Abstract:
The disclosed invention ensures safe operation of an electrical switchgear by preventing an operator from contacting or interacting with an active circuit breaker. One way this is accomplished is through a locking system that prevents a door to the interior of the switchgear from opening until the circuit breaker is in a disengaged position. A second way this is accomplished is by a manipulation restriction system that prevents the circuit breaker from being manually moved unless the door is closed. Another way this is accomplished is by a circuit breaker decoupler, accessible from the exterior of the switchgear that can directly manipulate the circuit breaker into disengagement.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Provisional Patent Application No. 62/255,519 entitled “Electrical Switchgear Manual Safety System and Mechanisms” by Neal Thomas Hare and Thomas Matthew Stevens filed on Nov. 15, 2015. That application is incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Switchgears are safety mechanisms that enclose circuit breakers to protect operators from being exposed to potentially lethal amounts of electrical current running though power distribution centers. Switchgears allow the operator to manipulate the circuit breaker as needed while preventing direct contact with the circuit breaker when it is coupled to a power supply. 
         [0003]    In previous switchgear embodiments, there has been a tradeoff between operator accessibility and operator safety. Switchgears may allow easy operator access to the circuit breaker, but risk exposing an operator to an electrical current. Alternatively, switchgears may prevent access to the circuit breaker, requiring the operator to damage part of the switch ear in order to access the circuit breaker. There is a need in the industry for a switchgear that allows easy operator access that incorporates safety systems to prevent operator interaction with a circuit breaker while there is electrical current running through a switchgear. 
       SUMMARY 
       [0004]    This disclosed invention has independent systems that may work individually or in concert to protect an operator from exposure to a powered circuit breaker. These are the Door Interlock Device (DID), the Manual Trip and Lockout (MT/L), and the Manual Racking Handle Exclusion Device (MRHED). 
         [0005]    The DID comprises a series of locking mechanisms and sensors coupled to the circuit breaker access compartment door  100  and the cable access compartment door  702 . These locking mechanisms and sensors are connected to a logic circuit or any device capable of equivalent operations. The logic circuit receives information from sensors throughout the switchgear  500  that prevent doors that restrict access to the circuit breaker  510  from being opened unless certain conditions are met. 
         [0006]    The MT/L is a device that can disable the circuit breaker  510  within the switchgear  500  from an external switch on the circuit breaker access compartment door  100 . By activating the switch, a decoupler  308  is activated, which will trip the circuit breaker  510 . 
         [0007]    The MRHED is an internal manipulation restriction device that prevents the use of a manual ratcheting handle from manipulating the racking device  108  that can move the circuit breaker  510  from a disengaged location to an engaged location within the switchgear  500 . This is accomplished by obstructing the worm gear  112  while the circuit breaker access compartment door  100  is opened, preventing manipulation of the racking device  108  unless the circuit breaker access compartment door  100  is closed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1 a    is an external view of a switchgear circuit breaker access compartment door  100  in an exemplary embodiment. 
           [0009]      FIG. 1 b    is a view of an external section of the circuit breaker access compartment door  100  with the DID override  210  exposed, the MT/L switch button  302  with a switch restrictor  314 , and the mechanical access outer aperture  410  exposed in an exemplary embodiment. 
           [0010]      FIG. 1 c    is an internal view of a section of switchgear circuit breaker access compartment door  100  that corresponds to the elements show in  FIG. 1 b    in an exemplar embodiment. 
           [0011]      FIG. 1 d    is an internal view of the mechanism at the base of the switchgear  500  in an exemplary embodiment. 
           [0012]      FIG. 2 a    is a view of the DID in an unlocked state in an exemplary embodiment. 
           [0013]      FIG. 2 b    is a view of the DID in a locked state in an exemplary embodiment. 
           [0014]      FIG. 2 c    is a view of the DID in an override state in an exemplary embodiment. 
           [0015]      FIG. 3 a    is a view of a mechanical gateway  406  without any shutters  414  in an exemplary embodiment. 
           [0016]      FIG. 3 b    is a view of the shutters  414  in an exemplary embodiment. 
