US3381102A

US3381102A - Synchronous-type hydraulic operator for alternating current synchronous type circuitinterrupter

Info

Publication number: US3381102A
Application number: US431833A
Authority: US
Inventors: Albert P Strom
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1965-02-11
Filing date: 1965-02-11
Publication date: 1968-04-30
Anticipated expiration: 1985-04-30

Description

Aprll 30, 1968 A. P. STROM 3,381,102

SYNCHRONOUS'TYPE HYDRAULIC OPERATOR FOR ALTERNATING CURRENT SYNCHRONOUS TYPE CIRCUIT INTERRUPTER Filed Feb. 11, 1965 WITNESSES ":figibgOR B El rom Mk Y ATTORNEY United States Patent 3,381,102 SYNCHRONOUS-TYPE HYDRAULIC OPERATOR FOR ALTERNATING CURRENT SYNCHRO- NOUS TYPE CIRCUIT INTERRUPTER Albert P. Strom, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 11, 1965, Ser. No. 431,833 14 Claims. (Cl. 200-148) ABSTRACT OF THE DISCLOSURE An alternating-current synchronous-type circuit interrupter has the movable contact hydraulically actuated. A synchronous operator has a saturable magnet core with an armature moving in the air gap of the core and mechanically connected to a driving hydraulic piston. A hydraulic line hydraulically interconnects the two pistons for synchronous breaker operation. A blast-valve synchronously operated is hydraulically connected to the driven hydraulic piston connected to the movable contact member.

This invention relates, generally, to circuit interrupters and, more particularly, to interrupters of the synchronous type wherein the contact members of an interrupter are opened at substantially Zero current on an alternating current wave.

For the operation of a synchronous interrupter, the utilization of an anmaturc located in a gap in an iron core and actuated by the magnetic field produced in the air gap by a conductor which passes through the core and carries the current to be interrupted has been proposed. One difliculty with such an arrangement is that of providing an adequate mechanical connection to transmit the high force produced in the armature to the contact members and to the gas or air valve that are to be operated synchronously by the armature.

An object of this invention is to provide hydraulic means for transmitting a force developed electrically by a synchronous operator to the movable contact member and the blast valve of a circuit interrupter.

Another object of the invention is to improve the effectiveness of an electromagnetic synchronous operator for a circuit interrupter.

A further object of the invention is to provide for reclosing the contact members and the blast valve of an interrupter if the arc is not interrupted at current Zero.

Still another object of the invention is to provide for immediately reclosing the blast valve if the current is interrupted.

A still further object of the invention is to provide for non-synchronous operation of a normally synchronously operated interrupter.

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, the armature of an electromagnetic synchronous operator is attached directly to a Nichrome beam connected to a double acting piston disposed in a cylinder open at both ends. Each end of the cylinder is connected through a hydraulic line to an open end of a second cylinder having a piston therein connected to a movable contact member of an interrupter, thereby constituting a closed hydraulic loop including said pistons. A blast valve which is spring biased to a closed position is opened by a piston disposed in a closed cylinder connected to the second cylinder through ports controlled by a skirt on the second piston. The hydraulic system is such that the contacts and the ice blast valve are both reclosed if the arc is not interrupted at current zero and the blast valve is reclosed if current is interrupted.

Fora 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 diagrammatic view of a hydraulic operating system embodying principal features of the invention, and

FIG. 2 is a diagrammatic view of the synchronous operation utilized in the system shown in FIG. 1.

Referring to the drawing, the circuit interrupter shown therein comprises a relatively stationary contact member 11, a movable contact assembly 12 which includes a plurality of contact fingers 13 for engaging the stationary contact member 11, an arcing contact member 14 and an orifice member 15 which is supported by a hollow conductor 16 leading from a high pressure chamber 17. The chamber 17 contains an interrupting fluid such as sulfur hexafluoride (SF gas, at a relatively high pressure. A blast valve 18 is disposed in the conductor 16 to control the admission of the interrupting gas into the orifice member 15 which constitutes an interrupting chamber.

The stationary contact member 11 is preferably of the tubular type having openings 19 therein to permit the interrupting gas to escape from the tubular member 11 during the arc extinguishing operation. The member 11 may be connected to a current conductor 21, which may be connected to one side of the circuit to be interrupted. The contact fingers 13 and the arcing contact member 14 are preferably removably attached to a conductor 22 which may be connected to the other side of the circuit to be interrupted. The orifice member 15 is preferably composed of polytetrafiuoroethylene which is sold under the trade name Teflon.

