US3364326A

US3364326A - Double-break synchronously operated circuit breaker with connecting bar rotating in enlarged opening in magnet structure

Info

Publication number: US3364326A
Application number: US419410A
Authority: US
Inventors: Winthrop M Leeds
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1964-12-18
Filing date: 1964-12-18
Publication date: 1968-01-16
Anticipated expiration: 1985-01-16
Also published as: JPS4431892B1

Description

Jan. 16, 1968 w. M. LEEDS 3,364,326

DOUBLE-BREAK SYNCHRONOUSLY OPERATED CIRCUIT BREAKER WITH CONNECTING BAR ROTATING IN ENLARGED OPENING IN MAGNET STRUCTURE Filed Dec. 18, 1964 TIM E To TRIPPING RELAY INVENTOR 6 Winthrop M. Leeds RESERVOIR BY ATTORNEY United States Patent 3,364,326 DOUBLE-BREAK SYN CHRONOUSLY OPERATED CIRQUET BREAKER WITH CUNNECTING BAR ROTATKNG IN ENLARGED OPENENG IN MAG- NET STRUCTURE Winthrop M. Leeds, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa, a corporation of Pennsylvania Filed Dec. 18, 1%4, Ser. No. 419,410 11 Claims. (Cl. 209-148) ABSTRACT OF THE DISCLOSURE A double-break synchronous type of circuit interrupter has a synchronous device including a magnet core with an enlarged opening, through which the interconnecting bar of the two movable contacts swings during operation. The annular magnet core has an air gap with a rotatable armature carrying a closed-circuit coil therein. The armature is mounted upon a shaft to which the movable contacts are secured and synchronously actuated. A blast valve is also synchronously actuated by the shaft at a current zero to force a blast of gas at the two series arcs.

This invention relates, generally, to circuit breakers and, more particularly, to a circuit breaker having a synchronous operating device of the type described in a copending application Ser. No. 97,656 filed Mar. 22, 1961, now US. Patent 3,215,866, issued Nov. 2, 1965, to Fritz Kesselring and Lutz Sequin.

The device disclosed in the aforesaid copending application comprises a saturating iron core energized by a conductor which carries the same current as the breaker contacts. A single turn coil is disposed to rotate in a circular gap in the core. As the short circuit current approaches a current zero of an alternating current wave the core unsaturates, and the high rate of change of flux induces a voltage in the coil which causes a current to flow. The interaction between this induced current and the flux across the air gap develops a relatively large torque which can be utilized to open the circuit breaker contacts and a gas blast valve just prior to the current zero. However, the problem of utilizing the torque is a diflicult one in view of the short time available for opening the contact members, particularly at a frequency of 60 cycles. Prior schemes for transmitting the torque have introduced an undesirable time delay in opening the contact members of the breaker.

An object of this invention is to provide a doublebreak circuit breaker having two sets of series-connected contact members which are opened simultaneously.

A more specific object of the invention is to provide for directly connecting a synchronous operating device to the breaker contacts and to a gas blast valve to utilize the torque developed by the device to open the contacts and the valve at substantially a current zero.

Another object of the invention is to utilize rocking contact arms of a breaker as a means for conducting current through an opening in the saturating iron core of a synchronous operating device to provide the magnetomotive force for energizing the core.

A further object of the invention is to provide for opening breaker contacts and a gas blast valve either non-synchronously when the current to be interrupted is relatively low, or synchronously with current zero when the short circuit current is above a predetermined magnitude.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of the invention, a double-break circuit breaker has a pair of rocking contact arms connected by a bar which goes through an opening in the iron core of a synchronous operating device and carries the current for energizing the core. The opening is large enough to permit the bar to swing in an are as the contact arms rock about the axis of the armature which supports the rotatable operating coil of the synchronous operator. A pair of insulating discs secured to the armature shaft at opposite sides of the core support the contact arms. A gas valve is mounted on the same shaft as the coil to contact a blast of interrupting gas to nozzles at the contact breaks. A latch holds the contacts closed. This latch is released by a high speed trip to permit the synchronous operator to open the contacts at the next zero current. For low current or load switching operations a normal speed trip unlatches a spring-driven operating rod attached to a contact arm by a lost-motion connection which permits the high speed operator to function ahead of the non-synchronous trip whenever high short circuit currents are to be interrupted.