           [0017]      FIG. 3 c    is a view of a mechanical gateway  406  in a closed state in an exemplary embodiment. 
           [0018]      FIG. 3 d    is a view of a mechanical gateway  406  in an opened state in an exemplary embodiment. 
           [0019]      FIG. 4 a    is a view of the MT/L integrated with a MRHED in a non-tripped state in an exemplary embodiment. 
           [0020]      FIG. 4 b    is a view of the MT/L integrated with a MRHED in a tripped state in an exemplary embodiment. 
           [0021]      FIG. 5 a    is a view of the MT/L with the decoupler  308  in a non-tripped position with the worm gear  112  omitted. 
           [0022]      FIG. 5 b    is a view of the MT/L with the decoupler  308  in a tripped position and acting on the circuit breaker  510  with the worm gear  112  omitted. 
           [0023]      FIG. 6 a    is a view of the circuit breaker  510  coupled in the racking device  108  in the installation position with the rod  312  and the decoupler  308  omitted. 
           [0024]      FIG. 6 b    is a view of the circuit breaker  510  coupled in the racking device  108  in the engaged position with the rod  312  and the decoupler  308  omitted. 
           [0025]      FIG. 7  is a top down view of the switchgear  500  showing the circuit breaker access compartment door  100  and the cable access compartment door  702  in open positions. 
           [0026]      FIG. 8  is a flow chart illustrating the logic of the DID to close a door. 
           [0027]      FIG. 9  is a flow chart illustrating the logic of the DID to open a door. 
           [0028]      FIG. 10  is a flow chart illustrating the logic of the DID to use the DID override  210  to open a door. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The interior of the switchgear  500  in an exemplary embodiment can be divided into two compartments: the circuit breaker access compartment  502  and the cable access compartment  504 . The circuit breaker access compartment  502  is the location where the circuit breaker  510  resides when installed in the switchgear  500 . The cable access compartment  504  is where the circuit breaker  510  interacts with the cables used for electrical power input and output. Dividing these two sections is a partition  508  that has two rows of three cylindrical apertures  514 . The location of these cylindrical apertures  514  in the partition  508  corresponds to the connectors  512  from the circuit breaker  510 . When the circuit breaker  510  is fully engaged as shown in  FIG. 6B , the connectors  512  are inserted within these cylindrical apertures  514  to couple to the electrical power inputs and outputs in the cable access compartment  504 . The cable access compartment door  702  is on the opposite side of the switchgear  500  from the circuit breaker access compartment door  100  in the exemplary embodiment and is used to access the power inputs and outputs for the switchgear  500 . 
         [0030]    The circuit breaker access compartment door  100  has a series of gauges and devices used by the operator to interact with the circuit breaker  510  within the switchgear  500  along with a manual locking mechanism  106 . In the disclosed embodiment, the circuit breaker access compartment door  100  has a DID override  210 , a MT/L button  302 , and a MRHED mechanical access outer aperture  410 . The cable access compartment door  702  also contains DID override  210  and a manual locking mechanism  106 . 
         [0031]    The casing of the switchgear  500  is arc resistant. The DID override  210  and the MRHED mechanical access outer aperture  410  are covered with an arc resistant cap  102  when not in use. Additionally, in the event of an overpressure within the switchgear  500 , a series of vents  704  will open in the top surface, directing the force upward away from the operators. 
         [0032]    The switchgear  500  has a racking device  108  where the circuit breaker  510  rests on the interior floor of the switchgear  500 . The racking device  108  moves the circuit breaker  510  from the installation position to the engaged position by operation of a worm gear  112  acted on my the racking motor  110 . When the racking device  108  is in the installation position shown in  FIG. 6 a   , the circuit breaker  510  may be installed. The worm gear  112  then moves the circuit breaker  510  into the engaged position shown in  FIG. 6 b   . The openings to the cylindrical apertures  514  are guarded by a series of louvers. As the racking device  108  moves the circuit breaker  510  into the engaged position, the louvers are opened, allowing the connectors  512  to pass through the cylindrical apertures  514  to couple with the power input and power output. 
