CN220358020U - Parallel connection on-off load switch and medium-voltage switch equipment with same - Google Patents

Abstract

The utility model relates to a parallel on-off load switch, comprising: -a stationary contact; -a moving contact, wherein the moving contact is arranged rotatable about a pivot axis between a closed position, a commutated position and an open position; -a vacuum interrupter, wherein the stationary contact is electrically connected with a stationary switch contact therein; -a cam assembly, wherein the cam assembly is provided with a small contact rotatable about a pivot axis; wherein the moving end of the movable switch contact is guidably operatively connected to the cam assembly, wherein the linear movement is of a travel no shorter than 7 mm. Thus, a high breaking distance can be achieved and the technical requirements of overstroke and the like can be flexibly set. The utility model also relates to a medium voltage switchgear with above-mentioned parallelly connected load switch that opens and shuts.

Description

Parallel connection on-off load switch and medium-voltage switch equipment with same

Technical Field

The utility model relates to a parallel load-break switch, in particular for breaking a power line of a medium-voltage electrical system, and comprising a load-break switch with a vacuum interrupter. The term "medium voltage" (MT,) is used in its usual sense to mean an alternating current of greater than 1000 volts but not more than 52,000 volts and a direct current of greater than 1500 volts but not more than 75,000 volts. Also relates to a parallel load switch with the parallel load switch

Background

As is known, circuit breakers and circuit breakers in medium or high voltage power lines or power cables generally comprise a box in which switching contacts are arranged so as to move between a mutually contact position, corresponding to the closing of the power lines, and a mutually separate position, corresponding to the opening of the power lines. The tanks are filled with a dielectric fluid in which the switch contacts are immersed, and the dielectric fluid assists in breaking the current by extinguishing an arc that may still remain after the switch contacts are separated from each other. Many different fluids (such as air, oil, nitrogen, etc.) have been proposed in the past, but sulfur hexafluoride (SF 6) is now commonly used, which has good dielectric properties and is therefore very suitable for this purpose. Even so, the use of this gas is limited because it has the disadvantage that its decomposition products are toxic and corrosive and that it contributes to the greenhouse effect. Thus, there is a need to use vacuum interrupters, which are also used in certain circuit breakers, the switch contacts being the internal components of these switch boxes, the vacuum interrupters being most effective at extinguishing the arc current; however, without further improvement, the use of vacuum interrupters in today's circuit breakers cannot be considered for cost reasons, because the vacuum interrupters used in these circuit breakers are too cumbersome from a material and size point of view, and must be of a material and size that can meet the different electrical and dielectric requirements, such as being capable of withstanding lightning strikes.

In order to solve the above drawbacks, it is particularly known from the document of chinese patent application publication No. CN102623234a to arrange the vacuum interrupter in a bypass circuit parallel to the main circuit of the main switch containing one phase of the electrical equipment. In this configuration, during normal operation, that is to say when the main switch is closed so that current passes through the main circuit, no current passes through the vacuum-interrupter (vacuum-interrupter). During operation of opening the main switch, the movable part of the main switch closes a parallel bypass circuit containing the vacuum interrupter before the current in the main circuit is interrupted. The current is then interrupted in the main circuit, so that all the current then passes through the vacuum interrupter. As it continues its opening stroke, the movable part of the main switch opens the contacts of the vacuum interrupter and the current is cut off. This then avoids arcing in the main switch, since at the moment the current is switched off, the current only passes through the vacuum interrupter. Because the vacuum interrupter has current passing only during the transient phase of breaking the current, such a vacuum interrupter can be simplified and of smaller size than a vacuum interrupter typically intended to be placed in series with a main switch.

In this device, however, the opening of the vacuum interrupter is only caused by the main switch in the opening stroke. Therefore, the relative arrangement of the vacuum interrupter and the main switch is limited. Furthermore, the kinematic connection between the vacuum interrupter and the main switch needs to be very precise. The dimensional tolerances of each element of the kinematic connection sequence must be strict in view of the number of elements involved in the assembly.

Accordingly, there is a technical need in the related art to allow a lower level of precision, a higher breaking distance, and to flexibly set an overstroke or the like in forming a moving part that facilitates the breaking of a vacuum interrupter in a simple and reliable manner.

