Power Transfer Switching Arrangement

Abstract

A switching arrangement having a plurality of electrical contacts configured for high speed electromechanical power switching applications such as transfer switches and circuit breakers. Contacts that contact one another when closed can include snubber portions or parallel snubber contacts that vary in resistance during sliding contact travel. One snubbering switching arrangement includes a first pair of snubbing contacts in parallel with a first pair of electrical contacts where the snubbing contacts make sliding contact before the electrical contacts when the load is being connected to one power source and a second pair of snubbing contacts in parallel with a second pair of electrical contact where the snubbing contacts make contact before the electrical contacts when the load is being connected to a second power source. One such switching arrangement includes the snubber or snubbing contact formed of a brush of electrically conductive bristles.

1 . A switching arrangement comprising:
 a first electrical contact;   a second electrical contact; and   wherein relative movement between the first and second contacts positions (1) the first contact in electrical contact with the second contact when located in a closed position, and (2) the first contact not in electrical contact with the second contact when located in an open position disposed from the closed position.   
     
     
         2 . The switching arrangement of  claim 1  wherein one of the first and second contacts comprises a snubbing contact. 
     
     
         3 . The switching arrangement of  claim 2  wherein the snubbing contact comprises a contact brush. 
     
     
         4 . The switching arrangement of  claim 3  wherein the contact brush is comprised of electrically conductive bristles. 
     
     
         5 . The switching arrangement of  claim 4  wherein the electrically conductive bristles are comprised of one of a tungsten, gold and silver alloy. 
     
     
         6 . The switching arrangement of  claim 1  wherein one of the first and second contacts has an electrically conductive portion and an adjacent electrically resistive snubber portion having a greater electrical resistance than the electrically conductive portion. 
     
     
         7 . The switching arrangement of  claim 6  wherein the switching arrangement comprises a circuit breaker. 
     
     
         8 . The switching arrangement of  claim 6  wherein the one of the first and second contacts has a pair of resistive snubber portions with one of the resistive snubber portions disposed on one side of the electrically conductive portion and the other one of the resistive snubber portions disposed on the other side of the electrically conductive portion. 
     
     
         9 . The switching arrangement of  claim 8  wherein the switching arrangement comprises a transfer switch. 
     
     
         10 . The switching arrangement of  claim 6  wherein the electrical resistance of the resistive snubber portion varies relative to at least one of the length, width or depth of the one of the first and second contacts. 
     
     
         11 . The switching arrangement of  claim 6  wherein the one of the first and second contacts comprises a sliding contact that slidably contacts the other one of the first and second contacts during relative movement between the open and closed positions. 
     
     
         12 . The switching arrangement of  claim 1  further comprising a third electrical contact comprising a snubbing contact spaced from the first contact that is disposed electrically in parallel with the first contact. 
     
     
         13 . The switching arrangement of  claim 12  further comprising an electrical load electrically connected to the first contact and an electrical snubber arrangement electrically connecting the snubber contact with the electrical load. 
     
     
         14 . The switching arrangement of  claim 13  wherein the electrical snubber arrangement comprises a voltage snubber. 
     
     
         15 . The switching arrangement of  claim 14  wherein the electrical snubber arrangement comprises a semiconductor switch that opens when the second contact is in electrical contact with the snubbing contact and not in electrical contact with the first contact when the second electrical contact is being moved from the closed position toward an open position. 
     
     
         16 . The switching arrangement of  claim 12  wherein the snubbing contact is in electrical contact with the second contact when the second contact is located in the closed position. 
     
     
         17 . The switching arrangement of  claim 12  wherein the second contact (a) is movable relative to the first contact and snubbing contact between the open and closed positions and (b) has an electrically conductive portion and an electrically resistive snubber portion with an electrical resistance greater than the electrically conductive portion. 
     
     
         18 . The switching arrangement of  claim 17  further comprising an actuator that moves the second contact relative to the first contact and snubber contact between the open and closed positions when actuated. 
     
     
         19 . The switching arrangement of  claim 18  wherein the actuator comprises a linear actuator having a linearly movable armature moving the second contact substantially in unison with the armature when actuated. 
     
     
         20 . The switching arrangement of  claim 17  wherein the electrically resistive snubber portion of the second contact makes contact with the snubber contact before the electrically conductive portion of the second contact makes electrical contact with the first contact when the second contact is moved from an open position to the closed position. 
     
     
         21 . The switching arrangement of  claim 17  further comprising a fourth electrical contact electrically connected to an electric power source and opposed to the first contact electrically connected to an electrical load and wherein the electrically conductive portion of the second contact electrically contacts the first contact and the fourth contact when located in the closed position allowing electric current flow from the electric power source to the electrical load. 
     
     
         22 . The switching arrangement of  claim 21  further comprising a fifth electrical contact comprising a snubber contact spaced from the fourth contact and disposed in parallel with the fourth contact, wherein the fifth contact is opposed to the third contact, and wherein the second contact electrically contacts the third contact and the fifth contact when located in the closed position. 
     
     
         23 . The switching arrangement of  claim 22  wherein the electrically resistive snubber portion of the second contact makes contact with the third and fifth contacts before the electrically conductive portion of the second contact makes electrical contact with the first and third contacts when the second contact is moved from an open position to the closed position. 
     