         [0033]    The cable access compartment  504  may be designed to receive power inputs and power outputs as needed. Additionally, the switchgear  500  may be connected with other switchgears via couplers  706  located on the sides of the switchgear  500 . Other features for the switchgear  500  include a control mechanism capable of receiving remote commands to disconnect the circuit breaker  510 . Such control mechanisms may be by any means known to those skilled in the art. 
         [0034]    The disclosed invention contains elements that work individually and in concert to prevent operators from accessing the circuit breaker  510  unless the circuit breaker  510  is disengaged. 
         [0035]    It is further understood that the disclosed invention may be practiced on an existing switchgear  500 . Such modification would require minimal installation of equipment and physical modification of the switchgear housing. Further, this disclosed modification components could be provided as a kit, where all elements necessary to practice the invention would be provided. 
       Door Interlock Device (DID) 
       [0036]    The DID is a locking system that restricts when the circuit breaker access compartment door  100  and the cable access compartment door  702  may be opened. The DID utilizes a series of sensors that provide input to a logic device, such as a primary logic circuit (PLC). In an exemplary embodiment, there are two proximity sensors for the circuit breaker access compartment door  100  and two proximity sensors for the cable access compartment door  702 . One proximity sensor determines when a door is closed. A second proximity sensor determines when the manual locking mechanism  106  has been engaged for the same door. The inputs from these proximity sensors go into the logic circuit which dictates the status of the DID in an exemplary embodiment. 
         [0037]    The DID uses a locking element, a deployment device, and a retraction device. In the exemplary embodiment, the DID comprises a locking bar  202  for the locking device, a lock spring for the deployment device, and a solenoid for a retraction device. The lock spring and the solenoid are contained in the spring/solenoid assembly  204 . When the logic device determines that certain conditions are met, the solenoid in the spring/solenoid assembly  204  may receive power to unlock the door as shown in  FIG. 2 a   . When the logic device determines that other conditions are present, or if it loses power, the solenoid in the spring/solenoid assembly  204  deactivates, and a lock spring forces the locking bar  202  into a lock receptacle  212  inside the switchgear  500 , preventing the associated door from opening as shown in  FIG. 2 b   .  FIG. 2 c    illustrates how the locking bar  202  may be manipulated by use of a DID override  210  that will be explained below. 
         [0038]    The DID operates once the circuit breaker  510  is installed n the switchgear  500 . The process is illustrated in  FIG. 8  with both the cable access compartment door  702  open and the circuit breaker access compartment door  100  initially open. The open cable access compartment door  702  facilitates the coupling of the switchgear  500  to the applicable electrical system. The process begins when the cable access compartment door  702  is closed (step  805 ), tripping the first cable access compartment door proximity sensor. The locking of the cable access compartment door  702  via the manual locking mechanism  106  of the cable access compartment door  702  (step  810 ) trips the second cable access compartment door proximity sensor. The circuit breaker  510  is coupled to the racking device  108  that can move the circuit breaker  510  from an installation position to a test position to an engaged position. The circuit breaker access compartment door  100  is closed (step  815 ), and this closure is detected by the first circuit breaker access compartment door proximity sensor. The cable access compartment door  702  solenoid now depowered (step  820 ), causing the spring in the spring/solenoid assembly  204  to push the locking bar  202  into the lock receptacle  212  locking the cable access compartment door  702 . The locking of the circuit breaker access compartment door  100  (step  825 ) by the manual locking mechanism  106  trips the second circuit breaker access compartment door proximity sensor. 
         [0039]    Once both of the proximity sensors for the circuit breaker access compartment door  100  indicate closed, the circuit breaker  510  may be moved to an engaged position (step  830 ). If the operator does not wish to engage the circuit breaker  510 , then the process concludes (step  845 ). 
