Abstract:
An apparatus to remotely reset a lock out mechanism of an electric distribution circuit breaker from a trip-free position includes a remote signal receiver to receive a remote reset signal and initiate movement of a lever based on the remote reset signal. The apparatus also includes a remote reset link assembly to move from a first position in response to the movement of the lever and cause a movement of a reset component. The movement of the reset component results in a reset of the lock out mechanism.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to a circuit breaker and, more specifically, to resetting the lock out mechanism of the circuit breaker from a remote location 
         [0002]    A circuit breaker protects loads in electrical circuits (e.g., electrical power distribution systems) from overload, short circuit, and ground fault conditions. Specifically, a lock out mechanism is provided in the circuit breaker to automatically open the circuit breaker when a fault occurs. Once the lock out mechanism has opened the circuit breaker due to a fault, the lock out mechanism is in a trip-free position and must be reset prior to closing the circuit breaker again in order to ready the system to handle a subsequent fault. 
         [0003]    In prior distribution systems, while the circuit breaker can be opened and closed remotely, resetting the lock out mechanism can only be done manually or automatically. Thus, the lock out mechanism may be manually reset, by an operator pushing the button provided on the lock out mechanism itself. Of course, this option requires the physical presence of an operator at the reset button of the lock out mechanism. The lock out mechanism may also be automatically reset, thereby circumventing the need for an operator to be physically present at the circuit breaker. In this case, however, whether the reset was necessitated by a fault or by a manual opening of the circuit breaker is indistinguishable. The loss of this information can be problematic in diagnosing and maintaining the system. Recently systems have been developed to resetting the lock out mechanism action with a coil plunger arrangement. A completely new coil was needed for that. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the invention, an apparatus to remotely reset a lock out mechanism of an electric distribution circuit breaker from a trip-free position includes a remote signal receiver configured to receive a remote reset signal and initiate movement of a lever based on the remote reset signal; and a remote reset link assembly configured to move from a first position in response to the movement of the lever and cause a movement of a reset component, wherein the movement of the reset component results in a reset of the lock out mechanism. 
         [0005]    According to another aspect of the invention, a method to remotely reset a lock out mechanism of an electric distribution circuit breaker from a trip-free position includes receiving a remote reset signal and initiating movement of a lever based on the remote reset signal; and positioning a remote reset link assembly to move from a first position and cause movement of a reset component based on the movement of the lever, wherein the movement of the reset component results in a reset of the lock out mechanism. 
         [0006]    According to yet another aspect of the invention, an electrical distribution system includes a circuit breaker configured to protect the electric distribution system from a fault condition; and a lock out mechanism integral to the circuit breaker and configured to open the circuit breaker based on the fault condition, the lock out mechanism being configured to be reset remotely. 
         [0007]    Key matter of the invention is to use the existing range of coils to perform remote reset function while the breaker is tripped and to maintain main function of the coil. 
         [0008]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a block diagram of a circuit protection system according to an embodiment; 
           [0011]      FIG. 2  depicts a circuit protection assembly of the circuit protection system in a trip free state according to an embodiment; 
           [0012]      FIG. 3  depicts a circuit protection assembly of the circuit protection system in a reset state according to an embodiment; and 
           [0013]      FIG. 4  depicts the processes involved in performing a remote reset of the lock out mechanism of a circuit protection assembly. 
       
    
    
       [0014]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Already existing disadvantages of both the manual reset, which requires the physical presence of an operator, and the automatic reset, which does not provide or retain fault history information, a remote reset that provides an indication of fault history (i.e., whether the circuit breaker was opened manually or due to a fault) would be appreciated by the electric power distribution industry. 
         [0016]      FIG. 1  is a block diagram of a circuit protection system  100  according to an embodiment. The circuit protection system  100  includes a lock out mechanism  110  of the circuit breaker, a shunt coil  117 , and a circuit protection assembly  200  that will be further detailed with reference to  FIG. 2 . The lock out mechanism  110  also includes a reset button  115  that allows a manual reset of the lock out mechanism  110  and also provides an indication of a fault-based trip to an operator who is physically present at the circuit protection system  100 . When a fault condition is encountered, the flux shifter solenoid  120  initiates opening of the circuit breaker (trip of the breaker) that subsequently results in a trip free condition for the lock out mechanism  110 . It is this trip free condition resulting from a fault that could not previously be reset from a location remote to the circuit protection system  100  and, specifically, remote to the reset button  115 . When a fault is not encountered, the circuit breaker can be opened remotely via the shunt coil  117 . This shunt coil  117  is now additionally used (based on additional mechanisms added to the circuit protection assembly  200 ), as detailed below, to add a functionality to also reset the lock out mechanism  110  based on a remote signal. Another mechanism (not shown) is used to close the circuit breaker after reset of the lock out mechanism  110 . 
