US2400936A - Line shorting contactor - Google Patents

Description

May 28, 1946. F. L. KRADEL ETAL LINE SHORTING CONTACTOR Filed'May 7, 1943 3 Sheets-Sheet l wuc/Wtou:

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sV H May 28, F L KRADEL EAL LINE SHORTING CONTACTOR Filed May 7, 1943 3 Sheets-Sheet 2 May 28, 1946.

F. L. KRADEL ETAL LINE SHORTING CONTACTOR Filed May 7, 1943 3 Sheets-Sheet 3 Patented May 28, 1946 LINE SHORTING CONTACTOR Fred L. Kradel and Rudolph Paulin, Greensburg,

Pa., assignors to Railway and Industrial Engineering Company, Greensburg, Pa., a corporation of Delaware Application May '7, 1943, Serial No. 486,()58

(Cl. ZUG-97) 13 Claims.

This invention relates to line shorting contactors that are employed on 'electrical distribution systems .to suppress the flow of a fault current by stablishing a metallic short circuit across the line at a point between the current source and the fault.

Protective systems that include line shorting contactors are described and claimed in the copending application of George A. Matthews, Ser. No. :333,875, filed May 7, 1940, Apparatus for protecting power lines", which became Patent No. 2,334,571 on November 16, 1943; and the present invention relates particularly to novel mechanical constructions for switch devices that have the Operating characteristics of the line shorting contactors described in that application.

An object of the present invention is to provide line shorting contactors that include blocking mechanlsms of relatively simple construction for preventing a reclosure of the shorting contactor immediately after a fault-actuated closure and opening thereof. An object is to provide a line shortlng contactor that includes a counter for registering the number of Operations thereof, and associated signal vanes for indicating the condition of the shorting ccntactor, i. e., normal open condition, closed, or open but locked against reclosure.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawings in which:

Fig. 1 is a vertical section through a line shorting contactor embodying the invention;

Fig. 2 is a fragmentary side elevation of the same as seen from the right of Fig. 1;

Fig. 3 is a schematic circuit diagram of the line .shorting contactor;

Fig. 4 is a fragmentary sectional View, on a larger scale, of the upper part of the device as seen from the rear of Fig. 1;

Fig. 5 is a perspective view of the part of the mechanism for blocking a reclosure of the line shorting contactor; and

Figs. 6, '7 and 8 are schematic views illustrating the control and indicating mechanism in, respectively, normal position, contactor closed position, and contactor locked-out position.

The protective switch or line shorting contactor is a, fully automatic self-contained unit within a chamber comprising a hollow insul'ator n having an approximately cylindrical metal casting I I cemented to its upper end to receive the domed cover [2 that termlnates in a flanged oil filler opening to which the filler cap !3 is threaded.

The cap s has a flange or skirt that fiares away from the cylindrical threaded section to cover vent openings M that extend through the cap, and the top portion of the cap is formed as a lifting ring. The lower end of the insulator ti! is closed except for a central bore through which a line shorting circuit connection extends, as will be more fully described hereinafter. The outer surface of the insulator is preferably of the usual petticoat type or is otherwise circumferentially grooved to receive a supporting bracket !5 by which the shcrting contactor is mounted on a pole at any desired point in the circuit.

A source or line terminal !6 enters the casting or shell II through an insulating bushing I?, and a load terminal s is integral with the shell H. The Operating winding of the contactor preferably comprises two coils IS, !9' of the same or of different designs that may be co-nnected to the terminals s, !8 in parallel or in series, the series connection providing a mld-point tap that adapts the contactor for use at a point along the line at which there may be a reversal of the direction of current flow under some Operating conditions. The series connection of the coils !9, 19' is illustrated in Figs. 1, 2 and 3. A connecting strap 20 joins the line terminal [6 to the lower end of coil I 9, and the lead 2! from the upper coil end extends downwardly along the I coil and is Secured to the strap 22 that is bolted to one end of a yoke 23.

