Insulation in medium to high voltage electric switchgears

Abstract

An electric switchgear (10) includes a visible disconnect switch (100) configured as a single-phase or multi-phase switch, wherein each phase structure (102) comprises an individual compartment (110) housing electric terminals (104) and movable contact bars (105) including electric contacts (107) for connecting or disconnecting with electrical terminals (104), and wherein the individual compartment (110) includes a first insulating shed (108) disposed inside the compartment (110) and a second insulating shed (152, 152') disposed outside the compartment (110), thereby increasing dielectric strength of the visible disconnect switch (100). Further, a method (1200) for connecting and disconnecting an electric switchgear (10) is provided.

Description

[0001] 202418862

[0002] INSULATION IN MEDIUM TO HIGH VOLTAGE ELECTRIC SWITCHGEARS

[0003] Technical Field

[0004] Aspects of the present disclosure generally relate to switchgear for electrical power distribution, and more specifically to insulation in a medium voltage to high voltage electric switchgear.

[0005] Background Art

[0006] Switchgear, switchboards, panel boards and other assemblies are general terms which cover metal enclosures or cabinets that house switching and interrupting devices such as fuses and circuit breakers along with associated control, instrumentation, and metering devices. Such assemblies typically include buses, interconnections and supporting structures used for distribution of electric power. In addition, the assemblies are categorized as high, medium, and low voltage switchgear and switchboards.

[0007] Medium voltage to high voltage switchgear products contain electrical switching mechanisms that can interrupt and / or energize an electrical circuit at medium to high voltages, for example to allow utility facilities, industrial users, and large data centers to selectively turn on and off parts of an electrical grid system. These electrical switching mechanisms are designed to be highly insulated because they are vulnerable to short circuits and leaks without proper insulation. Electrical insulation in switching mechanisms provides a strong barrier among various components within a switching device. Electrical insulation also acts as a precautionary shield against electrical shock. Moreover, such electrical insulation minimizes the operating hazards in order to ensure a safe work environment for system operators. Often, electrical insulation is accomplished by large air gaps or by using insulating materials. As switching devices become smaller, the distances between different components in the devices become smaller. It can be extremely challenging to design and manufacture a safe and small electrical switching mechanism with adequate insulation.

[0008] For the sake of brevity, a reference to the disconnect switch or visible disconnect switch shall hereinafter be also referenced as “DS”. The disconnect switch responsible for creating a visible open can also be referred to as a visible break. The interrupter / vacuum interrupter shall 202418862 hereinafter be also referenced as “VI”. In the embodiments to be presented, any reference to a vacuum interrupter should not limit the inclusion of a broader category of interrupters. The embodiments to be presented may use a vacuum interrupter or any category of interrupter or breaker.

[0009] Summary

[0010] Exemplary embodiments are described in the context of electric switchgears and switching mechanisms. Switchgears and switching mechanisms often comprise monitor, control, protection, and metering equipment. Further, switchgear equipment often incorporate the use of circuit breakers, relays, fuses, reclosers, interrupters, switches and control panels that are used to interrupt and / or energize a power distribution system. More specifically, switchgear equipment is responsible for managing power flow, by interrupting power, or diverting power to prevent equipment failure.

[0011] The present disclosure provides insulation designs for use in medium to high voltage electric switchgears. An aspect of the present disclosure provides an electric switchgear comprising a visible disconnect switch (DS) configured as a single-phase or multi-phase switch, wherein each phase structure comprises a pair of terminals, and a contact bar assembly comprising electrical contacts and contact housing for connecting or disconnecting the electric contacts from terminals. The disconnect switch comprises multiple compartments. Each compartment of the disconnect switch is associated with a phase of a power distribution system and is housed within a base and an insulating optically transmissive cover. The insulating optically transmissive cover is herein also referred to as simply “cover”. The terminals are fixed and are positioned preferably through the base of each compartment. The contacts are rotatably movable about the rotating shaft and are contained in a contact housing fixed to the rotating shaft. In addition to the terminals, contacts, and rotating shaft, each compartment comprises an insulating first shed, barrier or shield fixed to the rotating shaft or substantially surrounding the rotating shaft and within an interior spacing of the base and cover. Outside of the compartment, an insulating second shed may be positioned between the compartments as well as at the end of the rotating shaft, thereby increasing a dielectric strength of the disconnect switch overall. 202418862

[0012] Another aspect of the present disclosure provides a means for verifying that the interrupter and visible disconnect switch have both been disengaged and it is now safe for an operator to have access to the switchgear equipment. Verification is achieved by using an optically transmissive clear window that houses the switchgear equipment as well as the insulating optically transmissive cover over the compartment’s base.

