US2813166A - Automatic sectionalizing switch - Google Patents

Description

Nova 12, 1957 J. M. WALLACE 2,813,166

AUTOMATIC SECTIONALIZING SWITCH Filed Jul 23, 1952 Fig.|.

Automatic Reclosing Circuit Breaker WITNESSES: I v i0 28 INVENTOR d Fi .4, JomesMWoHoce. Q Ufim g at? 6 ATTORNE United States Patent AUTOMATIC SECTIONALIZING SWITCH James M. Wallace, Montclair, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 23, 1952, Serial No. 300,380 12 Claims. (Cl. 200-88) My invention relates, generally, to circuit interrupters, and it has reference, in particular, to automatic section alizing switches which open when the circuit in which they are connected is deenergized, and reclose a predetermined time after the circuit is reenergized.

In distribution systems it is fairly common to use automatic reclosing circuit breakers to provide protection for difierent sections of the system. Because of the use of many periodic types of loads, such as refrigerators, pumps, blowers and the like, the diversity of the load on the system may be largely lost if the system is deenergized for any length of time. normally only a relatively small percent of such loads will be energized at any one time, whereas after an extended outage, such as may be caused by a fault of sufficient duration to cause the reclosing circuit breaker to lock open, substantially all of these loads will be connected to the circuit awaiting its reenergization. This will often result in such a heavy in-rush of load current that the reclosing circuit breaker is over-loaded, and again operates to the locked open position. To prevent such operation of the reclosing circuit breaker, automatic sectionalizing switches may be used at different points along the system, which open only when the circuit is deenergized for a sufficiently long time, and reclose a predetermined time after voltage is reapplied to the circuit. This provides for sequentially reconnecting several adjacent sections of a distribution circuit, so that the reclosing circuit breaker is required to handle only a limited portion of the total load on the circuit at any one time.

Accordingly, it is an object of my invention to provide in a novel manner for delaying the reclosing of an automatic sectionalizing switch by using the thermal capacity of the whole switch for delaying reclosing of the switch after it has opened.

Yet another object of my invention is to provide in a circuit interrupter for using a plurality of biasing means of different strengths for operating a movable contact, and for selectively controlling the effectiveness of the different biasing means.

It is also an object of my invention to provide in a circuit interrupter for biasing a movable contact in opposite directions, and for utilizing time delay means for rendering one of the biasing means inoperative a predetermined time after the circuit is energized.

One important object of my invention is to provide in a circuit interrupter for utilizing a heater to raise the temperature of the oil when the interrupter is open and the circuit is energized, and for using thermally responsive means for delaying reclosing of the interrupter in accordance with a temperature condition of the oil.

Yet another important object of my invention is to provide in a circuit interrupter for using a thermally responsive latch for connecting a movable contact to a contact actuating member, and for releasing the latch when the This results from the fact that interrupter is open and the circuit to which is it connected is energized, so as to effect movement of the movable contact to the closed position a relatively long time after the circuit is energized.

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

In accordance with one of the embodiments of my invention, a movable contact of an automatic sectionalizing switch may be normally biased to the closed position. Biasing means may be provided for actuating a contact operating member to a contact-opening position, and electroresponsive means may be utilized to normally render such biasing means inoperative so long as current flows through the switch. The contact-operating member may be connected to the moving contact by means of a thermally responsive latch, and a heater may be connected in shunt relation with the contacts for heating the insulating oil in which the switch is immersed so as to provide for releasing the latch to permit closing of the contacts a relatively long time after the circuit has been reenergized.

For a more complete description and understanding of the invention, reference may be made to the following detailed description and the accompanying drawing, in which:

Figure 1 is a substantially vertical sectional view of a switch embodying the invention in one of its forms;

Fig. 2 is an enlarged sectional view taken along the line IIII of Fig. 1;

Fig. 3 is a diagrammatic view of a distribution system illustrating an application of the sectionalizing switch of Fig. 1; and

Fig. 4 is an enlarged view taken along the line IV-IV of Fig. 1.

Referring to Fig. 1 of the drawing, the reference numeral 10 may denote generally an automatic sectionalizing switch which may be disposed in a substantially cylindrical metal container or tank 12, having an outwardly projecting flange 13 around the upper edge. Suitable brackets 14 may be secured to the container 12 for supporting it from a pole or the like. The container 12 may be filled with a suitable insulating fluid such as oil or the like, designated by the numeral 15. A substantially cylindrical insulating liner 17 may be disposed about the interior of the walls of the tank, and the bottom thereof may be provided with an insulating liner 18 of any suitable material such as fiber or the like.