A strap 24 connects the other end of the yoke 23 to the lower terminal of coil s', and the upper coil terminal 26 is bolted to the flexible jumper 21 that extends to the metalllc supporting structure and thereby to the line terminal !8. Flexible jumpers 28 connect the opposite ends of` the yoke 23 to the shorting contact 29, Fig. 3, that is moved into engagement with the cooperating contact 30 upon a predetermined current flow through the coils te, IQ'.

The coils are connected in series in one conductor L of a tWo-Wire distribution system by means of the terminals !6, !8, and the other contact 3!! of the shorting contactor is connected to the other conductor L,-' i. e., the distribution circut is short-circuited by a closure of the contacts 28, 30 upon the occurrence of a fault that result in excessive current flow. The shorting contactor closes in from to 2 cycles, on a cycles per second distribution system, and results in a heavy current flow through the metallic short-circuit that operates the circuit protective equipment, for example the circuit breakers of a distribution system such as illustrated in the copending Matthew application, and stops the flow of current at the fault point, thereby protecting the line conductors against burnofi. The interrupticn of current flow at the circuit breaker deenergizes the coils 19 IS', and the shorting contactor opens and is prevented from reclosing for a preselccted period during which the protective equipment operates through a series of reclosures to a locked-out condition in the event of a permanent fault. The mechanism for delaying a reclosure of the shorting contactor preferably includes both a mechanical lock-out that will be described later and a switch, comprising Contacts 3l, 32, for shunting the coils !9, 19.'

The coils !9, 19' each comprise a single or multiple layer solenoid wound from flat copper bar and having both terminals at one end of and at diametrically opposite sides of the coil. The coils are mounted within a laminated yoke 33 and reversely arranged to locate ali terminals at the level of a transverse plane at the center of the coil assembly. This terminal design and coil arrangement simplifies the Construction of the circuit elements for connecting the coils in series or in parallel. Skeleton plates 34, 34' are riveted to the outer sides of the magnetic yoke 33 and ar Secured by bolts 35 to an upper pair of skeleton plates 36, 36' that have integral ears for securing the skeleton frame assembly to and grounding it upon the casting l I. The Operating coil or coils !9, l9' are anchored in fixed position by pressure screws 31 that extend through lugs of the frame plates 34, 34'.

The lower central section 38 of the yoke rests upon a rubber cushioning member 39 and serves as a stop for the armature 40, the cushioning member 39 bein supported on a plate 4| that is Secured to the plates 34, 34'. The armature 40 comprises laminations bolted to the switch rod or plunger 42 that extends above the armature to Carry a part of, and to actuate, the control mechanism. The movable contact 29 is secured to and insulated from the plunger 42 by a bushing 43 of insulating material. The cooperating contact 30 comprises a cylindrical assembly of resilient strips of a copper or bronze alloy carried by a bridge member 44 that is Suspended below the supporting plates 34, 34' by straps 45 of insulating material. The conducting yoke 23 is mounted on one of the insulating straps 45. The bridg 44 has a central bore for guiding the stem 46 that carries a conical contact 41 and is pressed by spring 46 towards a terminal assembly at the base of the insulator 10. Flexible jumpers 49 connect the bridge 44 to the contact 41 to provide a low resistance path for current flow when the shorting contactor is closed. The fixed terminal assembly comprises a stud 50 having a conically recessed head to receive the contact 41, and a stem that extends through the insulator l and has a lower end upon which the terminal member l is threaded.

When the coils l9, IS' are connected in parallel, the yoke 23 is not necessary and the shorting contact 29 is mounted directly upon the plunger 42 that is grounded on the supporting structure and thereby electrically connected to the terminal 18.