Disclosure of Invention

The object of the present utility model is therefore to provide a parallel-connected load switch, by means of which the disadvantages of the prior art described above are overcome.

According to one aspect of the present utility model, there is provided a parallel cut-off load switch for cutting off a power line of a medium voltage electrical system, characterized by comprising: a stationary contact including a first end for connection to a power line and a second end opposite the first end; a moving contact, wherein the moving contact is arranged rotatable about a pivot axis between a closed position, a commutating position and an open position, wherein the moving contact is connected to the second end of the stationary contact in the closed position and is electrically connected to the stationary contact, and wherein the moving contact is disconnected from the stationary contact when rotated about the pivot axis to the open position; a vacuum interrupter having a fixed switch contact and a movable switch contact disposed therein and wherein the fixed contact is electrically connected to the fixed switch contact therein; and a cam assembly, wherein the cam assembly is provided with a small contact rotatable about a pivot axis, and wherein the small contact has an electrical lead electrically connectable with the moving contact for electrical connection with a vacuum interrupter in response to rotation of the moving contact about the pivot axis; wherein the moving end of the movable switch contact is aligned along the axis of the vacuum interrupter and is linearly movable between an off position and an on position, and wherein the moving end of the movable switch contact is guidingly operatively connected to the cam assembly, wherein the stroke of the linear movement is not shorter than 7 millimeters; wherein in a closed position the movable contact is in contact with the stationary contact and spaced apart from the small contact, and the movable switch contact is in an on position in contact with the stationary switch contact, and wherein an electrical current can flow to the movable contact via the stationary contact; wherein rotation of the moving contact about a pivot axis in a first rotational direction rotates it from a closed position to a commutating position, wherein the moving contact is in contact with the small contact, such that current can flow through the stationary contact and vacuum interrupter to the moving contact via the small contact; and wherein further rotation of the movable contact about the pivot axis in a first rotational direction rotates it from the commutation position to the on-position, wherein the movable contact pivots the small contact about the pivot axis and actuates the cam assembly to move the moving end of the movable switch contact linearly along the axis of the vacuum interrupter from the on-position to space the movable switch contact of the vacuum interrupter from the fixed switch contact.

According to the parallel on-off load switch of the present utility model, the technical requirements of lower precision level, higher on-off distance, and flexible setting of overstroke, etc. can be allowed in a simple and reliable manner when forming the moving parts that contribute to the opening of the vacuum interrupter. In addition, the parallel connection on-off load switch has the advantages of less parts, low cost and good reliability.

In some embodiments, as a preferred aspect, the cam assembly includes: -a cam carrier, wherein the small contact is pivotably connected to the cam carrier and the cam carrier is provided with a guide groove for guiding a movement end of the movable switch contact to be linearly moved between an off position and an on position; -a cam pivotably connected to the cam carrier, wherein the cam has an abutment pin operatively connected to the small contact and a guide slot sandwiching the moving end of the movable switch contact therein; the small contact can drive the cam to pivot around the pivot axis together so as to enable the moving end of the movable switch contact to move linearly between the opening position and the closing position through the guide groove and the guide groove.

In some embodiments, as a preferred aspect, the small contact is designed as an elongated piece comprising a first end pivoted to the rack cam and a second end opposite to the first end, wherein the second end is provided with a spring piece capable of elastically abutting against the movable contact. This design thus ensures current continuity and enables a simple bypass circuit design

In some embodiments, as a preferred aspect, there is further included an insulating bracket constructed as a single piece and including a horizontal portion for fixedly mounting the cam carrier and the vacuum interrupter and a vertical portion for fixedly mounting the stationary contact. Thus, such a design ensures the accuracy of the transmission and can effectively reduce assembly errors.

In some embodiments, as a preferred aspect, the cam assembly further comprises a torsion spring fixedly mounted to the rack cam, wherein a leg of the torsion spring operatively abuts the cam to accumulate elastic potential energy as the cam pivots relative to the rack cam and then release the elastic potential energy to return the cam to its initial position.

In some embodiments, as a preferred aspect, the moving contact comprises a pair of contacts arranged at intervals, wherein one end of the contacts is provided with a spherical surface portion operatively connected to an outward protrusion of the actuator to allow rotation about the pivot axis by the actuation thereof between a closed position, a commutating position and an open position, and the other end of the contacts is provided with an abutment portion of the outward protrusion capable of making surface contact with the second end of the stationary contact.

