Patent Grant
9859084
The invention relates to remotely operated circuit breakers in general, and more specifically to circuit breakers that are remotely operated using a contact arm which can be operated using a solenoid mechanism that is separate from the circuit breaker handle mechanism.
A circuit breaker is a device that can be used to protect an electrical circuit from damage caused by an overload or a short circuit. If a power surge occurs in a circuit protected by the circuit breaker, for example, the breaker will trip. This will cause a breaker that was in the “on” position to flip to the “off” position, and will interrupt the electrical power leading from that breaker. By tripping in this way a circuit breaker can prevent a fire from starting on an overloaded circuit, and can also prevent the destruction of the device that is drawing the electricity or other devices connected to the protected circuit.
A standard circuit breaker has a line and a load. Generally, the line receives incoming electricity, most often from a power company. This is sometimes be referred to as the input into the circuit breaker. The load, sometimes referred to as the output, feeds out of the circuit breaker and connects to the electrical components being fed from the circuit breaker. A circuit breaker may protect an individual component connected directly to the circuit breaker, for example, an air conditioner, or a circuit breaker may protect multiple components, for example, household appliances connected to a power circuit which terminates at electrical outlets.
A circuit breaker can be used as an alternative to a fuse. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. When the power to an area shuts down, an operator can inspect the electrical panel to see which breaker has tripped to the “off” position. The breaker can then be flipped to the “on” position and power will resume again.
In general, a circuit breaker has two contacts located inside of a housing. Typically, the first contact is stationary, and may be connected to either the line or the load. Typically, the second contact is movable with respect to the first contact, such that when the circuit breaker is in the “off”, or tripped position, a gap exists between the first and second contact, and the line is disconnected from the load.
Circuit breakers are usually designed to be operated infrequently. In typical applications circuit breakers will be operated only when tripped by a power spike or other electrical disturbance. Power spikes do not regularly occur during normal operation of typical circuits.
In some applications however, it is desirable to operate circuit breakers more frequently. For example, in the interest of saving electricity it may be beneficial to control the power distribution to an entire floor of a building from one location. This can be done by manually tripping a breaker for the entire floor circuit. It may also be desirable to manually trip the circuit breaker remotely, using a remote control, timer, motion sensor, or the like.
In other applications, it is desirable to operate a circuit breaker remotely for maintenance purposes. For example, an operator may manually trip a circuit breaker to de-energize a protected circuit so that it can be inspected or serviced. However in some circuits, operating the breaker can produce a dangerous arc, creating a safety hazard for the operator. In still other circuits, the circuit breaker may be located in a confined or hazardous environment. In these situations, it is also beneficial to operate the circuit breaker remotely.
Known approaches to remotely controlling circuit breakers include incorporating a mechanism into the circuit breaker which can intentionally trip the circuit breaker mechanism and reset it. Examples of such mechanisms are solenoids or motors used to activate the trip mechanism, and solenoids or motors which are used to reset the circuit breaker by rearming the trip mechanism.
However, using a circuit breaker as a power switch or remote control in this way subjects the breaker to a far greater number of operational cycles than it would otherwise experience in a typical circuit protection application. This can result in an unacceptably premature failure of the circuit breaker. Typical circuit breaker mechanisms are designed to survive only 20,000-30,000 cycles before failure.
In order to increase the number of cycles that such circuit breakers can endure before failure, all of the components of the circuit breaker, including the tripping mechanism and any springs, linkages, escapements, sears, dashpots, bimetal thermal components, or other components that are part of the mechanism must be designed in a more robust way than would otherwise be required. This increases the cost of producing the circuit breaker considerably.
These problems were addressed with great success by the invention disclosed in U.S. patent application Ser. No. 13/598,217 filed on Aug. 29, 2012, which application is also assigned to the assignee of the present application. However, even though the design disclosed therein provides significant advantages over previously known remote operated circuit breaker designs, room for additional features has been discovered.