The mechanism for blocking a reclosure of the line shorting Contacts 29, 30 is illustrated in Figs. 1 and 4, and different stages of one Operating cycle are shown somewhat diagrammatically in Figs. 6-8. The stern 52 of the movable contact 32 of the shunting switch extends through and can rock on a double arm or bridge member 53 that is pivotally supported on a fixed shaft 54, and a fiexible jumper 55 extends through a sleeve 56 of the mor/able contact assembly and its ends ar bolted. to the supportin frame, preferably by the same bolt 35 that clamps the flexible jumper 21 to the frame plate 35', to provide a low resistance connection between the movable contact 32 and th line terminal !3. The bridge member 53 is urged clockwise by a helical spring 51 that has ends hearing on member 53, intermediate side sections coiled about the shaft 54 and a central section engaging the Operating and control arm 53; and the angular movement of the bridge member 53 is limited by the engagement of its crossbar 53' with the Operating arm 58, see Fig. 5.

The Operating and control arm 53 is pivoted on the shaft 54 and comprises a U-shaped member 59, hardened steel end bar 60 that connects the side bars of member 59, and a U-shaped or double-armed leaf spring 6! within the member 59 and riveted to the end thereof. The bridge member or contact-carrying arm 53 and the Operating arm 50 are urged counterclockwise, i. e., towards open circut position, by the coil spring 62 that is connected between the arm 53 and the supporting plates 36'. The ends of spring 65 flar inwardly and co-o erate with a downwardly directed spear-shaped member 63 on the plunger 42 to form a one-way coupling between the plunger arm 50 and the plunger 42. The spear-shaped member 63 spreads the ends of springs U! When the plunger moves down in response to a predetermined current flow through the coils 13, iS'. Upon interruption of current flow through coils 19, l9', the plunger 42 is lifted by the spring 64, and the control arm 59 i then turned clockwise, to close the shunting contacts 3I, 32, by engagement of the upper radial surfaces of th member 63 with the ends of the leaf springs 6 l.

The mechanism for mechanically looking the shunting Contacts in closed position includes the looking lever 65 and trigger 66 that are pivotally mounted on the plates 35, 36' by a shaft 61, the lever 65 and trigger 66 being normally retained in approximate alinement by a spring 69. The tail of the trigger 65 normally rests against the crossbar 65' of lever 65, and it strikes a stop pin 10 to arrest the trigger in looking position when the lever 65 is forced down by the lug 1! that is fixed to the plunger 42.

The lever 65 is coupled by a link 13 to the arm 14 of a time delay mechanism that impo'ses substantially no delay upon the clockwise movement of lever 65 upon downward movement of plunger 42 to close the shorting contacts 29, 30, and that delays the return movement of the lever into unlocking position. The time delay mechanism may be of any desired type and, as illustrated, the arm 14 is secured to a shaft carrying a ratchet wheel 15 that is coupled by pawls 16 or overrunning clutch to a gear 11 of an escapement mechanism, not shown. Rotation of arm 14 and shaft by link 13 coils a spring, not shown, that tends to rotate the arm 14 clockwise to lift the link 13 and locking lever 65. Gear 11 `is loose on the shaft, but is driven through the pawl and ratchet mechanism when the hait is rotated clockwise, thue delaying the lifting of the link 13 and locking lever 65.

The lever 65 is connected by link 18 to the operating arm of a Veeder counter 19 that is mounted within the casting ll at a window through which the counter is normally exposed to View.

Signa vanes 8l, 82 are carried by levers 83, 84, respectively, for movement into line with the window opening when the shorting contacts 29, 30 are closed and when the shorting contacts are open but locked against closure. The vanes 81, 82 are of diiferent colors, for example red and yellow respectively, to indicate the different condition of adjustment of the shorting contactor. The signal vanes are normally moved away from the window opening by the sprin 85 that joins the levers 83, 84, and the vanes are moved into operative positions by a resilient connection 86 from plunger 42 to lever 33, and by a link 81 from the bridge member 53 to the lever 84.

