Abstract
The invention disclosed is an arc protection system for an electrical switch mounted in an electrical cabinet. The system includes an arc suppression housing pivotally mounted in the electrical cabinet. The housing comprises an arc extinguishing chamber having an opening configured to face separable contacts of an electrical switch mounted in the cabinet when the housing has been rotated about the pivot into a closed position. The arc extinguishing chamber is configured to extinguish an electric arc produced by opening the separable contacts when the housing is in the closed position. The system further includes an interference mechanism mounted on the arc suppression housing. The interference mechanism is configured to prevent closure of an access door of the electrical cabinet, when the housing has been rotated about the pivot into an open position configured to enable operator access to the separable contacts of the electrical switch.
Claims
1. An arc protection system for an electrical switch mounted in an electrical cabinet, comprising: an arc suppression housing pivotally mounted on a pivot in the electrical cabinet, the housing including a top wall and opposing side walls surrounding an arc extinguishing chamber having a bottom opening configured to face separable contacts of the electrical switch mounted in the cabinet when the housing has been rotated on the pivot into a closed position, a rotation being about a pivot axis generally perpendicular to the side walls, the arc extinguishing chamber configured to extinguish an electric arc having been produced by opening the separable contacts when the housing is in the closed position; and an interference mechanism mounted on the top wall of the arc suppression housing, configured to prevent closure of an access door of the electrical cabinet, after the housing has been rotated about the pivot axis of the pivot into an open position configured to enable operator access to the separable contacts of the electrical switch.
2. The arc protection system of claim 1, wherein the interference mechanism is an extension projecting from the top wall of the arc suppression housing, configured to block closure of the access door of the electrical cabinet to insure a closed positioning of arc suppression housing prior to closure of the access door.
3. The arc protection system of claim 1, further comprising: the arc suppression housing supported by a pivot shaft mounted on the arc suppression housing and coincident with the pivot axis; and a base portion fastened to the electrical cabinet, to which the separable contacts of the electrical switch are mounted, the base portion including a pivot socket configured to receive the pivot shaft of the arc suppression housing, the pivot socket configured to allow the housing to be rotated about the pivot axis between the closed position and the open position.
4. The arc protection system of claim 3, further comprising: the pivot socket having a generally cylindrical shape with a cylindrical axis coincident with the pivot axis, with ends generally perpendicular to the pivot axis, and having a cylindrical hole through the pivot socket it coincident with the pivot axis, within which the pivot shaft can be inserted; and the pivot shaft having a shaft restraint device on one end, configured to allow the pivot shaft to be inserted into the hole of the pivot socket and further configured to restrain the pivot shaft from removal from the hole of the pivot socket, thereby restraining the arc suppression housing from being removed from the base portion once the pivot shaft has been inserted into the hole of the pivot socket.
5. The arc protection system of claim 3, further comprising: the pivot socket having a generally C-shaped cross section forming a slot opening parallel to the pivot axis and a hollow interior space coincident with the pivot axis, the slot opening enabling the pivot shaft to be inserted sideways through the slot opening into the hollow interior space by movement in a direction transverse to the pivot axis; and the pivot socket including a shaft retaining device configured to allow the pivot shaft to be inserted sideways through the slot opening into the hollow interior space so as to be coincident with the pivot axis, the shaft retaining device further configured to retain the pivot shaft from removal from the hollow interior space through the slot opening, thereby restraining the arc suppression housing from being removed from the base portion once the pivot shaft has been inserted sideways into the pivot socket.
6. The arc protection system of claim 1, wherein the interference mechanism prevents closure of the access door of the electrical cabinet, until the housing has been rotated about the pivot into the closed position.
7. The arc protection system of claim 1, wherein the housing further comprises a plurality of arc extinguishing chambers, each having an opening configured to face separable contacts of a corresponding plurality of electrical switches mounted in the cabinet when the housing has been rotated about the pivot into the closed position.