[0013] Another aspect of the present disclosure provides a method for disconnecting and connecting an electric switchgear, the method comprising disconnecting an interrupter, and then disconnecting a visible disconnect switch. When the interrupter and disconnect switch are disconnected, they are in an open state. Conversely, the method provides for first connecting the disconnect switch and then connecting the interrupter, such that when connected, the interrupter and disconnect switch are in a closed state. The method provides a means for connecting and disconnecting the visible disconnect switch and the interrupter by utilizing a safety interlock system.

[0014] Brief Description of the Drawings

[0015] FIG. 1A and FIG. 1 B illustrate perspective views of exteriors of two different switchgear housings with external components shown on the top surface in accordance with exemplary embodiments of the present disclosure.

[0016] FIG. 1C illustrates a cross-sectional side view of an insulated switching compartment in a disconnect switch of an electric switchgear in accordance with an exemplary embodiment of the present disclosure.

[0017] FIG. 2 illustrates a cross-sectional top view of an insulated switching compartment in a multiphase visible disconnect switch of the electric switchgear in accordance with an exemplary embodiment of the present disclosure.

[0018] FIG. 3 illustrates a perspective view of a drive shaft of a disconnect switch of the electric switchgear in accordance with an exemplary embodiment of the present disclosure. 202418862

[0019] FIG. 4 illustrates a top cross-sectional view of an insulated switching compartment in a multiphase visible disconnect switch of the electric switchgear including voltage jump distance in accordance with an exemplary embodiment of the present disclosure.

[0020] FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9 illustrate perspective views of a safety interlock system in the electric switchgear in accordance with exemplary embodiments of the present disclosure.

[0021] FIG. 10 and FIG. 11 illustrate exteriors views of two different switchgear housings with external components shown on the top surface including windows, exterior portion of safety interlock systems and operators / actuators in accordance with exemplary embodiments of the present disclosure.

[0022] FIG. 12 illustrates a flow chart of a method for connecting and disconnecting the electric switchgear in accordance with an exemplary embodiment of the present disclosure.

[0023] Detailed Description

[0024] To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments, wherein like reference numerals represent like elements throughout. They are described in the context of electric switchgear and switchgear assemblies, in particular medium voltage to high voltage electric switchgear although in certain applications, the present disclosure is likewise applicable to low voltage switchgear.

[0025] The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

[0026] In existing medium to high voltage switchgears, which are relatively large devices, insulation is accomplished by large airgaps or by using insulating materials, called “dielectrics.” As the size of the switchgear gets smaller, insulation becomes ever more important. In addition to using insulation material such as dielectrics to insulate the different components inside the switchgear, 202418862 the switchgear can also be designed with insulating components that are solid and act as electrical barriers. Examples of insulating components include panels and insulation sheds, often referred to as “sheds”, disposed in between various electrical conductors to prevent for example voltage from creeping and jumping (arcing) across these various electrical conductors.

[0027] In addition, utility companies, industrial users, and data centers deploy switchgear in a variety of settings, including underground distribution systems, and are required to ensure that their teams can safely perform work on them. This is typically accomplished by providing a window through which system operators can visually confirm that the electrical connections are isolated or separated from energized circuits prior to performing any work on the power distribution system. These windows are typically installed on switchgear housings that allow switchgear components to be visibly accessible through the windows. Such access allows for immediate visual verification that contacts are either in an open or closed position.

[0028] Due to the physical design of the switching devices such as a vacuum interrupter, the electrical contacts are often not visible through a window due to the insulation surrounding the interrupter. As an alternative, a second switching device is added in series with the main switch that can be seen through a window. These second switching devices are often referred to as “disconnect switches”. Other terms for these second switching devices include “visible break” or “visible open point”. Disconnect switches are typically used to control multiple switch operating mechanisms that can be used to open all switches at the same time, or in a sequence to stop the flow of electricity. The visible disconnect mechanisms provide system operators with the ability to visually confirm that the electrical contacts are disconnected from energized circuits.

[0029] FIG. 1A and FIG. 1B illustrate two variations of submersible switchgears 10 that incorporate the use of certain aspects of the present disclosure. The switchgear housing 159 is demonstrated in a circular or round form, although housing 159 is generally made to fit the locational environment. In these submersible versions, these two switchgears 10 are insertable through manhole covers and the housing 159 is hermetically sealed to prevent environmental intrusions such as water and sludge. In a different environment, such as above ground installation, switchgears 10 can be placed on concrete pads and are known as pad-mounted switchgear. In such pad-mounted environment, the shape of the switchgear housing 159 can take any required shape, however, 202418862 such switchgear equipment 10 is generally designed with a square or rectangular shape (not shown).

