US2467756A - Circuit interrupter - Google Patents

Description

R. H. LEITZEL CIRCUIT INTERRUPTER April 19, 1949.

5 Sheets-Sheet 1 Filed Aug. 15, 1946 lNVENTOR Fag mafia H. Lez'zzel.

WITNESSES:

lma 5M ATTORN EY April 19, 1949. R. H. LEITZEL CIRCUIT INTERRUPTER 3 Shets-Sheet 3 Filed Aug. 15, 1946 INVENTOR and H. Lez'zzel WITNESSES:

BY 5M ATTOR N EY Patented Apr. 19, 1949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Raymond H. Leitzel, Forest Hills, Pa., assig'nor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 15, 1946, Serial No. 690,626

13 Claims. 1

This invention relates to circuit interrupters and more particularly to circuit interrupters of the types that are operated by compressed gas.

An object of the invention is to provide a circuit interrupter of the compressed gas operated type having an electromagnetically operated pilot valve for controlling the admission of compressed gas to operate said interrupters, with a low voltage trip device for operating said pilot valve.

Another object of the invention is to provide a. circuit interrupter having an electromagnetically operated pilot valve operable in response to overload currents for controlling the admission of compressed gas to operate said interrupter, with a low voltage responsive means for operating said pilot valve,

Another object of the invention is to provide an interrupter having a fluid motor operated mechanism for operating said breakers to open and closed position and a single pilot valve for controlling the admission of compressed gas to said motor to operate the interrupter to open position with means for operating said pilot valve in response to overload currents and also in response to low voltage conditions.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, to-

gether with additional objects and advantages thereof, will be best understood from the following detailed description of an embodiment thereof when read in conjunction with the accompanying drawings; in which- Fig. 1 is a side elevational view, partly in section, showing a compressed gas operated circuit interrupter embodying the principles of the invention.

Fig. 2 is a front elevational view of the compressed gas operating mechanism for operating the circuit interrupter to open and closed positions.

Fig. 3 is an enlarged side elevation view showing the under voltage trip device.

Fig. 4 is an elevational view, partly in section, showing the compressed gas operating mechanism for the circuit interrupter illustrated in Fig. 1.

The invention is illustrated as applied to a circuit breaker of the type disclosed in the U. S. Patent No. 2,401,008, issued May 28, 1946, to Leon R. Ludwig and Benjamin P. Baker, and assigned to the assignee of the present invention.

Referring to Figs. 1 and 2 of the drawings, a storage tank 6 mounted within a metal frame 1 is provided for storing compressed gas. Extending from the top of the tank 6 are three flanged conduits 8 which, in turn, carry metallic valve casings H]. A tubular insulator [2 having a gas passage therethro-ugh is mounted on the upper end of each valve casing IE1, and an arc chute support l4 (Fig, 1) also of insulating material is secured to the upper end of the tubular insulator [2. The support I4 has mounted thereon a stationary contact It provided with an external terminal connection 18. An arc chute 22 is secured by means of bolts 24 to the support l4. Braces 25 of insulating material (only one being shown) connect the frame I and the insulating arc chute supports l4.

A movable contact blade 28 is provided for cooperating with the stationary contact l6. One arm St or the contact blade 28 is bifurcated and the two arms thereof are pivoted at 32 to a conducting bracket 34 securely clamped about the tubular insulator l2. The pivotal connection 32 is of the high-pressure type in order to provide a good electrical connection at all times between the bifurcated contact arm 30 and the mounting bracket 34. A terminal connector 36 extends from the right hand side (Fig. 1) of the bracket 34 and serves, together with the terminal connector l8 to connect the circuit interrupter in an electrical circuit. The circuit through the breaker extends from the terminal l8 through the stationary contact I6, the movable contact blade 28, contact arms 30 and the bracket 34 to the terminal 36.

An operating mechanism of the compressed gas type, indicated generally at 38 (Figs. 1, 2 and 4) is provided to actuate the three movable contact blades 28 about the pivots 32 to open and close the contacts. The operating mechanism 38 is mounted within the frame I and includes an operating cylinder 40 (Figs. 1, 2 and 4), a piston 42 (Fig. 4) reciprocalbly movable therein, and a connecting rod 44 attached to the piston and extending vertically through an air-tight opening in the upper end of the cylinder 40. The connecting rod 44 is connected by a pair of spaced links 46 to a crank arm 48 (Fig. 2) secured to a cross shaft 50 which is journaled in brackets 52 mounted on the side of the pressure tank 6.