More specifically, while as discussed in U.S. patent application Ser. No. 13/598,217, it may be desirable to “lock” the breaker in the “remote open” state if DC power to the solenoid is lost when the breaker is in that state for the sake of safety, it has been found that in some applications it may be desirable to enable “manual reset” of the circuit breaker in the event the solenoid loses DC power regardless of the position of the solenoid at the time power is lost. For example, when the breaker is in the “remote open” state and the DC power is lost, the permanent magnet in the solenoid may hold the plunger in that position. If this happens when using the previous design disclosed in U.S. patent application Ser. No. 13/598,217, the breaker will not be able to be manually reset to “closed” if the DC power is not present. While this may be desirable for some applications, it may not be desirable for all applications.
What is desired therefore, is a circuit breaker that can be remotely or manually activated and also that allows for the breaker to be able to be manually reset to the “closed” position even if DC power to the solenoid is lost when the breaker is in the “remote open” state.
Accordingly, it is an object of the present invention to provide a circuit breaker which can be turned on and off remotely.
It is another object of the present invention to provide a circuit breaker which can be turned on and off using a mechanism that is discrete from the circuit breaker mechanism.
It is a further object of the invention to provide a circuit breaker which can be manually reset to the “closed” position even if power to the remote on/off mechanism is lost when the breaker is in the “remote open” state.
These and other objects are achieved by providing a circuit breaker having first and second contacts moveable with respect to each other between a closed state in which electrical current flows through the circuit breaker and an open state in which electrical current is prevented from flowing through the circuit breaker. A linkage assembly is moveable between an engaged position and a disengaged position, wherein when in the disengaged position, the first and second contacts are in the open state. A remote actuator is moveable between an on position and an off position, wherein when the linkage assembly is in the engaged position and when the remote actuator is in the on position, the first and second contacts are in the closed state, and wherein when the linkage assembly is in the engaged position and when the remote actuator is moved to the off position, the first and second contacts are moved with respect to each other to the open state. A manual reset mechanism is provided that, upon actuation when power has been lost to the remote actuator when the remote actuator is in the off position, moves the remote actuator to the on position, thereby resetting the first and second contacts to the closed state.
In some embodiments, the remote actuator comprises a solenoid comprising a plunger and wherein the plunger is moveable between an extended position and a retracted position. In certain of these embodiments, the remote actuator is in the on position when the plunger is in the retracted position and the remote actuator is in the off position when the plunger is in the extended position. In some of these embodiments, the solenoid comprises at least one permanent magnet biasing the plunger to maintain the extended position when power to the solenoid has been lost. In certain of these embodiments, upon actuation of the manual reset mechanism when power to the solenoid has been lost when the remote actuator is in the off position, the plunger is moved against the bias of the at least one permanent magnet from the extended position to the retracted position.
In some embodiments, the circuit breaker further includes a handle manually actuable between an on position and an off position, wherein when the handle is in the on position, the linkage assembly is in the engaged position and wherein when the handle is in the off position the linkage assembly is in the disengaged position. In certain of these embodiments, the manual reset mechanism is actuated, when power has been lost to the remote actuator when the remote actuator is in the off position, by moving the handle from the on position, to the off position and then back to the on position.
In some embodiments, the circuit breaker of claim 1 further includes a tripping mechanism that causes the linkage assembly to move from the engaged position to the disengaged position in response to an electrical current passing through the circuit breaker that exceeds a threshold.
In some embodiments, one of the first and second contacts is stationary with respect to a housing of the circuit breaker and the other of the first and second contacts is moveable with respect to the housing. In certain of these embodiments, the moveable contact is disposed on a lever assembly that is pivotably mounted with respect to the stationary contact. In some of these embodiments, the lever assembly is biased toward a position where in the first and second contacts are in the closed state.
In some embodiments, the lever assembly comprises a contact portion and the camming member, the moveable contact being carried on the contact portion. In certain of these embodiments, the contact portion and the camming member are connected to one another such that there is limited pivotablity therebetween.