[0030] Common to switchgear 10, that incorporate certain aspects of the present disclosure, are the utilization of a switchgear housing window 160 positioned in the most convenient line of sight. In the illustrations, submersible switchgear 10 generally have windows 160 on a top surface of the switchgear housing 159 since it is the most convenient line of sight when viewing the switchgear 10 from street level and through the manhole opening. Alternatively, windows 160 can be placed on any surface of the switchgear housing 159. In certain cases, one or more windows 160 can be placed wherever there is a need for visual confirmation of the state of certain switchgear 10 components.

[0031] Another common aspect of switchgear 10 as shown in FIG. 1A and FIG. 1B are other external switchgear components such DS handle 132 and VI handle 142 that are part of a larger mechanical linkage 158 (see FIG. 6 to FIG. 9) below the top surface of the switchgear housings 159. Moreover, bushings 164 are shown and are the point of external connections to the VI 140 and the DS 100.

[0032] FIG. 1C illustrates a cross-sectional side view of an insulated DS through VI and through interrupter chamber and contacts and related operating mechanisms in accordance with an exemplary embodiment of the present disclosure.

[0033] In accordance with embodiments of the present disclosure, a visible DS 100 is located at a top portion of the electric switchgear 10. The visible DS 100, hereinafter also simply referred to as DS 100, may be configured as a single-phase or multi-phase DS 100. In FIG. 1C, the DS 100 is configured as a 3-phase switch. Each phase structure 102 comprises a DS 100 and a VI 140. Moreover, the DS 100 portion of the phase structure 102 comprises a pair of terminals 104, a contact bar assembly 106 for connecting or disconnecting the fixed terminals 104 to / from rotatably movable contacts 107 of contact bar 105 on a rotating shaft (shown in for example FIG. 2 and FIG. 3), and a compartment 110 comprising a base 111 and cover 112.

[0034] In the example of FIG. 1C, the contact bar assembly 106 comprises two contact bars 105 with electric contacts 107 at opposite ends, joined together within contact housing 109 (shown in 202418862

[0035] FIG. 3), and is shown in a closed position and connecting the terminals 104 with electric contacts 107.

[0036] More specifically, compartment 110 of each phase structure 102 is at the top portion of the DS 100. Each compartment 110 further comprises a shed 108 that is located near a wall of compartment 110. The contact bar assembly 106 is arranged in a mid-section of compartment 110. The contact bar assembly 106 and the shed 108 are connected to a drive shaft 150 (hidden from the view). The drive shaft 150 can be seen in FIG. 2 and FIG. 3 and will be described in more detail with reference to FIG. 3. The compartment 110 houses the terminals 104, contact bars 105, contacts 107, rotating drive shaft 150, and a first shed 108 with the foundational base 111 and insulating optically transmissive cover 112.

[0037] The base 111 and the insulating optically transmissive cover 112 mate to form an enclosure for all the internal components, namely, the rotation shaft 150, first shed 108, terminals 104, the contact bar assembly 106 including the contact bars 105, contacts 107 and contact housing 109. The base 111 and cover 112 are preferably made from insulative materials, such as epoxy resin for the base 111 and a polycarbonate optically transmissive material, such that the contacts 107 and terminals 104 are visible to the naked eye. Accordingly, users or system operators have the ability to immediately and visually confirm that the electrical contacts 107 are disconnected from live energized circuits. The base 111 and cover 112 are preferably assembled and disassembled in a snap-fit manner, although other methods of assembling the base 111 and cover 112 may be used by those skilled in the art of power distribution.

[0038] As noted, in single-phase and multi-phase designs disconnect switches such as DS 100, are designed with insulating components to prevent voltage from arcing across the electrical conductors or creeping across the electrical conductors when the circuits are energized. Voltage creeping refers to the fact that current travels along the surface of an insulating material due to a voltage difference between any two conductive points. Voltage arcing distances refer to the ability of the voltage potential to build up on surfaces and create an arc jumping through air to another electrical contact associated with another phase or to ground. Insulative materials include without limitation, epoxy resin, thermoset composite materials, mica, vulcanized fiber, polypropylene, polycarbonate, NEMA GPO-3, NEMA G-9, NEMA FR4, and Mylar etc. Epoxy resin is often used 202418862 to encapsulate electrically live component parts, i.e. , Solid Insulated Switchgear (SIS) as well as other well-known insulative materials.

[0039] Accordingly, the DS 100 comprises one or more shed insulators, also referred to as first sheds 108 and second sheds 152 (not visible in FIG. 1C, see for example FIG. 2 and FIG. 3). Sheds 108, 152 are generally insulators affixed or molded to, or substantially surrounding the drive shaft 150 in such a way as to increase the surface distance between energized parts, and also to increase the distance that an arc must travel along the drive shaft 150, thereby increasing the distance between energized parts without increasing the length of the shaft 150.

