US3475575A - Pressure gas operated circuit breaker with pressurized contact chamber - Google Patents

Description

CARL-DIETER FLOESSEL 3,475,575 PRESSURE GAS OPERATED CIRCUIT BREAKER WITH PRESSURIZED CONTACT CHAMBER Filed July 14, 1966 Get. 28, 1969 IN VEN TOR.

Carl Dieter F/oesseL United States Patent US. Cl. 200-148 2 Claims ABSTRACT OF THE DISCLOSURE A gas-pressurized circuit breaker comprises fixed and movable contact studs located within a contact chamber which is continuously gas-pressurized. The movable contact stud is tubular so as to vent the switch gases through the same to atmosphere, and movement of the tubular contact stud towards and away from the fixed contact stud is effected by means of a double-acting drive piston which forms a part of the movable contact structure. The piston which operates within a drive cylinder includes an inner cylinder spaced radially inward from the drive cylinder and this inner cylinder is provided with a valve seat at each end thereof which cooperate in an alternative manner with a generally stationary valve plate located within the inner cylinder. The switch contact studs are disengaged by applying pressurized gas to that side of the piston which is opposite the side on which the inner cylinder is located.

The present invention relates to electrical circuit breakers and more particularly to those wherein the circuit breaker contacts are enclosed within a switch chamber which is gas-pressurized both in the on and oif positions of the contacts. More particularly, the switch chamber contains a fixed contact stud and a movable contact stud which is actuated by a drive piston, and the switch contacts are blasted with compressed gas during a switching off operation as the contact members disengage as well as during a switching on operation as the contacts re-engage.

Compressed gas circuit breakers having one or more switch chambers which are gas-pressurized in the on and in the off position, that is, which are filled with compressed gas, are known. In such circuit breakers it is also known practice to blast the switch contacts both during switching off and during switching on. To achieve such blasting, there has been arranged behind the hollow contact stud a separate exhaust valve which is controlled through channels which are opened by the movable contact stud. This design, however, is complicated and expensive and requires a good deal of space. In circuit breakers which, in the on position, present a pressureless switch chamber, it is actually known how to close off from the atmosphere the chamber under pressure in the off position by means of the movable contact stud itself. But this design is not applicable to circuit breakers which are gas-pressurized in the on as well as the oil? position.

The object of this invention is to provide a simple and inexpensive construction for such a circuit breaker. According to the invention, therefore, it is proposed that the hollow movable contact stud has, on the side away from the switch point, two valve seats facing each other, between which a packing support with two packings is so arranged that the switch chamber is closed in the on as well as the oli position. In this way a separate blowing or exhaust valve is avoided.

The foregoing as well as other objects and advantages inherent in the invention will become more apparent from the following detailed description of one suitable em-' bodiment thereof and from the accompanying drawings wherein:

FIG. 1 shows in vertical central section a switch chamber according to the invention in the on position; and

FIG. 2 shows the same switch chamber in the off position.

With reference now to FIG. 1, 1 denotes the switch chamber insulator in which the switch point is housed. The fixed contact 2 is connected with a flange 3 and forms the lower seal of the chamber. Flange 3 is traversed by a tube connection 4 through which the interior of the switch chamber is continuously maintained filled with compressed gas. The movable contact stud 5 traverses and slides through the upper flange 6 in a sealed manner, the tulip-like contact 7 which is stationary and surrounds contact stud 5 serving for current transmission. The contact stud 5 is designed hollow and has a shoulder type enlargement 8 as well as a double acting drive piston part 9 of the different type which is guided hermetically sliding in the cylinder 10. Above the piston 9, the contact stud 5 is extended as an inner cylinder 11, the latter being guided hermetically sliding in an additional cylinder 12. Between the cylinders 10, 12 an annular space 13 is left free, in which is present the ring piston 14. A spring 15 located in the annular space 13 strives to press the ring piston 14 continuously downward against a shoulder type enlargement of the cylinder 10. The space 13 continuously communicates with the interior of the switch chamber insulator 1 through a tube connection 16 and the cut-out passage 17 in the upper flange 6. The space 18 below the piston part 9 contains a suction damping device 19. At the same time this space 18 is also connected through tube connection 20 with a control valve of known type not shown in detail. Between the two valve seats 21, 22 at the side of the contact stud 5 away from the switch point there is lodged an axially movable packing support 23. The packing support 23 contains the two packings 24, 25 and is mounted slidable on a collared bolt 27, the latter being biased upwardly by a spring 26. The packing support 23 and its two packings 24, 25 thus function as a double-acting valve plate which cooperates in an alternative manner with the two spaced valve seats 21 and 22.

