Abstract:
A group operated circuit disconnect apparatus for overhead electric power lines has a base in the form of a box-like housing which mounts on a pole, an upright shaft extends through the housing, and a transverse shaft also extends through the housing. A linkage is mounted on the shafts in the housing so that axial rotation of the transverse shaft axially rotates the upright shaft, and this causes three circuit disconnect switches mounted on the housing to be moved simultaneously between closed positions and open positions, or vice versa. An electric motor driven screw and nut drive subassembly for the transverse shaft is mounted in the housing; and the ends of the housing have removable closure plates for access to the linkage and for removal of the subassembly.

Description:
This is a continuation of application Ser. No. 74,127 filed Sept. 10, 1979, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     Overhead electric power distribution lines require circuit disconnect means at certain locations; and since such distribution lines commonly operate in a three-phase system, there are three associated lines which ordinarily must be disconnected and reconnected simultaneously. This requires group operated switches, and for safety and convenience during servicing of the lines, it is desirable that a person be able to open and close the circuit disconnect means on the overhead lines from ground level or from a remote central terminal. 
     The present invention is a power driven version of the group operated circuit disconnect apparatus of my U.S. Pat. No. 4,095,061. 
     There are power operated oil break units for remote switching of electric power transmission lines. The purpose of such units is generally to isolate a fault such as a short circuit. They are dangerous for a person working on the lines because the switches are concealed from view so there is no visual indication of whether they are open or closed. 
     In general, prior art power driven circuit disconnect apparatus which can be controlled either from the ground or from a remote central terminal has been mechanically very complex and has also been expensive. 
     SUMMARY OF THE INVENTION 
     The principal object of the present invention is to provide an improved power driven group operated circuit disconnect apparatus for three-phase overhead electric power lines; and one which is far less expensive than anything in the prior art. 
     Another object of the invention is to provide such an apparatus in which the power drive and the switch operating mechanism are all in a weather proof box-like housing which mounts on top of a pole and serves as a base for the three switches. 
     Still another object of the invention is to provide a power driven group operated, circuit disconnect apparatus which may be completely adjusted in the manufacturer&#39;s plant and mounted without field adjustment. 
     Still another object of the invention is to provide a group operated circuit disconnect apparatus in which driving force from an electric motor rotates one shaft by means of a simple screw and nut drive, with power from that shaft being transmitted to another shaft through a very simple mechanical driving connection so that all three switches are opened and closed simultaneously. 
     Yet another object of the invention is to provide an apparatus which can utilize either a battery operated D. C., motor or a 120 v. A.C. motor. 
     A further object of the invention is to provide an apparatus which has a power subassembly that can be easily disconnected from a driven shaft and removed as a unit from the weather-proof housing. 
     Still a further object of the invention is to provide a circuit disconnect apparatus for three phase electric power lines that can be easily changed from manual to power operation or vice versa. 
    
    
     THE DRAWINGS 
     FIG. 1 is a side elevational view of a power driven group operated circuit disconnect apparatus embodying the invention, with a control box shown partly in section; 
     FIG. 2 is a fragmentary longitudinal horizontal sectional view on an enlarged scale take substantially as indicated along the line 2--2 of FIG. 1; 
     FIG. 3 is a fragmentary longitudinal vertical sectional view with parts broken away, taken substantially as indicated along the line 3--3 of FIG. 2; and 
     FIG. 4 is a fragmentary transverse sectional view taken substantially as indicated along the line 4--4 of FIG. 2 with parts omitted for clarity. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings in detail, and referring first to FIG. 1, a pole, indicated generally at P, has an upper end U to which a mounting bracket 8 is attached; and bolted to the upper end of the bracket 8 is an angle bracket 9 to which is secured the circuit disconnect apparatus of the present invention, which is indicated generally at 10. 
     The apparatus 10 includes a base, indicated generally at 11, which consists of a box-like housing having side walls 12 and 13, a bottom wall 14 and a top wall 15. The base 11 has removable closures 16 and 16a at its ends. 
     Extending through the base 11 is an upright shaft means, indicated generally at 17, and transverse shaft means, indicated generally at 18. A first disconnect switch, indicated generally at 19a, surmounts the base 11 and is operated by rotation of the upright shaft means 17; while a second disconnect switch 19b is mounted upon the base side wall 12, and a third disconnect switch (not shown) is mounted on the sidewall 13. Both of said last named disconnect switches are operated by rotation of the transverse shaft means 18. 
     A mechanical connection, indicated generally at 20, interconnects the upright shaft means 17 and the transverse shaft means 18 so that the two shaft means rotate simultaneously and equally. 
     The shaft means 17 and 18 and the mechanical connection 20 are fully described in U.S. Pat. No. 4,095,061; so no detailed description is given here. 
     The power drive for the circuit disconnect apparatus consists of a subassembly, indicated generally at 21, which is best seen in FIGS. 2 and 3. A base plate 22 is secured to the housing bottom wall 14 by a pair of hex-headed machine screws 22a which screw into threaded holes in the base plate; and mounted upon the base plate is a terminal block 23; motor mounting brackets 24; and a bridge frame, indicated generally at 25. 
     The mounting brackets 24 support a fractional horsepower A.C. motor 26 which may, for example, be 0.5 h.p. A motor shaft 27 is provided with a flexible coupling 28; and a threaded shaft 29 has one end connected to the flexible coupling 28. 