In some embodiments, the camming member comprises an outer camming surface facing the remote actuator, the outer camming surface comprising two pockets separated by a protuberance, the pockets adapted to be engaged by a portion of the remote actuator when the remote actuator is in the off position. In certain of these embodiments, the camming member comprises an inner opening with a pin disposed therein, the pin being stationary with respect to a housing of the circuit breaker. In some of these embodiments, the inner opening is generally triangular in shape with one side thereof being generally parallel to the outer camming surface including the pockets, and with a detent being formed in the side thereof that is generally parallel to the outer camming surface including the pockets, the detent being sided and shaped to engage the pin disposed within the inner opening.
Still other objects of the invention and its particular features and advantages will become more apparent from consideration of the following drawings and accompanying detailed description.
Circuit breaker 100 includes a stationary contact 105 connected to a line terminal 110. The line terminal receives electricity from a power source such as a generator (not shown), which in some applications is supplied by a power company.
A movable contact 115 is disposed on a movable contact arm 120 which can be moved between a closed position 125 and open positions 200 and 300 (
The movable contact arm 120 is connected to a tripping mechanism 140 by a linkage 145. As shown, tripping mechanism 140 is in an untripped state. The linkage may include a spring mechanism (not shown), which is biased to move the movable contact arm from the closed position to the open position when tripping mechanism 140 is tripped.
A fault detector 150 is connected to the movable terminal and is configured to activate the tripping mechanism 140 when a fault condition occurs, such as excess current. In some applications, the fault detector is a solenoid which is disposed inline with the circuit. If the current through the solenoid exceeds a certain level, the solenoid generates an electromagnetic field sufficient to activate the tripping mechanism. The solenoid may also optionally incorporate a plunger or other armature which activates the tripping mechanism when the current exceeds a certain level.
It is understood that other fault detection methods may also be employed, which trip the tripping mechanism upon the occurrence of a specific condition.
Movable contact 115 is connected to load terminal 199 through fault detector 150 and connector 116. When movable contact 115 is in a closed position, as shown in
A handle 160 is also provided for resetting the tripping mechanism 140, or for manually tripping the tripping mechanism 140.
The moveable contact arm 120 includes a guide channel 165 which allows moveable contact arm 120 to slide and/or pivot around second pivot point 170. Moveable contact arm 120 also includes a lever 175. The lever may be formed in one piece with the movable contact arm 120, or may be a separate piece that is attached to the movable contact arm 120.
Actuator solenoid 180 has a plunger 185 which is connected to lever 175. The lever 175, movable contact arm 120, and guide channel 165 are disposed such that when tripping mechanism 140 is in an untripped condition, as shown, and actuator solenoid 180 is activated, plunger 185 moves in the direction of arrow 190, moving movable contact arm 120 from closed position 125 to a second open position (200,
Incorporating an actuator such as actuator solenoid 180 to open and close contacts 105 and 115 in this way can have the advantage of allowing the number of manual operational cycles of the circuit breaker to be increased without incurring the additional costs associated with increasing the robustness of trip mechanism 140 and its associated components, as they are not actuated when the contacts are opened via the actuator solenoid. In this way, operational life can be increased to approximately 200,000 cycles in a typical application.
Actuator solenoid 180 may be activated using a remote signal. Actuator solenoid 180 may be a bistable or latching solenoid, incorporating a permanent magnet 192. In this case, plunger 185 will hold its position unless actuator solenoid 180 is energized with the correct polarity.
A polarity switch 194 may be connected to actuator solenoid 180 using connector 196. Polarity switch 194 can provide a pulse signal of either polarity to actuator solenoid 180 in order to extend or retract plunger 185. When no signal is present, plunger 185 is held in place by solenoid 180.
Permanent magnet 192 may also be disposed such that when actuator solenoid 180 is de-energized, plunger 185 is drawn in the direction of arrow 190, opening the circuit by moving movable contact 115 from closed position 125 to second open position (200,
A biasing spring 198 may optionally be disposed to bias lever 175 such that plunger 185 only needs to provide force in one direction.