The container 12 may be provided with a suitable cover 20, which may be secured to the flange 13 in any suitable manner such as by means of bolts (not shown). Insulating bushings 22 and 24 may be mounted on the cover 20 for supporting conductors 25 and 26, the bushings extending through cover so as to permit entrance of the conductors 25 and 26 to the interior of the container 12.

A movable contact member such as the switch blade 28, having a movable contact 30 at one end, may be pivotally mounted by means of a pivot 32 at the other end to the inner end of the conductor 25. Biasing means such as a spring 33 may be utilized for urging the blade 28 in a counter-clockwise direction to engage a stationary contact 34 which may be supported on the inner end of the conductor 26 but insulated therefrom by means of insulation 35. The spring 33 may be connected between the blade 28 and a lug 31 adjacent the lower end of conductor 25.

In order to provide for actuating the switch blade 28 to the open position, an operating arm 37 may be disposed alongside the blade, pivotally mounted on the pivot 32, and connected by means of a link 39 to the armature 40 of solenoid 42 which is connected in series with the conductor 26 and the stationary contact 34. A coil spring 44 disposed within the bore of the solenoid normally biases the operating arm 37 in a clockwise direction. The spring 44 is sufiiciently stronger than the spring 33 to overcome the effect of the latter spring. The solenoid 42 may be supported from the cover 20, being disposed about a cylindrical extension 46 of a plate 48 having an upwardly projecting lug 50 thereon to receive a pivot 52 which passes through a downwardly extending insulating support 54 which may be secured to a boss 55 on the underside of the cover 20. The armature 46 may be disposed to have a relatively tight fitin the cylindrical extension 46, and means such as a ball-check valve 56 may be provided in conjunction with a bore 57 in the plate 48, so as to provide a unidirectional dashpot action for delaying downward movement of the armature 40. The lug 31 may be extended to project beneath the blade 28 and arm 37 to provide a stop 58 to limit downward movement thereof.

The operating arm 37 may be normally operatively connected to the switch blade 28 by'means of a releasable latch 64). The latch 60 may comprise a thermally-responsive bimetallic support 62 mounted on the operating arm 37, and a latch projection 64 which projects over the top side of the switch blade 28. The bimetallic support 62 may comprise a pair of laminations of materials having difierent rates of expansion which are suitably secured together in a manner well known in the art. In the present instance, for example Figs. 2 and 4, the left-hand laminations may be a brass or some such metal having a relatively high coefiicient of expansion, while the righthand lamination is made of iron or steel, having a lower coeflicient of expansion. In order to provide a relatively long time delay on the order of from 1 to substantially 3 hours in reclosing the switch after the circuit is reenergized, the thermal capacity of the entire switch may be used to delay reclosing, and means such as an electric heater or resistance element 66 may be disposed in the insulating oil and connected in circuit with the conductors 25 and 26 in shunt relation with the contacts 30 and 34 so as to be energized only when the contacts are open and the circuit is energized, to raise the temperature of the oil and operate the latch 69. Since the latch 60 is spaced from the heater 66, and the temperature of the oil is substantially that of the entire switch, operation of the latch 60 is basically dependent on the temperature and thermal capacity of the entire switch. By changing the spacing of the heater 66 and latch 60, the delay in operation and reset may be widely varied, from a few minutes to as much as 2 or 3 hours.

Referring to Fig. 3, it will be seen that several of the automatic sectionalizing switches may be connected between adjacent sections 76, 72, 73 and 74 of a distribution circuit which is connected by means of an automatic reclosing circuit breaker 75 to a source conductor 76. The reclosing circuit breaker 75 may be of any of the types which are well known in the art, and provide for one or more instantaneous openings and one or more delayed openings in response to a fault before the breaker is locked in the open position. The dashpot action of the armatures 46 is such that the switches 10 do not open in response to the several automatic openings of the breaker 75. When the reclosing circuit breaker locks open, the switches 16) open after time delay afforded by the dashpot action of armatures 46 as spring 44 overcomes spring 33 and separate the contacts 30 and 34. It will be noted that this action takes place only when the circuit is deenergized.

With the sectionalizing switches 10 in the open positions, as shown, it will be seen that the heater 66 will be connected in series circuit relation with solenoid 42 between the conductor 76 and the load 78 of the first switch when the reclosing circuit breaker 75 is closed. Accordingly, the oil of this switch may be slowly heated. Inasmuch as the heaters 66 may have a relatively high resistance compared with that of the load (five to ten thousand ohms, for example), only limited voltages will be applied under these conditions to the heaters of the other switches, and only limited current can flow through solenoid 42.

