Disconnectors and earthing switches with nested contacts

Abstract

To provide a reliable and compact switching device with a small footprint.SOLUTION: A device has: one or more switching mechanisms configured to disconnect a power supply from a load; and one or more disconnector and earthing switches, each disconnector and earthing switch associated with a respective switching mechanism. Each disconnector and earthing switch comprises a telescopic disconnector blade 432 having a first end 442 and a second end 434, where the disconnector blade is configured to pivot around the first end between three different positions.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] This application relates to ground disconnect switches (also referred to herein as disconnectors and grounding switches). In particular, this application relates to ground disconnect switches having telescopic or retractable contacts. In some implementations, the retractable contacts enable a three-position ground disconnect switch (or three-position disconnector and grounding switch, 3PS) to be provided in a compact footprint. [Background technology]

[0002] Switchgear and other switching devices are used to control and protect electrical equipment, such as equipment operated by utilities, commercial building owners, and operators of distributed renewable generation assets such as solar farms and wind turbines. Such switchgear includes a variety of medium voltage devices (e.g., devices rated at 12 kV or 24 kV) for various applications, such as ring main units (RMUs).

[0003] It is desirable to provide reliable, compact switchgear with a small footprint for any given equipment specification or application. It is also desirable to provide an earthing disconnect switch (or disconnector and earthing switch) with three positions: on, off (or isolation), and earthing, to facilitate field testing of cable integrity and improve ease of switchgear maintenance. It is particularly desirable to combine such a three-position disconnector and earthing switch or 3PS with compact switchgear or switching devices. Summary of the Invention

[0004] What is desired is set forth in the accompanying claims.

[0005] Disclosed herein is a device comprising one or more switching mechanisms configured to disconnect power from a load, and one or more disconnectors and grounding switches, each associated with a respective switching mechanism. Each disconnector and grounding switch comprises a telescoping disconnector blade having a first end and a second end, the disconnector blade configured to pivot about the first end between three different positions. The three positions include a first position in which the disconnector and grounding switch are closed and the power source is connected to the load through the disconnector blade; a second, isolation position in which the disconnector and grounding switch are open and the power source is disconnected from the load; and a third position in which the power source is disconnected from the load and the second end of the disconnector blade is electrically connected to a ground contact. Such a disconnector and grounding switch (also referred to as a ground disconnect switch) can be referred to as a 3PS switch (three-position disconnector and grounding switch).

[0006] The use of disconnectors and earthing switches with telescoping or retractable contacts (or disconnector blades) can facilitate the provision of reliable devices with small footprints and improved dielectric performance, which can be more easily and safely tested in the field (thereby improving ease of maintenance, for example). For example, a 3PS can be provided in a small footprint, which can result in a smaller device architecture.

[0007] In some examples, the telescoping disconnector blade comprises an outer contact and an inner contact, with a portion of the inner contact arranged to slide within the outer contact. Optionally, the outer contact comprises a first end of the disconnector blade, and the inner contact comprises a second end of the disconnector blade. Optionally, the outer contact comprises a guide hole, the inner contact slides within the guide hole, and the disconnector blade further comprises a compliant member disposed within the guide hole and configured to urge the inner contact out of the guide hole. Optionally, in response to an external force applied in a first direction and to the second end of the disconnector blade, the inner contact is configured to slide within the guide hole of the outer contact in a first direction, and the compliant member is configured to urge the inner contact in a direction opposite the first direction. Optionally, the compliant member is a compression spring. Any other suitable compliant member can be used. The compliant member may be compliant through shape and / or material.

[0008] In some examples, the telescoping disconnector blade is configured to move between an extended state and a compressed state, the disconnector blade being in the extended state in the first position and the third position, and the disconnector blade being in the compressed state in the second position.

[0009] In some examples, the device further includes a housing having a first sidewall and a second sidewall, and the telescoping disconnector blade is configured to rotate about a pivot axis from a first position to a second position, the rotation being toward the second sidewall of the housing. The use of a telescoping or retractable blade as described herein can help maintain a proper gap between the second sidewall and the tip or second end of the disconnector blade, which can help reduce the electric field strength at the end of the blade, thereby helping to reduce or avoid the risk of electrical breakdown between the housing and the blade.