Crank arms 54 (Figs. 1 and 2), secured at spaced intervals to the cross shaft 50, are connected by insulating operating rods 56 to the movable contact arms 30 for the three poles of the breaker.

If compressed gas is admitted to the cylinder 4!] above the piston 42 the piston will be moved downward in the cylinder and the connecting rod 44 will actuate the crank arm 48 and the cross shaft counterclockwise. This movement of the shaft 50 rotates the crank arms 54 in the same direction, and, through the connecting rods 56, rotate the movable contact arms 30 about their pivots 32 toward open position.

Each of the crank arms 54 (Fig. l) is provided with a cam surface 58 which cooperates with an anti-friction roller 6 carried by one arm of a bell crank 62. The bell crank 62 is pivoted at 64 on a suitable support and the other arm of, the bell crank is pivotally connected to a Valve stem 66 which, at its other end, carries a blast valve (not shown) seated within the valve casing I0. The cam surface 50 controls the blast valve to admit a blast of arc-extinguishing gas through the passage in the tubular insulator I2 at the separating contacts when the arc is drawn. The are drawn between the contacts is thus blown upwardly into the arc chute 22 and then extinguished by the blast of gas from the pressure tank 6. The cams 58 on the crank arms 54 are so shaped that the blast valves (not shown) are permitted to close when the moving contacts have reached full open position so as to shut oil the blast of compressed gas.

Upon admission of compressed gas to the cylinder below the piston 42 (Fig. 4) the piston will be moved upwardly in the cylinder reversing the above described operation to operate the movable contacts 28 to closed position. As the mechanism arrives at the closed circuit position, the crank arms 54 engage stops 55. In this position, the crank arms 54 and their connecting rods 56 form slightly overcenter toggles which maintain the movable contacts positively locked in the closed circuit position.

In order to effect opening and closing of the circuit interrupter, two control Valves indicated generally at 10 and 12 (Figs. 2 and 4) are provided to control the flow of compressed gas from the storage tank 6 to the operating cylinder 40. The control valve assemblies 10 and 12 are secured to the operating cylinder 40 and rest upon and are secured respectively to flanges 14 and 16 of two conduits 18 and 86 which extend into and communicate with the storage tank 6. The valves 10 and 12 which respectively control the flow of gas to the operating cylinder 40 to open and close the circuit interrupter are similar in construction. The opening control valve 10, shown in section in Fig. 4 comprises a valve casing I04, the lower face of which rests on the flange 14 of the conduit 18. The valve casin I04 is provided with a valve seat I06 with which a valve I08 of the poppet type cooperates to open and close the air passage leading from the storage tank 6 to the cylinder 40 above the piston 42. The valve I08 is provided with a valve stem II having a washer II2 secured to the upper end with which a spring II4 cooperates to normally bias the valve closed. The inner chamber of the valve casing I04 communicates, by means of a passage II6 to the upper end of the cylinder 40. The valve casing I04 is also provided with a passage I I8 which communicates with the storage tank and a valve chamber I 20 in an auxiliary valve casing I 22.

An electromagnetically operated pilot valve I24 communicates by means of a passage I26 with a piston chamber I28 at the upper end of the opening valve casing I04. A piston I30 operable in the cylinder I28 is normally held in raised position by a spring I32. The lower end of the skirt of'the piston I30 extends to a plurality of ports l34passing radially through the side of the valve casing I04. When the piston I36 is in the raised position (Fig. 4) the ports I34 are open, thereby connecting the space in the operating cylinder 66 above the piston 62 to atmosphere. Downward movement of the piston 136 closes the ports 34 and thereby seals the passage H6 and the cylinder 40 from the atmosphere and moves the main valve I68 to open position thus admitting compressed gas to the cylinder 46 above the piston 42 to operate the interrupter to open position.

The pilot valve 241 is actuated downwardly to open position by an electromagnet I36 mounted on the auxiliary valve casing I22. The electroa magnet may be energized from any suitable source of electrical energy none being shown. A spring I38 is provided to close the pilot Valve upon deenergization of the e'lectrcmagnet I36.