Since the coil spring 44 is stronger than the spring 33 it operated the operating arm 37 in a clockwise direction carrying the switch blade 23 with it to the open position as soon as the circuit was deenergized to engage stop 58. After a predetermined time, when the heater 66 has raised the temperature of the bimetallic support 62 to a predetermined value, the latch 60 will be actuated by the bimetallic support 62 in a direction to release the switch blade 28. The spring 33 is thereupon effective to operate the switch blade in a counter-clockwise direction to bring moving contact 30 into engagement with the stationary contact 34. The heater 66 is thereupon shunted and section 72 of the distribution circuit will thereupon be fully reenergized. The solenoid 42 of the first switch will therefore be sufficiently energized to be actuated to compress the coil spring 44 and operate the arm 37 in a counter-clockwise direction to a position alongside the switch blade 28. The oil 15 carries heat away from the latch support, and after a predetermined delay it operates to reset the latch 60. The other sectionalizing switches will operate in sequence, in a similar manner, so that the several sections of the distribution circuit are sequentially reenergized after an outage caused by opening of the reclosing circuit breaker 75.

From the above description and the accompanying drawing it will be apparent that I have provided in a simple and effective manner for sectionalizing a distribution circuit to facilitate reconnection of the load after an outage. By varying the proximity of the heater and latch, and thereby utilizing the thermal capacity of a major part of, or the entire switch device, in the manner hereinbefore described, time delays varying from a few minutes to a relatively great magnitude may be readily obtained. Periods up to as much as l to 3 hours are easily obtainable in this manner.

Since certain changes may be made in the above described constructions, 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 drawing shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. In a switch, a container for an insulating fluid, a pair of terminals, a stationary contact connected to one terminal and supported in the fluid, a movable contact connected to the other terminal and pivotally supported by a pivoted arm for engaging the stationary contact, a spring biasing the arm to actuate the movable contact toward the stationary contact, an operating arm pivotally disposed alongside the arm of the movable contact, an additional spring stronger than the first mentioned one biasing the operating arm in a direction to separate the movable contact from the stationary contact, a thermoresponsive latch normally connecting the operating arm and arm of the movable contact, electroresponsive means connected in series with the contacts and having an armature connected to the operating arm for rendering the additional spring ineffective when energized, and a heater connected between the contacts for efiecting release of the thermoresponsive latch when the temperature of the fluid reaches a predetermined value.

2. An automatic load pick-up switch for a circuit comprising, a container for an insulating fluid, a cover for said container, a pair of terminal conductors, insulating bushings for providing insulated passages through the cover for said conductors, a stationary contact mounted on one bushing in the container, a switch blade pivotally mounted on the other bushing for engaging the stationary contact, meansvbiasing the switch blade to engage the stationary contact, an operating arm pivotally mounted alongside the switch blade, electroresponsive means including a solenoid connected in series with the conductor of said one bushing and the stationary contact and having an armature connected to the operating arm to operate it in the contact closing direction when suflicient current flows in the solenoid, a spring biasing the armature in the contact separating direction, dashpot means retarding movement of the armature in response to the spring action, a thermoresponsive latch normally connecting the operating arm and the switch blade, and a heater connected in series with the terminals for rendering the latch inoperative when the circuit is energized and the contacts are separated.

3. In a switch device, a container for an insulating fluid, separable contacts disposed in said container, an operating mechanism for said contacts, means biasing the operating mechanism to close said contacts, operating means, means biasing the operating means in a direction to open the contacts, series solenoid means operable when energized to oppose said biasing means, means connected to heat the fluid in the container in response to application of voltage to the switch device while the contacts are separated, and releasable means connecting the operating means to the contact operating mechanism responsive to an increase in the temperature of the fluid for releasing the contact mechanism and rendering the closing means eflective.

4. A circuit interrupter comprising, separable contacts, means biasing the contacts closed, operating means ineluding electroresponsive means connected in series with the contacts responsive to a predetermined value of current for etfecting operation of said contacts in one direction to close them, means biasing the operating means to operate the contacts in the other direction, heating means for said interrupter responsive to energization of said circuit, and releasable means responsive to an increase in temperature condition resulting from operation of said heating means, for disconnecting the contacts from the operating means and rendering the biasing means effective to close the contacts.