[0040] With reference to FIG. 1A and FIG. 1B, The DS 100 further comprises disconnect switch (DS) handle 132. The drive shaft 150 connects the single-phase or multi-phase switch with the DS handle 132, such that the DS handle 132 is configured to open or close the single-phase or multiphase switch. The DS handle 132 is connected to the drive shaft 150 and can be turned to close or open the DS 100. More specifically, the drive shaft 150 and the contact bar assembly 106 are connected and operatively cause the terminals 104 to engage or disengage from contacts 107. As shown in FIG. 1C, FIG. 2 and FIG. 3, the drive shaft 150 is turned so that the contact bar assembly 106 disconnects / connects the terminals 104 with contacts 107 in substantially circular motion (see rotational arrow 134). As the drive shaft 150 rotates, the contact bar assembly 106 rotates away from and to the terminals 104, thereby opening and closing the contacts 107 and terminals 104.

[0041] The bottom portion of FIG. 1C shows the VI 140, also known as vacuum fault interrupter (VFI). In some embodiments, the visible DS 100 may be operatively connected to VI 140 via a safety interlock system, see for example FIG. 6 through FIG. 9. The visible DS 100 connected to VI 140 functions as a point of engagement and disengagement and ensures that the VI 140 is opened (off) first and closed (on) last. Further illustrated are movable terminal 190 and fixed terminal 144 of the VI 140.

[0042] The DS 100 and VI 140 are connected in series and function as a disconnect switch and circuit breaker (current interrupter). The generally accepted steps are to first open the VI 140 and then the DS 100. Opening the DS 100 first is not advisable since opening contacts while current is flowing can create extremely dangerous arcs and expose maintenance personnel to serious 202418862 injury. The V1 140 primarily functions as a circuit breaker to interrupt short circuits and overcurrent conditions. Afterthe VI 140 has interrupted the current and the circuit is de-energized, the DS 100 can then be safely operated to provide a utility maintenance worker visual confirmation that the switchgear 10 is isolated from the power source so that maintenance and repair services can be provided.

[0043] Although the DS 100 shown in FIG. 1C appears unitary with the VI 140, the DS 100 may be separately made and assembled and thereafter connected to the VI 140 in various ways known to those skilled in the art of power distribution equipment. Whether the DS 100 is unitary or separate in form, the VI 140 fixed terminal 144 must be conductive and connected to DS terminals 104. In FIG. 1C, the VI 140 fixed terminal 144 is connected to terminal 104 by conductor 146.

[0044] FIG. 2 illustrates a cross-sectional top view of three (3) insulated DS compartments 110 configured in a multi-phase visible DS 100 of the electric switchgear 10 in accordance with an exemplary embodiment of the present disclosure.

[0045] As illustrated in FIG. 2, the contact bar assembly 106 of each compartment 110 is in an open position to disconnect terminals 104 from movable contacts 107. Due to the safety interlocking mechanism / system (to be discussed later) used by the present disclosure, when the DS 100 is disconnected, the VI 140 is also mechanically disconnected. The safety interlocking mechanism requires that to disengage the DS 100, the VI 140 must first be disconnected and then the DS 100 may be disconnected. Likewise, connecting the DS 100, the contacts 107 and terminals 104 must first be connected before the VI 140 is connected. In a multi-phase configuration, the separate compartments 110 are ganged to operate (open and close) in a substantially simultaneous manner. Likewise, the internal contacts 144, 190 of VI 140 are engaged or disengaged in a substantially simultaneous manner. Both the DS 100 and VI 140 are open or closed by separate and interlocking handles 132 and 142, respectively. The safety interlocking mechanism is described in connection with FIG. 5 through FIG. 9.

[0046] In FIG. 2, the top view of the DS 100 is shown as a three (3) phase configuration that is controlled by a common or shared rotating drive shaft 150. Noticeable are the interior sheds 108 and exterior sheds 152 and 152’. However, it should be understood that in addition to the sheds 108, 152 202418862 and 152’, the base 111 and cover 112 (see FIG. 1C) also provide an enhanced level of insulation since the base 111 and cover 112 are made from insulating materials.

[0047] Although the insulating sheds 152, 152’ and 108 are shown as disc-like shape, the diameters of the sheds do not have to be the same and can be different. As shown in FIG. 2, the exterior shed 152 (also referenced as the second, exterior shed) in the demonstrated embodiment has a smaller diameter than the interior shed 108 (first, interior shed). Based on the application and configuration of the DS 100 relative to other proximate electric components within the switchgear equipment 10, the choice of shed insulation and dimension selection is selected based on specific operating requirements. In the embodiment shown, the larger shed 108 is configured to take up most of the circumferential space of one side of the compartment 110. It is noticeable that the interior shed 108 is sandwiched between two external sheds 152, 152’. Moreover, the shed 152’ proximate to a portion of an actuator assembly 154 that operates with the DS handle 132 and the VI handle 142 on the right, is larger in diameter than the other external sheds 152 that are not adjacent to a portion of an actuator assembly 154.