When the interrupter is in the closed position, the operating mechanism including the piston 62 is in the position in which it appears in Fig. 4. With the mechanism in the closed position, if an overload occurs the electromagnet I36 is energized to open the pilot valve I20, admitting compressed gas to the piston chamber I26 of the opening valve. The piston IE0 is thereupon moved downwardly closing the ports I34 and opening the valve I68 to admit compressed gas to the cylinder 30 above the piston 42. The piston 42 is thus moved downwardly to actuate the movable contacts 26 to the open circuit position in the previously described manner. The control circuit (not shown) for energizing the electromagnet I256 may be controlled by an opening relay and by an auxiliary switch I40 (Fig. 2) of any suitable construction mounted on the tank 6 and operated by means of a link I62 by the shaft 50.

It is also desirable to cause opening of the interrupter in the event of loss of voltage or failure of voltage in the control circuit. Means comprising an electromagnet indicated generally at I44 (Figs. 1, 2, 3 and 4) is connected across the control circuit and normally energized by the voltage in the control circuit. The electromagnet I 44 comprises a U-shaped core member I46 (Fig. 3) fixedly mounted on a pair of spaced rods I48 supported in a bracket I50 secured to the frame I by any suitable means as, for instance, by welding. An energizing coil I52 surrounds one leg of the core members and an armature I54 is pivotally mounted on a pin I56 (Fig. 3) supported in side plates I58 (only one being shown) secured to the sides of the other leg of the core member I46. Rigidly secured to opposite sides of the armature I54 are identical plates I60 each of which carries a spring stud I62 to which are anchored the lower endsof a pair of springs I66. The upper ends of the springs I64 are hooked over the ends of a shaft I66 supported in a pair of spaced plates I68 mounted on the rods E48 and disposed one on each side of the core member I 46.

The plates I66 which are secured to and move with the armature I54 are provided with vertically disposed slots I? (Fig. 3) through which project the ends of a pin I12 carried by the upper end of a trip rod I16. The enlarged lower end of the trip rod I14 normally rests on a button I16 which, when depressed, mechanically operates the pilot valve I24 to the open position. The weight of the trip rod I14 does not normally apply force enough to the button I16 to operate the pilot valve. When the voltage in the control circuit drops a predetermined amount or" fails entirely, the electro-magnet I44 is deenergized and releases the armature I54, which, accelerated by the springs I64, moves in a counterclockwise direction about the pivot I56. During this movement the upper ends of the slots I in the plates I60 strike the pins I12 and thrust the trip rod I14 downwardly to operate the button I16 and effect opening of the pilot valve I20. Opening of the pilot valve, as set forth previously, causes opening of the valve I08 and admission of compressed gas to the cylinder 40 above the piston to actuate the interruption to the open position.

The armature I54 is moved to attracted position when the interrupter mechanism moves to the open position. The means for resetting the armature I54 comprises an adjustable screw I18 (Fig. 3) mounted in a projection I80 rigidly mounted on the shaft 50 and locked in the adjusted position by means of a lock nut I82. These parts are shown in the closed position of the interrupter in dot and dash lines in Fig. 3 at I18, I80 and I82. When the interrupter moves to open position the shaft 50 rotates counterclockwise during which movement the screw I18 engages a resilient member I84 secured by means of rivets to a latch member I86 which is in turn rigidly secured to the armature I54. Continued counterclockwise movement of the shaft 50 after the screw I18 engages the resilient member I84, rotates the armature I54 clockwise about its pivot I62 to the attracted position in which it appears in Fig. 3.

Means is provided to latch the armature I54 in the attracted position until normal voltage is restored to the control circuit. This means comprises a latch I88 pivotally mounted on the shaft I66 and connected by means of a pin and slot connection I91I99 to a link I90 having its lower end pivotally connected to an. arm I92 secured to the shaft 50 for movement therewith. In the closed position of the interrupter the parts assume the positions indicated by dot and dash lines at I88, I90 and I92 respectively. In this position the latch I88 is out of engagement with the latch member I86 on the armature I54 so that the armature I54 may function in the above described manner to effect opening of the interrupter in the event of loss of voltage in the control circuit. When the interrupter moves to the open position and the shaft 50 rotates counterclockwise to the position shown by full lines in Fig. 3, the arm I92 acts through the link I90 to move the latch I88 to engage a latching notch I 94 therein into engagement with the end of the latch member I86, thus preventing movement of the armature I54 and the trip rod I14 to tripping position until normal voltage is restored to the control circuit or the interrupter is actuated to the closed position. Movement of the shaft 50 to close the interrupter raises the latch I80 to the position shown at I88 unlatching the armature in preparation for a subsequent low voltage tripping operation. Due to the pin and slot connection I91-I99 the latch I88 does not disengage the latch member I86 until near the end of the closing movement of the mechanism thus preventing tripping movement of the armature I54 until the breaker is substantially in the closed position.