In some embodiments, as a preferred aspect, there is further included a grading ring disposed adjacent to the spherical portion of the contact for grading an electric field of a current flowing through the moving contact, and a shielding case in a semicircular design disposed adjacent to the abutting portion of the contact at intervals for preventing partial discharge.

In some embodiments, as a preferred aspect, the small contact is made of an insulating material and its second end carries a layer of insulating material on the side opposite the dome.

In some embodiments, as a preferred aspect, there is further included a ground contact on one side of the movable contact that is electrically coupleable to a ground conductor, wherein the ground contact is configured to be generally U-shaped and includes a first end coupled to the ground conductor, a second end opposite the first end, and a hollow portion between the first end and the second end, wherein the second end has a pair of contact feet that are mateable with the movable contact.

According to another aspect of the present utility model, there is also included a medium voltage switchgear comprising a housing filled with an insulating gas and a parallel on-off load switch built into the housing.

Additional features and advantages of the utility model will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following, or may be learned from practice of the utility model.

Drawings

Embodiments of the present utility model are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 is a front view of a medium voltage switchgear with parallel-connected on-off load switches according to the utility model;

fig. 2 is a side view of a medium voltage switchgear with a parallel on-off load switch according to the utility model;

fig. 3 is a front view of a medium voltage switchgear with parallel-connected on-off load switches according to the utility model;

fig. 4 is a top view of a medium voltage switchgear with parallel-connected on-off load switches according to the utility model;

fig. 5-6 are perspective and side views of the main circuit of the parallel on-off load switch according to the utility model with the moving contact removed;

fig. 7 is a side view of the moving contact of the parallel on-off load switch according to the present utility model;

fig. 8 is a perspective view of a parallel on-off load switch according to the utility model with parts of the medium voltage switchgear removed to better show details;

FIG. 9 is a side view of the parallel on-off load switch with portions of the components of the medium voltage switchgear removed to better show details in accordance with the present utility model;

fig. 10-12 are views from different perspectives of a parallel on-off load switch according to the utility model, with parts of the medium voltage switchgear removed to better show details.

Reference numerals illustrate:

100. the load switch is connected in parallel; C. a housing; 1. a stationary contact; 11. a first end;

12. a second end; 10. an insulating support; 10A, vertical portion; 10B, horizontal portion;

2. a moving contact; 21. an actuator; 22. a face contact; 23. a shield;

24. equalizing rings; 25. a terminal; 3. a ground contact; 31. foot contact;

4. a vacuum arc extinguisher; 41. a fixed end; 42. a motion end; 5. a cam carrier;

51. a guide groove; 52. a pivot point; 53. a lead fixing frame;

6. an electrical lead; 7. a small contact; 71. a spring plate; 72. a bottom end; 73. copper sheets; 8. a cam; 81. a guide groove; 82. an abutment pin;

9. a torsion spring; a1, a pin joint axis; a2, pivot axis

Detailed Description

Referring now to the drawings, the schematic solutions of the parallel-connected breaking load switch and the medium voltage switchgear with the same disclosed in the present utility model are described in detail. Although the drawings are provided to present some embodiments of the utility model, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. The position of part of components in the drawings can be adjusted according to actual requirements on the premise of not affecting the technical effect. The appearances of the phrase "in the drawings" or similar language in the specification do not necessarily refer to all figures or examples.

Certain directional terms used hereinafter to describe the drawings, such as "inner", "outer", "above", "below" and other directional terms, will be understood to have their normal meaning and refer to those directions as they would be when viewing the drawings. Unless otherwise indicated, directional terms described herein are generally in accordance with conventional directions as understood by those skilled in the art.

The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

For a further understanding of the objects, construction, features, and functions of the utility model, reference will be made to the following detailed description of the preferred embodiments.

As shown in fig. 1-4 of the present utility model, the medium voltage switchgear according to the present utility model is particularly suitable for being connected as a load switch in a medium voltage circuit. It is therefore designed to provide both a circuit breaking functionality as well as a circuit breaking functionality in a specified circuit state (nominal or overload state), in particular to ground the load side of the circuit.