         [0040]    If the operator wants the circuit breaker  510  to engage (step  830 ) then the circuit breaker  510  is moved into the engaged position step  835 ). The circuit breaker  510  begins in the disengaged position as shown in  FIG. 6 a   . Once the circuit breaker  510  has left the disengaged position, the circuit breaker access compartment door  100  solenoid is now depowered (step  840 ), causing the spring in the spring/solenoid assembly  204  to push the locking bar  202  into the lock receptacle  212 , locking the circuit breaker access compartment door  100 . The process then concludes (step  850 ). The circuit breaker  510  is now engaged as shown in  FIG. 6 b   . The switchgear  500  will remain locked until the logic circuit energizes the solenoids or a DID override  210  is used. 
         [0041]    A circuit breaker proximity sensor monitors the location of the circuit breaker  510  within the switchgear  500 . The logic device will not allow a circuit breaker access compartment door  100  to open unless the circuit breaker  510  is in a disengaged position. Concurrently, the logic device will not allow the cable access compartment door  702  to open unless the circuit breaker access compartment door  100  is open in an exemplary embodiment. 
         [0042]      FIG. 9  is an illustrative flowchart showing an exemplary embodiment of how the logic may be set up to open all doors once the DID is engaged for both doors. If an operator wants to open the cable access compartment door  702  locked by the DID, then he would see if the circuit breaker access door  100  was open (step  905 ). If the circuit breaker access door  100  is open, then the cable access compartment door  702  may be unlocked (step  965 ) and opened (step  970 ), ending the process (step  975 ). If the circuit breaker access door  100  is not open, then the operator decides whether or not to use the DID override  210  on the cable access compartment door  702  (step  910 ). If he chooses not to use the DID override  210 , then the logic circuit determines if the circuit breaker  510  is in the disengaged position (step  920 ). If the circuit breaker  510  is not in a disengaged position, the operator would decide whether or not to use the circuit breaker access door DID override  210  (step  925 ). If he chose not to, then the circuit breaker  510  needs to he moved to a disengaged position (step  930 ). Once the circuit breaker  510  is in the disengaged position, the solenoid for the spring/solenoid assembly  204  for the circuit breaker access compartment door  100  will power up, and the locking bar  202  will retract from the locking receptacle  212  (step  935 ). The circuit breaker access compartment door  100  may be unlocked (step  940 ) and opened (step  945 ). Opening the circuit breaker access compartment door  100  triggers the logic circuit to power the solenoid in the spring/solenoid assembly  204  for the cable access compartment door  702  (step  950 ). The operator can the choose if wants to open the cable access compartment door  702  (step  955 ) to then unlock (step  965 ) and open (step  970 ) the cable access compartment door  702 . Alternatively, if the circuit breaker  510  was already in a disengaged position (step  920 ), then multiple steps may be bypassed and proceed to unlocking the circuit breaker access door  100  (step  940 ) and proceeding as previously disclosed. 
         [0043]    If the DID override  210  is used to open either the circuit breaker access compartment door  100  or the cable access compartment door  702 , then the applicable proximity sensors will indicate that the doors are not secured. In an exemplary embodiment, the PLC will electronically trip the circuit breaker  510  to return it to a non-powered state. 
         [0044]    Different scenarios require different paths through the logic of the DID. In the event that the operator only wanted to open the circuit breaker access compartment door  100 , then the process would begin by determining if the circuit breaker  510  was in the disengaged position (step  920 ). The logic would proceed as in the above disclosed exemplary embodiment. 
         [0045]    In the exemplary embodiments, when either the cable access compartment door  702  or the circuit breaker access compartment door  100  needs to be opened, and the logic device prevents this due to its programming or due to a lack of power to energize the solenoids as shown in  FIG. 2 b   , a DID override  210  is available. In the exemplary embodiment, there is a DID override  210  on both the circuit breaker access compartment door  100  and the cable access compartment door  702 . The DID override  210  is covered with an arc resistant cap  102 , making it part of the arc resistant surface  104  of the switchgear  500 . An operator would remove the arc resistant cap  102  (step  1010 ). Once the arc resistant cap  102  is removed, the DID override  210  is exposed. Using a specially designed tool to interface with the DID override  210 , the locking bar  202  may be retracted from the lock receptacle  212  (step  1015 ). In an exemplary embodiment, the rotation of the DID override  210  rotates the cam  206  with the knob  208  located adjacent the locking bar  202 . When the knob  208  moves, it exerts force on the locking bar  202  that pushes the locking bar  202  against the force of the lock spring in the spring/solenoid assembly  204 , removing the locking bar  202  from the lock receptacle  212  as shown in  FIG. 2 c   . The result is the locking bar  202  no longer locks the associated door, allowing the door to be opened by operating the manual locking mechanism  106 . The action also trips the circuit breaker  510  (step  1020 ) in the exemplary embodiment to prevent power flow when opening the applicable door. 