[0010] Optionally, the second sidewall comprises an insulating support configured to contact a second end of the disconnector blade when the disconnector blade is in the second position, The presence of the insulating support can act as an obstacle to aid in the breakdown current path, thereby helping to avoid breakdown by improving dielectric performance.

[0011] Optionally, the insulating support comprises a guide portion configured to move the disconnector blade from an extended state to a compressed state when the disconnector blade pivots from the first position to the second position. Optionally, the guide portion is further configured to move the disconnector blade from a compressed state to an extended state when the disconnector blade pivots from the second position to a third position.

[0012] In some examples, there is an electrical contact coupled to the insulating support, the electrical contact configured to contact the second end of the disconnector blade when the disconnector blade is in the second position. Optionally, the electrical contact comprises a partially spherical end configured to contact the second end of the disconnector blade when the disconnector blade is in the second position. Use of a spherical end can help reduce field end effects.

[0013] In some implementations, each disconnector and grounding switch comprises two or more nested disconnector blades. By using two disconnector blades, two parallel paths are created for current flow, which can help improve thermal performance. In other examples, each disconnector and grounding switch comprises a single nested disconnector blade.

[0014] Optionally, the device comprises a vacuum interrupter.Optionally, the one or more switching mechanisms include a vacuum interrupter.

[0015] In some examples, the device comprises a plurality of switching devices, each switching device comprising a plurality of poles, each pole associated with a respective switching mechanism of the one or more switching mechanisms and a respective disconnector and grounding switch of the one or more disconnectors and grounding switches. A more compact device architecture may be facilitated by the use of telescoping or retractable blades as described herein.

[0016] In some implementations, the telescoping disconnector blade comprises an outer contact and a plurality of contacts, a portion of a first inner contact arranged to slide within the outer contact and a portion of a second inner contact arranged to slide within the first inner contact.

[0017] In some other implementations, the telescoping disconnector blade includes an outer contact and an inner contact, a portion of the outer contact being positioned to slide over the inner contact, the inner contact comprising a first end of the disconnector blade, and the outer contact comprising a second end of the disconnector blade.

[0018] In some implementations, the telescoping disconnector blade includes an outer contact and a plurality of inner contacts, a portion of the outer contacts arranged to slide over a first inner contact, and a portion of the first inner contacts arranged to slide over a second inner contact, and the outer contacts include a second end of the disconnector blade.

[0019] A method for operating a disconnector and grounding switch (or disconnect-grounding switch) including a telescoping disconnector blade having a first end and a second end, the disconnector blade configured to pivot about the first end between three different positions. The method includes pivoting the disconnector blade about the first end from a first position in which the disconnector and grounding switch are closed and a power source is connected to a load through the disconnector blade to a second position, the second position being an isolation position in which the disconnector and grounding switch are open and the power source is disconnected from the load. The method further includes pivoting the disconnector blade about the first end from the second position to a third position in which the power source is disconnected from the load and the second end of the disconnector blade is electrically connected to a ground contact.

[0020] In some examples, the disconnector and earthing switch is a 3PS switch (3 position disconnector and earthing switch).

[0021] The method may further include compressing the disconnector blade as the disconnector blade pivots from the first position to the second position. The method may further include extending the disconnector blade as the disconnector blade pivots from the second position to the third position.

[0022] Also disclosed herein is a device comprising one or more switching mechanisms configured to disconnect power from a load, and one or more disconnectors and grounding switches, each associated with a respective switching mechanism. Each disconnector and grounding switch comprises a telescoping disconnector blade having a first end and a second end, the disconnector blade configured to pivot about the first end between two or more different positions. The two or more positions include a first position in which the disconnector and grounding switches are closed and the power source is connected to the load through the disconnector blade, and a second position in which the power source is disconnected from the load and the second end of the disconnector blade is electrically connected to a ground contact. This can be implemented as a two-position ground disconnect switch.

[0023] In some implementations, each disconnector and earthing switch comprises two or more telescoping disconnector blades.

[0024] In some examples, the two or more positions further include a third, isolation position in which the disconnector and grounding switch are open and the power source is disconnected from the load. In some examples, the disconnector and grounding switch (also called a ground disconnect switch) is a 3PS switch.

