US3076081A - Condition-responsive indicating means for an electric circuit breaker - Google Patents

Description

Jan. 29, 1963 J. A. oPPl-:L

CONDITION-RESPONSIVE INDICATING MEANS FOR AN ELECTRIC CIRCUIT BREAKER Filed May 22, 1961 In ven t or: John A. Oppel, ma. hm,

Attorneg.

United States Patent O 3,076,081 CONDITION-RESPONSIVE INDICATNG MEANS FOR AN ELECTRIC CIRCUIT BREAKER John A. Oppel, Aldan, Pa., assignor to General Electric Company, a corporation of New York Filed May 22, 1961, Ser. No. 111,827 5 Claims. (Cl. 20G- 167) This invention relates to an electric circuit breaker of the type that has its operation controlled by a fluid control valve and relates, more particularly, to indicating or control means for providing an indication that the breaker has functioned in its intended manner in response to operation of the control valve.

In the type of circuit breaker that the present invention is concerned with there is a control valve that is relied upon for controlling the motion of the usual contacts of the breaker. If the breaker is functioning in its intended manner, operation of the control valve will cause relative motion of the contacts to occur. But if for some unusual reason, the breaker is not functioning properly, then there is a possibility that the contacts will not respond to operation of the control valve. The present invention is concerned with providing an indication of whether or not the contacts have responded in the intended manner to operation of the control valve.

If the indicating means is at ground potential, then a problem arises as to how to convey information from the contacts at high potential to the indicating device at ground potential. One typical way of doing this is to couple one of the contacts to the indicating device by means of la long rod of insulating material capable of withstanding the full voltage between the contact and ground. A disadvantage of this approach is that it introduces additional creepage surfaces along which electrical breakdown from the contacts to ground is possible.

An object of the present invention is to convey the desired indication of contact-operation or of some other condition from a high potential location to ground without introducing any significant additional creepage surfaces along which breakdown might possibly occur, either between the contacts of the breaker or from a high voltage part to ground.

' Another object is to provide indicating means of the above character which is of a simple and highly compact construction that requires little additional space beyond that present in the absence of the indicating means.

One application of my invention is in conjunction with a circuit breaker of the type that includes a tank normally containing'pressurized gas within which the contacts of the breaker are located. Within the tank, which is at a 4high potential relative to ground, is a control valve that is operable to control motion of at least one of the contacts. Operation of the control valve is effected by control means at ground potential coupled to the control valve through an insulating operating rod that is adapted to withstand tank to ground voltage. The operating rod is moved in a longitudinal direction to effect operation of the control valve. In addition to being movable in a longitudinal direction, the operating rod is mounted for angular or rotary motion. The movable contact of the breaker is coupled to the operating rod `at its high potential end by means that produces angular motion of the `operating rod in response to motion of the movable contacts. This angular motion is transmitted through the operating rod to an indicating device at ground potential that responds by providing an indication of whether the movable contact has responded to operation of the control valve.

For a better understanding of my invention, reference may be had to the following description taken in con- 3,676,081 Patented Jan. 29, 1963 junction with the accompanying drawing wherein: the single FIGURE is a partially schematic side elevational view of a circuit breaker embodying one form of my invention.