For a better understanding of the nature and objects of the invention reference may be had to the following detailed description, taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a view, in elevation, of a synchronous operating device for a circuit breaker;

FIG. 2 is a view of curves showing the relationship between current and flux in the synchronous operating device;

FIG. 3 is a view, in plan, of the operating device and a portion of a circuit breaker structure shown in FIG. 4; and,

FIG. 4'is a diagrammatic view of the circuit breaker and operating device.

Referring to the drawing, and particularly to FIGS. 3 and 4, the portion of a circuit breaker structure shown therein comprises a pair of relatively stationary contact members 11, a pair of rocking contact arms 12 engaging the stationary contact members 11, are splitters 13, blast nozzles 14, a blast valve 15, a synchronous operating device 16, a non-synchronous operating mechanism 17, a high speed tripping magnet 18, and a normal tripping solenoid 19. The structure shown may be enclosed in a suitable housing (not shown) and the contact members 11 may be connected to power conductors through terminal connectors (not shown).

As shown more clearly in FIG. 3, the contact arms 12 are connected by a conductor 21 which may be formed integrally with the contact arms or may be bolted or brazed to the contact arms. Thus, when the contact arms are in the closed position, a series-circuit exists through the stationary contact members -11 and the two contact arms 12. This circuit is interrupted at two places when the contact arms are actuated to the open position, thereby providing a double-break circuit breaker which is suitable for operation at relatively high voltages.

As shown more clearly in FIG. 1, the synchrnous operating device 16 comprises a saturating iron core 22 and a closed circuit coil 23 on an armature member 24 rotatably disposed in a circular air gap 25 in the core 22. The core 22 has additional air gaps 26 therein and a central opening 2'7 therethrough. The conductor 21, which carries the current to be interrupted by the circuit breaker, extends through the central opening 27 to provide the magnetomotive force for energizing the saturating core 22.

As shown more clearly in FIG. 3, the armature member 24 and the coil 23 are carried by a shaft 28 rotatably mounted in bearings 29 which may be supported by a suitable structure (not shown). An insulating disc 31 is socured to the shaft 28 at each side of the core 22. Each contact arm 12 is attached to one of the discs 31 by bolts 32.

Thus, the contact arms 12. are actuated by the rotatable coil 23. The blast valve 15, which is mounted at one end of the shaft 28, is also actuated by the coil 23. It will be noted that the opening 27 in the core 22 is sufficientl large to permit the conductor 21 to swing in an are as the contact arms 12 rock about the axis of the coil 23 and its supporting armature member 24. The conductor 21 is disposed in a notch 33 in each one of the discs 31.

As explained in the aforesaid copending application, the synchronous operating device 16 provides a relatively large torque for opening the circuit breaker contacts and the blast valve 15. Referring to FIG. 2, it will be seen that the current I which fiows in the conductor 21 provides fiux (,5 which saturates the core 22. As the current I approaches zero, the core unsaturates, and the high rate of change of flux, dqb/a't, induces a voltage in the coil 23 which causes a current i, to flow in the coil. The interaction between this induced current and the flux across the air gap develops a torque in the shaft 28 to which the coil is attached. Thus, the contact arms 12, which are also attached to the shaft 28, are rocked about the axis of the coil to open the contact members of the circuit breaker just prior to a current zero of the alternating current wave. The blast valve 15 is also opened at this time to control a blast of interrupting gas, preferably SP from a high pressure reservoir (not shown). The interrupting gas is directed by the nozzles 14 across the arcs drawn between the contact arms and the stationary contact members 11 to drive the arcs into splitters 13 to extinguish the arcs. At the end of the opening contact stroke, the gas valve 15 has reached a closed position, thereby keeping gas consumption to a minimum.