The switching mechanism operates as follows: For switching oif, the space 18 below piston 9 is set under pressure through line 20. Due to the upwardly directed excess of force onto the piston 9 which results from the fact that, as shown in FIG. 1, the working area at the under face of the piston in communication with line 20 is greater than the working area at the opposite face of the piston in the annular space between the outer cylinder 10 and the inner cylinder 11, the contact stud 5 is moved upward. In so doing, the valve seat 22 lifts off the packing ring 25, owing to which quenching gas flows out of the switch chamber through the hollow contact stud 5 into the open air via the apertures 28. The are drawn between the contact studs 2, 5 is thereby blown in known manner. The blowing time ends in that finally at the ends of its oif-switching movement, the other valve seat 21 comes to rest on its packing ring 24, as shown in FIG. 2, and thus again closes off the switch chamber from the outside atmosphere. However, this off-switching movement does not take place promptly, but is delayed in the optimum quenching position. This occurs due to the fact that during its movement the piston 9 strikes against the spring loaded ring piston 14. The ring piston, however, presents a resistance to upward movement due to the fact that the gas pressure in the space 13 strives to push the piston 14 downward, because negative pressure prevails in the space 29 forming below the piston 14 (FIG. 2). The ring piston 14 thus, provides a suction damping action. Owing to the fact that the off-switching movement ocurs more slowly during last part provision is made that the blowing time is long enough to insure a reliable extinction of the arc.

For switching on, the space 18 below the piston 9 is deaerated through line 20 and the control valve, not shown, communicating therewith. Thereby the contact stud is moved downward by the excess of pressure prevailing above the piston 9. Just before the contacts 2, 5 re-engage, the collar type enlargement 8 impinges on the suction damping device 19, which thus becomes operative and brakes the on-switching movement at the last moment. The blowing of any on-switching arc takes place analogously, in that at the beginning of the switch contact movement, the valve seat 21 lifts 011 its packing 24 and thereby releases gas flow through the hollow contact stud 5 into the open. The blowing ceases when again the onswitching position shown in FIG. 1 is reached, in which valve seat 22 engages its packing ring 22. The diameters of the valve seat 25 and piston 9 are so selected that the packing force directed upward onto the packing support 23 is smaller than the downwardly directed force produced by means of piston 9, which insures the contact pressure. Due to the fact that the packing support 23 has a certain axial displaceability on the collared bolt 27, provision is thus made that a simultaneous re-engagement of the contact studs 2, 5 and a reliable seating of the packing ring 25 on the valve seat 22 is insured. In this way any deviations of the cooperating parts from the theoretical dimensions, as may result for example by contact wear or erosion and inaccuracy of manufacture, are compensated.

I claim:

1. In a gas-pressurized circuit breaker, the combination comprising a contact chamber which is continuously gaspressurized both during the on as well as the off positions of the circuit breaker contacts, said gas-pressurized contact chamber including therein a fixed contact stud and a tubular movable contact stud provided with a double-acting drive piston of the differential type located in an outer drive cylinder adjacent said contact chamber, said drive piston being provided with an inner cylinder spaced radially inward from said outer cylinder to provide an annular space therebetween and which is continuously gas-pressurized to thereby establish a driving force at the corresponding side of said piston which serves to continuously urge the same and hence also said movable contact stud in the direction in which it engages said fixed contact stud, said inner cylinder being in communication with the interior of said movable contact stud through said piston and being provided with a valve seat at each end thereof, a double-acting valve plate located within said inner cylinder, the opposite faces of said valve plate cooperating respectively with said valve seats and in an alternative manner, means mounting said doubleacting valve plate for yieldable movement in a direction longitudinally of said inner cylinder, said valve plate closing off communication between said inner cylinder and the atmosphere when engaging one of said seats and closing off communication between said inner cylinder and the interior of said movable contact stud when engaging the other of said seats, and means for applying pressurized gas to the opposite side of said drive piston to drive the same and hence also said movable contact stud in the direction to disengage from said fixed contact stud, the working area of said opposite side of said drive piston being greater than that which exists at the other side thereby establishing the force differential necessary to shift said piston in the direction to effect disengagement of said contacts under a condition of equal gas pressure conditions on opposite sides of said piston.

2. A gas-pressurized circuit breaker as defined in claim 1 and wherein said annular space between said inner and outer cylinders is gas-pressurized by a tube which connects said space to the interior of said gas-pressurized contact chamber.

References Cited UNITED STATES PATENTS 2,886,672 5/ 1959 Forwald.

3,268,697 8/ 1966 Morioka 200-148 FOREIGN PATENTS 1,368,422 6/ 1964 France.

ROBERT S. MACON, Primary Examiner

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