The method of operation of the shorting contactor will be apparent from a consideration of Figs. 6, '7 and 8 that illustrate the positions of the several elements of the control mechanism whenmespectively, (l) the contactor is in normal inactive condition, (2) when the shorting contacts 29, 30 are closed, and (3) when the shorting contacts 29, 33 are open and locked against reclosure. A fault on the line L, L' results in excessive current fiow through the windings le, lil' and the plunger 42 is moved downwardly by the armature 40 to close the shorting contacts 29, 3& The control and indicating mechanisms are then in the positions illustrated in Fg. 7. The control arm 58 has not changed position but the spear member 63 on plunger .2 has forced aside the leaf springs ai and moved below the same. Lever 65 was forced down by the lug 'H on plunger 42, and set the time delay mechanism by pulling down the arm 74. The trigger 66 moved clockwise with lever 55 until its tail engaged the stop pin 10, and the counter la was actuated by the lever 65. The vane 8! was moved downward into line 'with the window opening 80 by its spring connection 85 to the plunger 42.

Upon interruption of current flow through the coils !9, IS', by operation of the circuit breakers or otherwise depending upon the design of the protective equipment, the plunger 42 is lifted by the spring G i to open the shorting contacts 29, 30. The contro mechanism elements then occupy the positions illustrated in Fig. 8. The control arm 58 is turned clockwise by the spear member 63, thereby closing the contacts 31, 32 that Shunt the coils iii, iii' and block a reclosure of the shorting contacts. The end bar 60 of the control arm forces the trigger 66 aside as the arm 53 is lifted, and then rests upon the end surface of the trigger when the spear member 53 moves above the leaf springs Si and the arm 58 is turned counterclockwise by the spring 62. This partial return movement of the arm 58 bring the encls of the leaf springs 61 against or closely adjacent the sloping surfaces of the spear member 63 and mechanically locks the plunger against downward movement. The signal vane 8! moved out of the window openingwhen the plunger 42 lifted but the vane 82 was movedinto the window opening by thelink 87 when the shunting contacts closed. The lever 65 is rotated counterclockwise by the link ?3 and the' time delay mechanism and, after a preselected interval, the crossbar 65' of the lever 65 engages the tail of the trigger 66 and moves the trigger out of the path of the control arm 58. The control arm 58 is then moved counterclockwise by the spring 62, and thereby the shunting contacts 3l, 32 are opened and the mechanical lock against reclosure i removed. All parte then occupy their normal positions as illustrated in Figs. 1, 3, 4 and 6.

The Operating coils 19, I 9' and restoring spring 12 are so related that the shorting contacts 29, 30 close substantially instantaneously, i. e., in from %20 to of a second, upon the occurrence of a fault, thus suppressing the flow of fault current by placing a metallic short circuit upon the line. The short circuit current actuates a circuit interrupter (fuse or circuit breaker) to remove the voltage from the line, and the shorting contacts are then opened by the restoring spring 64 and are locked out for a predetermined period to permit the circuit interrupter mechanism to operate through a series of reclosures to a lockout in the event of a permanent fault. The great majority .of all faults are of a transient nature, however,

and normal service is usually restored upon the first reclosure of the circuit interrupter mechanisin.

There is considerable latitude in the design, Construction and relative arrangements of the several elements of the shorting contactors and it therefore is to be understood that various changes may be made in the disclosed constructions without departure from the spirit of our invention as set forth in the following claims.

We claim:

1. A line shorting contactor of the type including a normally open switch having a, fixed and a movable contact for connection to opposite sides of a power distribution line, electrically actuated switch closing means including a plunger carrying the movable contact for closing said switch, and blocking means operative upon an opening of said contacts to prevent reclosure thereof for a predetermined interval, characterized by the fact that said blocking means comprises a pivotally mounted arm, a one-way coupling for moving said arm into actuated position upon a switchopening movement of said plunger, said coupling comprising a member on said plunger and spring means on said arm in the path of said member and deflectible therefrom by the member on a switch-closing movement of said plunger, spring means tending to return said arm from its actuated position, and means including a time-delay mechanism for controlling the return of said arm from its actuated position.