The interrupter is operated to the closed position by operating the closing valve 12 (Figs. 2

' and 4) to admit compressed gas to the cylinder 40 below the piston 42. This causes the piston to move upwardly reversing the movement of the mechanism and moving the movable contact arms 30 to closed position. The closing valve 12 is identical with the valve 10 for effecting opening of the interrupter. The valve 12 is provided with an electromagnet I96 (Fig. 2) which, when energized from any suitable source of electrical current, opens a pilot valve I98 to admit compressed gas to open the closing valve 12 which admits compressed air to the cylinder 40 below the piston 42 to close the interrupter in the manner previously described.

From the foregoing description it will be apparent to those skilled in the art to which this invention appertains that there is provided a novel low voltage trip device which operates a pilot valve, common to both the overload and under voltage trip devices, to effect opening of the interrupter.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made therein without departing from some of the essential features of the invention. It is, therefore, desired, that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

I claim as my invention:

1. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a cylinder and a piston operable therein for moving said contacts to open and closed positions, a source of gas under pressure, an opening control valve operable by compressed gas to admit compressed gas to said cylinder to cause said piston to move to open position, a pilot valve operable to admit compressed gas to said control valve to operate said control valve, electroresponsive means operable in response to overload currents to operate said pilot valve, an undervoltage device operable in response to predetermined voltage conditions to operate said pilot valve, and means preventing operation of said undervoltage device during closing operations of said circuit interrupter.

2. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a cylinder and a piston operable therein for moving said contacts to open and closed positions, a source of gas under pressure, an opening control valve operable by compressed gas to admit compressed gas to said cylinder to cause said piston to move to open position, a pilot valve operable to admit compressed gas to said control valve to operate said control valve, electroresponsive means operable in response to overload currents to operate said pilot valve, and an undervoltage device operable in response to predetermined voltage conditions to operate said pilot valve, and means operable by said operating mechanism when said mechanism moves to open position to reset said undervoltage device.

3. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a cylinder and a piston operable therein for moving said contacts to open and closed positions, a source of gas under pressure, an opening control valve operable by compressed gas to admit compressed gas to said cylinder to cause said piston to move to open position, a pilot valve operable to admit compressed gas to said control valve to operate said control valve, electroresponsive means operable in response to overload currents to operate said pilot valve, and an undervoltage device operable in response to predetermined volt-,-

7 age conditions to .operate said pilot valve, means Operable by said operating mechanism when said mechanism moves to open position to reset said undervoltage device, and means operable by said operating mechanism to restrain said undervoltage device in reset position during a closing operation.

4. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a cylinder and a piston operable therein for moving said contacts to open and closed positions, a source of gas under pressure, an opening control valve operable by compressed gas to admit compressed gas to said cylinder to cause said piston to move to open position, a pilot valve operable to admit compressed gas to said control valve to operate said control valve, electroresponsive means operable in response to overload currents to operate said pilot valve, and an undervoltage device comprising an electromagnet having an armature operable in response to predetermined voltage conditions to operate said pilot valve, and means operable by said operating mechanism to reset said armature to operative position.

5. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a cylinder and a piston operable therein for moving said contacts to open and closed positions, a source of gas under pressure, an opening control valve operable by compressed gas to admit compressed gas to said cylinder to cause said piston to move to open position, a pilot valve operable to admit compressed gas to said control valve to operate said control valve, electroresponsive means operable in response to overload, currents to operate said pilot valve, and an undervoltage device comprising an electromagnet having an armature operable in response to predetermined voltage conditions to operate said pilot valve, means operable by said operating mechanism to reset said armature to operative position, and means operable by said operating mechanism to latch said armature in operative position during a closing operation.

6. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a fluid motor for operating said contacts to open and closed position, a source of gas under pressure, an inlet valve operable by compressed gas to admit compressed gas to said motor to effect opening of said interrupter, an overload trip device, an undervoltage trip device, a pilot valve operable by said overload trip device under certain conditions and also operable by said undervoltage trip device under certain other conditions to admit compressed gas to operate said inlet valve to thereby effect opening of said interrupter, and means for preventing operation of said pilot valve by said undervoltage device during a closing operation of said interrupter.

7. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a fluid motor for operating said contacts to open and closed position, a source of gas under pressure, an inlet valve operable by compressed gas to admit compressed gas to said motor to effect opening of said interrupter, an overload trip device, an undervoltage trip device, a pilot valve operable by said overload trip device under certain conditions and also operable by said undervoltage trip device under certain other conditions to admit compressed gas to operate said inlet valve to thereby effect opening of said interrupter, and

8, means operated by said operating mechanism to reset said undervoltage trip device.

8. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a fluid motor for operating said contacts to open and closed position, a source of gas under pressure, an inlet valve operable by compressed gas to admit compressed gas to said motor to eifect opening of said interrupter, an overload trip device, an undervoltage trip device, a pilot valve operable by said overload trip device under certain conditions and also operable by said undervoltage trip device under certain other conditions to admit compressed gas to operate said inlet valve to thereby eifect opening of said interrupter, means operable by said operating mechanism to reset said undervoltage trip device, and means for retaining said undervoltage trip device in reset position until said interrupter is closed.

9. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a fluid motor for operating said contacts to open and closed position, a source of gas under pressure, an inlet valve operable by compressed gas to admit compressed gas to said motor to effect opening of said interrupter, an overload trip device, an undervoltage trip device, a pilot valve operable by said overload trip device under certain conditions and also operable by said undervoltage trip device under certain other conditions to admit compressed gas to operate said inlet valve to thereby effect opening of said interrupter, and means operable by said operating mechanism during an opening movement to engage and move said undervoltage trip device to reset position.

10. In a circuit interrupter, separable contacts, operating mechanism therefor comprising a fluid motor for operating said contacts to open and closed position, a source of gas under pressure, an inlet valve operable by compressed gas to admit compressed gas to said motor to effect opening of said interrupter, an overload trip device, an undervoltage trip device, a pilot valve operable by said overload trip device under certain conditions and also operable by said undervoltage trip device under certain other conditions to admit compressed gas to operate said inlet valve to thereby effect opening of said interrupter, means operable by said operating mechanism during an opening operation to engage and move said undervoltage trip device to reset position, and latch means operable by said operating mechanism during an opening operation to engage and restrain said under voltage trip device in the reset position during a closing operation of said breaker.

11, In a circuit interrupter, separable contacts, operating means therefor comprising a fluid motor for operating said contacts to open and closed positions, a source of compressed gas, an inlet valve operable by compressed gas to admit compressed gas to said motor to efiect opening of said interrupter, a pilot valve operable to admit compressed gas to operate said inlet valve, a trip device comprising electroresponsive means operable in response to overload currents for operating said pilot valve, an undervoltage trip device comprising an electromagnet having an armature normally held in attracted position and releasable in response to a drop in voltage, means operable by said armature when said armature is released to mechanically operate said pilot valve. and latch means restraining said armature against operation during closing operations of said interrupter irrespective of variations in voltage.

12. In a circuit interrupter, separable contacts, operating means therefor comprising a fluid motor for operating said contacts to open and closed positions, a source of compressed gas, an inlet valve operable by compressed gas to admit compressed gas to said motor to efiect opening of said interrupter, a pilot valve operable to admit compressed gas to operate said inlet valve, a trip device comprising electroresponsive means operable in response to overload currents for operating said pilot valve, an undervoltage trip device comprising an electromagnet having an armature normally held in attracted position and releasable in response to a drop in voltage, and means operable by said armature when said armature is released to mechanically operate said pilot valve, and means operable by said operating means during an opening movement thereof for engaging and resetting said armature to attracted position.

13. In a circuit interrupter, separable contacts, operating means therefor comprising a fluid motor for operating said contacts to open and closed positions, a source of compressed gas, an inlet valve operable by compressed gas to admit compressed gas to said motor to effect opening of said interrupter, a pilot valve operable to admit compressed gas to operate said inlet valve, a trip device comprising electroresponsive means operable in response to overload currents for operatin said pilot valve, an undervoltage trip device comprising an eiectromagnet having an armature normally held in attracted position and releasable in response to a drop in voltage, and means operable by said armature when said armature is released to mechanically operate said pilot valve, means operable by said operating means during an opening movement thereof for engaging and resetting said armature to operative position, and means operable by said operating mechanism durin an opening movement for engaging and restraining said armature in operative position during a closing operation.

RAYMOND H. LEITZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,292,651 Rippl Jan. 28, 1919 1,780,395 Kellner Nov. 4, 1930 2,401,008 Ludwig et a1. May 28, 1946

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