[0025] Also disclosed herein is a switching device configured to disconnect power from a load, the switching device comprising a telescoping disconnector blade having a first end and a second end, the disconnector blade configured to pivot about the first end between two or more different positions. The two or more positions include a first position in which the power source is connected to the load through the disconnector blade and a second position in which the power source is disconnected from the load. In the second position, the second end of the disconnector blade can optionally be electrically connected to a ground contact.

[0026] Any of the features or examples described above may be combined in any suitable combination, for example, device features may be combined with method features and vice versa. [Brief explanation of the drawings]

[0027] The following description refers to the drawings. [Figure 1] 1 illustrates a front view of an exemplary device having one or more switching mechanisms and one or more disconnectors and grounding switches as described herein. [Figure 2A] 1 illustrates a front view of an exemplary disconnector and grounding switch in a first, on position. [Figure 2B] 1 illustrates a front view of an exemplary disconnector and grounding switch in a second, off or isolation position. [Figure 2C] FIG. 10 shows a front view of an exemplary disconnector and grounding switch in a third, grounded position. [Figure 3A] 1 shows a perspective view of breakdown paths in an exemplary disconnector and earthing switch; [Figure 3B] FIG. 1 illustrates a front view of an exemplary disconnector and earthing switch clearance, showing the clearance between the switch and the housing. [Figure 4A] 1 illustrates an exemplary telescoping or retractable blade in a first, extended or uncompressed position. [Figure 4B] 4B shows the blade of FIG. 4A in a second, compressed position. [Figure 5A] 1 illustrates a front view of an exemplary disconnector and grounding switch with telescoping blades in a first, on position. [Figure 5B] FIG. 1 shows a front view of an exemplary disconnector and grounding switch in a second, off or isolation position (with compressed telescoping blades). [Figure 5C] FIG. 3 illustrates a front view of an exemplary disconnector and grounding switch in a third, grounded position. [Figure 6A] FIG. 6A shows a perspective view of an insulating support. [Figure 6B] FIG. 6B shows a perspective view of an insulating support in combination with an exemplary disconnector and earthing switch. [Figure 7A] FIG. 10 is a schematic diagram of another exemplary telescoping blade. [Figure 7B] FIG. 10 is a schematic diagram of another exemplary telescoping blade. DETAILED DESCRIPTION OF THE INVENTION

[0028] 1, a device 100 is described that includes one or more switching mechanisms 110 configured to disconnect power from a load, and one or more corresponding disconnect and ground switches 330. Each disconnect and ground switch is associated with a respective switching mechanism. In the example described herein, the disconnect and ground switches are 3PS switches (3-position disconnect and ground switches), but it will be understood that the nested blade principle can be applied to other ground disconnect switches (e.g., 2-position ground disconnect switches) and other switch types more generally.

[0029] The device 100 may be a switchgear or any other switching or disconnecting device. The device may comprise, for example, a circuit breaker, optionally a vacuum circuit breaker (VCB), or a load switch / breaker. In some examples, the device 100 may comprise multiple switching devices, each of which includes multiple poles. For example, the device 100 may be a three-way, three-pole device. Each pole may be associated with a respective switching mechanism of one or more switching mechanisms and with a respective disconnector and grounding switch of one or more disconnectors and grounding switches. Each of the multiple switching devices may optionally be implemented, for example, as a vacuum circuit breaker (VCB) or a load switch / breaker. In the examples below, three switching mechanisms 110 are shown, but any suitable number of switching mechanisms (of any suitable type, e.g., mechanical, electromechanical, and / or solid state) may be used.

[0030] The switching mechanism is provided within a housing 216. The housing has a first side wall 216a, a second side wall 216b, and a bottom plate 216c. The switching mechanism shown here is disposed along a first axis 102 between the first side wall 216a and the second side wall 216b of the housing 216.

[0031] 1, each disconnector and grounding switch has a disconnector blade 332 pivotally connected at a first end 342 to an associated switching mechanism. The disconnector blade 332 is a disconnector and grounding switch contact that facilitates electrical connection of a load to a power source via the disconnector and grounding switch. In the example of FIG. 1, the first end 342 of the disconnector blade (or contact) is pivotally connected or coupled to an upper portion of a housing that encloses the switching mechanism. The disconnector blade 332 also includes a second end 334 opposite the first end.