Referring now to the drawing, the circuit breaker shown therein comprises a metallic tank 12 mounted on a hollow insulating column 14. The tank is at a high voltage with respect to ground, and the insulating column 14 serves to electrically isolate the tank from ground as well as to support the tank. The tank 12 is normally lled with pressurized gas that serves both as an arc-extinguishing medium and as a medium for operating the usual cont-acts of the breaker, as will soon appear more clearly. The basic circuit breaker structure within the tank generally corresponds to that disclosed in detail and claimed in U.S. Patent No. 2,783,338--Beatty, assigned to the assignee of the present invention. In the present application this structure will be described only to the extent believed necessary to convey an understanding of the present invention. Reference may be had to the Beatty patent if a more detailed description is desired. Referring now to the structure within the tank 12, there are two pairs of contacts disposed therein. One pair of contacts comprises a stationary contact 20 and a movable contact 21 that is movable into and out of engagement with the stationary contact 2li. The other pair of contacts comprises a stationary Contact 20a and a movable contact 21a that is movable into and out of engagement with the stationary contact 26a. The movable contacts 21 and 21a are mounted on two stationary pivots 23 carried by a central metallic support 25 that is mechanically and electrically connected to the tank. Each of the stationary contacts 2t) or Ztla is mounted on the inner end of a lead-in bushing that serves to insulate the stationary contact from the tank when the breaker is open and serves further to conduct electrical current to and from the stationary contact from a point outside of the tank l2. In this regard, the stationary contact 20 is shown mounted on the inner end of a leadin bushing 3G projecting into the tank through its right hand end wall and providing an electrical connection through a conductive stud 31 between the stationary contact 20; and a terminal 33 of the circuit breaker. The other stationary contact 26a is shown mounted on an identical bushing 32 projecting into the tank through its left hand end wall and providing a connection between the other terminal 34 of the circuit breaker and the contact 29a while insulating the contacts 2da from the tank 12 when the circuit breaker is open.

The two pairs of contacts are electrically connected in series between the terminals 33 and 34 of the circuit breaker. It will therefore be apparent that the power circuit through the breaker extends from one terminal 33 through parts 31, 20, 21, 25, 21a, 20a and the stud of bushing 32 to the terminal 34.

Interruption of this power circuit through the breaker is effected by driving the movable contacts 21 and 21a from their solid line position into their respective dotted line positions. More specifically, opening of the movable contact 21 is .effected by driving the movable contact 21 in a clockwise direction about its pivot 23 so that its lower end separates from the stationary contact 20. Closing is effected by returning the movable contact 21 in a counterclockwise direction to its solid line position shown on the drawing. Opening of the other movable contact 21a is effected by driving this contact in a counterclock- Wise direction about its pivot 23, whereas closing is effected by returning movable contact 21a in aclockwise direction to its solid line position shown in the drawing.

For imparting opening or closing motion to the movable contacts 21 and 21a, a common driving member in aovaoel the form of a reciprocable crosshead is provided. The movable contact 21 is coupled to this crosshead 35 by means of a link 37 pivotally connected at its respective opposite ends to the crosshead 35 and the movable contact 21, whereas the movable contact 21a is coupled to the crosshead 35 by means of another link 37a pivotally connected at its respective opposite ends to the crosshead 35 and the movable contact 21a. Movement of the crosshead upward from its solid line position into its dotted line position causes the lower ends of the movable contacts 21 and 21a to separate from their respective stationary contacts and move into their dotted-line open positions, whereas return movement of the crosshead from the dotted line to the solid line position returns the movable contacts from their dotted-line open position to their solid line closed position.k

For controlling the motion of the crosshead 55 so as to effect opening and closing of the movable contacts in this manner, a pneumatic operating mechanism is provided within the cylindrical support 25. The details of this operating mechanism form no part of the present invention and therefore will not be described in this application. Preferably, however, the operating mechanism is of the type disclosed and claimed in the aforementioned Beatty patent, 2,783,338.

For controlling this operating mechanism, the crosshead 35, and the connected contacts 21 and 21a, a control valve 4t) is provided. This control valve 40, which is located within the tank and is at the potential of the tank, comprises a movable valve member 42 that is mounted for reciproca/tion in a vertical direction in a cylindrical housing 44. When the valve member 42 is in its uppermost position of FIG. 1 it blocks communication between the pressurized gas inside the tank 12 and a control passage 45 leading to the contact-operating mechanism inside of the housing 25. This blocking relationship follows from the fact that the movable valve member 42, in its position of FIG. l, covers the inlet port 46 connecting the control passage 45 and the interior of tank 12. In its position of the drawing, the valve member 42 does, however, afford communication between the control passage 45 and an exhaust line 47 leading to atmosphere, so that the operating mechanism is then vented to atmosphere through control passage 45, a venting port 50 in the movable valve member 42, an outlet port 52, and the exhaust line 47.