2. A line shorting contactor as recited in claim 1, wherein said blocking means includes a normally open switch for rendering said switch closing means inoperative, and means movable by said arm on displacement into actuated position to close said second switch.

3. A line shorting contactor as recited in claim 1, wherein said blocking means includes means on said plunger and cooperatng with said arm for looking said plunger against switch-closing movement when said arm is in actuated position.

4. A line shorting contactor as recited in claim 1, wherein said member on said plunger and said spring means on said arm have cooperating surfaces locking said plunger against' switch-closing movement when said arm is in actuated position.

5. A line shorting contactor as recited in claim 1, wherein said blocking means includes a normally open switch for rendering said switch closing means inoperative, and means movable by said arm on displacement into actuated position to close said second switch; and said member on said plunger and said spring means on said arm have cooperating surfaces looking said plunger against switch-closing movement when said arm is in actuated position.

6. In a line shorting contactor, a normally open switch having contacts for connection to opposlte sides of a power distribution line, electrically actuated means including a plunger for closing said switch, and means mechanically looking said plunger against a switch-closing movement upon a switch-opening movement thereof; said locking means includin a pivotally mounted control arm, a one-way coupling including a member on said plunger for moving said control arm to actuated position upon a switch-opening movement of said plunger, a pivoted trigger member engageable with said control arm when in actuated position to prevent return thereof to normal nonactuated position, and time-delay means for moving said trigger member out of engagement with said control arm, thereby rendering said looking means inoperative.

'7. In a line shorting contactor, the invention as recited in claim 6, in combination with switch means operable by movement of said control arm to actuated position to render said electrically actuated means inoperative.

8` In a line shorting contacto' including normally open switch Contacts and means including a plunger for closing said switch Contacts; blocking' means to prevent reclosure of said. switch contacts upon an opening thereof, said blocking means comprising a pivotally mounted control arm and means for moving the same into actuated position upon a switch-opening movement of said plunger, a trigger, a. locking leve` operable by said plunger on a switch-closing movement thereof to move said trigger into the path of return movement of said control arm, and means including said locking lever and a time-delay mechanlsm for moving said trigger out of the path of return movement of said control arm.

9. In a line shorting contacto' including a pair of normally open switch Contacts and means including a plunger for closing said switch contacts; blockin means for preventing a reolosure of the switch Contacts upon an opening thereof, said blocking means comprising a control arm, a resilient one-way coupling of said plunger to said control arm for moving the latter to actuated position upon a switch-opening movement of the plunger, and looking means for preventing return of said control arm from actuated position, said looking means including a looking lever and means on said plunger for moving said looking lever into actuated position upon a switch-closing movement of said plunger.

10. In a line shorting contactor, the nvention as recited in claim 9 wherein said control arm comprises a pivotally mounted member having side bars at opposite sides of said plunger; and said resilient one-way coupling includes a leaf spring, Secured within said mounted member and having inwardly flared ends, and a spear-shaped member on said plunger for pressing aside and moving beyond the ends of said leaf spring member upon a switch-closing movement of said plunger,

11. In a line shorting contactor, the invention as recited in claim 9, in combination with means operated by said control arm for rendering said contact-closing means inoperatve upon movement of said control arm into actuated position.

12. In a line shorting contactor, a pair of normally open switch contacts electrcally actuated means i'or closing said switch contacts upon excessive current flow, means for separating said switch contacts upon a removal of voltage after a closure of said switch contacts, means for blocking reclosure of said switch Contacts for a predetermined interval after an opening thereof, a counter operated by said blocking means for registering the number of closures of said switch Contacts, a signal vane, and means operable by said electrically actuated means to move said signal vane to prevent obse'vation of said counter simultaneously with a closure of said switch contacts.

13. In a line sho'ting contactor, the invention as recited in claim 12, in combination with a second signal vane, and means for displacing the second signal vane into position to block observation of said counter, said displacing means being operable by said blocking means upon actuation the'eof to block a reclosure of said switch contacts.

FREE L. KRADEL. RUDOLPH PAULIN.

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