GB2101810A - An intermittent driving apparatus for a change-over switch in an on-load tap-changer - Google Patents

Abstract

An intermittent driving apparatus of an on-load tap-changer connects the driving side of the tap changer 2 with a change-over switch for the purpose of broadening the regulation range of the tapping coil and comprises a multiple intermittent driving means 11, 12, 13 of the pin gear type having its input side 11 connected at 5 to the driving side of a quick-motion mechanism, and a Geneva gear means 14, 15, the input side of which is integral with the output side 13 of the multiple intermittent driving means and the output 8 of which is connected to the moving contact of the change-over switch, the multiple intermittent driving means being provided with as top means 13b, 13c which cooperates with member 11c to prevent movement of the output shaft 8 when not driven, and the centre line of the output side 15 of the Geneva gear means coincides with the centre line of the driving side of the quick-motion mechanism. <IMAGE>

Description

SPECIFICATION An intermittent driving apparatus for a change-over switch in an on-load tap-changer The present invention relates to an intermittent driving apparatus for a change-over switch in an on-load tap-changer.

A change-over switch which has the object of broadening the regulation range of a tapping coil in an on-load tap-changing transformer has been hitherto constituted such that the actuation of the moving contact of the change-over switch is allowed only at the time when the moving contacts of the tap changer are at predetermined stationary contacts thereof.

Atypical on-load tap-changer has a constitution as shown schematically in Figure 1 of the attached drawings. As shown, a worm wheel 1 which is a power source for a so-called quick-motion mechanism is rigidly connected to one end of a change-over switch driving shaft 3 which passes through a tap changer or tap selector 2, all of them contained in an insulating vessel 4. The other end of change-over switch driving shaft 3 is connected to a moving contact (not shown) within a change-over switch 9 by a coupling 5, a diverter switch input shaft 6, an intermittent driving apparatus 7 and an output shaft 8.

With this constitution, diverter switch driving shaft 3 can be operated at all positions of the tap changing operation. Nevertheless, the moving contact of change-over switch 9 must be intermittently driven and also be subjected to a further limitation that it must be operated within a time period shorter than the time period necessary for tap selector 2 to carry out one tapping operation.

Moreover, in general, since the voltage applied between the stationary contacts of the change-over switch is higher than the voltage applied between the stationary contacts of the tap selector, the distance between the stationary contacts of the change-over switch is required to be largerthanthat in the tap selector. Therefore, in the change-over switch the operational angle must be larger than that in the tap selector. Further, since it is necessary to arrange change-over switch 9 below tap selector 2 within insulating vessel 4 in order to make the overall dimensions of the apparatus compact, it is required that change-over switch input shaft 6 and output shaft 8 be arranged in a line. In addition, change-over switch 9 is subject to another limitation that it can be expected to undergo almost no maintenance inspection during the whole life of a transformer of this kind.

Thus it will be appreciated that the change-over switch in an on-load tap-changer is subjected to various constitutional and operational limitations.

It is an object of the present invention to provide an intermittent driving apparatus for connecting the driving side of a tap changer or a tap selector and a change-over switch in an on-load tap-changer which can overcome all of the limitations of a conventional intermittent driving apparatus of this kind.

It is another object of the present invention to provide an intermittent driving apparatus for connecting the driving side of a tap changer or a tap selector and a change-over switch in an on-load tap-changing transformer which is simple in constitution and can be manufactured economically.

It is a further object of the present invention to provide an intermittent driving apparatus for connecting the driving side of a tap changer or a tap selector and a change-over switch in an on-load tap-changer which can allow the change-over switch to operate properly over the whole life of the transformer and which exhibits excellent reliability.

To achieve the above objects, the present invention provides an intermittent driving apparatus for connecting the driving side of a tap selector and a change-over switch in an on-load tap-changer which comprises a multiple intermittent driving mechanism of the pin gear type, the input side of which is connected to the driving side of a quick-motion mechanism and a Geneva gear, the input side of which is integrally formed with the output side of the multiple intermittent driving mechanism and the output side of which is connected to the moving contact of the change-over switch, the multiple intermittent driving mechanism being provided with a constraint means to prevent its output side from being moved when it is not driven, and the axial line of the output side of the Geneva gear is coaxially arranged with the axial line of the driving side of the quick-motion mechanism.

