US2871415A

US2871415A - Switches and circuit interrupters

Info

Publication number: US2871415A
Application number: US373467A
Authority: US
Inventors: Leonard V Chabala
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1953-08-11
Filing date: 1953-08-11
Publication date: 1959-01-27
Anticipated expiration: 1976-01-27

Description

Jmm 2% 159 L. V. CHABALA SWITCHES AND CIRCUIT INTERRUPTERS 2 Sheets-Sheet 1 Filed Aug. 11, 1953 lnsulmion INVENTOR Leonard V. Chafocilu. 6i BY WlTNESSES:

A L A B A H V L SWITCHES AND CIRCUIT INTERRUPTERS Fild Aug. 11, 1953 2 Sheets-Sheet 2 INVENTOR Leonard V. Chabaia.

BY I 'W ATTQ WITNESSES:

RNEY

United States Patent O SWITCHES AND CIRCUIT INTERRUPTERS Leonard V. Chabala, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 11, 1953, Serial No. 373,467

12 Claims. (Cl. 317-35) My invention relates generally to switches and circuit interrupters and it has reference in particular to means for preventing opening of a switch or circuit interrupter during an excessive overcurrent.

Generally stated it is an object of my invention to provide in a novel manner for preventing opening of a switch while it is carrying a current in excess of its interrupting ability.

More specifically it is an object of my invention to provide for preventing operating of the trip means of a circuit interrupter or switch during an overcurrent in excess of a value which the circuit interrupter or switch is capable of interrupting safely.

Another object of my invention is to provide for using electromagnetic means energized in accordance with the current through a switch for preventing operation of the trip means of the switch while such current is flowing.

It is also an object of my invention to provide for interrupting the tripping circuit of a switch during overcurrent in excess of a predetermined maximum value.

An important object of my invention is to provide in an electromagnetically operated switch, for adjustably connecting a load responsive restraining element to the operating means of the switch for preventing tripping during currents in excess of a predetermined value.

Yet another object of my invention is to provide in an electrically operated oil switch having a trip solenoid for opening the switch, for preventing opening of the switch in the event an attempt is made to energize the trip solenoid at a time when the current the switch is carrying is in excess of that which the switch is capable of safely interrupting.

Other objects will in part be obvious, and will in part be explained hereinafter.

In accordance with one embodiment of my invention, a circuit interrupter having an overcenter toggle mechanism for operating separable contacts is provided with an operating solenoid having an armature connected to one lever of the toggle mechanism, and trip and close windings which may be suitably energized to effect either separation or closing of the contacts. An additional solenoid is provided having an armature and a holding winding. The holding Winding is Connected in series with the contacts and the armature of the additional solenoid is adjustably connected to the armature of the operating solenoid so as to restrain it and prevent tripping of the switch at predetermined different maximum values of current.

For a more complete understanding of the nature and the scope of my invention, reference may be made to the following detailed description which may be read in connection with the accompanying drawings in which:

Fig. 1 is a substantially central sectional view of a switch embodying the invention in one of its forms;

Fig. 2 is a diagrammatic view of the switch of Fig. 1 showing the Contact arrangement;

ice

Fig. 3 is a partial central sectional view of the contact supporting structure and operating means of a similar switch embodying the invention in another of its forms;

Fig. 4 is a partial similar view of the Contact supporting structure and operating means of a similar switch embodying the invention in yet another form; and

Fig. 5 is a sectional view through an insulating bushing such as shown in Fig. 4 showing the structure of the relay for controlling the trip circuit of the switch in Fig. 4.

Referring to Fig. 1 the reference numeral may denote generally an oil switch of the type disclosed in copending application Serial No. 187,566 of Andrew W. Edwards et al. which was filed on September 29, 1950 and is entitled Electrically Operated Switches and Sectionalizers, now Patent No. 2,701,828. As therein disclosed the switch It may comprise a metal tank 11 provided with a peripheral flange 12 and a liner 14 of insulating material around the sides together with a bottom liner 15 also of insulating material. The tank 11 which is disposed to be filled with an insulating oil to the level L, may be surmounted by a cover casting 17 having a peripheral flange 18 disposed to be aligned with the flange 12 and having a gasket 19 disposed therebetween.