[0032] In some examples, each switching mechanism includes a fixed contact and a movable contact, and an actuation mechanism including a shaft 214 (extending into the page and perpendicular to the first axis 102 here) and a drive rod 344. The shaft is configured to rotate (here, about an axis of rotation perpendicular to the first axis 102) to transmit an external input to move the movable contact and open or close the switching mechanism. The drive rod 344 is connected to the shaft 214 and converts the rotation of the shaft 214 in response to the external input into movement of the movable contact along a second axis 106 perpendicular to the first axis. The second axis is also referred to herein as the operating axis. The movable contact is movable by the actuation mechanism drive rod 344 and is disposed between the fixed contact and the actuation mechanism shaft 214. Each disconnector and grounding switch 330 is disposed along the second axis 106 between the active portion of the switching mechanism 110 (here, the movable contact and the fixed contact) and the shaft 214.

[0033] In some particular examples, the switching mechanism 110 is implemented as or comprises a vacuum interrupter (or VI). The VI may be implemented as part of a VCB or other circuit breaker, or as part of any other type of switching device (such as a load break switch, or LBS). The upper contact of the vacuum interrupter VI is a movable contact that is movable by an actuation mechanism in response to rotation of the shaft 214. Referring to FIG. 1 , the fixed contact of the vacuum interrupter VI is fixed to a bottom plate 216c of the housing 216 via a support plate (not shown). The bottom plate 216c and the first and second side walls 216a, 216b at least partially define a switching compartment of the switchgear 100, 200. Although the switching compartments described herein are air insulated, any other insulating medium (such as vacuum, pressurized air, SF6 (sulfur hexafluoride) or other gaseous dielectric medium, or inert gas) that meets the necessary dielectric / thermal requirements can be provided within the switching compartment.

[0034] The VI housing covers the fixed and moving contacts and is bolted to the support plate. Post supports (not shown) formed of insulating material may be bolted between the support plate and bottom plate 216c to hold the support plate within the switching compartment of housing 216. In this particular example, the VI is attached to bushing 350, which is bolted to bottom plate 216c and secured to the support plate with epoxy.

[0035] Here, the VI housing serves as a support for a hinge or pivot point at a first end 342 of the disconnector blades 332. The first end of each disconnector blade is pivotally coupled to the switching mechanism 110. The first end of the disconnector blades 342 may be pivotally coupled to the switching mechanism between the movable contact and the shaft 214. In this particular example, the first end of the disconnector blades 342 is pivotally coupled to the top of the VI housing, which encloses the fixed and movable contacts of the switching mechanism 110.

[0036] A metal shield (not shown) may be provided within the VI housing and disposed between the movable contact and the first end of the disconnector blade. The metal shield acts to help shield the disconnector blade and hinge / pivotable connection from any electric fields within the vacuum interrupter. As described above, the movable contact moves within the VI housing in response to actuation / rotation of shaft 214. In particular, rotation of shaft 214 actuates actuation mechanism drive rod 344, pulling the movable contact along the actuation axis toward shaft 214 and opening switch 212.

[0037] The disconnector blade of each disconnector and earthing switch 330 is arranged to pivot about a first end to move between three different positions, as further shown in FIG.

[0038] 2A, the disconnector blade 332 is placed in a first position where the disconnector and grounding switch are closed and power is connected to the load through the disconnector blade 332. In this first position, current flows through the device 100 via the switching mechanism 110 and the disconnector blade 332.

[0039] In response to user actuation of a direct break mechanism (not shown), the disconnector blade is moved from a first position to a second position shown in FIG. 2B. The direct break mechanism includes a second shaft and a second actuation mechanism operated by rotation of the second shaft. A user can rotate the second shaft by turning or rotating an external handle, and the second actuation mechanism rotates in response to the rotation of the shaft. In this example, the second actuation mechanism is a four-bar crank rocker mechanism 348, although any suitable actuation / drive mechanism can be used. In particular, in response to rotation of the second shaft of the direct break mechanism, the disconnector blade is configured to rotate from a first position to a second position about a pivot axis, the rotation being toward the second side wall 216b of the housing.