These and other objects of the present invention will become more readily apparent upon reading the following specification and upon making reference to the accompanying drawings, in which: Figure 1 is a schematic side elevational sectional view of the whole of an on-load tap-changer having a change-over switch and provided with an intermittent driving apparatus in accordance with the present invention; Figure 2 is a partial side elevational sectional view of the intermittent driving apparatus in accordance with the present invention shown in Figure 1; Figure 3 is a cross sectional view of the driving apparatus shown in Figure 2 taken along the lines III Ill in Figure 2;; Figures 4A, B and C are explanatory diagrams showing the states of the main components of the multiple intermittent driving mechanism of the intermittent driving apparatus shown in Figure 2 at various stages of the operation; Figures 5A, B and Care explanatory diagrams showing the states of the main components of the Geneva gear of the intermittent driving apparatus shown in Figure 2 at the various stages of the operation; and Figure 6 is an explanatory diagram of the intermittent driving apparatus shown in Figure 2 at the state of the stoppage of the interlocking member with the stop member thereof being engaged by the constraint member of the Geneva gear.

Figures 2 and 3 of the attached drawings show an embodiment of the present invention wherein an input shaft 6 of a change-over switch is connected to a driving shaft 3 of the change-over switch (see Figure 1) trough a coupling 5. Shaft 6 is rotatably supported at its upper portion by bearings 1 Oa and oil sealing means 1 Ob in a support frame 10 which constitutes a part of an insulating vessel 4 which isolates a tap changer or tap selector 2 from an intermittent driving device 7 and change-over switch 9 (See Figure 1). Rigidly connected to input shaft 6 at its lower end portion is a driving member 11 on which is formed a driving lever 1 lea which is one of the constitutional elements of a multiple intermittent driving mechanism of the pin gear type.Rotatably connected to input shaft 6 at its lower end portion below driving member 11 is a follower wheel 15, one of the constitutional elements of a Geneva gear, through a bearing 15a.

Rotatably mounted to a support frame 1 Odwhich protrudes from support frame 10 or isolating vessel 4 on the side nearest change-over switch 9 near the free end portion of driving lever 11 is an interlocking member 13 supported by bearings lOc on which is formed on the side nearest driving lever 1 lea a sprocket wheel 13a, one of the constitutional elements of the multiple intermittent driving mechanism, the center lines of sprocket wheel 13a and input shaft 6 being separated by a predetermined value, and sprocket wheel 13a has a predetermined pitch circle diameter. Interlocking member 13 is further provided with on the side nearest change-over switch 9, a driving pin 14, one of the constitutional elements of the Geneva gear.On interlocking member 13 between sprocket wheel 13a and driving pin 14 is additionally formed a circular disc-shaped stop member 13e with two concave arcuate portions 13b each having a predetermined radius being formed symmetrically, one of the constitutional elements of a stop device for constraining the operation of sprocket wheel 13a.

Driving member 11 is provided with a driving lever 1 lea as stated above, on the side nearest tap selector or tap changer 2 and this driving lever 11 a is provided with a number of pins 12, which in the present embodiment are four in number, such that they lie on a circle, the center of which is concentric with the center line of input shaft 6 and the radius of which is determined so that the pins can contact the pitch circle of sprocket wheel 13a.Also on driving member 11 on the side nearest diverter switch 9 is formed a circular disc-shaped constraint member 1 1c in alignment with stop member 13c, one of the constitutional elements of the stop device, which has a radius substantially the same as the radius of arcuate portion 13b of stop member 13c and is formed with a straight peripheral portion 1 1b so as not interfere with the rotation of stop member 13c of interlocking member 13, while when interlocking member 13 is stopped the circular peripheral portion of constraint member 1 1c engages one of arcuate portions 1 3b of stop member 1 3c so that the reversing of interlocking member 13 is prevented, but driving member 11 itself is allowed to freely rotate, as will be described fully later.

Follower wheel 15 of the Geneva gear is provided witha slot 1 sub so that wheel 15 can be rotated when slot 15bis engaged by driving pin 14 of interlocking member 13 as the result of the rotation thereof.

An output shaft 8 is rigidly connected to follower wheel 15 so as to be concentric with input shaft 6 so that when output shaft 8 is rotated it can drive the moving contact of change-over switch 9.

