FR2524696A1 - Aerial switch closing device at operator independent speed - has extension spring coupled to rotation shaft and to chassis - Google Patents

Abstract

The device allows the closure of an aerial switch on an overhead power distribution network at a predetermined speed independent of the operator. A metal chassis (1) supports the rotation insulator (2) and a moving insulator (4) which is fixed on a shaft (5) pivoting around an axis (6). The moving insulator controls the pivotation of the cutter (8) by sliding along the roller (7). The rotation of the shaft (5) is governed by a part-hole (9) coupled onto a cross bar (10). Turning of the shaft causes the closing of the cutter onto the contact of the closing insulator (3). The device allowing the closing speed independent of the operator has a coupling tab (11) on the shaft (5), a shaft turning lever (12), a prestretched extension spring (13) and a coupling tap (14) of the spring on the chassis. The device passes the dead point w.r.t. the rotation axis of the shaft in the open and closed positions.

Description

 The present invention relates to aerial switches, used to establish or interrupt a medium voltage electric current on overhead rural electrical distribution networks.

 These devices are generally installed on top of vertical concrete posts. They are maneuvered from the ground by means of a mechanical control, constituted by a control faceplate, actuating metal tubes, controlling the rotation of the shaft of the air switch.

 For the operating needs of these electrical distribution networks, and because of the power increases, it has become essential to produce overhead switches, possessing not only breaking power, but also closing power.

 The breaking capacity can be ensured by a breaking "whip", which, in the form of a spring, causes an extremely fast breaking of the current, and above all at a speed independent of that of the operation of the operator.

 The closing power requires a similar principle, although less rapid, but this device must obligatorily ensure that the contacts are closed at a sufficient speed, and above all independent of the operating speed of the operator.

 The object of the present invention is to obtain this independent closing speed, under particularly economical conditions, with parts of such simplicity that they exclude any possibility of adjustment, or of faulty operation.

 A number of methods are known for achieving this closing speed independent of the operating speed of the operator.

 All these processes are based on the use of compression springs, or tension in pretensioning, or tensioned by the operator, then suddenly released at the end of the stroke to activate only the final phase of closing the air switch.

The springs used can work in traction or compression, and are located in one of the following three points - at the control faceplate - at the guide linkage of the linkage - on the air switch itself
At the control panel, the solution is expensive, because it involves axes, levels, connecting rods, but above all a covering of the assembly essential to invite possible injuries during the maneuver.

 The return of linkage gudage, the solution is also not satisfactory, because it also impliqje a relatively complex mechanical set, and a delicate adjustment likely to deteriorate during operation.

 On the overhead switch, a known solution uses a compression spring fitted to a linkage passing through a neutral point, and usually called a "tumbler".

 This solution is also expensive, because it necessarily involves internal or external guidance of the spring as well as multiple axes of rotation.

 The present invention, on the contrary, while being located on the overhead switch, consists only of two parts apart from the attachment parts; a tension spring and a bypass of the pivoting shaft of the overhead switch. This provision is therefore particularly economical, and completely foolproof.

 The drawings illustrate by way of nonlimiting example, an embodiment of an overhead switch equipped with a closing device at speed independent of the operator.

 In figure 1, open overhead switch, (1) represents the metal frame of the overhead switch, (2) the rotation insulator, (3) the closing insulator, (4) the movable insulator fixed on the shaft pivoting (5) around the axis (6). The mobile insulator (4) controls the pivoting of the knife (8) by sliding along the latter of the roller (7).

 Thus, according to the direction of rotation of the shaft (5), the closing or opening of the contacts of the overhead switch is obtained.

 The upper part of the mechanical control, the only one shown, includes a light (9), coupled to the lifter (10) fixed on the shaft (5), which therefore controls the rotation of the latter.

 From the drawing, it can be seen that by lifting the control rod comprising the light (9), the shaft (5) is pivoted to the left, which causes the knife (8) to close on the contact of the insulator (3).

 The reverse maneuver causes the opening of the switch after prior catching of the light (9).

 The part essentially constituting the invention, and therefore allowing a closing speed independent of that of the operator, comprises (11) the coupling tab on the shaft (5), (12) the bypass rocker of the shaft, (13) the tension spring previously tensioned to ensure independent closure, (, 4) the hitch tab of the spring on the frame (1). The lug (11) is integral with the shaft, while the lug (14) is integral with the frame.

 In Figure 2, overhead switch closed, we find the same elements, but closed device. Indeed, to reach this "closed" position, the operator, from the bottom of the post, and by means of the control faceplate, raised the light (9) which caused the lifter (10) and itself the rotation of the 'shaft (5) around the axis (6). This rotation obviously led to that of the insulator (4), and that of the knife (8) via the roller (7) thus causing the closing of the overhead switch, and establishing the circuit between the contacts of the insulators ( 2) and (3).

 At the end of the closing operation, the assembly ensuring independent closing, namely (11), (12), (13), (14), is in the position of FIG. 2.

 The operation of the independent closure is deduced from FIGS. 1 and 2.

 In position, Figure 1, open air switch, the points (15), (16) and (17) are aligned under the effect of the spring (13), and this alignment passes below the axis (6) of l 'tree (5).

 This "open" position is therefore stable without movement of the light (9) and the switch is kept open by the pretensioning of the spring (13).

 The closing maneuver begins with the raising of the light (9) and when it has reached the bottom, it rotates the lifter (10) and therefore the shaft (5).

 Via the tab (11), the point (15) goes back up, and the set of points (15), (16), (17), arrives at alignment, with the axis of rotation (6 ). Until this alignment, what can be called "preclosing", is always dependent on the operating speed of the operator, but the contacts are not closed.

 Continuing the lifting of the light (9), the alignment of the points (15), (16), (17) passes above the axis (6), and therefore of the equilibrium point of the tree (5) of the overhead switch. As soon as friction is more than balanced by the torque caused by the spring (13), this alone causes the closure of the air switch at a speed determined by its power and independent of the operator.

 During this end of closing at independent speed, the light (9) prevents the operator from involuntarily retaining the closing.

 The object of the invention is therefore achieved; apart from the hitching tabs (11) and (14), two parts alone provide independent closure; the shaft bypass rocker (12) and the spring (13).

 It is particularly obvious that this solution is extremely economical, and foolproof.

Claims (5)

1 - Device fixed to an air switch, allowing it to close at a predetermined speed, independent of that of the operator; characterized in that it is constituted by the assembly of a tension spring previously tensioned, and a rocker for bypassing the shaft; this assembly being coupled on the one hand to the rear of the shaft, and on the other hand to the frame so that it passes neutral in relation to the axis of rotation of the shaft of the 'air switch in the open and closed positions. 2 - Device according to claim 1, characterized in that the spring may be disposed inside a tube to prevent the formation of ice between its turns. 3 - Device according to claim 1, characterized in that the entire device can be covered, to prevent the formation of ice between the turns of the spring and at the level of the bypass of the shaft. 4 - Device according to claims 1, 2, or 3 characterized in that the coupling points on the shaft and on the frame can be sliding. 5 - Device according to claims 1, 2, 3 or 4 comprising several assemblies mounted in parallel.