CS255043B1 - Electric earthing switch and shorting - Google Patents

Abstract

An electrical earthing switch with a short-circuit breaker, intended for high-voltage distribution, which has an advance contact with a moving mechanism arranged inside the lower rosette contact, the action of which controls the vacuum interrupter. An advance contact with a contact head and a return spring is arranged inside the lower rosette contact, slidably mounted in a solid insulating partition, which, together with the vacuum interrupter, forms a short-circuit breaker for currents whose value is limited by the switching capacity of this interrupter. The earthing switch with a short-circuit breaker is particularly suitable for busbars connecting a generator with a transformer in power plants.

Description

The invention relates to an electrical earthing switch and a short circuit for high voltage distribution.

Enclosed busbar earthing switches are used to prevent life-threatening voltages on electrical equipment being worked on. · In enclosed busbars connecting the generator to the transformer (in power plants) / there are additional requirements for earthing switches, eg · The possibility of passing the rated current for a specified time to set the differential protections of the generator, the possibility of passing a current smaller than the rated (for drying the generator) and the possibility of switching currents caused by the remanent magnetism of the generator during its idling. In particular, this latter requirement becomes increasingly important as the power of the generators increases. Here, the earthing switch is required to be able to conduct the rated currents in the on state, and to enable and disable short-circuit currents when the generator is idling, ie retentive generator currents. . It must be ensured that the contacts of this interrupter are closed before the main earthing contacts of the earthing switch are closed and the main earthing contacts of the earthing switch are opened before the contacts of the interrupter are disconnected. The reason for this requirement is that the earthing switch's main contacts are moving slowly and therefore cannot switch on or off any currents. To meet this requirement, a lead-in contact upstream of the short-circuit main contact is usually used.

The earthing and short-circuiting devices used so far for the purposes described above are designed in such a way that the lead-in contact is mechanically coupled to the main contact and is connected to a separate terminal isolated from the earthing earth frame.

The 255 043 contact (including its 8-pin connection) was electrically isolated not only from the earthing frame but also from the main contact. The retentive currents of the generator are then switched by a separate switch, eg a contactor, located in a separate space outside the earthing switch. The disadvantage of this construction is the complicated arrangement of the advance contact and also the necessity of using a separate switch including its connection with the earthing switch. Another known design uses a lead-in contact coupled via an inverter mechanism to an auto-pneumatic arc quenching system.

The aforementioned disadvantages are eliminated by the earthing switch and short-circuit device according to the invention, characterized in that an early contact with the contact head and the return spring is disposed inside the lower rosette contact, slidably mounted in a fixed insulating partition provided with a longitudinal groove at its bottom. a displacement pin connected to the switching springs and at the same time to a connecting rod provided with a closed control pin groove fixed at the other end, fixedly connected to a segment of a circular sector shape rotatably mounted on the pin, the shape groove forming a guide pin for the pin firmly connected to the movable contact of the vacuum interrupter.

The advantages of the shorting and earthing switch according to the invention reside in the precise function of the forward contact with respect to the movement of the main contact. By appropriately selecting the groove length and spring force, the vacuum interrupter can be engaged at a predetermined moment in relation to the stroke of the main contact. Another advantage is the simplicity of construction, the small number of components and the overall smaller dimensions compared to the previous designs.

An exemplary embodiment of the invention is illustrated in the enclosed drawing, wherein the earthing switch and shorting device are in longitudinal section.

The earthing switch and short-circuit consists of the upper flange 1, connected firmly by the insulating tube 3 with the lower flange 2. The upper flange 1 has the upper rosette contact 5, the lower flange 2 has the lower rosette contact 6. The upper flange 1 is fixed: a housing not shown in the drawing and a lower flange 2 with a busbar outlet 7. A linearly movable main contact 8 is disposed between the upper rosette contact 5 and the lower rosette contact 6.