Now the operation of the present invention the constitution of which has been described above will be explained while referring to Figures 4A, B and C, and Figures 5A, B and C which show the operation of the multiple intermittent driving mechanism and the Geneva gear, respectively, at the various operational phases. In both Figures 4 and 5, A, B, and C represent the state prior to the initiation of the operation, the state during the operation, and the state after completion of the operation, respectively. It will be needless to say that the states shown in Figures 4A, B and C occur at the same as the states shown in Figures 5A, B, and C, respectively.

First, in the state wherein pins 12 of driving lever 11 a do not mesh with sprocket wheel 13a, as shown in Figure 6, one of the arcuate portions 13b of stop member 13coy interlocking member 13 engages the circular peripheral portion of constraint member 1 1c so that the free movement of interlocking member 13 is prevented, but driving member 11 is maintained in a position in which it can be freely rotated.

From this state, when driving member 11, and thus driving lever 11a is rotated counterclockwise as shown in Figure 4A by the arrow marked with an X due to the rotation of input shaft 6 of change-over switch 9 as a result of driving member 11 being connected to input shaft 6 of four pins 12 mounted to driving lever 11 a begin to mesh with sprocket wheel 13a, but as to the Geneva gear, as shown in Figure saithe meshing of driving pin 14 with slot 15b of follower wheel 15 does not yet occur.At this state, as constraint member 1 1c continues to rotate, since its circular peripheral portion has now come outside one of the arcuate portions 13b of stop member 13c as shown in Figure 4A and the straight peripheral portion 1 b of constrain member 1 1c corresponds to that of stop member 13c, constraint member 1 Ic is allowed to continue to be rotated with the rotation of input shaft 6. Therefore, driving lever 1 1a secured to input shaft 6 can be rotated together with pins 12 secured thereto so that sprocket wheel 1 3a is forced to rotate.

When driving member 11, and thus driving lever 11 a continues to rotate from this state, sprocket wheel 13a continues to rotate due to its meshing with pins 12 secured to driving lever 1 lea, and during the rotation of sprocket wheel 13a, the driving pin 14 which is rigidly secured to interlocking member 13 moves from the position shown in Figure 5A by the solid line at 14 to a position shown in Figure 5A by the dot-and-dash line at 14' so that driving pin 14 thereafter meshes with slot 1 sub of follower wheel 15, causing output shaft 8 connected thereto to be rotated, actuating the contact of change-over switch 9.

As a result of the movement of the respective elements ofthe intermittent driving mechansim as described above they occupy the positions shown in Figures 4B and 5B, and as they continue to move further, when driving pin 14 reaches a position shown in Figure Sc by the dot-and-dash line at 14", driving pin 14 and slot 1 sub unmesh.Therefore, the rotation of follower wheel 15 stops and its movement is prevented by the engagement of the circular periphery of the shaft portion of interlocking member 13 with one of the concave arcuate portions formed on the outer periphery of follower wheel 15 in symmetry with slot 1 sub, the radius of the concave arcuate portion of follower wheel 15 corresponding to that of the shaft portion of interlocking member 13, and the shaft portion thereof is formed with a cutout part so as not to interfere with the rotation of follower wheel 15. However, even in this state, owing to the separation of output shaft 8 to which follower wheel 15 is rigidly secured from input shaft 6, driving lever 1 1a, and thus also interlocking member 13 can still continue to be rotated, and they finally occupy the states shown in Figures 4C and 5C.

At this state, for the first time the pins 12 secured to driving lever 1 1a and sprocket wheel 13a unmesh.

Therefore, notwithstanding the continuous rotation of driving shaft 11, interlocking member 13 is stationary, and, upon engagement of the circular peripheral portion of contraint member 1 1c with one of concave arcuate portions 13b of interlocking member 13, the reverse motion of interlocking member 13 is prevented as shown in Figure 6.

