Circuit breaker

Details Circuit breaker Circuit breaker

2001-02-02

2004-04-20

Donovan, Lincoln (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

Automatic circuit-interrupting devices

C335S020000, C335S172000, C335S202000

Reexamination Certificate

active

06724284

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to circuit breakers for protecting electric power circuits and, more particularly, to such circuit breakers including separable contacts, an operating mechanism and a switch, such as a micro-switch, which follows the ON, tripped and OFF states of the operating mechanism.
2. Background Information
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 condition.
Circuit breakers used in residential and light commercial applications are commonly referred to as miniature circuit breakers because of their limited size. Such circuit breakers typically have a pair of separable contacts opened and closed by a spring biased operating mechanism. A thermal-magnetic trip device actuates the operating mechanism to open the separable contacts in response to persistent overcurrent conditions and to short circuits.
Circuit breakers typically provide status feedback by a visual indication only (e.g., by the position of the circuit breaker handle, by an indication window).
Some circuit breakers employ a status contact for reporting the status of the circuit breaker's separable contacts. For example, electrical switching devices may optionally include an auxiliary connection or an auxiliary switch located therein to externally indicate the status of the device. Such an auxiliary connection may include, for example, a connection from an internal auxiliary switch to a bell alarm and/or other external circuits for enunciating and/or monitoring the open/closed/tripped status of the electrical switching device.
U.S. Pat. Nos. 5,301,083 and 5,373,411 describe a remotely operated circuit breaker, which introduces a second pair of switching relay contacts in series with the main separable contacts. The main contacts still interrupt the overcurrent, while the secondary contacts perform the discretionary switching operations (e.g., load shedding). The secondary contacts are opened by a solenoid, which is spring biased to close the contacts. Feedback circuitry, including normally open and normally closed auxiliary feedback contacts, provides a status indication of the condition of the secondary contacts.
Known circuit breakers of such types only provide the status of the switching contacts. There is a need, therefore, to also provide the status of the main contacts.
Typically, there are significant space limitations in relatively small, miniature circuit breakers. Adding micro-switches to small circuit breakers has been found to be difficult because such breakers typically have limited space due to their configuration for mounting in a standardized load center or panelboard. U.S. Pat. No. 5,552,755 discloses an example of a small residential or light industrial or commercial circuit breaker, which is provided with a micro-switch to generate an electrical indication that the circuit breaker contacts are opened. Two cascaded actuating members, one actuated by the handle structure and one by the cradle, are incorporated into the circuit breaker for actuating a plunger of the micro-switch and indicating the operating status of the breaker.
U.S. Pat. No. 5,907,461 discloses a circuit breaker including a bell switch and an auxiliary switch positioned in the circuit breaker housing for actuation by levers mounted on a cradle pin and crossbar, respectively.
U.S. Pat. No. 6,040,746 discloses micro-switches mounted in a compartment and molded housing of a circuit breaker separate from the compartment in which the circuit breaker mechanism is mounted. The micro-switches are actuated to indicate the operating status of the circuit breaker by cascaded first and second actuating members. The first actuating member bears against a cam surface on the operating handle of the circuit breaker. The cam surface actuates the micro-switches through the first actuating member when the operating handle is in the OFF position. The second actuating member engages a cradle of the circuit breaker and actuates the micro-switches through the first actuating member when the cradle is unlatched (i.e., tripped).
U.S. Pat. No. 6,104,265 discloses a miniature circuit breaker including side-by-side ganged cases. One of the ganged cases includes the main circuit breaker operating mechanism and contacts and the other ganged case includes an actuable micro-switch having a switch bar. A handle tie arrangement interconnects one circuit breaker handle with a similar handle in the parallel cell of the circuit breaker arrangement. If the circuit breaker mechanism of the active cell is opened, a common tie-in member causes the handle and, thus, a peninsula portion of the handle to move toward the switch bar and cause it to actuate the switch and provide an external indication that the circuit breaker has opened. However, a different mechanism actuates the switch when the circuit breaker is tripped. A rotatable axial shaft extending from the adjacent chamber includes an electrically insulating triggering device having an elongated cam member, which rotates toward the switch bar and causes it to actuate the switch.
There is room for improvement in circuit breakers including a switch which follows the ON, tripped and OFF states of the operating mechanism.
SUMMARY OF THE INVENTION
This need and others are satisfied by the invention, which is directed to a circuit breaker, which includes a switch that provides the status of the circuit breaker's separable contacts (i.e., ON, tripped, OFF). A switching mechanism, such as a micro-switch, is provided internal to the circuit breaker housing and is actuated by the operator handle or movable contact arm of the operating mechanism. The contact of the switch, in turn, is wired in a variety of fashions. As one example, the switch contact is used in conjunction with a remote controlled circuit breaker in order to provide feedback of both the main separable contacts as well as the relay switching contacts.
As one aspect of the invention, a circuit breaker comprises: a housing; at least one set of separable contacts including a set of main contacts; an operating mechanism including an operator handle for opening and closing the separable contacts, the operator handle having a surface, an ON position, a tripped position, and an OFF position, the separable contacts being closed in the ON position, being open in the tripped position, and being open in the OFF position; a trip mechanism releasing the operating mechanism to move the operator handle to the tripped position; and a switch including an actuator lever movable between an actuated position and a non-actuated position and adapted to engage the surface of the operator handle of the operating mechanism, the switch also including a contact having a first state corresponding to the actuated position and a second state corresponding to the non-actuated position, the surface of the operator handle engaging and moving the actuator lever to the actuated position in only the ON position of the operator handle, the actuator lever being in the non-actuated position in the OFF position and the tripped position of the operator handle.
According to a preferred practice, the housing includes a base portion and a cover portion; and the switch is a micro-switch having a first side, which engages the base portion, and an opposite second side, which engages the cover portion.
As another preferred practice, the at least one set of separable contacts is the set of main contacts; and the contact of the switch has an input adapted to receive a voltage and an output adapted to provide a feedback voltage external to the housing when the set of separable contacts is closed.
As another aspect of the invention, a circuit breaker comprises: separable contacts; an operating mechanism including a movable contact arm for opening and closing the separable contacts, the movable contact arm having a surface, an ON position, a tripped position, and an OFF position, the separable contacts being c

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