[0040] 2B , the disconnector and grounding switch are open, disconnecting the power source from the load (the current path between the load and the power source through the disconnector blade 332 is interrupted). This second, intermediate position is an isolation position in which the disconnector and grounding switch are “off.” In some implementations, the disconnector blade 332 can be moved to this “off” or isolation position without corresponding actuation of the switching mechanism 110 (i.e., independent of rotation of the shaft 214). However, in other implementations, this operation depends on the position of the switching mechanism 110. For example, if the disconnector and grounding switch are an off-load 3PS arranged in series with the switching mechanism, the off-load 3PS switch can operate only when the switching mechanism (optionally a VCB) is in the open state. This can be achieved by an interlock / interlocking mechanism, where the 3PS direct disconnection mechanism interlocks with the switching mechanism to ensure that the device operates in accordance with the mechanical interlock requirements.

[0041] In response to further user actuation of the second shaft of the direct disconnection mechanism in the same rotational direction, the disconnector blade is moved from the second position to the third position shown in FIG. 2C . In particular, the disconnector blade is configured to rotate about a pivot axis from the second position to the third position, with the rotation again toward the second side wall 216b of the housing. In the third position, the power source is disconnected from the load, and the second end 334 of the disconnector blade is electrically connected to the ground contact 336. In some implementations, the disconnector blade 332 can be moved to this ground position without corresponding actuation of the switching mechanism 110 (i.e., independent of rotation of the shaft 214). However, in other implementations, this operation depends on the position of the switching mechanism 110, as described above. For example, if the disconnector and grounding switch are an off-load 3PS arranged in series with the switching mechanism, the off-load 3PS switch can operate only when the switching mechanism (optionally a VCB) is in the open state.

[0042] Thus, the disconnector and grounding switches 330 can be actuated or controlled independently of the shaft 214, which controls or actuates the movable contacts of the switches. In the above example, the disconnector blade 332 is coupled to a fixed component (e.g., the housing of the VI) and is therefore decoupled from the actuation of the switching mechanism 110; in other words, actuation of the device 100 via the shaft 214 does not actuate the disconnector and grounding switches 330. However, it will be appreciated that in other examples, the second actuation mechanism (of the disconnector and grounding switches) can be configured such that when the movable contacts are opened by the shaft 214 to disconnect the power source from the load, the disconnector blade 332 of the disconnector and grounding switches is correspondingly moved to a third, grounded position. In this way, the current path through each switching mechanism 110 is automatically opened in two different positions when the switching mechanism is opened. In other examples, an interlock mechanism can prevent actuation of the direct interruption mechanism when the switching device is open.

[0043] As mentioned above, device 100 includes a three-position disconnector and earthing switch 330. To facilitate field testing of cable integrity and improve ease of maintenance of the switchgear, it is desirable to provide a disconnector and earthing switch having three positions: on, off (or isolation), and earth. It is particularly desirable to combine a three-position disconnector and earthing switch with compact switchgear, as described below with reference to FIG. 3.

[0044] It will be appreciated that the device housing 216 (also referred to as the enclosure) is always at ground potential. In the third position, the disconnector plate is also grounded, while in the second, “off” or isolated position, the disconnector blade 332 is at live potential. In accordance with the IEC 62271 standard for metal-enclosed switchgear, the “off” position isolation test should be performed at an 85 kVp (or 85 kilovolts peak) impulse voltage and a 32 kV power-frequency withstand voltage (the maximum rms value of the voltage the device can permanently withstand). However, because the disconnector blade tip (otherwise referred to as the second end 334) is free in air when in the second position, an end effect causes a high-intensity electric field to be generated at the second end of the disconnector blade 332. This can lead to system breakdown and the formation of an electrical breakdown path 360 between the disconnector blade 332 and the second sidewall 216b of the device 100 (as shown in FIG. 3A ).

[0045] Therefore, to avoid such dielectric breakdown between the housing or enclosure 216, the electric field strength should be reduced and an appropriate clearance d should be maintained between the second sidewall 216b and the tip or second end 334 of the disconnector blade (see FIG. 3B ). Increasing the clearance d directly by moving the sidewall 216b away from the switching mechanism 110 and the disconnector and earthing switch 330 would increase the overall dimensions of the device 100 and prevent the provision of a compact device 100. Therefore, in order to provide a reliable device with a small footprint that can be more easily and safely tested in the field (thereby improving ease of maintenance, for example), it is desirable to increase the clearance d and achieve better dielectric performance within a compact device footprint.