When it is desired to cause the operating mechanism to lift the crosshead 35 to produce opening motion of the movable contacts 21, 21a, the vertically-movable valve member 42 is driven downward from its Vposition shown in the drawing to uncover the inlet port 46 and cover the outlet port 52. This establishes communication between the pressurized gas in the interior of tank 12 and the control passage 45 through the inlet port 46 allowing pressurized gas to ilow from the interior of tank-12 into the operating mechanism to effect upward contact opening motion of the crosshead 35. To return the contacts 21, 21a to closed position, the valve member 42 is returned in an upward direction to its position of the drawing, thereby venting the operating mechanism through control passage 45, venting passage 50, outlet port. 52,; and the exhaust line 47.. Such venting causesA the operating mechanism to drive the crosshead 35 downwardly to, close the contacts, as is described in greater detail in thev aforementioned Beatty patent. y

For controlling the position of the movable valve member 42, a fluid motor 56 is provided at the base of the insulating column 14.V This luid motor 56, which is at ground potential, comprises a vertically movable piston. 58 which is coupled to the movable valve member 42 by means ofY a long operating rod 60 of insulating materia-l extending through the hollow insulating column 14. This operating rod 60 is of suicient length to withstand without breakdown the high voltage present between the tank 12 and ground. The fluid motor 56 further comprises a cylinder 59 in which the piston 58 is slidable.

For controlling the position of piston 58 of the tluid motor 56, a suitable three-way valve 61 is provided in a control line 62 that leads from a pressure source (not shown) to the cylindervspace beneath piston 58. The cylinder space above piston 58 is normally maintained at the pressure of the source by virtue of a line 64 connecting this upper space and the source. When the motor control valve 61 is in its position of the drawing both sides of the piston are in communication with the pressure source and therefore equal pressures are present on both sides of the piston. The pressurized iluid in the motor 56 is therefore exerting no net force on piston 58 during this interval. Under these conditions, a compression spring 66 disposed at the top of the operating rod and acting between a stationary support 68 and a shoulder 70 iixed to the operating rod maintains the valve member 42 and the operating rod 66 in their uppermost position of the drawing.

Downward, or opening, motion of the valve member 42 from its position of the drawing is etected by vent- `ing the cylinder space beneath the piston 58 of the fluid motor 56 to atmosphere. This is accomplished by operating the motor control valve 61 into a position wherein an exhaust line 71 and the control line 62 are in communication. When the cylinder lspace below the piston 5S is thus vented, the pressure above the piston 58 becomes efective to force the piston 58 rapidly downward against the opposition of spring 66, thus driving the movable valve member 42 downwardly into its open position, thereby causing the operating mechanism to effect a contact-opening operation, as was previously described.

For returning the valve member 42 from this lower, or open, position to its position of the drawing, the motor control valve 61 is rotated to a position in which the space beneath piston 5S communicates with the pressure source. This equalizes the pressure on opposite sides of the piston 58, thus permitting the spring 66 to drive the valve member 42 and the operating rod 60 upwardly to close the breaker control valve 40, thus effecting closing of the circuit breaker, as was previously described.

If the circuit breaker is not in proper working order there is a possibility that the movable contacts will not respond to operation of the control valve 40. For example, if for some unusual reason one of thel movable cc-ntacts should become welded in its closed position, the operating mechanism might not be capable of opening the contacts in response to an opening operation of the control valve 40. It is therefore desirable in certain applications to provide some indicating or control means for providing an indication of whether or not the movable contacts have responded to operation of the control valve 40.

Generally, it is desirable that the indicating device be at ground potential so that it is readily visible or so that its operation can be readily used for performing some appropriate control function.