As shown in fig. 1, in an embodiment according to the present utility model, the medium voltage switchgear is of the multiphase (e.g., three-phase) type and comprises a plurality of (e.g., three) electrodes. Further, the medium voltage switchgear comprises a housing C, preferably of an insulating material, which advantageously defines an internal volume in which the electrodes can be accommodated. As shown in fig. 1, the insulating housing C has an elongated shape (e.g., substantially rectangular parallelepiped shape) developed along a main longitudinal axis. The plurality of electrodes are arranged side by side along respective transverse planes perpendicular to a main longitudinal axis of the medium voltage switchgear. Wherein the internal volume of the medium voltage switchgear is filled with pressurized dry air or another insulating gas (such as a mixture of oxygen, nitrogen, carbon dioxide and/or fluorinated gases) with low environmental impact.

As shown in fig. 1, for each electrode, which is electrically connected to the power line of the medium voltage electrical system and is accordingly broken by the parallel breaking load switch of the present utility model, wherein the parallel breaking load switch 100 comprises a stationary contact 1 comprising a first end 11 for connection to the power line and a second end 12 opposite to the first end, wherein the first end 11 protrudes outwards from the upper side of the insulating housing C and is provided with a connector for connection to an external power line, and the second end 12 thereof is an inwardly protruding tab built into the inside of the insulating housing C. Of course, the person skilled in the art will also appreciate that the stationary contact 1 may be implemented according to other solutions of known type (for example, according to a multi-blade configuration comprising a plurality of fixed contacts), which are not described in detail here for the sake of brevity.

The parallel opening load switch 100 further comprises a moving contact 2, which is at least partly made of an electrically conductive material and which can be electrically connected to the power line of the electrical system via its terminal 25 at the lower end. As shown in fig. 1 and 3, the moving contact 2 is reciprocally pivotable about a corresponding pivot axis A2 substantially parallel to the main longitudinal axis of the medium voltage switchgear. In particular, the moving contact 2 is rotatable according to a first or second rotation direction, which is remote from the second end 12 of the stationary contact 1 and towards the ground contact 3, the second rotation direction being opposite to the first rotation direction and being remote from the ground contact 3 and oriented towards the second end 12 of the stationary contact 1. As will be better explained below, the moving contact 2 moves in a first rotational direction during the switching-off operation and the commutation operation of the medium voltage switchgear and it moves in a second rotational direction during the closing operation or reconnection of the switchgear. Thereby, the moving contact 2 can be reciprocally moved about the pivot axis A2, so that the moving contact 2 can be electrically connected to the second end 12 of the stationary contact 1 or disconnected from the second end 12 of the stationary contact 1, or it can be electrically connected to the ground contact 3 or disconnected from the ground contact 3.

As a preferred aspect, the movable contact 2 may be formed of a pair of contact pieces made of a conductive material at intervals. Each contact has an end hinged to a corresponding terminal 25 at a pivot axis A2 and an opposite free end forming an electrical engagement with the second end 12 of the stationary contact 1. Further, in order to achieve a rotation of the moving contact 2 about the pivot axis A2, the medium voltage switchgear comprises an actuator 21, which actuator 21 provides a suitable actuation force to actuate the moving contact 2 (fig. 1). Here, the actuator 21 may be, for example, a mechanical actuator, an electric motor, or an electromagnetic actuator.

As a preferred aspect, as shown in fig. 11, one end of the contact piece of the moving contact 2 is provided with a spherical surface portion operatively connected to the outer protrusion of the actuator 21 to allow rotation about a pivot axis A2, which will be described in detail below, between a closed position, a commutating position and an open position, and the other end of the contact piece of the moving contact 2 is provided with an abutment portion 22 of the outer protrusion capable of making surface contact with the second end 12 of the stationary contact 1. The contact area between the moving contact 2 and the stationary contact 1 can be increased significantly by adding the contact portion 22, so that the current passing ability is improved, which makes it difficult for ablation and fusion welding to occur when the moving contact 2 is used for the opening operation. Meanwhile, as the lower part of the movable contact 2 adopts a spherical design, the friction or resistance of pivoting movement can be reduced, and the requirements of a temperature rise test are further met. More preferably, as shown in fig. 10-11, the moving contact 2 is also provided with a grading ring 24, arranged adjacent to the spherical portion of the contact, for grading the electric field of the current flowing through the moving contact, and a shielding cover 23, arranged adjacent to the abutment portion of the contact, spaced apart, in a semicircular design, for preventing partial discharges, which helps to prevent partial discharges and to homogenize the electric field inside the medium voltage electrical apparatus during normal operation of the medium voltage electrical apparatus, which is beneficial for providing operational reliability and service life of the medium voltage electrical apparatus.