[0046] Referring to Figure 4, a telescoping or retractable contact / disconnector blade 432 is described that can help achieve some of the above-mentioned advantages. The telescoping contact or blade 432 is configured to move between an extended state, shown in Figure 4A, and a compressed or retracted state, shown in Figure 4B. Any suitable configuration of the telescoping or retractable blade can be provided. The telescoping blade 432 is a specific embodiment of the disconnector blade 332 described above.

[0047] 4 , the telescoping disconnector blade 332, 432 includes an outer contact 404 and an inner contact 402, with a portion of the inner contact arranged to slide within the outer contact. These features of the blade 332, 432 are referred to as "contacts" because they electrically connect (to facilitate connection of power to the load via the disconnector and grounding switch 330). In other words, the inner contact 402 can be inserted into the outer contact 404 and can slide relative to the outer contact. The outer contact comprises the first end 342, 442 of the disconnector blade (the end about which the disconnector blade is configured to pivot). The inner contact comprises the second end 334, 434 (the free end or tip) of the disconnector blade.

[0048] With further reference to FIG. 4A , the outer contact 404 includes a guide hole, and the inner contact 402 slides within the guide hole. The disconnector blade further includes a compliant member 406 disposed within the guide hole and configured to urge the inner contact 402 out of the guide hole. In other words, the inner contact can be configured to retract into the outer contact, with the compliant member acting to oppose the retraction. While the compliant member 406 in FIG. 4 is shown as a compression spring, any other compliant member may be used. The compliant member may be compliant through shape and / or material.

[0049] As shown in FIG. 4B , in response to an external force F applied in a first direction 408 and to the second end 434 of the disconnector blade 432, the inner contact 402 is configured to slide in the first direction 408 within the guide hole of the outer contact 404. The compliant member compresses in response to movement of the inner contact in the first direction 408. The compressed compliant member is then configured to bias the inner contact 404 away from the outer contact in a direction opposite the first direction. In this manner, the disconnector blade 432 can be in the extended state of FIG. 4A in the absence of force F. The disconnector blade is configured to move to the compressed state of FIG. 4B in response to an external force. From the compressed state, the disconnector blade is configured to return to the extended state of FIG. 4A by biasing or urging of the compliant member 406.

[0050] With further reference to FIG. 5 , the disconnector blade 432 is in an extended state in the first and third positions (of FIGS. 2A , 5A , and 2C and 5C , respectively), and the disconnector blade 432 is in a compressed state in the second position (of FIGS. 2B and 5B ). Specifically, as seen in FIGS. 4 and 5 , in the first “on” position and the third “grounded” position, the disconnector blade 432 is in an extended state and has an overall length l_1. In contrast, in the second “off” position, the disconnector blade 432 is in a compressed (or retracted) state and has an overall length l_2. The particular lengths l_1 and l_2 may be determined by the device size and application requirements, as well as the stiffness of the compliant member 406, although L_2 is less than l_1. In this manner, a larger clearance d can be provided for “off” or isolation testing without increasing the overall footprint of the device 100. Thus, by using disconnectors and earthing switches having telescoping or retractable contacts (or disconnector blades), a highly reliable device can be provided with a small footprint, improved dielectric performance, and which can be more easily and safely tested in the field (thereby improving ease of maintenance, for example). It will be appreciated that the telescoping blades described herein may also be used with any other form of disconnect and / or earthing switch.

[0051] 5, the second side wall 216b may further comprise an insulating support 500 configured to contact the second end 434 of the retracted / compressed disconnector blade 432 when the disconnector blade is in the second position (having a length l_2). This insulating support 500 is further described in FIG. 6 (FIGS. 6A, 6B).

[0052] 6A , the insulating support 500 includes an insulating guide portion 662 configured to move the disconnector blade 432 from an extended state to a compressed state as the disconnector blade 432 pivots from a first position to a second position. A section 662a of the guide portion 662 is shaped to gradually decrease the distance between the (fixed length) outer contact 404 and the guide portion 662, thereby increasing the displacement of the inner contact 402 of the blade 432 along the first direction 408 (and increasing the compression of the compliant member) as the blade pivots. The reaction force F exerted by the guide portion 662 on the second end 434 of the blade is greater than the reaction force from the compression of the compliant member 406, and therefore the disconnector blade retracts.