When the tripping mechanism 140 is in an untripped state as shown in
Similarly, if power to polarity switch 194 is lost preventing actuation of actuation solenoid 180 while it is in the extended position, it remains possible to open contacts 115 and 105 using tripping mechanism 140 or handle 160, and to close contacts 115 and 105 using handle 160. However, if power to polarity switch 194 is lost preventing actuation of actuation solenoid 180 while it is in the retracted position, it is impossible to re-close the contacts using handle 160. This can have the advantage of increasing safety by preventing any attempts to re-close the breaker by operating handle 160 that would result in a hazardous condition. In some applications, an additional mechanism (not shown) may be incorporated to allow plunger 185 of actuation solenoid 180 to be moved to the extended position without requiring power to polarity switch 194. In other embodiments (discussed below in connection with
When both the circuit breaker mechanism 140 and the lever 175 are in the on position (State A), the movable contact arm is in the closed position, and current can flow through the circuit breaker 100.
From State A, if the circuit breaker mechanism 140 is toggled, e.g. by tripping the circuit breaker mechanism 140 manually or via an overcurrent condition, the moveable contact arm 120 moves to the first open position 300, and current can no longer flow through the circuit breaker 100.
From State A, if the lever 175 is toggled, e.g. by remotely activating an actuation solenoid, the moveable contact arm 120 moves to the second open position, and current can no longer flow through the circuit breaker 100.
When both the circuit breaker mechanism 140 and the lever 175 are in the off position (State B), the contact arm is in the first open position 300, and current cannot flow through the circuit breaker 100.
From State B, if the circuit breaker mechanism 140 is toggled, e.g. by resetting the circuit breaker mechanism, the movable contact arm 120 moves to the second open position, and current still cannot flow through the circuit breaker 100. This can have the advantage of enabling a remote operator to prevent current flow even if a local operator were to reset the circuit breaker, for example, when a safety hazard is known to the remote operator.
From State B, if the lever 175 is toggled, e.g. by remotely activating an actuation solenoid, the moveable contact arm 120 moves to the first open position 300, and current still cannot flow through the circuit breaker 100. This can have the advantage of enabling a local operator to prevent current flow even if a remote operator attempts to switch on the breaker, for example, when a safety hazard is known to the local operator.
When the circuit breaker mechanism 140 is in the on position and the lever 175 is in the off position (State C), the movable contact arm is in the second open position, and current cannot flow through the circuit breaker.
From State C, if the circuit breaker mechanism 140 is toggled, e.g. by tripping the circuit breaker mechanism 140 manually or via an overcurrent condition, the moveable contact arm 120 moves to the first open position 300, and current still cannot flow through the circuit breaker 100.
From State C, if the lever 175 is toggled, e.g. by remotely activating an actuation solenoid, the movable contact arm moves to the closed position, and current can flow through the circuit breaker 100.
When the circuit breaker mechanism 140 is in the off position and the lever 175 is in the on position (State D), the movable contact lever 175 is in the first open position 300, and current cannot flow through the circuit breaker 100.
From State D, if the circuit breaker mechanism 140 is toggled, e.g. by resetting the circuit breaker mechanism, the movable contact lever 175 moves to the closed position, and current can flow through the circuit breaker 100.
From State D, if the lever 175 is toggled, e.g. by remotely activating an actuation solenoid, the movable contact arm moves to the first open position 300, and current still cannot flow through the circuit breaker 100.
A transition to State A from State D is controlled by the circuit breaker mechanism 140, e.g., the local operator who can reset the mechanism. A remote operator can initiate a transition from State B to State A only by encountering State D, which is controlled by the local operator.
Similarly, a transition to State A from State C is controlled by a lever operator, e.g., a remote operator actuating the lever 175 using solenoid 180. A local operator can initiate a transition from State B to State A only by encountering State C, which is controlled by the remote operator.
In this way, the circuit breaker 100 can be configured to provide an added layer of safety by requiring logical agreement between the operators of the circuit breaker 100 before energizing a protected circuit.