Further, the medium voltage electrical apparatus may further comprise a ground contact 3 on one side of the moving contact 2, which ground contact 3 is designed to be substantially U-shaped and comprises a first end coupled to the ground conductor, a second end opposite to the first end and a hollow between the first end and the second end, wherein the second end is provided with a pair of contact feet 31 (see fig. 8-10) capable of cooperating with the moving contact. In the utility model, since the grounding contact 3 is designed into a U shape, a person skilled in the art will know that the direction of the electromotive force is opposite to the direction of the electromotive force according to the right-hand rule, and most of the electromotive force acting on the moving contact 3 can be counteracted, so that the grounding closing test is more stable and reliable.

Further details of the parallel on-off load switch 100 according to the present utility model are shown next in connection with fig. 5-6. Specifically, the parallel on-off load switch 100 further includes a vacuum interrupter 4 in which a fixed switch contact and a movable switch contact are built and in which the fixed contact 1 is electrically connected with the fixed switch contact therein. Here, the vacuum interrupter 4 as an example comprises a pair of fixed and movable switch contacts, wherein the fixed switch contacts may be electrically connected to the first end 11 of the stationary contact 1 and the vacuum interrupter 4 itself is fixedly connected to the stationary contact 1. Meanwhile, the movable switch contact is driven by a moving end 42 extending from the housing of the vacuum interrupter 4. In this configuration, during normal operation, that is to say when the moving contact 2 and the stationary contact 1 are closed and are thus switched on, so that current passes through the main circuit, no current passes through the vacuum interrupter 4. During the operation of opening the moving contact 2 and the stationary contact 1, the movable part of the moving contact 2 turns on the parallel bypass circuit containing the vacuum interrupter before the current in the main circuit is interrupted. The current is then interrupted in the main circuit, so that all the current then passes through the vacuum interrupter. As it continues its opening stroke, the movable part of the main circuit opens the contacts of the vacuum interrupter and the current is cut off. This then avoids arcing in the main circuit, since the current only passes through the vacuum interrupter at the moment the current is switched off. The structure of the vacuum interrupter 4 is known per se, and may be, for example, a vacuum interrupter of the type VI-8 commercially available from the company eaton, the structure of which is not described in detail here for the sake of brevity.

Since the medium voltage electrical apparatus according to the utility model does not use sulfur hexafluoride (SF 6) gas as insulating medium, but instead uses other gases with poor insulating properties, higher demands are made on the opening and closing distance of the arc extinguisher and the kinematic connection between the components of the load switch, which will be described further below with reference to the accompanying drawings,

as shown in fig. 5 to 6, the parallel on-off load switch 100 here comprises a cam assembly, wherein the cam assembly is provided with a small contact 7 rotatable about a pivot axis A1, and wherein the small contact 7 is provided with an electrical conductor 6 electrically connectable with the moving contact 2 for electrical connection with the vacuum interrupter 4 in response to a rotation of the moving contact 2 about the pivot axis A2. Preferably, the cam assembly comprises a cam carrier 5, wherein the small contact 7 is pivotably connected to the cam carrier 5 via a pivot point 52, which may be a pivot pin for example, and the cam carrier 5 is provided with a guide slot 51 for guiding a linear movement of the moving end 42 of the movable switch contact between its off and on positions, and a cam 8 pivotably connected to the cam carrier 5, wherein the cam 8 is designed to be substantially half-moon-shaped and is likewise pivoted to the pivot point 52 by means of the pivot pin, wherein the cam 8 is provided with an abutment pin 82 operatively connected to the small contact 7 and a guide slot 81 in which the moving end 42 of the movable switch contact is clamped, whereby, when the small contact 7 brings the cam 8 together to pivot about the pivot axis A1, the moving end 42 of the movable switch contact can be moved linearly between the off and on positions via the guide slot 81 and the guide slot 51, wherein the moving end 42 of the movable switch contact is aligned and moves linearly along the axis of the vacuum interrupter 4 by no more than 7 mm.

