US3054877A

US3054877A - Compressed air actuated electric switch with power switching contacts and voltage disconnecting contacts

Info

Publication number: US3054877A
Application number: US740153A
Authority: US
Inventors: Thommen Hans
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1957-06-07
Filing date: 1958-06-05
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18
Also published as: CH352728A; DE1042715B; FR1196689A; BE568382A

Description

Sept. 18, 1962 H. THOMMEN 3,054,877 COMPRESSED AIR ACTUATED ELECTRIC SWITCH WITH POWER SWITCHING CONTACTS AND VOLTAGE DISCONNECTING CONTACTS Filed June 5, 1958 INVENTOR Hans Thom m en BY ATTORNEYS United States Patent ()1 3,054,877 COMPRESSED AIR ACTUATED ELECTRIC SWITCH WITH PGWEJR SWITCHING CONTACTS AND VOLTAGE DISCONNECTING CONTACTS Hans Thommen, Baden, Switzerland, assignor to Alttiengesellschaft Brown, Boveri 8; Cie, Baden, Switzerland, :1 joint stock company Filed June 5, 1958, Ser. No. 740,153 Claims priority, application Switzerland June 7, 1957 Claims. (Cl. 200-148) The present invention relates to electric switches and more particularly to switches of the air blast type provided with power switching contacts and voltage disconnecting contacts which are blasted with compressed air in order to assist in the extinction of the are drawn between the contacts upon their separation.

In switch constructions of the general type described it is important, in order to save compressed air lines and complicated arrangements of the drive and of the valves, to provide as many simplifications as possible. Thus it has been proposed to conduct the compressed air to the switching contacts in common through an insulator and to distribute it only in the direct vicinity of the switch chambers enclosing the contacts. Also, intermediate tanks for the compressed air have been provided to distribute the air from there over the various switch elements.

In accordance with the present invention, the above structural simplifications can be further simplified by using the exhaust air from the power switching contacts to act upon elements for the voltage disconnecting contacts. In particular, this objective is achieved by arranging a valve in the exhaust duct of the power switching contacts, such valve serving as an exhaust valve for the power switching contacts and as a valve for introducing the exhaust air after leaving the power switching contacts to auxiliary pneumatic operating means such as a pneumatic motor of the piston and cylinder type, the piston of which is mechanically connected to a movable one of the voltage disconnecting contacts to disengage the same from the other, stationary contact.

The foregoing objects and advantages of the invention will become more apparent from the following detailed description of a preferred embodiment and the appertaining drawing.

The view is principally a vertical longitudinal section with certain parts shown in elevation of one embodiment of the invention wherein compressed air from a supply tank is used to move the contacts of the voltage disconnecting switch component to closed position, wherein a valve in the exhaust duct of the power switching contacts performs a second valve function in conjunction with the voltage disconnecting contacts, namely, to cause their separation, and wherein compressed air stored in the chamber containing the voltage disconnecting contacts is caused to flow, subsequent to opening of the power switching contacts, over the disengaged voltage disconnecting contacts into the supply tank.

With reference now to the drawing, the switch structure comprises a tank 1 containing compressed air. Upstanding on tank 1 is a tubular insulator column 2 within which are arranged the power switching contacts comprising a movable pin contact member 3a and a stationary nozzle contact member 3b. Mounted atop the insulator column 2 is metallic section 4 which provides an outlet 4a for compressed air discharged upward through the nozzle contact member 3b. A dual purpose valve 6 is disposed within the metallic section 4 and it is constituted by one valve closure member 6a which serves to close the upper end of the nozzle contact member 3b and a second valve closure member 6b which serves to close an outlet 4b from the section 4 into a cylinder 7 3,054,877 Patented Sept. 18, 1962 which is arranged with its longitudinal axis perpendicular to the axis of the insulator column 2. Cylinder 7 contains a piston 8 which is structually united with the movable contact member 9a of the voltage disconnecting contacts, and which is adapted to engage and be disengaged from the stationary contact member 9b of the voltage disconnecting contacts as the piston 8 is shifted back and forth in its cylinder 7. Thus cylinder 7 and piston 3 constitute a double action pneumatic motor. The voltage disconnecting contacts 9a, 9b are enclosed within a tubular insulator casing 10 which constitutes a longitudinal extension of cylinder 7. The left end portion of cylinder 7 is arranged to communicate with the interior of the compressed air tank 1 by means of a tubular column 11 of insulating material which is arranged parallel with the upstanding insulator column 2. A valve 12 located at the lower end of the column 11 within tank 1 is so arranged that in one position of the valve, the interior of column 11, and hence the left end of cylinder 7, is placed in communication with the interior of tank 1 and thus permits the compressed air to flow upward through column 11 and into the left end of cylinder 7. In the other position of valve 12, the lower end of column 11 is cut ofii from the compressed air in tank 1 and placed in communication with a discharge outlet pipe 13 which passes through to the outside of tank 1. For actuating the movable pin contact member 3a it will be seen that such member is united with a piston 14 operating in a cylinder 14a located in the interior of tank 1.

In the drawing, the switch is shown with the main power switching contacts 311, 3b closed and the voltage switching contacts 9a, 9b open. To close a load circuit through the switch, the power switching contacts 3a, 3b being arranged in series with the voltage disconnecting contacts 9a, 9b, valve 12 is moved to the position which admits compressed air from tank 1 upwardly through tubular column 11 into cylinder 7 at the left side of piston "8 thus causing piston 8 and the movable voltage disconnecting contact member 9a to move to the right and engage the stationary contact member 912. At the same time, compressed air passes through small ports 8a in piston 8 to the interior of cylinder 7 at the right-hand side of piston 8 and thence through nonreturn valves 7a in the separating wall between cylinder 7 and casing 10 thus filling the latter with compressed air, the non-return valves reclosing, of course, when there is suflicient pressure in casing 10.