As shown in FIG. 4, an overcenter toggle spring 34, attached to the discs 31 by a pin 35, biases the contact arms 1?. to either the closed or the opened position whenever its line of action is moved over center.

In order to keep the contacts of the breaker closed on through faults when other breakers are called on to open the circuit, a spring-biased holding latch 36 is provided to retain the contact arms 12 in the closed position. The latch 36 engages one of the discs 31 at the side of the notch 33. When a tripping relay operates to energize the high speed trip 18, the latch 36 is disengaged from the disc 31, and, as the next zero of short circuit current is approached, the synchronous operator is permitted to snap the contacts open. If a reignition of the arc should take place, a reversal of direction of flux in the core develops a torque in the opposite direction and the contacts are immediately reclosed to carry the current another half cycle until the next current zero is approached when they are again opened and the circuit is cleared.

The non-synchronous operating mechanism 17 is provided for low current or load switching operations where the torque developed by the synchronous operator is too weak to overcome the force of the toggle spring 34 holding the contacts closed. An operating rod 37 is attached to one of the Contact arms 12 by means of a lost motion connection which includes a pin 39 disposed in a slot 38 in the end of the rod 37. The rod 37 is driven upwardly by an accelerating spring 41 which may be compressed by means of a closing solenoid 42. The rod 37 is retained in its closed position by a spring-biased latch 43 which is released by the normal tripping solenoid 19.

The high speed trip 18 and the normal trip 19 are both energized by means of a tripping relay in the usual manner. However, the lost-motion connection between the operating rod 37' and the contact arm 12 permits the high speed trip and the high speed synchronous operator to 7 function one or two half cycles ahead of the non-synchronous operator whenever high short circuit currents are to be interrupted. Thus, the synchronous operator opens the contact members at substantially a zero current under high short circuit conditions, and the non-synchronous operator opens the contact members for load current and load switching operation.

The non-synchronous operating mechanism 17 may be utilized to close the contact members of the breaker. When the closing solenoid 22 is energized, the operating rod 37 is pulled downwardly to swing the contact arms 12 past the overcenter position of the toggle spring 34, which then snaps the contact arms to the fully closed position shown in the drawing.

As previously explained, the operating rod 37 is retained in the closed position by the latch 43 until this latch is released by the normal tripping solenoid 19. However, the lost-motion connection between the rod 37 and the contact arm 12 permits the breaker contacts to be opened by the high speed trip prior to the releasing of the latch 43. Thus, the latch 36 is always released to permit the contacts to be opened by the non-synchronous operating mechanism since the high speed tripping device 18 is energized simultaneously with the normal tripping device 19 which is slower in operation than the high speed device From the foregoing description it is apparent that the invention provides for contact opening and arc quenching gas blast action either non-synchronously, when the current to be interrupted is relatively low, or synchronously with current zero when the short circuit current is above a predetermined magnitude. In this manner, a circuit breaker normally having a relatively low interrupting capacity may be made effective in interrupting high power short circuit currents.

Since numerous changes have been 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 subject matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a double-break circuit breaker, in combination, a pair of relatively stationary contact members, a pair of contact arms engaging the stationary contact members, a synchronous operating device having a saturable iron core with an air gap therein, a closed circuit armature coil carried by a shaft rotatably mounted in the air gap, said pair of contact arms carried by the shaft and rocked about the axis of the coil to engage and disengage the stationary contact members, and a conductor rotatable with and connecting the contact arms and passing through an enlarged opening in the core to energize the core by the current flowing through the contacts of the breaker.

2. In a double-break circuit breaker, in combination, a pair of relatively stationary contact members, a pair of contact arms engaging the stationary contact members, a synchronous operating device having a saturable iron core with an air gap therein, a closed circuit armature coil carried by a shaft rotatably mounted in the air gap, said pair of contact arms carried by the shaft and rocked about the axis of the coil to engage and disengage the stationary contact members, a conductor rotatable with and connecting the contact arms and passing through an enlarged opening in the core to energize the core by the current flowing through the contacts of the breaker, and a blast valve carried by the shaft to control the flow of an interrupting gas to extinguish arcs drawn between the separated contacts.