Those skilled in the art will appreciate that the cam assembly described above effects the opening and closing of the vacuum interrupter 4 by rotating the small contact 7, which may be used as a lever. The whole process is divided into a rotating pair realized by the movable contact 2, a lever realized by the small contact 7, a guide groove 81 and a movement synthesis of the guide groove 51 and the like. The contact angle of the movable contact 2 and the turn-off stroke of the vacuum interrupter 4 can be controlled by the length of the guide groove 81 in the cam 8 and the guide groove 51 in the cam carrier 5 and the interaction relationship with each other, and the length of the arm of the small contact 7 so as not to be shorter than 7 mm and also an overstroke can be set. As a preferred aspect, to ensure that the vacuum interrupter 4 is electrically on in the initial position, the cam assembly further comprises a torsion spring 9 fixedly mounted to the cam carrier 5, wherein the legs of the torsion spring 9 operatively abut the cam 8 to accumulate elastic potential energy as the cam 8 pivots relative to said cam carrier 5 and then release the elastic potential energy to return the cam 8 to its initial position, whereby the cam 8 can be quickly reset under the influence of the torsion spring 9 upon clockwise or counterclockwise rotation.

As a preferred aspect, as shown in fig. 7 and 9, the small contact 7 is designed as an elongated piece comprising a first end pivoted to the cam carrier 5 and a second end opposite to the first end, wherein the second end is provided with a spring plate 71 capable of elastically abutting against the movable contact 2, wherein the spring plate 71 is designed to be expandable outwards, which is located on top of the second end of the small contact 7, whereby the spring plate 71 can be snapped into the inside of both contacts of the movable contact 2 when the movable contact 2 is opened and closed about the pivot axis A2. This design ensures current continuity. The copper sheet 73 which is electrically connected with the electric wire 6 is arranged below the spring plate 71, the copper sheet 73 is contacted when the movable contact 2 continues to operate, and current is transmitted to the vacuum arc extinguisher 4 through the copper sheet 73 and the electric wire 6, so that the design of the bypass circuit can be realized simply. In order to avoid that the movable contact 2 closes the bypass circuit when pivoted in the opposite direction into the closed position, the small contact 7 is preferably made of an insulating material and its second end carries a layer of insulating material on the side opposite the spring plate 71.

In order to fixedly mount the cam assembly to the medium voltage switchgear, as shown in fig. 5 to 6, wherein the parallel on-off load switch 100 further comprises an insulating bracket 10, which is constructed as one piece and comprises a horizontal portion 10B for fixedly mounting the cam carrier 5 and the vacuum interrupter 4 and a vertical portion 10A for fixedly mounting the stationary contact 1, wherein the insulating bracket 10 is injection molded using a high strength PC material, three-phase co-planar mounting. After the vacuum arc extinguisher 4 and the fixed contact 1 are installed, the cam component and the fixed contact 1 can be installed on the same insulating bracket 10, and the design ensures the transmission accuracy and can effectively reduce the assembly error. Further, a wire holder 53 may also be fixedly mounted on the horizontal portion 10B of the insulating holder 10, wherein the wire holder 53 has a horizontal mounting section for mounting to a lower plane of the horizontal portion 10B and an arcuate section for guiding the electrical wire 6, as best shown in fig. 6, thereby being mirrored "5" in cross section. As best shown in fig. 10, a recess is provided in the arcuate section in which the supply line 6 engages, whereby in the installed state the movement of the electrical line follows an arcuate path defined by the recess in the arcuate section, which effectively prevents repeated bending of the electrical line 6 and thus prevents disconnection, which would affect the reliability and service life of the overall parallel load switch 100.

Next, in operation, the parallel on-off load switch 100 is capable of performing different types of maneuvers, each corresponding to a given transition among the above-described operating states, in accordance with the present utility model. In particular, in fig. 8 the moving contact 2 is shown in its closed position, when the vacuum interrupter 4 is in its default closed position, i.e. both the fixed and the movable switch contacts are closed. When the moving contact 2 is in its closed position, the moving contact 2 is held in close contact with its abutment 22 with both the second end 12 of the stationary contact 1, and current can flow through the moving contact 2 from the first end of the stationary contact 1 into the stationary contact and further through the moving contact 2 up to its terminal 25, and the parallel on-off load switch 100 can then be considered in its closed configuration.