[0048] As noted, each compartment 110 comprises a first shed 108. Further, second sheds 152, 152’ are arranged outside the compartments 110, wherein a second shed 152, 152’ is arranged on sides of the compartments 110. In FIG. 2, the DS 100 comprises in total three (3) first sheds 108 (one first shed 108 per compartment 110) and four (4) second sheds 152, 152’. One second shed 152, 152’ is arranged between the compartments 110 and at end sides of the compartments 110 and drive shaft 150. A voltage creep distance between the first shed 108 and the second shed 152 is longer than a physical dimension of the compartment 110, see also FIG. 4. The first shed 108 and second shed 152, 152’ are coupled to or integrated into or substantially surround the drive shaft 150.

[0049] In the present embodiment, the sheds 108, 152, 152’ and / or the drive shaft 150 can be made from epoxy resin or any other insulating material. Moreover, to add strength to the rotating drive shaft 150, the core of the drive shaft 150 may be comprised of a more rigid material such as stainless steel or another rigid material prior to the encapsulation of the drive shaft 150 with an insulating material such as an epoxy resin, or a thermoset composite material. This type of arrangement maintains a good voltage creep and voltage arc / jump distance for its size. The present disclosure includes novel designs that change positions and quantity of the sheds 108 202418862 inside a compartment 110 to make the voltage creep distance and voltage arc / jump distance longer than the actual dimension of the compartments 110.

[0050] With respect to FIG. 2 and FIG. 3, in an exemplary embodiment, a contact housing 109 is integral with the rotating drive shaft 150 and interior shed 108, although the integration of the shed 108 with the contact housing 109 is not necessary. In a variant of the present embodiment, the shed 108 can be configured apart from the contact housing 109 and not in contact with the contact housing. In yet an alternative variation of the present embodiment, the shed 108 may be fixed to the base 111 and does not rotate during the operation of the DS 100. The drive shaft 150 may be positioned through an opening at the center of the shed 108. Within the contact housing 109, two substantially parallel contact bars 105 comprising the electrical contacts 107 are attached to a midline support wall 156 within an opening in the contact housing 109. The contact bars 105 sandwich the midline support wall 156 by using connecting screws 103 at both ends of the contact bars 105.

[0051] FIG. 3 illustrates a perspective view of a drive shaft 150 of a DS 100 of switchgear 10 in accordance with an exemplary embodiment of the present disclosure, comprising interior shed 108, exterior shed 152, 152’ and contact housing 109 having a midline support wall 156.

[0052] In an exemplary embodiment of the present disclosure, the rotatable drive shaft 150 incorporates the first sheds 108 and the second sheds 152, 152’. The drive shaft 150 with the sheds 108, 152 and 152’ is designed so that, when the drive shaft 150 is assembled in the DS 100, the first sheds 108 are positioned inside the individual compartments 110, whereas the second sheds 152, 152’ are positioned outside the compartments 110, see for example FIG. 2. The second sheds 152, 152’ are arranged on each side next to the compartments 110.

[0053] The first sheds 108 and second sheds 152, 152’ are disc-shape-like and may comprise different sizes, specifically different diameters / dimensions. In the present embodiment, the first sheds 108 all comprise the same size, e.g. same diameter. The second sheds 152, 152’ comprise different sizes, wherein some second sheds 152 have a smaller diameter, and some second sheds 152’ have the same diameter as the first sheds 108. In the present embodiment, one (1) second shed 152’ comprises substantially the same size as the first sheds 108. However, it should be noted that all sheds 108, 152 and 152’ may also comprise the same size and same diameter or 202418862 may comprise several different sizes and different diameters depending on the needs of the DS 100. As noted earlier, the sheds 108, 152. 152’ are insulators affixed or molded to or surround the drive shaft 150 in such a way as to increase the surface distance between energized parts and thus to increase the distance that an arc must travel along the drive shaft 150, thereby increasing the distance between energized parts without increasing the length of the shaft 150.

[0054] The drive shaft 150 further incorporates the use of contact housing 109. Each contact housing 109 is designed and formed so that the contact bar assembly 106 can be easily attached or affixed to the housing 109. The contact bar assembly 106, see for example FIG. 1 C, comprises substantially parallel bars 105 to form contacts 107. Each pair of substantially parallel contact bars 105 is formed by positioning the two substantially parallel contact bars 105 in contact with midline support wall 156 by connecting the ends of the contact bars 105 with connecting screws 103 at both ends of the contact bars 105 to form contacts 107. The connecting screws 103 can be seen in FIG. 2 and FIG. 4.

[0055] The rotatable drive shaft 150 including sheds 108, 152, 152’ and contact housing 109 may be for example fabricated by a molding process using insulating materials, such as epoxy resin, thermoset composites, plastics of various compositions and other insulating materials.