When it is subsequently desired to open the load circuit through the switch, compressed air from tank 1 is admitted into cylinder 14a through valve 16 thus moving piston 14 downwardly and carrying with it the movable power switching contact member 3a. The latter is thus caused to separate from the nozzle contact member 3b and compressed air from tank 1 is then free to flow upwardly through insulator column 2 as an end closure plate 15 constituting a structural part of piston 14 is removed from the lower end of column 2. This air which thus blasts the contact area and helps to extinguish the arc flows upwardly through noZZle contact member 3b and actuates the dual purpose valve 6, the valve closure member 6a being caused to rise from its seat to place the interior of nozzle contact member 3b in communication with the outlet 4a, and the valve closure member 6b being caused to rise from its seat thus to permit part of the compressed air discharged upwardly through the nozzle contact member 3b to flow through outlet 4b into cylinder 7 at the right side of piston 8 thus causing the latter and the movable voltage disconnecting contact 9a to move to the left and thus disengage it from the stationary contact member 9b. The compressed air in cylinder 7 at the left side of piston 8 is discharged downwardly through hollow column 11 and through valve 12 and outlet 13 to atmosphere, the valve 12 being, of course, actuated to such position after the power switching contacts 3a, 3b has been closed by the procedure previously explained and prior the opening. Due to the switching of the power switching contacts to their open, i.e. disengaged position, and the attendant use of compressed air from tank 1, the air pressure in the tank will be reduced temporarily. Because of this drop in air pressure, compressed air from the casing 10 is then enabled to flow past the disengaged voltage disconnecting contact members 9a, 9b thus helping to extinguish the are drawn between the same upon their separation, and thence downwardly through another hollow insulator column 18 paralleling column 2 and through a non-return valve 17 into tank 1.

In conclusion, it is desired to point out that the inventive concept makes it possible to save a complete valve unit for a switch of the type described. Moreover, compressed air lines become unnecessary, so that savings are also made in the space required.

I claim:

1. In an electrical switch of the air-blast type the combination comprising a power switching assembly including a set of power switching contacts enclosed within a first hollow insulator, a voltage disconnecting assembly including a set of voltage disconnecting contacts enclosed within a second hollow insulator and connected electrically in series with said set of power switching contacts in relation to a line to be connected through said switch, means for introducing compressed air into said first hollow insulator for efiecting separation of said set of power switching contacts, a pneumatic motor separated from said second hollow insulator and having a movable element thereof mechanically coupled to a movable one of said voltage disconnecting contacts, and valve means arranged cooperatively with an outlet for compressed air exhausted from said first hollow insulator and with an inlet to said pneumatic motor for actuating the latter by said exhausted compressed air thereby to effect separation of said voltage disconnecting contacts.

2. An electrical switch of the air-blast type as defined in claim 1 wherein said pneumatic motor comprises a stationary cylinder pneumatically separated from said second hollow cylinder and a piston slidable therein and which is connected to said movable voltage disconnecting contact.

3. An electrical switch of the air-blast type as defined in claim 2 and wherein said valve means is constituted by two commonly operated valve elements, one of said valve elements controlling the outlet from said first hollow insulator and the other of said valve elements controlling the inlet to said cylinder of said pneumatic motor.

4. An electrical switch of the air-blast type as defined in claim 1 wherein said pneumatic motor comprises a stationary cylinder and a piston slidable therein and which is connected to said movable voltage disconnecting contact, the compressed air exhausted from said first hollow insulator being led through said valve means to one side of said piston to cause the latter to move in one direction so as to disengage said voltage disconnecting contacts, and which further includes means for introducing compressed air to the other side of said piston to cause the latter to move in the opposite direction so as to reengage said voltage disconnecting contacts.

5. In an electrical switch of the air-blast type, the combination comprising a power switching assembly includ' ing a set of relatively movable power switching contacts enclosed within a first hollow insulator, a voltage disconnecting assembly including a set of relatively movable voltage disconnecting contacts enclosed within a second hollow insulator and connected electrically in series with said set of power switching contacts in relation to a line to be connected through said switch, means for introducing compressed air into said first hollow insulator for effecting separation of said set of power switching contacts, a double action pneumatic motor comprising a stationary cylinder and a piston slidable therein and which is connected to a movable one of said voltage disconnecting contacts, said piston being provided with ports therethrough, wall means including non-return valve means therein separating a first interior portion of said pneumatic motor cylinder at one side of said piston from said second hollow insulator, said non-return valve means opening in the direction of said second hollow insulator, valve means arranged cooperatively with an outlet for compressed air exhausted from said first hollow insulator and with an inlet to said first interior portion of said pneumatic motor cylinder for actuating said piston by said exhausted compressed air in such direction as to effect separation of said voltage disconnecting contacts, and means for introducing compressed air into a second interior portion of said pneumatic motor cylinder at the opposite side of said piston for actuating said piston in the opposite direction so as to efiect reengagement of said voltage disconnecting contacts, said compressed air also passing through the ports in said piston into said first interior portion of said pneumatic motor cylinder and thence through said non-return valves into said second hollow insulator.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,577 Uebermuth Apr. 18, 1933 2,345,724 Baker et al Apr. 4, 1944 2,453,555 Thommen Nov. 9, 1948 FOREIGN PATENTS 115,692 Sweden Jan. 22, 1946 581,236 Great Britain Oct. 4, 1946 933,819 Germany Oct. 6, 1955