Then, as the actuator 21 is activated, the moving contact 2 starts to rotate about the pivot axis A2 and at a certain point of rotation it comes into contact with the second end of the stationary contact 1 and with the cam assembly (in particular the small contact 7 in the cam assembly) operatively connected to the vacuum interrupter 4, thereby constituting a commutation point, wherein both the fixed and the movable switch contacts are closed as a result of the vacuum interrupter 4, thereby forming a by-pass current path from the first end 11 of the stationary contact 1 directly through the vacuum interrupter 4 and the electrical conductor 6 to the moving contact 2. The parallel on-off load switch 100 is now considered to be in the commutation configuration described above.

The moving contact 2 then continues to rotate about the pivot axis A2 under the actuation of the actuator 21 and thereby breaks contact with the second end 12 of the stationary contact 1, but now remains in electrical contact with the small contact 7, and both the fixed and the movable switch contacts of the vacuum interrupter 4 remain in contact with each other, so that current flows only from the first end 11 of the stationary contact 1 to the vacuum interrupter 4 and through the vacuum interrupter 4 to the moving contact 2. Then the moving contact 2 remains rotated and, in so doing, the small contact 7 accordingly continues to rotate, at which time the cam 8 is also brought together by means of the abutment pin 82 about the pivot point 52 as pivot axis A1 with respect to the cam carrier 5, as a result of which, as the cam assembly rotates, the moving end 42 of the movable switching contact clamped in the guide groove 51 and the guide groove 81 of the cam assembly is made to move linearly along the axis of the vacuum interrupter 4 from the on position to the off position to separate the movable switching contact of the vacuum interrupter 4 from the fixed switching contact, wherein the stroke of this linear movement is not shorter than 7 mm. As a result, the contacts of the vacuum interrupter 4 have now opened to break the current. Finally, the moving contact 2 continues to rotate and turn past the small contact 7, at which time the small contact 7 is reset under the action of the torsion spring 9 and drives the vacuum interrupter 4 back to its default closed setting, but since the moving contact 2 has now been decoupled from the small contact 7 and the first end 12 of the stationary contact 1, the parallel on-off load switch 100 is now in its on-off configuration and as it rotates until contact and thus stopping with both the ground contacts 3, at which time the parallel on-off load switch 100 is in its ground configuration.

As will be appreciated by those skilled in the art, by actuating the rotation of the movable contact 2 about the pivot axis A2 in the opposite rotational direction by the actuator 21, the parallel on-off load switch 100 can be switched from the grounded configuration to the closed configuration and a current path is formed between the second end 11 of the stationary contact 1 and the movable contact 2, and the vacuum interrupter 4 is placed in a contact closed state and no current passes through the vacuum interrupter. The parallel switch 100 is then ready for another switch-off operation as described above. Due to the insulating design of the rear side of the small contact 7, the bypass circuit is now prevented from being closed when the movable contact 2 is pivoted back into the closed configuration.

It should be understood that although the present disclosure has been described in terms of various embodiments, not every embodiment is provided with a separate technical solution, and this description is for clarity only, and those skilled in the art should consider the disclosure as a whole, and the technical solutions in the various embodiments may be combined appropriately to form other embodiments that will be understood by those skilled in the art.

The foregoing is illustrative of the present utility model and is not to be construed as limiting the scope of the utility model. Any equivalent alterations, modifications and combinations thereof will be effected by those skilled in the art without departing from the spirit and principles of this utility model, and it is intended to be within the scope of the utility model.

Claims (11)

1. A parallel break load switch for breaking a power line of a medium voltage electrical system, comprising:

-a stationary contact comprising a first end for connection to a power line and a second end opposite to the first end;

-a moving contact, wherein the moving contact is arranged rotatable about a pivot axis between a closed position, a commutating position and an open position, wherein the moving contact is connected to the second end of the stationary contact and is in electrical communication with the stationary contact in the closed position, and wherein the moving contact is disconnected from the stationary contact when rotated about the pivot axis to the open position;

-a vacuum interrupter having a fixed switch contact and a movable switch contact built therein and wherein the fixed contact is electrically connected with the fixed switch contact therein; characterized by also comprising