8. An arc protection system for an electrical switch mounted in an electrical cabinet, comprising: an arc suppression housing in the electrical cabinet, the arc suppression housing including a pivot shaft; a base portion fastened to the electrical cabinet, including a pivot socket configured to receive the pivot shaft of the arc suppression housing, the pivot socket configured to allow the arc suppression housing to be rotated about a pivot axis of the pivot shaft between a closed position and an open position; the electrical switch mounted in the base portion, the electrical switch including separable contacts; the arc suppression housing including a top wall and opposing side walls surrounding an arc extinguishing chamber having a bottom opening configured to face the separable contacts of the electrical switch when the arc suppression housing has been rotated about the pivot axis into the closed position, the arc extinguishing chamber configured to extinguish an electric arc having been produced by opening the separable contacts when the arc suppression housing is in the closed position; and an interference mechanism mounted on the top wall of the arc suppression housing, configured to prevent closure of an access door of the electrical cabinet, after the arc suppression housing has been rotated about the pivot axis into the open position configured to enable operator access to the separable contacts of the electrical switch.
9. The arc protection system of claim 8, wherein the interference mechanism is an extension projecting from the top wall of the arc suppression housing, configured to block closure of the access door of the electrical cabinet to insure a closed positioning of arc suppression housing prior to closure of the access door.
10. The arc protection system of claim 8, wherein the interference mechanism prevents closure of the access door of the electrical cabinet, until the arc suppression housing has been rotated about the pivot axis into the closed position.
11. The arc protection system of claim 8, wherein the arc suppression housing further comprises a plurality of arc extinguishing chambers, each having an opening configured to face separable contacts of a corresponding plurality of electrical switches mounted in the base portion when the arc suppression housing has been rotated about the pivot axis into the closed position.
12. A method for accessing an electrical switch protected by an arc protection system in an electrical cabinet, comprising: removing electrical power from the cabinet and from the electrical switch; opening an access door of the electrical cabinet; releasing a latch on an arc suppression housing, from a latch seat on a base portion to which the arc suppression housing is pivotally mounted about a pivot axis; opening the arc suppression housing by rotating the arc suppression housing about the pivot axis of the base portion into an open position; blocking closure of the access door with interference projections on the arc suppression housing after the arc suppression housing has been rotated about the pivot axis into the open position, to insure that the arc suppression housing will be replaced by an operator in the closed position while the switch is in operation; and accessing the electrical switch while the arc suppression housing is in the open position.
Description
DESCRIPTION OF FIGURES
(1) FIG. 1 shows a top perspective view from the left side, of an example embodiment of the invention, showing an electrical cabinet within which is contained a safety switch comprising an arc suppression housing that is pivotally mounted to a base within the cabinet. Electrical switch contacts are mounted in the base. The arc suppression housing may be rotated from a closed position to an open position shown in the figure, to enable operator access to the switch contacts. An access door of the cabinet is shown open in the figure. When the arc suppression housing has been rotated into its open position, closure of the access door of the cabinet is blocked by an interference projection of the arc suppression housing, which is shown extending out of the cabinet. The access door is thereby prevented from closing when the arc suppression housing is in its open position, to enable operator access to the switch contacts.
(2) FIG. 2 shows a top perspective view from the left side, of an example embodiment of the invention, showing the closed position of the arc suppression housing and the base to which it is pivotally mounted.
(3) FIG. 3 shows a top perspective view from the right side, of an example embodiment of the invention, showing the safety switch comprising the arc suppression housing and a pivot shaft including a shaft restraint device comprising a shaft head and shaft slot configured for insertion into a pivot socket with snap-in feature, which is mounted on the base of the safety switch.
(4) FIGS. 3A and 3B show a top perspective view from the right side, of an example embodiment of the invention, respectively showing a disassembled (FIG. 3A) and an assembled (FIG. 3B) arrangement of the pivot shaft and the pivot socket. The shaft restraint device is configured to allow the pivot shaft to be inserted into the pivot socket of the base portion and is further configured to restrain the pivot shaft from removal from the pivot socket, thereby restraining the arc suppression housing from being removed from the base portion once the pivot shaft has been inserted into the pivot socket.