Although the present invention operates as described above, in the embodiment described above the constitutional elements have been determined to have such a relationship that (i) the number of pins 12 is four, (ii) the rotational angle of driving lever 1 1a during the time period of the meshing of pins 12 with sprocket wheel 13 is 36", the same as one tapping angle of tap changer 2; and (iii) the rotational angle of sprocket wheel 13a is 180 , the rotation of sprocket wheel 13a is multiplied relative to that of driving lever 1 1a to be broadened, and at the same time, owing to the Geneva gear the rotation of follower wheel 15, and therefore, that of output shaft 8 rigidly connected thereto, or the rotation of the moving contact of change-over switch 9 can be reduced by the idle rotation angle of driving pin 14, i.e. the angle a before and after the rotation of follower wheel 15 as shown in Figures 5A and 5C. In the embodiment shown this angle a corresponds to about 1/5 times the full rotational angle of sprocket wheel 13a.

Thus an allowance can be given to the rotation of follower wheel 15 relative to the that of sprocket wheel 13a. The operational angle of the moving contact of change-over switch 9 can be adapted as desired within the range of the permissible operational angle of follower wheel 15 of the Geneva gear.

Further the value of the operational angle of follower wheel 15 itself and its operational angle with respect to the range of the operational angle of sprocket wheel 1 3a for the purpose of, for example, approaching the start of operation of follower wheel 15 to the start of operation of sprocket wheel 13a or retarding the former from the latter, can be adjusted by suitably setting the position of driving pin 14 of the Geneva gear.

Further, since in the present invention the intermittent driving apparatus comprises two combined stages, one being a pin gear device comprising driving lever 11 and sprocket wheel 13a, and the other being the Geneva gear comprising driving pin 14 and follower wheel 15, the concentric arrangement of input shaft 6 and output shaft 8 is made possible so that an on-load tap-changer can have a simple outside configuration as a whole as shown in Figure 1.

From the foregoing it will be appreciated that the present invention is quite advantageous in that it exhibits high electrical and mechanical reliability, giving high freedom, and it has a simple configuration, easily applicable to a transformer in terms of shape, allowing an easy manufacture, and makes an on-load tap-changer provided with a change-over switch easily realizable.

Although a preferred embodiment of the present invention has been described and illustrated, it will be understood by those skilled in the art that modifications may be made in structure, form, and relative arrangement of parts without necessarily departing from the spirit and scope of the present invention. Accordingly, it should be understood that all such modifications which fall within the scope of the invention are covered by the appended claims.

Claims (2)

1. In an on-load tap-changer provided with a quick-motion mechanism, a tap changer which carries out the tap changing by said quick-motion mechanism, a change-over switch which is part of said tap changer and an intermittent driving apparatus connecting the driving side of said quick-motion mechanism to said change-over switch, said intermittent driving apparatus comprising a multiple intermittent driving means of the pin gear type, the input side of which is connected to said driving side of said quich-motion mechanism, and a Geneva gear means, the input side of which is integral with the output side of said multiple intermittent driving means and the output side of which is connected to the moving contact of said change-over switch, said multiple intermittent driving means provided with a stop means adapted to prevent said output side thereof from moving when it is not driven, the center line of said output side of said Geneva gear means being concentric with that of said driving side of quick-motion mechanism.

2. An intermittent driving apparatus for a change-over switch in an on-load tap-changer as claimed in claim 1 wherein said multiple intermittent driving means comprises a driving member rigidly connected to the input shaft of said change-over switch coaxiallythereto which is connected to a rotary shaft of a worm gear constituting said driving side of said quick-motion mechanism, a number of pins mounted to a driving lever integral with said driving member, an interlocking member integral with a sprocket wheel so as to mesh with said pins, whereby said pins and the teeth of said sprocket wheel are arranged on their respective pitch circles such that said pins and said teeth mesh with each other with one of said pitch circles inscribing the other and the number of said pins and the diameters of said pitch circles are selected in accordance with an operational angle for effecting one tapping action of said tap-changer and in accordance with a desired multiple of said operational angle, and said Geneva gear means comprises a driving pin mounted to said interlocking member acting as its input side and a follower wheel acting as its output side and adapted to engage with said driving pin and rigidly connected to the output shaft of said change-over switch coaxially therewith which carries said moving contact and said stop means comprises a stop member integral with said interlocking member and having generally a disc shape with the periphery being partly cut off so as to form concave arcuate portions, and a constraint member integral with said driving member of said multiple intermittent driving means and having generally a disc shape, the diameter of which corresponds to that of said concave arcuate portions of said stop member, whereby said constraint member is adapted to prevent said interlocking memberfrom being moved in reverse while the free revolution of said constraint member is allowed.