In order to provide for opening the contact members of the interrupter at substantially zero current on an alternating current wave a synchronous operator 25 is provided. The operator 25 comprises a core 26 of laminated magnetic material having an air gap 27 therein and a central opening 28 therethrough. An armature 29 is movably disposed in the air gap 27 and electrically connected to a fixed bar 31 by

flexible conductors

32 and 33 to complete a closed circuit through the armature conductor 29. The bar 31 may 28 in the core 26.

As shown more clearly in FIG. 2, the core is energized by several turns of the conductor 21 which carries the current to be interrupted by the interrupter. The core is so constructed that at all currents above normal load current the iron is saturated except as the current approaches the zero point on the wave at which time the flux suddenly reverses, as the primary current reverses.

In the secondary turn including the armature 29, no voltage is generated during peak current since the core is saturated and flux linking the secondary turn is not changing. Hence, no (or negligible) current flows in the armature. But when the flux begins to reverse as current zero approaches, the secondary including the armature 29 suddenly has a relatively high voltage impressed on it. A high current rises sudenly in the armature, and, since it is simultaneously in a field of near saturation, a high force is exerted on the armature in a direction to open the contacts of the interrupter. Then, if the current is not interrupted at current zero and the flux reverses, the force reverses thus acting to close the contacts of the interrupter. The force produced may be expressed by the formula:

be disposed in the central opening where L is the effective length of the conductor 29, B

is the flux and I is the current in the armature conductor 29.

As explained hereinbefore, one difficulty is that of transmitting the high force produced in the armature 29 to the contacts 11, 13 and to the blast valve 18 that are to be operated synchronously by the armature. Calculations show that a single 6 inch long armature conductor 29 in a twenty thousand gauss field will exert a force at twenty thousand amperes, of approximately 1344 lbs.

In order to overcome the foregoing difiiculty, the hydraulic system herein described is provided. As shown, a metal beam is attached to one side of the armature conductor 29. The beam 35 is preferably composed of Nichrome or other material having a high resistance. Nichrome has a resistivity of 60 times copper and hence will keep nearly of the current 1 in the armature where it is most effective, and still permits the use of a strong metallic connection to operate a hydraulic driving piston 38. Alternatives would be to use an insulating material for the connecting beam, or an insulated metal beam.

The beam 35 is connected to the lower end of a piston rod 36 which is slidably disposed in a supporting structure 37. The piston rod 36 carries the double acting piston 3 8 slidably disposed in a cylinder 39 which is open at both ends.

A similar piston 41 is carried by the movable conductor 22 which is slidably disposed in a supporting structure 42 and functions as a piston rod. The piston 41 is slidably disposed in a cylinder 43 which is open at both ends. The upper end of the

cylinders

39 and 43 are connected by a hydraulic line or conduit 44. Likewise, the lower ends of the cylinders are connected by a hydraulic line 45. The hydraulic lines and the cylinders are filled with a hydraulic fluid, such as oil. Thus, the hydraulic lines and the cylinders constitute a closed hydraulic system which includes the pistons 38 and 41.

For best results, the cylinders and the pistons should be relatively small to give the highest pressure that can be handled practically, and the pistons and the piston rods should be of a light construction in order to minimize the moving mass. Also, the connecting lines or

conduits

44, 45 should be relatively large in order to reduce the delay of available force at the contact operating piston 41.

Assuming that the force on the armature 29 is in a downward direction, the piston 38 is moved downwardly in the cylinder 39. The applied pressure on the lower side of the piston 41 in the cylinder 43 will move the piston upwardly, thereby opening the contact members of the interrupter. If the current is interrupted at zero current, the pistons and the contact members are retained in the open contact position by spring

biased latches

46 and 47 which engage the

piston rods

36 and 22, respectively. If the current is not interrupted at zero current, the force on the armature 29 is reversed and the piston 38 is moved upwardly, thereby driving the piston 41 downwardly to reclose the contact members in .order that they may be reopened at the next zero current. It will be noted that springs 48 and 49 are provided to bias the pistons toward the contact closing positions.