(5) FIG. 4 shows a side perspective view from the right side, of an example embodiment of the invention, showing a partially open position of the arc suppression housing and the base to which it is pivotally mounted to enable an operator to reach the contacts of the electrical switch for wiring or maintaining the contacts.
(6) FIG. 5 shows an exploded, top perspective view from the right side, of an example embodiment of the invention, showing the arc suppression housing and the base.
(7) FIG. 6 shows a top perspective view from the right side, of an example alternate embodiment of the invention, showing an open position of the arc suppression housing and the base to which it is pivotally mounted, with a pivot socket that has a generally C-shaped cross section mounted on the base portion. The generally C-shaped cross section forms a slot opening along the length of the pivot socket and a hollow interior space coincident with the pivot axis. The slot opening enables the pivot shaft to be inserted sideways through the slot opening into the hollow interior space by movement in a direction transverse to the pivot axis.
(8) FIG. 7 shows a top perspective view from the right side, of the example alternate embodiment of the invention of FIG. 6, showing the shaft retaining device configured to allow the pivot shaft to be inserted sideways through the slot opening into the hollow interior space. The shaft retaining device is further configured to retain the pivot shaft from removal from the hollow interior space through the slot opening, thereby restraining the arc suppression housing from being removed from the base portion once the pivot shaft has been inserted into the pivot socket.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
(9) FIG. 1 shows a top perspective view from the left side, of an example embodiment of the invention, showing an electrical cabinet 170 within which is contained a safety switch 50. The safety switch 50 comprises an arc suppression housing 100 that is pivotally mounted to a base 150 within the cabinet 170. Electrical switch contacts 120 (shown in FIG. 5) of an electrical switch may be mounted in the base 150 of the arc suppression housing 100 and may be actuated by the handle 175. The arc suppression housing 100 includes a top wall 101 and opposing side walls 109A and 109B surrounding an arc extinguishing chamber 106 having a bottom opening 108 configured to face the separable contacts 120 of the electrical switch. The arc suppression housing 100 may be rotated from a closed position shown in FIG. 2 to an open position shown in FIG. 4, to enable an operator to gain access to the switch contacts 120 in the base 150 for wiring or maintaining the contacts. An access door 180 of the cabinet is shown open in FIG. 1. When the arc suppression housing 100 has been rotated into its open position, closure of the access door 180 of the cabinet is blocked by interference projections 110 and 110 of the arc suppression housing 100, which are shown extending out of the cabinet doorway. The access door 180 is thus safely prevented from being closed by an operator after the arc suppression housing 100 has been rotated by the operator into its open position.
(10) FIG. 2 shows a top perspective view from the left side, of an example embodiment of the invention, showing the safety switch 50 with the closed position of the arc suppression housing 100 and the base 150 to which it is pivotally mounted. The arc suppression housing 100 is pivotally mounted on a pivot shaft 102. The pivot shaft 102 is shown inserted or snapped into a pivot socket 104 configured to receive the pivot shaft 102, to allow the arc suppression housing 100 to be rotated about a pivot axis 111 between the closed position and an open position shown in FIG. 4. The arc suppression housing 100 comprises the arc extinguishing chamber 106 having the opening 108 configured to face the separable contacts 120 (shown in FIG. 5) in the base 150 when the arc suppression housing 100 has been rotated about the pivot axis into the closed position. The arc extinguishing chamber 106 is configured to extinguish an electric arc flash produced by opening the separable contacts 120.