I have shown such an indicating device in the form of a lever fixed to the operating rod 60 at its lowermost end. This indicating lever 90 is angularly movable about the longitudinal axis of operating rod 60 between a rst position shown in solid lines and a second position shown in dotted lines. When the lever 90 is in its solid line position, this indicates that the contacts of the breaker are closed. When the indicating lever 90 is in its dotted line position, this indicates that the contacts of the breaker are open.

For transmitting information on whether the contacts are open or closed to the indicating device 90, I rely, inpart, upon the same insulating operating rod 60 that is used for controlling the control Valve member 42. To adapt the operating rod 60 for this added duty, it is mounted for angular rmotion about its longitudinal axis as well as for the reciprocatory motion already described.

In this regard, the operating rod 60 is freely rotatable with respect to the piston 58 of the fluid motor and is journaled in the end walls of the cylinder 59 at 92 and 94 and is also journaled in the stationary support 68 at the top of the operating rod 60. Additionally, a suitable coupling 96 is provided Iat the top of the operating rod 60 between the movable member 42 and the operating rod for permitting rotary motion of the operating rod relative to the valve member 42 but for preventing longitudinal motion of the operating rod 60 relative to the valve member 42.

For producing angular motion of the insulating operating rod 60 in response to motion of the contacts 21 and 21a, a suitable push-pull type flexible coupling is provided between the crosshead 35 and a crank 100 fixed to the operating rod 60. Preferably, this flexible coupling is of the Bowden push-wire type, and as such, it comprises a hollow flexible tube 102 and a relatively stiff wire 104 within the tube, closely surrounded by the tube, but readily slidable axially through the tube. The tube 102 is suitably fixed to the stationary housing 25, so that pushing and pulling motions and forces applied at one end of the wire 104 are transmitted to the other end. Suitable clamps such as 105 disposed at spaced-apart locations along the tube 102 are provided for fixing the tube to the housing 25.

When the crosshead 35 is driven Iupwardly during a contact opening operation, it acts through the-Bowden push-wire 104 to pivot the crank 100 in a counterclockwise direction. Since the crank 100 is fixed to the insulating operating rod 60, its counterclockwise rotation rotates the operating rod 60 in a counterclockwise direction and thus also rotates the indicating device 90 in a counterclockwise direction. When the contacts 21, 21a reach their open position, the indicating device 90 reaches its dotted line position of the drawing. If desired, a suitable electric switch 110 can be actuated by the indicating lever 90 in response to movement into its dotted line position to elect any desired control or indicating function. As an example, the switch 110 can be a disagreement switch which compares the contact-position of the illustrated circuit breaker with that of corresponding circuit breakers connected in other phases of a polyphase system.

When the crosshead 35 is driven downwardly from its dotted-line contact-open to its solid-line contact-closed position a pushing force is applied to the upper end of the Bowden pushwire 104, thus rotating the crank 100 clockwise from its dotted line position back to its solid line position to eiect return of the indicating lever 90 to its solid line position of FIG. 1. Return of the indicating lever 90 to this position therefore indicates that the contacts are in closed position.

lf the control valve 40 had been operated, say to open the contacts of 4the breaker, and for some unusual reason the contacts had not responded, the Bowden pushwire 104 would not have been pulled upwardly through its surrounding tube 102 and thus the insulating operating rod 60 and the indicating lever 90 would not have been angularly moved out of their solid line position. Failure of lever 90 to change its position under these circumstances Would provide the operator with an indication that the contacts 21, 21a had not properly responded to opening of the control valve 40.

For assuring that the operating rod 60 will readily rotate in response to pushing or pulling force on the Bowden wire 104, the rod 60 is made rotatable with respect to the piston 5S. Thus, the rod 60 is free to rotate without rotating the relatively large piston 58 with its piston ring 111 that frictionally engages the inner wall of cylinder 59. Such frictional engagement over this relatively large surface would tend to unduly oppose the desired rotation of the operating rod 60 if the operating rod were fixed to the piston 58. Suitable shoulders 112 fixed to the operating rod 60 on opposite `sides of piston 58 are provided to assure that the piston and operating rod are coupled -together for movement in unison in a longitudinal direction.