[0053] The insulating guide portion 662 can be further configured to move the disconnector blade from a compressed state to an extended state as the disconnector blade pivots from the second position to the third position. In this example, the section 662b of the guide portion is shaped to gradually increase the distance between the (fixed length) outer contact 404 and the guide portion 662, thereby allowing the inner contact 402 of the blade 432 to slide in a direction opposite the first direction 408 as the blade pivots in response to the biasing or urging of the compliant member 406 (and the extension of the compliant member). The reaction force F exerted by the guide portion 662 on the second end 434 of the blade is less than the biasing force from the compression of the compliant member 406, and therefore the disconnector blade extends.

[0054] The use of one or more insulating or isolating features, such as insulating support 500, can improve electrical safety in the isolated (second) location by improving dielectric performance. In particular, insulating support 500 can help reduce field edge effects at second end 334 of disconnector blade 332, providing better dielectric performance compared to high electric fields in air. Insulating support 500 can be provided individually or in combination with one or more other insulating features (including features not described herein).

[0055] In some examples, an insulating sheet 550 may be provided. The insulating sheet 550 may be formed from any suitable insulating material. When the disconnector blade is in the second position, the insulating sheet 550 does not need to contact the second end 434 of the disconnector blade 432. The presence of the insulating sheet 550, even in the absence of physical contact, can act as an obstacle to the breakdown current path and help avoid dielectric breakdown, thereby improving dielectric performance.

[0056] The use of the insulating supports 500 and / or insulating sheet 550 on the second side wall 216b of the housing / enclosure facilitates the use of the three-position disconnect and grounding switch 330 within a compact device footprint. Thus, by using the insulating features provided herein, a more compact and reliable device can be provided.

[0057] In the example of FIG. 6B , the disconnector and grounding switch 330 includes two disconnector blades 434 disposed on either side of the second actuation mechanism 348. In other words, each disconnector and grounding switch can include two or more nested disconnector blades. By using two disconnector blades, two parallel paths for current flow are formed, which can help improve thermal performance. In such an implementation, two guide portions 662 are also provided, one guide portion for each disconnector blade. However, it will be understood that other configurations are possible. For example, a single nested blade can be provided. In such an implementation, the size / shape of the contacts in the on / off / ground positions can be implemented, for example, as jaw contacts, to facilitate good electrical connection between the blades and the contacts.

[0058] The disconnector blades can be operated or actuated by operation of the second actuating mechanism 348. However, as noted above, in this example, the disconnector blades are actuated by the second actuating mechanism only when the switching mechanism is open. In other words, the actuating mechanisms are geared such that the disconnector and earthing switch or 3PS can be operated only when the switching mechanism (such as a VCB) is in an open state. In this example, the second actuating mechanism is implemented as a four-bar crank rocker mechanism (i.e., the nested disconnector blades are actuated by a four-bar crank rocker mechanism).

[0059] In some examples, the electrical contact 664 is coupled to the insulating support 500 and configured to contact the second end(s) 434 of the disconnector blade(s) 432 when the disconnector blade(s) 432 are in the second position. When two disconnector blades are provided, the electrical contact 664 is configured to be disposed between the second ends 434 of the respective blades 432. The electrical contact 664 is disposed between the two guide portions 662. The electrical contact 664 may include a partially spherical end. The use of a spherical (i.e., curved) portion at the second end of the electrical contact 664 acts to reduce or avoid high electric fields at the electrical contact 664. Therefore, dielectric performance can be further improved.

[0060] In the example described herein, the telescoping contacts or blades of the disconnector and grounding switch 330 include two contacts that are movable relative to one another. However, in other implementations, there may be three or more movable contacts, as shown in FIG. 7A . In this example, there are two inner contacts 402 a, 402 b and one outer contact 404. The inner contacts 402 a, 402 b are configured to slide relative to each other and relative to the outer contact to provide the telescoping blade 432. Two compliant members 406 a, 406 b may be provided to facilitate the return of the telescoping blade 432 to its extended state (e.g., of FIG. 4A ). The compliant members may be disposed in respective guide holes. In some other examples, three or more inner contacts and corresponding compliant members may be provided.