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3 an extension 9 in which the guide ring 10 is movably mounted, fixedly connected to the movable "main contact" 3. The guide ring 10 is further firmly connected to the nut 11 of the drive screw 4, connected to a drive (not shown). The cylindrical space 12 inside the movable main contact 8 is reserved for the drive screw 4. Inside the lower rosette contact 6 there is an advance contact 32 which with its contact head 13 extends above the lower rosette contact 6. The forward contact 32 passes through a sliding rigid insulating partition 19 On the cylindrical part of the advance contact 32, a return spring 14 is inserted, supported by its ends between the fixed insulating partition 19 and the contact head 13. A longitudinal groove 20 is formed in the lower part of the advance contact 32 in which the sliding pin 21 is slidably mounted. connected to the switching springs 22 and at the same time to the connecting rod 23 provided at the other end with a groove 24 for a slidingly mounted actuating pin 25 fixedly connected to the segment 26 in the shape of a circular sector. The switching springs 22 are pushed and are supported at their ends between the transfer pin 21 and the support pins 34, 35. The segment 26 is rotatably arranged about the pin 33, and a segment groove 27 is formed in the segment 26 forming a guide for the switching pin 28 The fixed contact 17 of the vacuum interrupter 15 is connected to the insulating bottom 30 forming the lower part of the whole device so that it is clamped between two nuts 31 in the insulating bottom 30. At the same time the fixed contact 17 is conductively connected by conductor 18 with the bottom The vacuum interrupter 15 _f, including all mechanisms, is enclosed in the support structure 29. The lead contact 32 with the contact head 13 is electrically conductively connected via a connecting rod 23 and segment 26 to the movable contact 16 of the vacuum interrupter 15.

The function of the earthing switch and short-circuiting device according to the invention is as follows: Upon actuation of the non-indicated drive, the drive screw 4 starts to rotate, whose rotary movement is transmitted to the nut 11 which converts the rotary movement to linear. As a result, the movable main contact 8 begins to move from the basic off position to the second on position. Before reaching the on position, the movable main contact 8 is connected to the contact head 13 of the advance contact 32. When the advance contact 32 moves downwards, the switching springs 22, supported by the support pins 34, 35, are compressed into a horizontal position.

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At the same time, the connecting rod 23 moves downwards. In the closed groove 24, the actuating pin 25 is thereby moved in a straight line, the segment 26 being at rest. When the spring springs 22 are compressed in the horizontal position, the control pin 25 reaches the end of the closed groove 24. As the forward contact 32 moves further, the spring springs 22 move beyond the horizontal position and move in a flashing motion from the OFF position to the ON position. As the pin 28 is rigidly connected to the movable contact 16 of the vacuum interrupter 15, the movement of the shaped groove 27 formed in the segment 26 / will also cause a momentary movement of the movable contact 16 of the vacuum interrupter 15 downward and thereby closing. At the same time, by the momentary movement of the switching springs 22, the displacement pin 21 in the longitudinal groove 20 of the advance contact 32 is moved to the lower position. By closing the vacuum interrupter 15, the electrical circuit between the upper flange 11 is closed via the movable main contact 8, the forward contact 32, the connecting rod 23, the segment 26, the vacuum interrupter 15 and the conductor 18 to the lower flange 2. With the capability of the vacuum interrupter 15, these currents are closed before the movable main contact 8 is inserted into the lower rosette contact 6. Upon further movement of the movable main contact 8, it connects to the lower rosette contact 6 and bridges the vacuum interrupter 15. to which it is dimensioned. When switching off, the function is reversed. First, the main circuit is disconnected, i.e., the movable main contact 8 leaves the lower rosette contact 6, then the vacuum interrupter 15 flashes open and finally the contact head 13 of the advance contact 32 contacts the movable main contact bar 8.

The use of the earthing switch and shorting device according to the invention is envisaged for encapsulated busbars for high rated currents, in particular busbars for connecting a generator to a transformer in power plants.

Claims (1)

An electrical earthing switch and short-circuiting for a sealed, gas-insulated busbar with a movably mounted movable main contact fixedly connected to a guide ring moving in a tubular extension, characterized in that a forward contact (32) with a contact head is arranged inside the lower rosette contact (6). (13) and with a return spring (14) slidably mounted in a fixed insulating partition (19) provided with a longitudinal groove (20) at its bottom forming a path. For a displacement pin (21) connected to the switching springs (22) and with a tie rod (23) provided with a closed groove (24) for the control pin (25) at the other end, fixedly connected to a segment (26) of a circular sector shape rotatably mounted on the pin (33), , a shaped groove (27) forming a guide for the switching pin (28), fixedly connected to the movable contact (16) of the vacuum interrupter (15), and furthermore the contact (32) with the contact head (13) is electrically conductively connected via a connecting rod (23) and a segment (26) to the movable contact (16) of the vacuum interrupter. (15) ·