(11) The bottom opening 108 in the arc extinguishing chamber 106 is shaped and sized to allow the moveable contact portion of the electrical switch, such as an electrically conductive knife or blade, to freely pass through the arc extinguishing chamber 106 and engage electrically conductive jaws contact 120 of the switch. An example of such knife or blade-type electrical switch is disclosed, for example, in U.S. Pat. No. 6,331,684, to Hamid S. Abroy et al., which is incorporated herein by reference. Wiring channel 125 is shown in the base 150, to enable wiring the electrical contacts 120 while the arc suppression housing 100 is in the open position shown in FIG. 4. The arc extinguishing chamber 106 has a plurality of shelves between the opposing sidewalls 109A and 109B. A plurality of arc suppressing plates extend through the arc extinguishing chamber 106 and are seated on the shelves, as described in U.S. Pat. No. 8,476,546, to Hamid S. Abroy et al., which is incorporated herein by reference. The arc extinguishing chamber 106 and plates effectively surround the blade and jaws contacts 120 of the electrical switch to quench electrical arc flashes released when the blade engages or disengages the jaws 120 and to protect other components in the switch assembly. The arc suppressing plates are configured to extinguish electrical arc flashes between the blade and the jaws contacts 120. The arc extinguishing chamber 106 diverts the arc flash against the arc suppressing plates, to split the arc flash up into a number of elementary arcs, to dissipate the energy of the arc flash.
(12) FIG. 3 shows a top perspective view from the right side, of an example embodiment of the invention, showing the arc suppression housing 100 and the pivot shaft 102, including a shaft restraint device 160. The shaft restraint device 160 comprises a shaft head 103 and shaft slot 105 configured for insertion into the pivot socket 104, which is mounted on the base 150 of the safety switch 50 of FIG. 2. In example embodiments of the invention, the shaft restraint device 160 may also be similarly formed on the other pivot shaft 102 and be configured for insertion into the other pivot socket 104 of FIG. 2.
(13) FIGS. 3A and 3B show a top perspective view from the right side, of an example embodiment of the invention, respectively showing a disassembled (FIG. 3A) and an assembled (FIG. 3B) arrangement of the pivot shaft 102 and the pivot socket 104. The pivot socket 104 has a generally cylindrical shape with a cylindrical axis coincident with the pivot axis 111. The ends of the cylinder are generally perpendicular to the pivot axis 111 and the cylinder has a cylindrical socket hole 107 through it coincident with the pivot axis 111, within which the pivot shaft 102 may be inserted. The shaft restraint device 160 is configured to allow the pivot shaft 102 to be inserted into the socket hole 107 of the pivot socket 104 of the base portion. The shaft restraint device 160 is further configured to restrain the pivot shaft 102 from removal from the pivot socket 104 after insertion. The example embodiment of the pivot socket 104 shown in FIGS. 3A and 3B may be referred to as a side-feeding pivot socket, because the arc suppression housing 100 on which the pivot shaft 102 is mounted, is moved sideways with respect to the base 150, when inserting or feeding the pivot shaft 102 into the socket hole 107 of the pivot socket 104 of the base portion. In this manner, the arc suppression housing 100 is restrained from being removed from the base portion 150 once the pivot shaft 102 has been inserted into the pivot socket 104.
(14) FIG. 4 shows a side perspective view from the right side, of an example embodiment of the invention, showing a partially open position of the arc suppression housing 100 and the base 150 to which it is pivotally mounted to enable an operator to reach the contacts of the electrical switch for wiring or maintaining the contacts. In example embodiments of the invention, the arc suppression housing 100 further comprises a plurality of arc extinguishing chambers 106, 106, and 106, each having a respective opening 108, 108, and 108 configured to face separable contacts 120, 120, and 120 (shown in FIG. 5) of a corresponding plurality of electrical switches mounted in the base 150, when the arc suppression housing 100 has been rotated about the pivot shaft 102 into the closed position of FIG. 2. A latch 130 on the arc suppression housing 100 engages and securely fastens to a latch seat 132 on the base 150 when the arc suppression housing 100 has been rotated about the pivot shaft 102 into the closed position of FIG. 2.
