool, such as the example flat blade 112 of the screwdriver 114 into one of the two recesses 108,110 on either side of the device housing 6 and rotating the locking device 2 out of the circuit breaker 4.
The example two-piece assembly 6,8 of the disclosed locking device 2 provides the user with the ability to lock the example circuit breaker operating handle 64 in either the “ON” or “OFF” position while requiring minimal space for installation in the operating handle opening 58.
The example molded housing 6 of the locking device 2 is much safer than a single piece, metal version, which would be more difficult to install and would have relatively sharp edges.
While specific embodiments of the invention 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 invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
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