3. In a double-break circuit breaker in combination, a pair of relatively stationary contact members, a pair of contact arms engaging the stationary contact members, a synchronous operating device having a rotatable memher for rocking the contact arms about the axis of the member to disengage the contact arms from the stationary contact members at substantially a current zero, latch means for retaining the contact arms in engagement with the stationary contact members, and high speed trip means for releasing the latch means.

4. In a double-break circuit breaker, in combination, a pair of relatively stationary contact members, a pair of contact arms engaging the stationary contact member, a synchronous operating device having a rotatable member for rocking the contact arms about the axis of the member to disengage the contact arms from the stationary contact members at substantially a current zero, a blast valve actuated by said member to control the flow of an interrupting gas to extinguish arcs drawn between the separated contacts, non-synchronous operating means attached to a contact arm by a lost-motion connection, .spring means for driving the non-synchronous operating means, means for compressing said spring means, latch means for retaining the spring means compressed, and trip means for releasing the latch means.

5. In a double-break circuit breaker, in combination, a pair of relatively stationary contact members, a pair of contact arms engaging the stationary contact members, a synchronous operating device having a rotatable member for rocking the contact arms about the axis of the member to disengage the contact arms from the stationary contact members at substantially a current zero, a blast valve actuated by said member to control the flow of an interrupting gas to extinguish arcs drawn between the separated contacts, non-synchronous operating means attached to a contact arm by a lost-motion connection, spring means for driving the non-synchronous operating means, means for compressing said spring means, latch means for retaining the spring means compressed, trip means for releasing the latch means, additional latch means for retaining the contact arms in engagement with the stationary contact members, and high speed trip means for releasing the additional latch means prior to the releasing of the first named latch means by the first named trip means.

6. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, an insulating disc secured to the shaft at each side of the core, a contact arm attached to each disc, and a conductor extending through the central opening and rotating with said contact arms to carry the current flowing through the arms to supply magnetomotive force for energizing the core.

7. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, an insulating disc secured to the shaft at each side of the core, a contact arm attached to each disc, a conductor extending through the central opening and rotating with said contact arms to carry the current flowing through the arms to supply magnetornotive force for energizing the core, and overcenter spring toggle means opposing the rotational torque of the coil.

8. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, a contact arm attached to the shaft, and a conductor rotating with the contact arm and extending through the central opening and connected to the contact arm to carry the current flowing through the arm to supply magnetomotive force for energizing the core.

9. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, an insulating disc secured to the shaft, a contact arm attached to the disc, and a conductor rotatable with the contact arm and extending through the central opening and connected to the contact arm to carry the current flowing through the arm to supply magnetomotive force for energizing the core.

10. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, an insulating disc secured to the shaft, a contact arm attached to the disc, and a conductor rotatable with the contact arm and extending tlu )ugh the central opening and connected to the contact a1 n to carry the current flowing through the arm to supply magnetomotive force for energizing the core, and overcenter spring toggle means attached to the disc to oppose the rotational torque of the coil.

11. A synchronous operator for a circuit breaker comprising a saturating core having a central opening therethrough and an air gap therein, a rotatable shaft extending through the air gap, an armature member secured to the shaft, a closed circuit coil mounted on the armature for developing a torque to rotate the shaft, an insulating disc secured to the shaft, a contact arm attached to the disc, and a conductor extending through the central opening and connected to the contact arm to carry the current flowing through the arm to supply magnetomotive force for energizing the core, latch means engaging the disc to prevent rotation of the disc in one direction, and high speed trip means for releasing the latching means.

References Cited UNITED STATES PATENTS 2,486,887 11/1949 Schleicher 335-488 X 3,215,866 11/1965 Kesselring et al 200-148 3,257,531 6/1966 Kesselring et a1. 200-148 FOREIGN PATENTS 612,7l2 5/ 1935 Germany. 346,771 3/1937 Italy.

ROBERT S. MACON, Primary Examiner.