It should be apparent from the above description that I have been able to incorporate my contact-position indicating means without the necessity for including an additional insulating operating rod between the tank and ground. In this regard, by relying upon the operating rod 60 to perform the dual function of controlling valve member 42 and of transmitting information on the contact position to the indicating device 90, the need for an extra insulating rod has been eliminated; and thus no additional potential breakdown paths between the tank and ground have been introduced. By coupling the operating rod 60 to a part (35) that is always at the potential of the tank and also at the potential of the moving contacts, no significant insulation problems within the tank are introduced by inclusion of the indicating coupling -104. The arcing gaps between the contacts and the insulating creepage paths between the contacts remain intact, unimpaired by the presence of coupling 100-104.

By utilizing longitudinal motion of the operating rod 60 to control the valve member 42 and angular motion of the operating rod to control the indicating function, I am .able to perform each of these functions without interference from the parts responsible for the other. In this regard, reciprocation of the operating rod 60 is not significantly restrained by the Bowden pushwire 104 since the pushwire has enough flexibility to permit this slight motion of the operating rod without significantly changing the angular position of the crank 100. On the other hand, angular motion of the crank 100 by forces transmitted through the pushwire 104 have no significant effect on the longitudinal position of the operating rod 60 inasmuch as the pushwire applies to longitudinal forces to the operating rod 60, nor does the position of the operating rod 60 in any way impair the ability of the pushwire to produce the desired angular motion of the operating rod.

In one typical embodiment of my invention, the total longitudinal movement of operating rod 60 is only 1A; inch as compared to a total of 1% inches for the cross-head 35. Obviously, this slight longitudinal motion of the operating rod 60 can occur without Significant restraint from the pushwire and without significantly changing the angular position of the crank 100 unless operation of the circuit breaker occurs. The pushwire 104 extends substantially perpendicular to the operating rod 60 in the region of the operating rod 60 so as to prevent the pushwire from applying longitudinal forces to the operating rod. The longitudinal motion of the operating rod 60 is so slight that this substantially perpendicular relationship exists irrespective of whether the valve 40 is open or closed. If it is desired to maintain this perpendicular relationship even more precisely, the crank 100 can be suitably splined on the operating rod to permit independent longitudinal motion of the rod relative to the crank.

That the indicating means is a highly compact arrangement is evident from the fact that the Bowden pushwire follows closely the external surface of the housing 25, requiring no extra insulation, and from the additional fact that no extra insulating rods are needed for proper functioning of the indicating arrangement.

Although I have specifically described the indicating means as being used for providing an indication of the position of the main contacts of the breaker, it is to be understood that in accordance with the broader aspects of this invention, the indicating means could be used for conveying other information from the vicinity of the tank to an indicating device at ground potential. For example, the indicating means could alternatively be used for conveying information as to the condition of a resistor switch (not shown) that is coupled to the main contacts of the breaker for operation in response to operation of these contacts. Such a resistor switch is shown in my Patent No. 2,911,546, assigned to the assignee of the present invention. As another example, information on certain electrical relationships can be transmitted from the tank to ground by rotation of the operating rod 60 in the general manner shown.

It will be obvious to those skilled in the art that various other changes and modiiications may be made Without departing from my invention in its broader aspects, and I, therefore, intend in the appended claims to cover all such changes and modifications as Afall within the true spirit and scope of my invention.