         [0017]      FIGS. 2 and 3  depict the circuit protection assembly  200  of the circuit protection system  100  according to an embodiment. The circuit protection assembly  200  includes the flux-shifter solenoid  120 , activator link assembly  130 , remote reset link assembly  140 , pivot assembly  150 , reset link assembly  160 , and biasing spring  170 . As shown at  FIG. 2 , the lock out mechanism  110  is in the trip free position (indicating that the circuit breaker had been opened based on a fault).  FIG. 3  shows the circuit protection assembly  200  in the reset position or in the position in which the lock out mechanism  110  is ready to open the circuit breaker based on a fault. The remote reset is made possible through the additional mechanisms according to embodiments shown in  FIGS. 2 and 3 . The remote reset link assembly  140 , pivot assembly  150 , and biasing spring  170  may be thought of together as add-on mechanisms to facilitate remote reset using the shunt coil  117 . Through the mechanisms of the circuit protection assembly  200 , the shunt coil  117  ultimately acts to reset the lock out mechanism  110 . In addition, whether or not the breaker is open due to a fault (thereby necessitating the reset prior to closing the breaker) is known in the following way. 
         [0018]    If the breaker opening is due to a fault condition, the flux shifter  120  opens the circuit breaker and renders the lock out mechanism  110  trip free by popping the reset button  115  ( FIG. 1 ). If, instead, the circuit breaker opening is due to the shunt coil  117  (i.e., no fault), then the circuit breaker (lock out mechanism  110 ) will not become trip free and can be easily identifiable in this state. When the breaker is opened due to a fault condition, the breaker (lock out mechanism  110 ) can be reset using the shunt coil  117 . In this case, the shunt coil  117 , the shunt coil  117  can be thought of as a reset coil. Based on a remote reset signal, a movement of the activator link assembly  130  is initiated by the shunt coil  117  plunger. The movement is downward relative to the position of the activator link assembly  130  in the trip free state (shown at  FIG. 2 ). The activator link assembly  130  has roller contact with an edge  140   a  of the remote reset link assembly  140 . Thus, the downward movement of the activator link assembly  130  in turn initiates moving of the remote reset link assembly  140 , as indicated by the arrow in  FIG. 2 . The movement of the remote reset link assembly  140  is about the pivot assembly  150 . The reset link assembly  160 , which moves upwards (to the position shown at  FIG. 2 ) to put the breaker  110  into the trip free state, is pushed back downward (to the position shown at  FIG. 3 ) because of the movement of the remote reset link assembly  140 . This movement of the reset link assembly  160  resets the lock out mechanism  110  (and circuit breaker). As is shown in  FIG. 3 , the lock out mechanism  110  is in the reset position when the reset link assembly  160  has pushed down the lock out mechanism  110  arm, relative to its position in the trip free state. Once the lock out mechanism  110  has been reset, the biasing spring  170  functions to pull back the remote reset link assembly  140 , as indicated by the arrow in  FIG. 3 . That is, the biasing spring  170  is biased (in its default un-extended position) to the position in which the remote reset link assembly  140  is pulled back to the position shown in  FIG. 3 . 
         [0019]      FIG. 4  depicts the processes  400  involved in performing a remote reset of the lock out mechanism of a circuit protection assembly. At block  410 , the processes  400  include receiving a remote signal at the shunt coil  117 . The signal starts the remote reset within the circuit protection system  100  through the mechanisms of the circuit protection assembly  200 . At  420 , positioning the activator link assembly  130  to move based on the shunt coil  117  plunger not only is part of the reset processes  400  but is also part of the process of opening the circuit breaker (lock out mechanism  110 ) when a fault has occurred. This fault-based opening of the circuit breaker would happen through initiation by the flux shifter  120 . The processes  400  at block  430  involve disposing the remote reset link assembly  140  such that the remote reset link assembly  140  both moves based on the movement of the activator link assembly  130  and also causes reset by pushing the reset pivot assembly  150  to the reset position. Once reset has been accomplished, the biasing of the biasing spring  170  at block  440  ensures that the remote reset link assembly  140  is pulled back to its default reset position. 
         [0020]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.