     
         24 . The switching arrangement of  claim 1  further comprising a first alternating current electrical power source electrically connected to a third electrical contact opposed to the first contact, an electrical load electrically connected to the first contact, a second alternating current electrical power source electrically connected to a fourth electrical contact, and a fifth electrical contact opposed to the fourth contact and electrically connected to the electrical load, and wherein the second contact is movable between a first position electrically contacting the first and third contacts supplying electric current from the first alternating current electrical power source to the electrical load and a second position electrically contacting the fourth and fifth contacts supplying electrical current from the second alternating current electrical power source to the electrical load. 
     
     
         25 . The switching arrangement of  claim 24  further comprising a pair of snubber contacts with one of the snubber contacts disposed adjacent the first contact and the other one of the snubber contacts disposed adjacent the fifth contact, wherein the second contact comprises an electrically conductive portion disposed between a pair of electrically resistive snubber portions, wherein one of the electrically resistive portions of the second contact electrically contacts the one of the snubber contacts disposed adjacent the first contact before the electrically conductive portion of the second contact electrically contacts the first contact when the second contact is moved from the second position to the first position, and wherein the other one of the electrically resistive portions of the second contact electrically contacts the other one of the snubber contacts disposed adjacent the fifth contact before the electrically conductive portion of the second contact electrically contacts the fifth contact when the second contact is moved from the first position to the second position. 
     
     
         26 . The switching arrangement of  claim 24  further comprising a pair of snubber contacts with one of the snubber contacts disposed adjacent the first contact and the other one of the snubber contacts disposed adjacent the fifth contact, wherein the second contact comprises an electrically conductive portion disposed between a pair of electrically resistive snubber portions, wherein one of the electrically resistive portions of the second contact breaks electrical contact with the one of the snubber contacts disposed adjacent the first contact after the electrically conductive portion of the second contact breaks electrical contact with the first contact when the second contact is moved from the first position to the second position, and wherein the other one of the electrically resistive portions of the second contact breaks electrical contact with the other one of the snubber contacts disposed adjacent the fifth contact after the electrically conductive portion of the second contact breaks electrical contact with the fifth contact when the second contact is moved from the second position to the first position. 
     
     
         27 . A switching arrangement comprising:
 (a) a first source contact electrically connected to a first source of electrical power;   (b) a first load contact electrically connected to an electrical load and disposed adjacent the first source contact;   (c) a second source contact electrically connected to a second source of electrical power;   (d) a second source contact electrically connected to the electrical load and disposed adjacent the second source contact; and   (e) a switching contact movable between (i) a first source connecting position electrically connecting the first source contact to the first load contact providing electrical power from the first source to the electrical load, and (ii) a second source connecting position electrically connecting the second source contact to the second load contact providing electrical power from the second source to the electrical load.   
     
     
         28 . The switching arrangement of  claim 27  further comprising a first snubber contact generally parallel with the first source contact, a second snubber contact generally parallel with the second source contact, and an electrical snubber arrangement electrically connecting the first and second snubber contacts to the electrical load. 
     
     
         29 . The switching arrangement of  claim 28  wherein the electrical snubber arrangement comprises a snubber switch that turns off when the switching contact is moving from the first source connecting position toward the second source connecting position and has electrically broken contact with the first source contact while still being connected to the first snubber contact. 
     
     
         30 . The switching arrangement of  claim 29  wherein the snubber switch comprises a semiconductor switch. 
     
     
         31 . The switching arrangement of  claim 28  wherein the electrical snubber arrangement comprises a switch that turns off when the switching contact is moving from the second source connecting position toward the fires source connecting position and has electrically broken contact with the second source contact while still being connected to the second snubber contact. 
     
     
         32 . The switching arrangement of  claim 28  wherein the switching contact comprises a pair of electrically resistive snubber portions having an electrical resistance greater than an electrically conductive portion with one of the electrically resistive snubber portions disposed on one side of the electrically conductive portion and the other one of the electrically resistive snubber portions disposed on the other side of the electrically conductive portion. 
     
     
         33 . The switching arrangement of  claim 32  wherein the electrically conductive portion breaks contact with the first load contact with the one of the electrically resistive snubber portions remaining in electrical contact with the first snubber contact when the switching contact is moving from the first source connecting position toward the second source connecting position. 
     
     
         34 . The switching arrangement of  claim 32  wherein the other one of the electrically resistive snubber portions makes electrical contact with the second snubber contact before the electrically conductive portion makes contact with the second load contact when the switching contact is moving from the first source connecting position to the second source connecting position. 
     
     
         35 . The switching arrangement of  claim 27  wherein the first and second snubber contacts each comprise a contact brush. 
     
     
         36 . The switching arrangement of  claim 35  wherein each contact brush is comprised of a plurality of electrically conductive bristles. 
     
     
         37 . The switching arrangement of  claim 27  further comprising a linear actuator carrying the switching contact moving the switching contact between the first source connecting position and the second source connecting position during actuation of the linear actuator. 
     
     
         38 . The switching arrangement of  claim 27  wherein the switching arrangement comprises a transfer switch. 
     
     
         39 . The switching arrangement of  claim 38  wherein the transfer switch comprises a three position transfer switch.