[0061] In another exemplary implementation shown in Figure 7B, the inner and outer contacts may be interleaved to form nested blades 432. The outer contact 404 comprises the second end 334, 434 (free end or tip) of the disconnector blade. The inner contact 402b comprises the first end 342, 442 of the disconnector blade (the end about which the disconnector blade is configured to pivot). In this configuration, the outer contact slides over the inner contact(s) (rather than the inner contact(s) sliding within the outer contacts as in Figures 4 and 7A).

[0062] Other configurations of the telescoping blades as described herein may also be provided. It is understood that the foregoing embodiments are not to be construed as limiting, and that other variations, modifications, and equivalents will be apparent to those skilled in the art and are intended to be encompassed by the claims unless expressly excluded by such claim language.

[0063] Moreover, the disclosure of this application should be understood to include any novel feature or any novel combination of features explicitly or implicitly disclosed herein or in any generalization thereof, and the claims may be formulated to cover any such feature and / or combination of such features derived therefrom.

Claims

1. A device (100, 200) comprising: one or more switching mechanisms (110) configured to disconnect the power source from the load; one or more disconnectors and earthing switches (330), each disconnector and earthing switch associated with a respective switching mechanism, each disconnector and earthing switch comprising a telescoping disconnector blade (332, 432) having a first end (342, 442) and a second end (334, 434); a housing (216) having a first sidewall (216a) and a second sidewall (216b); Equipped with The disconnector blade is configured to pivot about the first end between three different positions, the three positions including: a first position in which the disconnector and earthing switch are closed and the power source is connected to the load through the disconnector blade; a second, isolation position in which the disconnect switch and grounding switch are open and the power source is disconnected from the load; a third position in which the power source is disconnected from the load and the second end of the disconnector blade is electrically connected to a ground contact (336); Including, the telescoping disconnector blade is configured to rotate about a pivot axis from the first position to the second position, the rotation being toward the second side wall (216b) of the housing (216); the second sidewall (216b) includes an insulating support (500) configured to contact the second end of the disconnector blade when the disconnector blade is in the second position. Device (100, 200).

2. 2. The device of claim 1, wherein the telescoping disconnect blade comprises an outer contact (404) and an inner contact (402), a portion of the inner contact being arranged to slide within the outer contact.

3. The device of claim 2 , wherein the outer contact comprises the first end of the disconnector blade and the inner contact comprises the second end of the disconnector blade.

4. The outer contact has a guide hole, and the inner contact slides within the guide hole; 4. The device of claim 2 or claim 3, wherein the disconnector blade further comprises a compliant member (406) disposed within the guide hole and configured to bias the inner contact out of the guide hole.

5. 5. The device of claim 4, wherein in response to an external force applied in a first direction (408) and to the second end of the disconnector blade, the inner contact is configured to slide in the first direction within the guide hole of the outer contact, and the compliant member is configured to bias the inner contact in a direction opposite the first direction.

6. The device of claim 4 , wherein the compliant member is a compression spring.

7. the telescoping disconnect blade is configured to move between an extended state and a compressed state; 3. The device of claim 1 or claim 2, wherein the disconnector blade is in the extended state in the first position and the third position, and the disconnector blade is in the compressed state in the second position.

8. 3. The device of claim 1 or claim 2, wherein the insulating support comprises a guide portion (662) configured to move the disconnector blade from the extended state to the compressed state when the disconnector blade pivots from the first position to the second position.

9. 9. The device of claim 8, wherein the guide portion is further configured to move the disconnector blade from the compressed state to the extended state when the disconnector blade pivots from the second position to the third position.

10. 3. The device of claim 1 or claim 2, further comprising an electrical contact (664) coupled to the insulating support, the electrical contact configured to contact the second end of the disconnector blade when the disconnector blade is in the second position.

11. 11. The device of claim 10, wherein the electrical contact comprises a partially spherical end configured to contact the second end of the disconnector blade when the disconnector blade is in the second position.

12. 3. A device according to claim 1 or claim 2, wherein each disconnector and earthing switch comprises two or more telescoping disconnector blades.

13. 3. The device of claim 1 or claim 2, comprising a plurality of switching devices, each switching device having a plurality of poles, each pole associated with a respective switching mechanism of the one or more switching mechanisms and a respective disconnector and earthing switch of the one or more disconnectors and earthing switches.

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