The cover 17 may be provided with a pair of insulating bushings for permitting a pair of conductors to pass through. Since the figure shown is a substantially central section, only one of the insulators 20 is shown together with its conductor 21, it being understood that the other insulating bushing is substantially similar thereto. The bushing 20 projects into the tank 11 and the lower end portion thereof is beneath the level of the insulating oil. The conductor 21 extends through the insulating bushing and provides a support for a stationary contact member 22 at the lower end thereof, it being understood that there will be two such Contact members, one for each bushing. As shown in Fig. 2, the other conductor 16 similarly supports a contact 23. A movable bridging contact 24 may be slidably supported on a pull rod 25 of the insulating material. The contact member 24 may be resiliently supported on the pull rod 25 to engage

contacts

22 and 23 by means of a spring 26 which rests upon a transverse pin 28 extending through the lower end of the rod. Guide links 29 may be pivotally mounted at one end on the pin 28 and pivotally connected to suitable brackets 30 mounted on insulating supports 32 which depend from the cover casting 17. A somewhat C-shaped bracket 34 having lower legs 35 secured by the pin 28 and an angularly related upper leg 36 surrounding the rod 25, may be provided for restraining upward movement of the contact member 24 under the influence of the spring 26.

Operation of the pull rod 25 may be effected by means of a lever mechanism indicated generally by the numeral 38. This mechanism may comprise a substantially triangular lever 40 connected to the pull rod 25 by means of a pivot 41 and pivotally supported by means of a pivot 42 secured to an L-shaped bracket 44 which may be fastened to a boss 45 depending from the top of the cover casting 17, by means of a bolt 46. Operation of the lever 40 may be effected by an overcenter toggle linkage com prising a lever 48 and a link 49. The link 49 may be connected to the lever 40 by means of a pivot 50 and to the lever 48 by means of a pivot 52. The lever 48 may be pivotally mounted on a partition 53 of the cover casting 17, by means of a pivot 54 and a bracket 55, and have a handle portion 57 which extends through an opening 58 in the partition so as to be positioned under a hooded extension 60 of the cover casting with the

contacts

22 and 24 in the closed position as shown. The

lever 48 and link 49 are in an overcenter toggle relation with the handle 57 abutting an adjustable stop 62, and pivot 52 slightly below the line adjoining the pivots 50 and 54. The

contacts

22 and 24 will accordingly be maintained in the closed position by this toggle relationship.

Operation of the mechanism 38 to open and close the

contacts

22 and 24 may be effected by solenoid means 64 having an armature 65 pivotally connected to the lever 48 intermediate the pivots 52 and 54 by means of a pivot 66. Trip and

close operating windings

68 and 69 may be provided being sandwiched between

plates

70, 71 and 72 of a magnetic material which may be connected by means of bolts 73 and 74 and supported from the cover casting by means of an insulating support 76. The plates are provided with centrally aligned openings for permitting passage of the armature 65 therethrough, and the

operating windings

68 and 69 are so arranged that energization of windings 68 pulls the armature 65 upwardly to break the toggle relation of

levers

48 and 49, and permit the pull rod 25 to drop and separate

contacts

22 and 24. Energization of the closing winding 69 pulls the armature 65 downwardly to the position shown in which the

contacts

22 and 24 are held closed. Springlike lever 77 is mounted on pivot 42 for actuation by link 49, for operating a cutoff switch 78 having a movable contact member 780 for selectively engaging

contact members

78b or 780 depending upon whether the switch is open or closed. The switch 78 is connected in circuit relation with the

windings

68 and 69 to provide for interrupting the energizing circuits therefor when the switch is operated from one position to another.

In order to provide for preventing the

contacts

22 and 24 from separating while the switch is carrying a current within its current carrying capacity, and yet which it may be dangerous to interrupt, a holding solenoid 80 may be provided as shown in Figs. 1 and 2. The solenoid 80 may comprise an armature 82 disposed to be adjustably connected by means of a sleeve of insulating material 83 to the armature, and a hold winding 85. The winding 85 may be supported between plates of

magnetic material

86 and 87 having central openings for permitting passage of the armature 82, and supported from the solenoid means 64 by means of bolts 89 and insulating spacers 90. The winding 85 may be connected in series circuit with the

contacts

22 and 24 by means of

conductors

91 and 92 which connect respectively to to the conductor 21 and to the stationary contact 22, having insulating material 94 disposed therebetween.

By adjustment of the insulating sleeve connection 83 between the

armatures

82 and 65, the effective pull of the armature 65 for any given value of current through the

contacts

22 and 24 may be varied. Since the armature 82 is acted upon by the current through the contacts and tends to hold the lever 48 down against the tripping effect of the trip winding 68, it will be realized that tripping of the switch may be effectively prevented for currents in excess of a number of different predetermined maximum values, depending on the adjustment of the insulating connection 83.