         [0046]    The use of the DID override  210  in the exemplary embodiment allows the logic circuit to be bypassed from previous exemplary embodiment in this disclosure. It an operator wants to open the cable access compartment door  702  and chooses to use the DID override  210  (step  980 ), then the operator removes the arc resistant cap  102  (step  1010 ) and manipulates the DID override  210  to move the locking bar  202  to act against the spring in the spring/solenoid assembly  204  (step  1015 ). The circuit breaker  510  is now tripped (step  1020 ). The operator then leaves the DID override  210  (step  985 ). The operator may choose to unlock the cable access compartment door  702  (step  955 ) as previously disclosed. 
         [0047]    If an operator wants to open the circuit breaker access compartment door  100  and chooses to use the DID override  210  (step  990 ), then the operator removes the arc resistant cap  102  (step  1010 ) and manipulates the DID override  210  to move the locking bar  202  to act against the spring in the spring/solenoid assembly  204  (step  1015 ). The circuit breaker  510  is now tripped (step  1020 ). The operator then leaves the DID override  210  (step  995 ). The operator may unlock (step  940 ) and open (step  945 ) the circuit breaker access compartment door  100 . Additionally, with the circuit breaker access compartment door  100  opened, the spring/solenoid assembly  204  on the cable access compartment door  702  may be powered (step  950 ). The operator may choose to open the cable access compartment door  702  (step  955 ). This allows the cable access compartment door to be unlocked (step  965 ) and opened (step  970 ). Alternatively, the operator may choose not to open the cable access compartment door  702 , ending the process (step  960 ) 
       Mechanical Trip and Lockout (MT/L) 
       [0048]    The MT/L is a circuit breaker trip device than comprises a MT/L switch, a strike plate  304  and the decoupler  308 . The MT/L switch comprises a spring loaded button  302  and a rod  312  operated by the spring loaded button  302 . The button  302  for the MT/L switch extends from the outer surface of the circuit breaker access compartment door  100 . The button  302  is in communication with the rod  312 , which extends from the inner surface of the circuit breaker access compartment door  100 . The rod  312  is normally in a retracted position as show in  FIGS. 4 a  and 5 a   . When the button  302  is depressed, the rod  312  acts on a strike plate  304 . Coupled to the strike pate is a decoupler  308 . The decoupler  308  in the exemplary embodiment is a projection that lines up with an external tripping mechanism of an engaged circuit breaker  510 . When the rod  312  acts on the strike plate  304 , the strike plate  304  then moves away from the circuit breaker access compartment door  100 , and the decoupler  308  is pushed back as shown in  FIGS. 4 b  and 5 b   . The decoupler  308  then makes contact with the circuit breaker external tripping mechanism, deactivating the circuit breaker  510 . The decoupler  308  further comprises a mechanism to return the decoupler  308  back to its disengaged position when the button  302  is not depressed. In the exemplary embodiment, the mechanism is a decoupler spring  310 . 
         [0049]    Once the circuit breaker external tripping mechanism has engaged, the circuit breaker  510  will remain disengaged unless it is reactivated by a means known to those skilled in the art. The MT/L has an additional option where the cover for the button  302  may further include a mechanism to keep the button  302  in the depressed position. In the exemplary embodiment, the mechanism is a switch restrictor  314 . 
         [0050]    The MT/L may be connected to the MRHED described below such that when the mechanical ratchet is attached this engages the MT/L system as well in an exemplary embodiment. 
