Abstract:
A circuit breaker having a movable contact arm for opening and closing the circuit which is controlled separately by a circuit breaker mechanism for circuit protection and by a switch lever mechanism which does not require actuation of the circuit breaker mechanism to function. The switch lever may be activated by a solenoid or other suitable means, and various interlocking mechanical states exist among the elements that provide added safety features.

Description:
FIELD OF THE INVENTION 
     The invention relates to remotely operated circuit breakers in general, and to a circuit breaker that is remotely operated using a contact arm which can be operated using a solenoid mechanism that is separate from the circuit breaker handle mechanism. 
     BACKGROUND OF THE INVENTION 
     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. 
     What is desired therefore, is a circuit breaker that can be remotely or manually activated which addresses these limitations. 
     SUMMARY OF THE INVENTION 
     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. 
     These and other objects are achieved by providing a circuit breaker which includes a first contact; a second contact which is moveable between a closed position relative to the first contact and an open position relative to the first contact, and which is disposed to contact the first contact only in the closed position; a circuit breaker mechanism having a tripped state and an untripped state, which is disposed to change the position of the contacts when the circuit breaker mechanism changes state and; an actuator having an on state and an off state, which is disposed to change the position of the contacts without changing the state of the circuit breaker mechanism when the actuator changes state. 
     In some embodiments, if the circuit breaker mechanism is in the tripped state, the contacts are in the open position. 
     In some embodiments, if the circuit breaker mechanism is in the tripped state, the contacts cannot move to the closed position. 
     In some embodiments, if the actuator is in the off state, the contacts are in the open position. 
     In some embodiments, if the actuator is in the off state, the circuit breaker mechanism cannot move the contacts into the closed position. 
     In some embodiments, the actuator is disposed to change the state of the lever in response to a signal. 
     In some embodiments, the circuit breaker mechanism is disposed to move the contacts from the closed position to the open position in response to an overcurrent condition. 
     In some embodiments, the circuit breaker mechanism is disposed to move the contacts from the closed position to the open position in response to a manual operation. 
     In some embodiments, the actuator moves the contacts between the closed position and the open position using a lever. 
     In some embodiments, the actuator is a solenoid. 
     In some embodiments, the contacts are biased using a spring. 
     In some embodiments, the contacts are biased using a permanent magnet. 
     In some embodiments, the solenoid comprises a permanent magnet disposed to bias the contacts. 
     In some embodiments, the permanent magnet is disposed to bias the contacts when the solenoid is de-energized. 
     In some embodiments, the solenoid comprises a permanent magnet disposed to move the contacts to the open position when the solenoid is de-energized. 
     In some embodiments, the circuit breaker mechanism comprises an escapement. 
     In some embodiments, the circuit breaker mechanism comprises a dashpot. 
     In some embodiments, the circuit breaker mechanism is separate from the actuator. 
     Other objects of the invention are achieved by providing a circuit breaker which includes contacts relatively moveable between an open position and a closed position; a circuit breaker mechanism disposed to change the position of the contacts when the circuit breaker is actuated; and a switching mechanism disposed to open and close the contacts without actuating the circuit breaker mechanism. 
     Further objects of the invention are achieved by providing a circuit breaker which includes a first contact; a movable member having a closed position and an open position; a second contact on the movable member disposed to contact the first contact only when the movable member is in the closed position; a circuit breaker mechanism having a tripped state and an untripped state, which is connected to the movable member and disposed to move the moveable member when the circuit breaker mechanism changes state; a solenoid having an on state and an off state, which is connected to the movable member and disposed to move the moveable member without changing the state of the circuit breaker mechanism when the solenoid changes state; and, a permanent magnet biasing the solenoid to the off state. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an example circuit breaker according to aspects of the invention, showing a closed position. 
         FIG. 2  is another side view of the example circuit breaker shown in  FIG. 1 , showing a remotely opened position. 
         FIG. 3  is another side view of an example circuit breaker shown in  FIGS. 1 and 2 , showing a tripped position. 
         FIG. 4  is a table reflecting various combinations of positions of the elements of the example circuit breaker shown in  FIGS. 1-3  according to aspects of the invention. 
         FIG. 5  is a state diagram reflecting various state transitions possible for the example circuit breaker shown in  FIGS. 1-3  according to aspects of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an example circuit breaker  100  according to aspects of the invention. 
     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  ( FIGS. 2 and 3 ) by pivoting on a first pivot  135  and second pivot  170 . 
     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  FIG. 1 , stationary contact  105  and moveable contact  115  are in contact with each other, and electricity can flow from line terminal  110  to load terminal  199  through contacts  105  and  115 . 
     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 ,  FIG. 2 ) by pivoting movable contact arm  120  around pivot point  135  and sliding guide channel  165  along second pivot point  170 . 
     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 ,  FIG. 2 ). 
     A biasing spring  198  may optionally be disposed to bias lever  175  such that plunger  185  only needs to provide force in one direction. 
       FIG. 2  illustrates example circuit breaker  100  in a state where as in  FIG. 1 , the tripping mechanism  140  is untripped, but where movable contact arm  120  is in a second open position  200 . 
       FIG. 3  illustrates example circuit breaker  100  in a state where tripping mechanism  140  is tripped. Here, movable contact lever  120  has been moved by tripping mechanism  140  via linkage  145  such that movable contact  115  is held at open position  300 . With tripping mechanism  140  in a tripped state, movable contact  115  cannot return to a closed state with stationary contact  105  regardless of the position of plunger  185 . This means that it is impossible to re-engage the circuit breaker after a fault using a remote system via actuator solenoid  180 . 
     When the tripping mechanism  140  is in an untripped state as shown in  FIGS. 1 and 2 , contacts  115  and  105  may be freely opened and closed by actuating solenoid  180 . However, when the tripping mechanism  140  is in a tripped state, contacts  115  and  105  cannot be brought back into a closed state by actuating solenoid  180 . This can have the advantage of increasing safety by allowing an operator who is directly in the presence of circuit breaker  100  to override any attempts to re-close the breaker remotely or automatically which would result in a hazardous condition. 
     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 . 
       FIG. 4  is a table illustrating the various combinations of circuit breaker positions possible according to an example embodiment of the invention. 
     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 . 
       FIG. 5  is a state diagram illustrating the different state transitions possible according to an example implementation of the invention, and as reflected in the table of  FIG. 4 . The only state which allows current to flow through the circuit breaker is State A. It is clear from the state diagram that it is impossible to transition directly from State B to State A without first passing through either State D or State C. Thus, State B can be thought of as a safety state of 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. 
     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.