-a cam assembly, wherein the cam assembly is provided with a small contact rotatable about a pivot axis, and wherein the small contact is provided with an electrical lead electrically connectable with the moving contact for electrical connection with a vacuum interrupter in response to rotation of the moving contact about the pivot axis;

wherein the moving end of the movable switch contact is aligned along the axis of the vacuum interrupter and is linearly movable between an off position and an on position, and wherein the moving end of the movable switch contact is guidingly operatively connected to the cam assembly, wherein the stroke of the linear movement is not shorter than 7 millimeters;

wherein in a closed position the movable contact is in contact with the stationary contact and spaced apart from the small contact, and the movable switch contact is in an on position in contact with the stationary switch contact, and wherein an electrical current can flow to the movable contact via the stationary contact;

wherein rotation of the moving contact about a pivot axis in a first rotational direction rotates it from a closed position to a commutating position, wherein the moving contact is in contact with the small contact, such that current can flow through the stationary contact and vacuum interrupter to the moving contact via the small contact; and is also provided with

Wherein further rotation of the movable contact about the pivot axis in a first rotational direction rotates the movable contact from the commutation position to the open position, wherein the movable contact drives the small contact to pivot about the pivot axis and actuates the cam assembly, thereby moving the moving end of the movable switch contact linearly along the axis of the vacuum interrupter from the open position to space the movable switch contact of the vacuum interrupter from the fixed switch contact.

2. The parallel on-off load switch of claim 1, wherein the cam assembly comprises:

-a cam carrier, wherein the small contact is pivotably connected to the cam carrier and the cam carrier is provided with a guide groove for guiding a movement end of the movable switch contact to be linearly moved between an off position and an on position;

-a cam pivotably connected to the cam carrier, wherein the cam has an abutment pin operatively connected to the small contact and a guide slot sandwiching the moving end of the movable switch contact therein;

the small contact can drive the cam to pivot around the pivot axis together so as to enable the moving end of the movable switch contact to move linearly between the off position and the on position through the guide groove of the guide groove box.

3. The parallel on-off load switch according to claim 2, wherein the small contact is designed as an elongated member including a first end pivotally connected to the rack cam and a second end opposite to the first end, wherein the second end is provided with a spring piece capable of elastically abutting against the movable contact.

4. The parallel on-off load switch according to claim 2, further comprising an insulating bracket constructed as a single piece and including a horizontal portion for fixedly mounting the cam bracket and the vacuum interrupter and a vertical portion for fixedly mounting the stationary contact.

5. The parallel on-off load switch of claim 2, wherein the cam assembly further comprises a torsion spring fixedly mounted to the rack cam, wherein a leg of the torsion spring operatively abuts the cam to accumulate elastic potential energy as the cam pivots relative to the rack cam and then release the elastic potential energy to return the cam to its initial position.

6. The parallel break load switch of claim 1, wherein the moving contact comprises a pair of spaced apart contacts with one end of the contacts having a spherical surface portion operatively connected to an outward projection of the actuator to permit rotation about the pivot axis thereabout between a closed position, a commutated position and a broken position, and the other end of the contacts having an outward projecting abutment portion capable of making surface contact with the second end of the stationary contact.

7. The parallel on-off load switch according to claim 6, further comprising a grading ring disposed adjacent to the spherical portion of the contact for grading an electric field of a current flowing through the moving contact, and a shielding case of semicircular design disposed adjacent to the abutting portion of the contact at intervals for preventing partial discharge.

8. A parallel on-off load switch according to claim 3, wherein the small contact is made of an insulating material and the second end thereof is provided with a layer of insulating material on the side opposite the spring plate.

9. The parallel break load switch of claim 1, further comprising a ground contact on one side of the moving contact that is electrically coupled to a ground conductor, wherein the ground contact is configured to be generally U-shaped and includes a first end coupled to the ground conductor, a second end opposite the first end, and a hollow between the first end and the second end, wherein the second end has a pair of contact feet that are mateable with the moving contact.

10. The parallel on-off load switch of claim 4, further comprising a lead holder connected to the lower horizontal portion of the insulating support, wherein the lead holder has an arcuate section for guiding the electrical lead, the arcuate section having a recess in which the electrical lead is embedded.

11. Medium voltage switchgear comprising a housing filled with an insulating gas and a parallel on-off load switch built into the housing, characterized in that the parallel on-off load switch is a parallel on-off load switch according to one of claims 1 to 10.