Referring now to
In many respects, the circuit breaker 600 operates in substantially the same way as does the circuit breaker 100 described above in connection with
One of the most obvious differences relates to the position of the solenoid. In the embodiment of the circuit breaker 100 shown in
Another obvious difference is that the relatively simple lever 175 of the circuit breaker 100 has been replaced with a much more complex lever assembly 675 that provides significantly different functionality.
Like lever 175 of circuit breaker 100, lever assembly 675 includes a contact portion 676 on which moveable contact 615 is disposed, the contact portion 676 being pivotally mounted on a linkage 645 about a pivot point 635 and having a pin 670 slideably disposed within a channel 665. As operation of these elements is similar to operation of the circuit breaker 100 described above, further detail is not provided.
However, unlike circuit breaker 100, wherein the lever 175 includes a simple extension engaged by the plunger 185 of the solenoid 180, lever assembly 675 includes a camming member 677 having a much more complex shape. The camming member 677 is attached to the contact portion 676 with limited pivotability about a pivot point 678. What is meant by limited pivotability is described in more detail below.
An outer surface of the camming member 677 facing the solenoid includes two pockets 679 separated by a protuberance therebetween, the pockets 679 adapted to be engaged by a terminal end of the plunger 685 of the solenoid 680 when the plunger 685 is extended. The purpose of these pockets 679 is explained in more detail below.
The camming member 677 also includes an inner opening 681 provided therein. The inner opening 681 is generally triangular in shape with one of its sides 683 being generally parallel to the external surface of the camming member 677 including the pockets 679. A detent 682 is provided toward the upper end of the aforementioned side 683, the detent being sized to accommodate a pin 684 disposed within the opening 681 and mounted in stationary fashion with respect to the housing. Again, the purpose of the opening 681, the detent 682 and the pin 684 is described in more detail below.
The camming member 677 may be provided with a magnet 690 that may be employed to trigger one or more (two are shown in
Referring now to
Referring first to
Referring now to
It should be noted that the gap between the contacts 605, 615 in this remote open position is smaller than the gap that exists when the circuit breaker is in the tripped or manual off positions (shown in
As mentioned above, suppose now that the solenoid 680 loses power (usually DC power) thereto while in the remote open position shown in
More specifically, as shown in
First, the stationary pin 684 is moved out of the detent 682 in the side 683 of the inner opening 681, and as the camming member 677 moves upward, the pin 684 slides down the side 683 until it reaches the bottom of the generally triangular opening 681. Additionally, the camming member 677 pivots with respect to the contact portion 676 of the lever assembly 675 about the pivot point 678 (i.e., as can be seen in
As a result of this upward movement and pivoting of the camming member 677, outer surface of the camming member 677 slides upwardly with respect to the plunger 685 of the solenoid 680, so that the terminal end of the plunger 685 is now disposed in and engaging the lower pocket 679.
From the position shown in
It should be noted that it is not required for movement of the camming member 677 to move the plunger 685 all the way back to its retracted position. Instead, the plunger is 685 is generally held in the extended position by the permanent magnets, but is biased toward its retracted position, such that all that is required is for the camming member 677 to move the plunger 685 far enough (such as to the position shown in
This can be accomplished, for example, as follows. As the handle is moved toward its on/closed position, camming member 677 of the lever assembly 675 is moved downward. As this occurs, the stationary pin 684 slides up the side 683 of the inner opening 681, while at the same time, the terminal end of the plunger 685 slides up the outer surface of the camming member 677 and out of the lower pocket 679. Consequently, the horizontal thickness of the portion of the camming member 677 between the stationary pin 684 and the terminal end of the plunger 685 increases (due in part to the raised portion between the pockets 679 of the outer surface of the camming member 677), such that generally opposing outward forces are created on both the stationary pin 684 and the terminal end of the plunger 685. The stationary pin 684, being stationary, the forces cause the plunger 685 to move to the left, as shown in
Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many modifications and variations will be ascertainable to those of skill in the art.
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