       Manual Racking Handle Exclusion Device (MRHED) 
       [0051]    The MRHED is a mechanism that restricts manual operation of an element within the switchgear  500 . In an exemplary embodiment, the MRHED allows manual operation of the worm gear  112  to move the racking device  108  only when the circuit breaker access compartment door  100  is closed. When an operator wants to have the circuit breaker  510  moved to a disengaged position, the operator may use a mechanical ratchet to manipulate the worm gear  112  to move the racking device  108 , causing the circuit breaker  510  to decouple from the power inputs and power outputs. The MRHED operates in a manner that requires the circuit breaker access compartment door  100  to be closed when using the mechanical ratchet to move the circuit breaker racking device  108 . 
         [0052]    In the exemplary embodiment, the MRHED has components that are fixed to the interior of the circuit breaker access compartment  502  and components that are integrated into the inner surface of the circuit breaker access compartment door  100 . The circuit breaker access compartment door  100  comprises a mechanical access outer aperture  410  and a tongue  402  that extends perpendicularly from the interior surface of the circuit breaker access compartment door  100 . The mechanical access outer aperture  410  is covered with an arc resistant cap  102 , maintaining the arc resistant integrity of the switchgear  500 . 
         [0053]    In the exemplary embodiment, a mechanical gateway  406  is positioned between the end of the worm gear  112  and the location of the mechanical access outer aperture  410  when the circuit breaker access compartment door  100  is closed. The mechanical gateway  406  comprises a mechanical access inner aperture  408 , and a mechanical shutter interface  412  as shown in  FIG. 3 a   . The mechanical gateway  406  has a set of mechanical shutters  414  shown in  FIG. 3 b    that are used to open and close the mechanical gateway  406  in accordance with the exemplary embodiment 
         [0054]    In an exemplary embodiment, the mechanical access inner aperture  408  is closed as shown in  FIG. 3 c    when the circuit breaker compartment access door  100  is open. When the circuit breaker access compartment door  100  is closed, the tongue  402  enters the mechanical shutter interface  412  and forces the mechanical shutters  414  to separate, opening the mechanical access inner aperture  408  as shown in  FIG. 3 d   . The arc resistant cap  102  may be removed, exposing the mechanical access outer aperture  410 . With both the mechanical access outer aperture  410  and the mechanical access inner aperture  408  open, a mechanical ratchet may now interface with the worm gear  112  to manipulate the racking device  108 . 
         [0055]    In a further exemplary embodiment, the strike plate  304  of the previously discussed MT/L maybe modified to interface with the MRHED. In an exemplary embodiment, the strike plate  304  may contain a strike plate aperture  306  as shown in  FIGS. 4 a  and 4 b   . The strike plate aperture  306  may be positioned to line up with the mechanical access outer aperture  410  and the mechanical access inner aperture  408 . This would not interfere with the manipulation of the worm gear  112  as the strike plate aperture  306  allows unobstructed access to the worm gear  112 . The strike plate aperture  306  may be large enough for the worm gear  112  to pass through, but not wide enough for the head of the mechanical ratchet. By placing the mechanical ratchet in contact with the worm gear  112 , the mechanical ratchet will push on the strike plate  304 , activating the MT/L and tripping the circuit breaker  510  as shown in  FIG. 4 b   . This exemplary embodiment would have the ratchet mimic the function of the rod  312  from the MT/L. 
         [0056]    One of skill in the art will appreciate that embodiments provide improved switchgears and improved electrical safety mechanisms at any location where high voltage electrical components are located. Although specific embodiments are illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose can be substituted for the specific embodiments shown. This specification is intended to cover any adaptations or variations of embodiments. In particular, one of skill in the art will appreciate that the names and terminology are not intended to limit embodiments. Furthermore, additional apparatus can be added to the components, functions can be rearranged among components, and new components corresponding to future enhancements and future physical devices used in embodiments can be introduced without departing from the scope of the invention. The terminology used in this application is intended to include all embodiments and alternatives which provide the same functionality as described herein.