[0056] The drive shaft 150 is connected to an actuator assembly 154, such as switch handle 132, see FIG. 6 through FIG. 9, via a mechanical and spring-loaded linkage 158. The actuator assembly 154 comprises all external and internal components that are responsible for opening and closing the VI 140 fixed and movable contacts 144, 190 and the DS terminals 104 and contacts 107. By actuating the switch handle 132, the linkage 158 opens and closes the DS 100, and rotates the drive shaft 150 as well as the contact bar assemblies 106. As previously noted, each phase structure 102 provides a visual confirmation that the DS 100 contacts 107 and terminals 104 are disengaged or engaged. Confirmation is achieved by visually observing from outside the switchgear 10 through window 160 and optically transmissive cover 112.

[0057] FIG. 4 illustrates a cross-sectional representation of a top view of the three (3) insulated switching compartments 110 and related components. The cross-section specifically shows cross-sections of sheds 108, 152, 152’, contact housing 109 to expose contact bars 105, connecting screws 103, and terminals104. 202418862

[0058] With reference to FIG. 4, the disclosed shed configuration comprises an increased voltage arc / jump distance between two electric circuits in neighboring compartments 110 shown by darkened line 170. Because line 170 wraps around the shed 152 disposed between two neighboring compartments 110, a length of the line 170, representing the voltage creepage distance in this new configuration, is longer than the voltage arc / jump distance 172. The redesigned shed structure described in the present disclosure is improved in its dielectric strength.

[0059] The DS 100 employs a shed 152, 152’ between each of the switch compartments 110 in a “ganged” or multi-switch configuration and at the two ends of the switch 100, and only one internal shed 108 in each of the switch compartments 110. This innovation significantly increases dielectric strength by increasing both the voltage creepage distance 170 and the arc jump distance 172. As noted, the rotatable drive shaft 150 incorporates the first sheds 108 and the second sheds 152, 152’. Further, the actuator assembly 154 coupled to the drive shaft 150 is partially shown.

[0060] FIG. 5 through FIG. 9 illustrate perspective views of a safety interlock system utilizing a mechanical linkage assembly 158, hereinafter “linkage assembly”, for controlling the opening and closing of the visible disconnect switches 100 and the fixed and movable contacts 144, 190 of the interrupters 140 in accordance with an exemplary embodiment of the present disclosure.

[0061] Shown in FIG. 5 is a perspective view of a three (3) phase DS 100, wherein the three compartments 110 are illustrated along with the internal and external components used to rotate drive shaft 150 and protect surrounding components from damage. The three compartments 110 and related components previously discussed during description of FIG. 2 are shown in place in its relative proximity to the internal linkage assembly 158 and external DS handle 132 and VI handle 142.

[0062] More specifically, FIG. 5 details the open state of both the DS 100 and VI 140. Note that the contact bar assemblies 106 are shown in a vertical position and in substantially 90 degrees with respect to terminals 104. DS handle 132 is shown as transverse to the surface of the switchgear housing 159 and not in a substantially parallel orientation to the surface of the switchgear housing 159, in a closed state. Operationally, the DS handle’s 132 rotation causes the first DS linkage 194 to cooperate with second DS linkage 196 to apply a rotational force / torque on the 202418862 drive shaft 150. As the drive shaft 150 rotates, so does the contact housing 109 (see for example FIG. 3 and FIG. 4) and the contact assembly 106.

[0063] To impart an applied force to DS switch handle 132, an operator may use any means to impart rotation, including without limitation a hot-stick (also known as live-line tool) with a hook at an end of the hot stick to engage with hole 133 and pull or push the DS handle 132 in either a clockwise or counterclockwise direction to position the DS handle 132 in an open or closed orientation. The hot stick (not shown) is generally made from wood or fiberglass and is insulated to ensure the safety of the utility operator. Noticeable is the VI handle 142 positioned in a rotated manner, indicative that the VI 140 contacts are in an open state. Functionally, VI handle 142 must have been rotated first before the DS switch handle 132 can be rotated. A more detailed description of the interlocking safety mechanism will be later discussed in FIG. 8 and FIG. 9.

[0064] FIG. 6 and FIG. 7 illustrate the components and mechanism for opening and closing of the VI contacts respectively (not shown). In the open state, VI handle 142 is substantially transverse (non-horizontal) to the top surface of the switchgear housing as shown in FIG. 6. The VI handle 142 is shown rotated clockwise to an open position. To close the VI 140 contacts, the VI handle 142 is rotated counterclockwise in a downward motion. The movement of the VI handle 142 to open or close the VI 140 contacts 144, 190 set in motion a kinetic chain of mechanical components. To close the VI 140 contacts 144, 190, a downward counterclockwise force is applied to the VI handle 142 which in turn applies a force to the first VI linkage 176. The VI linkage 176 in turn imparts the downward force to the second VI linkage 178 which then pushes the third VI linkage 179 downward causing the spring bars 180 to rotate clockwise. The VI 140 contacts 144, 190 are shown in FIG. 1C.