(15) FIG. 5 shows an exploded, top perspective view from the right side, of an example embodiment of the safety switch 50, showing the arc suppression housing 100 and the base 150. The separable switch contacts 120 may be part of a blade or knife-type electrical switch mounted in the base 150 of the arc suppression housing 100. The circuit for each phase may be completed through a pivotable, electrically conductive knife or blade that engages a corresponding pair of electrically conductive jaws contacts 120, 120, and 120 to electrically connect the line current to the load. The blade and the jaws contacts 120 form the separable contacts of the electrical switch. The blade-type switch may be mounted in the base 150 of the arc suppression housing 100, which may incorporate an insulating base to carry an incoming line terminal for each phase.
(16) In the normally closed position shown in FIG. 2, the arc suppression housing 100 is configured to extinguish an electric arc flash produced by opening the separable contacts of the switch when electrical power is being applied to the switch. When an operator needs to wire the contacts 120 or to clean or repair the contacts 120, electrical power must be removed from the cabinet 170 and from the separable contacts of the switch. The handle 175 on the cabinet 170 may also be actuated to open the switch contacts 120. The access door 180 of the cabinet may then be opened. A latch 130 on the arc suppression housing 100 engages and securely fastens to a latch seat 132 on the base 150 when the arc suppression housing 100 has been rotated about the pivot shaft 102 into the closed position of FIG. 2 To open the arc suppression housing 100 by rotating it about the pivot axis 111 into the open position of FIG. 4, the operator must release the latch 130 from the latch seat 132 on the base 150. The operator may then open the arc suppression housing 100 by rotating it about the pivot axis 111 into the open position of FIG. 4. The interference projections 110 and 110 are configured to block closure of the access door 180 of the electrical cabinet 170, after the arc suppression housing 100 has been rotated about the pivot axis 111 into the open position of FIG. 4, without first rotating the arc suppression housing 100 back into the closed position of FIG. 2. This insures that the arc suppression housing 100 will always be placed by the operator in the closed position while the switch is in operation. With the arc suppression housing 100 now having been rotated into the open position of FIG. 4, the operator has access to wire the contacts 120 or to clean or repair the contacts 120.
(17) The arc suppression housing 100 and the base 150 may be assembled either in the factory or in the field, by inserting the pivot shaft 102 into the pivot socket 104 and the pivot shaft 102 and the pivot socket 104. The shaft restraint devices on the pivot shaft 102 and on the pivot shaft 102 restrain the arc suppression housing 100 from being removed from the base portion 150 once the pivot shafts 102 and 102 have been inserted into the respective pivot sockets 104 and 104.
(18) FIG. 6 shows a top perspective view from the right side, of an example alternate embodiment of the invention, showing an open position of the arc suppression housing 100 and the base 150 to which it is pivotally mounted. A pivot socket 104A has a generally C-shaped cross section mounted on the base portion 150. The generally C-shaped cross section forms a slot opening 112 (shown in FIG. 7) along the length of the pivot socket 104A and a hollow interior space coincident with the pivot axis 111. The slot opening 112 enables the pivot shaft 102 to be inserted sideways through the slot opening 112 into the hollow interior space by movement in a direction from front to back, transverse to the pivot axis 111.
(19) FIG. 7 shows a top perspective view from the right side, of the example alternate embodiment of the invention of FIG. 6, showing a shaft retaining device 160A configured to allow the pivot shaft 102 to be inserted sideways through the slot opening 112 into the hollow interior space. The shaft retaining device 160A is further configured to retain the pivot shaft 102 from removal from the hollow interior space through the slot opening 112. The example embodiment of the pivot socket 104A shown in FIG. 7 may be referred to as a front-feeding pivot socket, because the arc suppression housing 100 on which the pivot shaft 102 is mounted, is moved from front to back with respect to the base 150, when inserting or feeding the pivot shaft 102 through the slot opening 112 into the hollow interior space of the pivot socket 104A of the base 150. In this manner, the arc suppression housing 100 is restrained from being removed from the base 150 once the pivot shaft 102 has been inserted sideways through the slot opening 112 into the hollow interior space pivot socket 104A.
(20) Although specific example embodiments of the invention have been disclosed, persons of skill in the art will appreciate that changes may be made to the details described for the specific example embodiments.