5. In a switch, separable contacts, a container maintaining an insulating fluid about said contacts, operating means operable to close said contacts, actuating means operable to opening said contacts, means operable to heat the insulating fluid, thermal releasable means connecting the actuating and operating means together responsive to a predetermined rise in temperature condition of the fluid for releasing them and rendering the operating means operative, and current responsive means connected in series with the contacts opposing said actuating means.

6. A switch comprising, a container for an insulating fluid, a cover for said container, separable contacts, operating means for said contacts supported in the insulating fluid from said cover, means biasing said operating means to close said contacts, opening means opposing said biasing means, current responsive means opposing said opening means, a heater operable to heat the fluid in response to application of voltage to the switch only when the contacts are open, and thermoresponsive means releasably connecting the biasing means to the operating means operable to render the biasing means effective to close the contacts in response to a predetermined increase in the temperature condition of said fluid.

7. In a switch, separable contacts, operating means therefor, means biasing said operating means to close the contacts, additional biasing means stronger than the aforesaid biasing means opposing said biasing means to open said contacts, series connected electroresponsive means responsive to energization opposing said additional biasing means, a heater connected between said contacts operable in response to application of voltage to the switch when the contacts are open to heat the switch, and thermal releasable means normally connecting the additional biasing means to the operating means operable in response to a predetermined temperature condition of the switch to release them and render the biasing means effective to close the contacts.

8. In an automatic load pick-up switch, a container for an insulating fluid, separable contacts operable to connect the load to a source, operating means therefor, actuating means including electroresponsive holding means connected in series with and holding the contacts closed and opposing biasing means effecting separation of the contacts in response to deenergization of a circuit, means actuating the operating means and reclosing said switch, a heater responsive to reenergization of the circuit while the load contacts are separated to supply heat to the insulating fluid, and thermoresponsive latch means connecting the operating means to the actuating means operable in response to a predetermined thermal condition of the fluid to release them and render the reclosing means operative.

9. A switch comprising, separable contacts, operating means including a pair of pivotally mounted members having opposing biasing means for effecting relative movement of said members in opposite directions, a heater responsive to application of voltage to said switch for supplying heat to the switch, and means for effecting operation of said operating means including a thermoresponsive latch element normally connecting the members together operable in response to a predetermined rise in thermal condition of the switch to release said members to permit one of the biasing means to close said contacts 10. In a switch, a container for an insulating fluid, separable contacts disposed in the fluid in said container, operating means for said contacts, means biasing said operating means to open said contacts, series electroresponsive means for opposing said biasing means, heating means connected between the contacts for heating the fluid in response to energization of a circuit when the contacts are open, additional biasing means biasing the operating means for closing said contacts, and releasable thermoresponsive means normally connecting the biasing means to the operating means operable in response to a predetermined rise in temperature condition of the switch to release them and render said additional biasing means effective.

11. A switch comprising, a stationary contact member, a movable contact member, an operating mechanism for the movable contact member, means biasing the operating mechanism to urge the movable contact member to engage the stationary contact member, actuating means for actuating the movable contact member to separate from the stationary contact member, current responsive means opposing the actuating means when the switch is closed, a heater connected across the contacts operable to supply heat to the switch while the contact members are separated and the circuit is energized, and thermal releasable means connecting the actuating means and the movable contact member, said releasable means being operable to release the movable contact member and the actuating means in response to a predetermined rise in temperature condition of the switch.

12. A switch comprising, separable contacts, operating means for the contacts, biasing means for actuating the operating means and closing the contacts, actuating means operable to overcome the biasing means and actuate the operating means to separate the contacts, a solenoid having an armature connected to the actuating means operable to oppose and render the actuating means inoperative so long as the solenoid remains energized, thermoresponsive means including a releasable element normally connecting the actuating and operating means operable in response to predetermined rise in the temperature condition of the switch to release them and render the actuating means inefiective to open the contacts, and heater means connected between the contacts for heating the switch while said contacts are open to effect operation of the thermoresponsive means.

References Cited in the file of this patent UNITED STATES PATENTS Hill Jan. 26, 1909 Brobst Mar. 24, 1925 Parks et a1 Aug. 15, 1933 Walle Dec. 30, 1941 10 Frank et a1 Feb. 24, 1942 Rawlins et a1 Dec. 1, 1942 8 Grant et al. Jan. 12, 1943 Leonard June 20, 1944 Ludwig et a1 Oct. 24, 1944 Link Nov. 6, 1945 Kyle, Jr. et a1. Jan. 18, 1949 Moorhead Oct. 11, 1949 Lincks Octv 23, 1951 Edwards et a1 Mar. 20, 1956 FOREIGN PATENTS Germany Jan. 10, 1924 Germany June 24, 1907

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