[0065] Note that the spring 182 is held in position by the two spring mounting bars 184 and when force is applied to VI handle 142, the spring 182 is moved counterclockwise to the left and about the lower spring bar mount 184. This movement causes the spring 182 to temporarily compress and then decompress and move counterclockwise to the right.

[0066] The bottom of the spring bars 180 are pivotally connected to the drive bar 186. When the force is applied to VI handle 142, drive bar 186 is moved in a clockwise direct and imparts a force to the slide bar 188. The slide bar 188 moves substantially to the left causing the actuating bars 166 to 202418862 move in substantially a vertical position from the previously open state, in which the actuating bars 166 were transverse with respect to a vertical reference. Subsequently, the fixed and movable contacts 144, 190 of the VI 140 come in contact with each other and render the VI 140 in a closed position. This kinetic chain of movement can be reversed in order to open the VI 140 contacts 144, 190.

[0067] FIG. 8 and FIG. 9 illustrate the closed and open state of the DS 100 and VI 140 as shown by the positioning of the DS handle 132 and VI handle 142. In FIG. 8, both the DS handle 132 and VI handle 142 are shown to be in substantially a horizontal position and therefore both the DS 100 and the VI 140 are in a closed or conductive state.

[0068] To open the VI 140, the VI handle 142 must be first rotated counterclockwise into a non-horizontal position. Likewise, to open the DS 100, the DS handle 132 comprising hole 133 must be rotated clockwise into a non-horizontal position. It should be understood that before the DS 100 can be opened as shown in FIG. 9, the VI handle 142 must first be rotated to open, thereafter the DS handle 132 can be accessed and rotated to open DS 100. To close from an open state, the reverse steps must be followed, whereby the DS handle 132 must first be closed before the VI handle 142 may be closed.

[0069] Once the DS handle 132 is in the open position, the DS lock bar 147 (with hole) can be used to insert a lock through the openings of DS lock bar 147 and the switchgear’s lock bar 149. The use of a lock adds another level of safety for the utility operators since the DS handle 132 also performs a blocking action in the event that the VI 140 is attempted to be closed by rotating VI handle 142 in a clockwise manner. Moreover, bushings 164 are shown and are the point of external connections to the VI 140 and the DS 100. Further, the switchgear housing windows 160 are illustrated which provide visual confirmation that the DS 100 is disengaged or engaged.

[0070] In FIG. 10 and FIG. 11 , as well as in FIG. 1, the exterior housing 159 of various types of switchgear 10 are illustrated. More specifically, these switchgears demonstrate the use of a window 160 that allows a utility operator to confirm visually that both the DS 100 and the VI 140 are in an open state - confirming the open position of the VI handle 142 and the DS handle 132. 202418862

[0071] The window 160 may be placed in any convenient location that the utility operator will have visual access to and should coincide with a line of sight of cover 112 of DS 100. Visually, the window 160 allows a utility operator to see through the window 160 and cover 112 to confirm that the terminals 104 and the contacts 107 are not engaged. As previously mentioned, the window 160 and the optically transmissive cover 112 may be made of various clear materials that can withstand harsh outdoor environments. In the present embodiment, the window 160 and cover 112 may be made of a optically transmissive polycarbonate material.

[0072] FIG. 10 and FIG. 11 also illustrate the use of operators or actuators 192 that can on command from an intelligent device, send a message to the operator to perform an opening or closing of the DS 100 and VI 140. The use of these operators 192 will have certain requirements that under certain conditions may preclude the use of such operators 192. Operationally, these operators 192 have an independent power source that will not be affected by the opening of the VI 140 or DS 100. Moreover, such operators 192 will likely be used in a SCADA environment whereby utility operators will work with headend operators to perform testing and maintenance functions.

[0073] FIG. 12 illustrates a flow chart of a method 1200 for connecting and disconnecting the electric switchgear 10 in accordance with an exemplary embodiment of the present disclosure. The method 1200 incorporates multiple steps or acts to ensure the safety of a utility operator.

[0074] Generally, a first step is the opening of the contacts of DS 100 and VI 140, see acts 1210, 1220. A second step is to verify that the contact bars 105 are disengaged from terminals 104, see acts 1230, 1240. A third step is to lock the DS lock bar 147 with switchgear lock bar 149 by using a lock or any other locking mechanism, see act 1250. At act 1260, the method 1200 may end.