As previously explained, the blast valve 18 controls the admission of the interrupting gas into the interrupting chamber to assist in extinguishing the are drawn between the contact members. The valve 18 is biased closed by a spring 51 which engages the upper side of a piston 52 disposed in a closed cylinder 53. The valve 18 and the piston 52 are carried by a piston rod 54 which extends through the ends of the closed cylinder 53. Thus, the piston has equal areas on both sides so that no cavitation takes place as it moves upwardly or downwardly.

The operation of the valve 18 is controlled by a plurality of ports which communicate with the closed hydrau lic system and are controlled by a skirt 55 on the piston 41. If desired, a separate control valve actuated by the piston rod 22 may be utilized.

When the contacts and the valve 18 are closed and high pressure is applied to the lower side of the piston 41 to open the contact members pressure is also applied through a port 56 to the lower side of the piston 52 to open the blast valve 18. However, as the contact piston 41 moves upwardly, slots are so arranged in the lower piston skirt that as full contact open position is reached, port 56 to the under side of the valve piston 52- is closed to the high pressure hydraulic side and a port 57 leading from the high pressure hydraulic side to the upper side of the valve piston opens. Simultaneously, by a slot in the upper side of the piston skirt a port 58 to the upper side of the valve piston leading to the low pressure hydraulic side closes, and a port 59 leading to the lower side of the valve piston connecting this side of the piston to low pressure side of the hydraulic system opens. Hence, the pressure on the system and/ or the piston spring 51 can immediately reclose the blast valve if current is interrupted. In this manner the interrupting gas can be conserved. As previously explained, the contact members are reclosed if current is not interrupted and the reopening of the contact members and the blast valve is repeated at the next current zero.

In order to provide for a non-synchronous operation of the interrupter, a piston 61 is slidably disposed in a cylinder 62 having open ends communicating with the closed hydraulic system. The piston 61 is carried by a piston rod 63 which is normally latched with the piston 61 in an intermediate position by means of a spring biased latch 64. The latch 64 may be released by energizing a solenoid 65 in a manner well known in the art. When the solenoid is energized a latch 66 engages the rod 36 to lock the piston 38 during operation of the piston 61. When the latch 64 is released, the rod 63 may be operated by any suitable means to move the piston 61 to drive the piston 41 in the proper direction to either open or close the contact members and the blast valve in the manner hereinbefore described.

The system herein described makes it possible to locate the interrupter at any convenient position with respect to the armature 29 of the synchronous operator. A single armature may be utilized to operate a number of interrupters connected in series, or several armatures all at relatively equal potential can operate separate interrupters that are connected in series. Insulation between the armature and the interrupter can be provided by the use of insulating tubing in the hydraulic lines. In addition to the foregoing advantages, a practical system of lower effective mass, and hence better response, than a mechanically connectedsystem is provided by the hydraulic system herein described.

Since numerous changes may be made in the above described construction and diflerent 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 hydraulic system for operating a circuit interrupter having a movable contact member, in combination, a synchronous operator having a movable armature, a first cylinder open at both ends, a first piston disposed in the cylinder, high resistance means mechanically connecting the armature to the piston, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting said cylinders in a closed loop including said pistons, and mechanical means connecting the second piston to the contact member, whereby the contact members is actuated in accordance with movement of the armature of the synchronous interrupter.

2. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the cur rent to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, and mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous op erator.

3. In a hydraulic system for operating a circuit interrupter having a movable contact member, in combinationfa synchronous operator having a movable armature, a first cylinder open at both ends, a first piston disposed in the cylinder, high resistance means mechanically connecting the armature to the piston, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting said cylinders in a closed loop including said pistons, mechanical means connecting the second piston to the contact member, whereby the contact member is actuated in accordance with movement of the armature of the synchronous interrupter, valve means for admitting an interrupting fluid into the interrupter, and means controlled by the second piston for actuating said valve means.

4. In a hydraulicsystem for operating a circuit interrupter having a movable contact member, in combination, a synchronous operator having a movable armature, a first cylinder open at both ends, a first piston disposed in the cylinder, high resistance means mechanically connecting the armature to the piston, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting said cylinders in a closed loop including said pistons, mechanical means connecting the second piston to the contact member, whereby the contact member is actuated in accordance with movement of the armature of the synchronous interrupter, valve means for admitting an interrupting fluid into the interrupter, and hydraulically operated means controlled by the second piston for actuating the valve means.