Referring to Fig. 3 it will be seen that instead of providing a separate holding solenoid 80 with its armature connected to the armature 65, a hold winding 95 may be added to the solenoid means 64' comprising the trip winding 68 and closing winding 69. The hold winding 95 may be sandwiched between lower magnetic plate 72 and additional magnetic plate 96 and the armature 65' may be modified so as to have its lower portion disposed within the hold winding 95. Energization of the hold winding 95 may be efiected by connecting it to a current transformer 97 of the ring type, which may be disposed at the lower end of the insulating bushing 20.

When the trip winding 68 is energized to elfect separation of the

contacts

22 and 24 the winding 68 tends to pull the armature 65 upwardly. At the same time the hold winding 95 will be energized from the current transformer 97 in accordance with the current through the

contacts

22 and 24. Since the winding tends to pull the armature 65 downwardly, opposite to the pull of the trip winding 68, tripping of the switch may be effectively prevented so long as the current through the

contacts

22 and 24 is above a predetermined value which the switch may not be capable of safely interrupting.

Referring to Fig. 4, it will be seen that the solenoid 64 comprises trip and

close windings

68 and 69, respectively, similar to those described in connection with Fig. l of the drawings. Instead of providing electromagnetic means for restraining movement of the armature 65 as shown in Figs. 1, 2 and 3, an electromagnetic relay represented generally by the dot-dash outline 99 may be provided for interrupting the energizing circuit of the trip winding 68 when the current through the

contacts

22 and 24 exceeds a predetermined value which the switch is capable of safely interrupting.

As shown in Fig. 5 the relay 99 may comprise a substantially C-shaped core 100 of a magnetic material disposed about the lower end of the bushing 20. This core may be provided with an armature 102 of magnetic material pivotally mounted on one leg of the core as by a pivot 103, and normally biased by means of a spring 105 away from the other end of the core so as to normally close the contacts 102a and 10% connected in series circuit with the trip winding 68 and the switch 78 by means of conductors 107 and 108.

The relay 99 will normally be, as shown, with the contacts 102a and 1021) closed, so as to provide a circuit for the trip winding 68 whenever the switch 10 is closed and contact members 78a engages stationary contact members 780. So long as the current through the

contacts

22 and 24 does not exceed a value which the switch may safely interrupt, the trip winding 68 may be energized to separate the contacts in response to any suitable energization thereof. Should the current through the

contacts

22 and 24 exceed a predetermined safe value, the magnetic flux in the air gap between the core 100 and the armature 102 will increase to a value sufiicient to attract the armature to the core and separate contacts 102a and 102]). This interrupts the energizing circuit for the trip Winding 68, thus effectively preventing tripping of the switch even though attempt is made to energize the trip winding.

From the above description and the accompanying drawings it will be apparent that I have provided in a simple and effective manner for preventing damage to a switch by preventing opening thereof under current conditions in excess of that which may be safely interrupted. The application of my invention to existing switches requires a minimum of change and a minimum of expense. Few if any moving parts are required, and the maintenance problems on a switch embodying the features of my invention will be no greater than those of the previously existing switch.

Since certain changes may be made in the above-described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawings shall be considered as illustrated and not in a limiting sense.

I claim as my invention:

1. A switch comprising, separable contacts including stationary and movable contacts, remotely controlled electromagnetic trip means operable instantaneously to effect separation of said contacts insulating means sup porting said stationary contact, and means including a part carried by said insulating means operable in response to an overcurrent in excess of a predetermined value to prevent operation of the trip means.

2. In a circuit interrupter, a container, a cover for said container, separable contacts including movable and stationary contacts supported by said cover, releasable means for maintaining said contacts closed, instantaneous trip means for efiecting release of said releasable means, and electromagnetic means supported by said cover for preventing operation of the trip means when current through the contacts is in excess of a value which may be safely interrupted by said contacts.

3. A circuit interrupter comprising, separable contacts, an operating mechanism including a releasable toggle linkage for effecting relative movement of said contacts and maintaining them closed, instantaneous electromagnetic means having an armature with a pair of windings operable to actuate said toggle linkage in opposite directions to open and close said contacts, and means responsive to a current in excess of a predetermined maximum value acting on said armature in the closing direction for preventing operation of said electromagnetic means to efiect separation of said contacts.