What Iclaim as new and desire to secure by Letters Patent of the United States is:

l. An electric circuit breaker comprising a tank adapted to contain pressurized gas, separable contacts within said tank, at least one of which is movable relative to said tank, means for electrically connecting said movable contact togsaid tank when said movable contact is in its open and closed positions, means for insulating said tank from groundcontrol valve means at the potential of said tank operable to control the motion of said one contact, an insulating operating rod for said control valve means extending from said control valve means to a point at ground potential, means for effecting longitudinal motion of said operating rod to control operation of said control valve means, means responsive to motion of said movable contact for eiecting angular motion of said insulating operating rod, and means at ground potential responsive to angular motion of said operating rod to provide an indication that said movable contact has responded to operation of said control valve means. y

2. An electric circuit breaker comprising a tank adapted to contain pressurized gas, separable contacts within said tank, at least one of -which is movable relative to said: tank, means for electrically connecting said movable con tact to said tank for all operative positions of said movable contact, means for insulating said tank from ground, control valve means at the potential of said tank operable to control the motion of said one contact, an insulating operating rod for said control valve means extending from said control valve means to a point at ground potential, coupling means between said movable contact and said operating rod producing angular motion of said operating rod in response to movement of said' movable contact,

8 said coupling means comprising a push-pull flexible cou. pling interconnecting a part coupled to said movable contact and said operating ro'd for converting motion of said part into angular motion of said operating rod, and means at ground potential responsive to angular motion of .said operating rod to provide an indication that said movable contact has responded to operation of said control valve means. y

3.` An electric circuit breaker comprising a tank adapted to contain pressurized gas, separable contacts within said tank, means` for insulating said tank fromtground, control valve means at the potential of said tank operable to control the motion of one of said contacts, an insulating operating rod for said control valve means extending from said control valve means to a point at ground potential, means for electing longitudinal motion of said operating rod to produce operation of said control valve means, a device in the vicinity of said tank at substantially the voltage of said tank for effecting a predetermined operation, and coupling means responsive to the occurrence of said predetermined operation for effecting angular motion of said insulating operating rod, and means at ground potential responsive to angular motion of said operating rod to provide an indication of whether said predetermined l operation in the vicinity of said tank has occurred.

4. The circuit breaker of claim 3 in Which said means Vresponsive to said predetermined operation of the device in the vicinity of said tank comprises a push-pull type v'vire coupling interconnecting said device and said operating rod for converting motion accompanying operation of said device into rotary motion of said operating rod.

5. The circuit breaker of claim 3 in which said coupling means is constructed to permit longitudinal motion of said insulating operating rod without causing a change in the angular position of said operating rod until said device operates and in which said coupling means is further constructed to produce angular motion of said operating rodV without changing the longitudinal position of the operating rod irrespective of the then-prevailing longitudinal position of the operating rod.

No references cited.

Claims (1)

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING A TANK ADAPTED TO CONTAIN PRESSURIZED GAS, SEPARABLE CONTACTS WITHIN SAID TANK, AT LEAST ONE OF WHICH IS MOVABLE RELATIVE TO SAID TANK, MEANS FOR ELECTRICALLY CONNECTING SAID MOVABLE CONTACT TO SAID TANK WHEN SAID MOVABLE CONTACT IS IN ITS OPEN AND CLOSED POSITIONS, MEANS FOR INSULATING SAID TANK FROM GROUND, CONTROL VALVE MEANS AT THE POTENTIAL OF SAID TANK OPERABLE TO CONTROL THE MOTION OF SAID ONE CONTACT, AN INSULATING OPERATING ROD FOR SAID CONTROL VALVE MEANS EXTENDING FROM SAID CONTROL VALVE MEANS TO A POINT AT GROUND POTENTIAL, MEANS FOR EFFECTING LONGITUDINAL MOTION OF SAID OPERATING ROD TO CONTROL OPERATION OF SAID CONTROL VALVE MEANS, MEANS RESPONSIVE TO MOTION OF SAID MOVABLE CONTACT FOR EFFECTING ANGULAR MOTION OF SAID INSULATING OPERATING ROD, AND MEANS AT GROUND POTENTIAL RESPONSIVE TO ANGULAR MOTION OF SAID OPERATING ROD TO PROVIDE AN INDICATION THAT SAID MOVABLE CONTACT HAS RESPONDED TO OPERATION OF SAID CONTROL VALVE MEANS.

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