     The bridge frame 25 consists of an upright support block 30 and an upright bearing block 31 which are surmounted by parallel rails 32 and 33. An opening in the support block 30 accommodates the outer end portion of the flexible coupling 28; and the bearing block 31 serves as a mounting for a flanged bearing 34 which rotatably receives a coupling 35 which carries the outer end of the threaded shaft 29 and is a part of an assembly including the threaded shaft 29, a universal joint 36, and a coupling 37 to which the inner end of a power screw 38 is fixedly secured. 
     As best seen in FIGS. 3 and 4, the power drive is operatively connected to the transverse shaft means 18 by a threaded drive nut 39 which is adapted to travel along the power screw 38, and a crank yoke, indicated generally at 40. The crank yoke includes a collar member 41 which is fixedly secured to the transverse shaft means 18 and has an offset crank arm 42, and a yoke arm 43 which includes a mounting portion 44 and an offset yoke portion, so integral trunnions 45 on the threaded drive nut 39 may be received in holes in the offset crank arm 42 and the offset yoke portion 43, and the crank assembly 40 can be disconnected from the drive nut 39 by removing a machine screw 46 by which the offset crank arm and the offset yoke arm are secured together. 
     The power screw 38 and the threaded drive nut 39 provide a driving connection between a power unit (motor 26) and the crank arm 42. In that driving connection the drive nut 39, with its trunnions 45 received in the holes in the crank arm 42 and the yoke portion 43, serves as a member which is fixedly pivotally connected to the outer end of the crank arm, and the threaded connection between the drive nut 39 and the power screw 38 provides means for linearly reciprocating said member. Further, the universal joint 36 serves as mounting means which permits displacement of the linear reciprocating means 38-39 relative to the axis of rotation of the transverse shaft means 18 and in the plane of the crank arm 42, to compensate for the difference between the linear reciprocation of the drive nut 39 and the arcuate movement of the outer end of the crank arm 42. 
     From the foregoing description, it is apparent that the entire power subassembly 21 may be removed from the housing 11 by removing the end closures 16 and 16a, removing the machine screw 46 and disengaging the trunnions 45 from the crank member 40, and removing the machine screws 22a that secure the subassembly to the housing bottom wall 14. It is also necessary, of course, to disconnect from the terminal block 23 an electrical cable 47 which extends through a hole in the housing side wall 12 and has a lower end connected to a control box 48 which is near ground level on the post P. A flanged rubber sealing collar 49 snugly grips the cable 47 and makes a tight sealing fit in the hole in the housing side wall 12. 
     Mounted upon the bridge frame rail 32 are limit switches 50 and 51 which are seen in FIG. 2 to have respective actuator arm follower rollers 50a and 51a extending into the space above an opening between the rails 32 and 33 where they may be contacted by a threaded traveler 52 which is mounted upon the threaded shaft 29 and has an upper actuating portion 53 above the horizontal plane of the rails 32 and 33 where it has first and second actuating cam faces 53a and 53b which may contact the limit switch follower rollers 50a and 51a, respectively, as the traveler 52 moves back and forth responsive to rotation of the threaded shaft 29. 
     In the drawings the traveler 52 is seen to be in contact with the follower roller 51a of the limit switch 51, which is therefore a switch that stops operation of the motor 26 when the disconnect switches are fully closed. The limit switch 50, therefore, serves to stop operation of the motor 26 when the disconnect switches reach their fully open positions. 
     In order that the present apparatus may be readily converted from manual to power operation, the lower end of the shaft means 17 has a removable cap 54 (FIGS. 3 and 4) which has holes 55 in its side wall that align with a bore in the lower end portion of the shaft means 17. When the cap 54 is removed a manual operating crank shaft may be operatively connected to the lower end of the shaft means 17 by a pin extending through the bore as taught in U.S. Pat. No. 4,095,061. 
     A safety stop bracket 56 alongside the cap 54 has a hole 57 which is in the same horizontal plane as the holes 55 and the aligned bore of the shaft means 17. The disconnect switches, of course rotate 90° from the enclosed position of FIG. 1 to a fully open position; so when the switches are open the bore in the shaft 17 and the aligned holes 55 in the cap 54 are also aligned with the hole 57, permitting insertion of a retaining pin through the bore and through the holes 55 and 57 to mechanically lock the disconnect switches in their open positions for the added safety of anybody working on the line. 
     The control box 48 contains a switch 47a for starting the motor 26; and in case the circuit disconnect apparatus is also intended for control from a central point, as in increasingly the case in major power distribution systems, the control box 48 must also, of course, have a terminal to the central control system with an interlock which permits a person working on the line to disable the central control hook-up to eliminate the possibility that the switch may be closed from the switching center while he is working on the line. 
     When the power drive has an A.C. motor as here described, it is easily driven either to open or close the disconnect switches by a 110 volt energizing circuit from the power line. On the other hand, where a direct current motor is used the control box must also contain a transformer and storage batteries to furnish a direct current source for energizing the motor, which may be as small as 0.25 h.p. There is some advantage in direct current operation in the event of a power failure, because current batteries, which are kept constantly charged, can reliably open and close the switches as much as 25 or 30 times, even if the power is off. However, the A.C. operating system is, of course, simpler and much less expensive. 
     The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.