4. A switch comprising, separable contacts, an operating mechanism for said contacts including a toggle linkage having a first overcenter position when the contacts are closed and movable to its other overcenter position to open the contacts, instantaneous shunt type electroresponsive means having an armature connected to a part of said linkage and a pair of windings energizable for operating the linkage to said positions to close and trip said contacts, and means responsive to the current through said contacts acting to move said armature in the direction to close said contacts for preventing operation of the electroresponsive means to trip said contacts.

5. In a switch, separable contacts, an operating mechanism comprising a pair of levers connected in an overcenter toggle relation for closing the contacts and holding them closed, instantaneous electromagnetic means having an armature connected to one of the levers for actuating it to one position or to another to open or close said contacts, and electrorespective means including a solenoid responsive to current through the contacts acting on said armature to prevent operation of the eletromagnetic means to open said contacts when the current through the contacts exceeds a predetermined value.

6. In a circuit interrupter, a container having a cover, a pair of separable contacts, an operating mechanism for said contacts supported from the cover including a pair of levers one of which is connected with one of the contacts and the other of which has an extension for manually operating the contacts, said levers being pivotally connected together in an overcenter toggle relation, instantaneous shunt type electromagnetic means supported by the cover connected to one of the levers for actuating it to one position or to another to open or close said contacts, and circuit means supported in the container by said cover responsive to prevent operation of the electromagnetic means to effect opening of said contacts when the current through said contacts exceeds a predetermined value.

7. A circuit interrupter comprising, separable contacts, releasable means holding said contacts closed, instantaneous electromagnetic means having a trip winding normally energized to actuate an armature to efiect tripping of said contacts without any intentional delay, and an additional winding responsive to current through said contacts acting on the same armature for opposing the effect of said trip winding.

8. A circuit interrupter comprising, separable contacts, a releasable toggle mechanism for effecting relative movement of said contacts, an electromagnet having an armature connected to actuate said mechanism and a shunt trip winding for actuating the armature when energized to effect instantaneous separations of said contacts, and a hold winding acting on said armature energized in accordance with the current through the contacts for preventing such actuation of the armature.

9. A circuit interrupter comprising, separable contacts, an operating mechanism for said contacts including an overcenter toggle linkage, solenoid means having an armature connected to said linkage and trip and close windings energizable for actuating said linkage to different positions to open and close said contacts, an additional solenoid means having an armature and a hold winding connected in series with said contacts, and insulating means connecting said armatures to prevent the trip winding from actuating its armature to effect separation of the contacts when current therethrough exceeds a predetermined value.

10. A circuit interrupter comprising, separable contacts, an operating mechanism for said contacts including a pair of levers arranged in overcenter toggle relation, electromagnetic means having an armature connected to one of the levers and trip and close windings energizable for actuating said levers in different directions to open and close said contacts, additional electromagnetic means including an armature and a hold winding connected in series with said contacts, and an insulating link adjustably connecting said armatures to permit relative movement of said armatures to prevent operation of the trip means to effect separation of the contacts at currents above different predetermined values.

11. In a circuit interrupter, separable contacts including stationary and movable contacts, an operating mechanism for operating said movable contacts to open and close the interrupter including a pair of levers arranged to be actuated to an overcenter toggle position to close said contacts and maintain them closed solenoid means having an armature connected to one of the levers and trip and close windings for actuating the armature to open and close said contacts, an insulating bushing sup-' porting a stationary one of said contacts, and a relay mounted on said bushing responsive to currents above a predetermined value having contacts connected in series with the trip winding to prevent operation of the armature when the current exceeds a predetermined value.

12. In a circuit interrupter, separable contacts, an operating mechanism for actuating said contacts, an insulating bushing supporting a conductor element connected to one of said contacts, a solenoid having an armature connected to a part of said mechanism and trip and close windings for actuating the armature to open and close said contacts, means including a switch actuated by the mechanism and having contacts providing energizing circuits for the trip and close windings, and a relay having a magnetic core structure surrounding a portion of said conductor element operable in response to a current above a predetermined value to open the circuit of the trip winding.

References Cited in the file of this patent UNITED STATES PATENTS 799,790 Hilliard Sept. 19, 1905 1,654,316 Wickerham Dec. 27, 1927 1,763,202 Von Sickle June 10, 1930 1,919,895 Luthi July 25, 1953 2,701,828 Edwards Feb. 8, 1955