5. In a hydraulic system for operating a circuit interrupter having a movable contact member, in combination, a synchronous operator having a movable armature, a first cylinder open at both ends, a first piston disposed in the cylinder, high resistance means mechanically connecting the armature to the piston, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting said cylinders in a closed loop including said pistons, mechanical means connecting the second piston to the contact member, whereby the contact member is actuated in accordance with movement of the armature of the synchronous interrupter, valve means for admitting an interrupting fluid into the interrupter, hydraulically operated means for actuating the valve means, and port means controlled by the second piston for controlling the hydraulically operated means.

6. In a hydraulic system for operating a circuit interrupter having a movable contact member, in combination, a synchronous operator having a movable armature, a first cylinder open at both ends, a first piston disposed in the cylinder, high resistance means mechanically connecting the armature to the piston, a second cylinder open at :both ends, a second piston disposed in the second cylinder, hydraulic lines connecting said cylinders in a closed loop including said pistons, mechanical means connecting the second piston to the contact member, whereby the contact member is actuated in accordance with movement of the armature of the synchronous interrupter, valve means for admitting an interrupting fluid into the interrupter, a piston for actuating the valve means, a closed cylinder containing the valve actuating piston, and

ports controlled by the second piston connecting the closed cylinder to the second cylinder.

7. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, spring means biasing said pistonsto the contact closed positions, and latch means releasably retaining the pistons in the contact open positlons.

8.--In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, a normally closed blast valve for admitting an interrupting gas into the interrupter, and hydraulically operated means controlled by the second piston for opening the valve.

9. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed 'loop including said pistons, mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, a spring closed blast valve for admitting an interrupting gas into the interrupter, hydraulically operated means for opening the valve, and port means controlled by the second piston for controlling the hydraulically operated means.

10. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a sec ond piston disposed on the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, a spring closed blast valve for admitting an interrupting gas into the interrupter, hydraulically operated means for opening the valve, port means controlled by the second piston for controlling the hydraulically operated means, and said valve being reclosed after the opening of the contact members.

11. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, a third cylinder having a third piston therein, and said third cylinder being connected to said hydraulic lines to provide for .nonsynchronous operation of the circuit interrupter.

12. In a circuit interrupter, in combination, contact members openable to interrupt current flowing therethrough, a synchronous operator energized by the current to 'be interrupted, said operator having an armature movable to control the operation of the contact members, a first cylinder open at both ends, a first piston disposed in the cylinder, mechanical means attaching the piston to the armature, a second cylinder open at both ends, a second piston disposed in the second cylinder, hydraulic lines connecting the ends of the cylinders to constitute a closed loop including said pistons, and mechanical means attaching the second piston to one of the contact members to actuate it in accordance with the movement of the armature of the synchronous operator, a third cylinder having a third piston therein, said third cylinder being connected to said hydraulic lines to provide for non-synchronous operation of the circuit interrupter, and releasable latching means for retaining the third piston in an intermediate position in the third cylinder.

13. In an alternating-current synchronous-type circuit interrupter, in combination, a synchronous operator having a saturable magnet core magnetically energized by at least a portion of the series line current to be interrupted and having an air gap, an armature (29) located within said air gap and constituting a portion of a closed loop, whereby current will be induced therein upon changing flux conditions in the air gap, a driving hydraulic piston (38) mechanically connected to the armature so as to move therewith, a hydraulic cylinder within which the hydraulic driving piston reciprocates, separable contact means including a movable contact, a driven hydraulic piston (41) mechanically connected to said movable contact (13) so as to elTect at least the opening motion thereof, and a hydraulic line (45) hydraulically interconnecting the two pistons, whereby opening mechanical motion of the armature (29) will effect through the hydraulic line opening synchronous motion of the movable contact close to a current zero.

14. The alternating-current synchronous-type circuit interrupter of claim 13, wherein a blast valve (18) con trols the flow of fluid from a high-pressure source (17) toward the arc established between the separable contact means, a hydraulic piston for effecting the opening of said blast valve, and means controlled by the location of said driven hydraulic piston for actuating said last-mentioned hydraulic piston, whereby a synchronized blast of fluid may be obtained at the established arc.

References Cited UNITED STATES PATENTS 799,064 9/1905 Kowsky -54.6 X 3,002,073 9/1961 Cobine 200-448 X 3,150,245 9/1964 Leeds et al 200-148 X 3,257,531 6/1966 Kesselring 200-148 2,286,465 11/1966 Cerles et al. 60-54.5

ROBERT S. MACON, Primary Examiner.