[0075] The method 1200 is described in connection with switchgear assemblies and disconnect switches as described herein. More specifically, the method 1200 is described in connection with the electric switchgear 10 and visible DS 100 as described herein. More specifically, the method 1200 may start at 1205 and comprises act 1210 of opening the VI 140 by rotating VI handle 142, and act 1220 of opening DS 100 by rotating DS handle 132. Thereafter the method 1200 progresses with the act 1230 of looking through window 160 and cover 112, and act 1240 of determining whether contacts 107 are disengaged from terminals 104, and act 1250 locking the DS lock 202418862 bar 147 with the switchgear lock bar 149 to ensure safety that the switchgear 10 is not active or conductive. Thereafter, this method ends at act 1260.

[0076] It should be readily appreciated that the present disclosure is susceptible to broad utility and application. Many embodiments and adaptations of the present disclosure other than those herein described, as well as many variations, modifications, and equivalent arrangements, will be apparent from, or reasonably suggested by, the present disclosure and the foregoing description thereof, without departing from the substance or scope of the present disclosure. Accordingly, while the present disclosure has been described herein in detail in relation to specific embodiments, it is to be understood that this disclosure is only illustrative and presents examples of the present disclosure and is made merely for purposes of providing a full and enabling disclosure. This disclosure is not intended to be limiting to the particular apparatus, assemblies, systems, and / or methods disclosed, but, to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the claims.

Claims

202418862Claims1 . An electric switchgear (10), comprising: a visible disconnect switch (100) configured as a single-phase or multi-phase switch, wherein each phase structure (102) comprises an individual compartment (110) housing electric terminals (104) and movable contact bars (105) including electric contacts (107) for connecting or disconnecting with electrical terminals (104), and wherein the individual compartment (110) includes a first insulating shed (108) disposed inside the compartment (110) and a second insulating shed (152, 152’) disposed outside the compartment (110), thereby increasing dielectric strength of the visible disconnect switch (100).

2. The electric switchgear (10) of claim 1 , wherein placement of the first shed (108) and the second shed (152, 152’) increases a voltage creep distance (170) and a voltage arc distance (172).

3. The electric switchgear (10) of claim 2, wherein the voltage creep distance between the first shed (108) and the second shed (152) is longer than a physical dimension of the individual compartment (110).

4. The electric switchgear (10) of claim 1 , 2 or 3, wherein the individual compartment (110) comprises only one first shed (108) disposed inside the compartment (110).

5. The electric switchgear (10) of any of the preceding claims 1 to 4, wherein the individual compartment (110) comprises an insulating optically transmissive cover (112) and a clear window (160) to visibly confirm a connecting or disconnecting status of the electric contacts (107).2024188626. The electric switchgear (10) of any of the preceding claims 1 to 5, further comprising: a disconnect switch handle (132), and a rotatable drive shaft (150) connecting the disconnect switch (100) with the disconnect switch handle (132), wherein the disconnect switch handle (120) is configured to open or close the disconnect switch (100).

7. The electric switchgear (10) of claim 6, wherein the rotatable drive shaft (150) comprises the first shed (108), the second shed (152, 152’) and a contact housing (109) for fastening the contact bars (105).

8. The electric switchgear (10) of claim 7, wherein the rotatable drive shaft (150) with the first shed (108), the second shed (152, 152’) and the contact housing (109) is manufactured as monolithic component.

9. The electric switchgear (10) of claim 7 or 8, wherein the rotatable drive shaft (150) with the first shed (108), the second shed (152. 152’) and the contact housing (109) is molded from insulating material(s).

10. The electric switchgear (10) of claim 7, 8 or 9, wherein the contact bars (105) are fastened to a midline support wall (156) of the contact housing (109).

11. The electric switchgear (10) of any of the preceding claims 1 to 10, further comprising: an interrupter (140) connected with the disconnect switch (100).

12. The electric switchgear (10) of claim 11 , wherein the interrupter (140) comprises a vacuum fault interrupter or a load breaker.20241886213. The electric switchgear (10) of claim 11 or 12, wherein the interrupter (140) and the visible disconnect switch (100) are connected via a safety interlock system, and wherein the safety interlock system is configured to prevent the visible disconnect switch (100) from being opened unless the interrupter (140) is opened and prevent the interrupter (140) from being closed unless the visible disconnect switch (100) is closed.

14. The electric switchgear (10) of claim 11 , 12 or 13, wherein the safety interlock system is formed by a disconnect switch handle (132) and an interrupter switch handle (142), and wherein the disconnect switch handle (132) and the interrupter switch handle (142) are arranged so that the interrupter switch handle (142) must open before the disconnect switch handle (132) opens.

15. The electric switchgear (10) of claim 11 , 12, 13 or 14, wherein a lock bar (147) is coupled to the disconnect switch handle (132), and wherein, in an open position, the lock bar (147) secures and prevents the disconnect switch handle (132) from closing.

16. A method (1200) for connecting and disconnecting an electric switchgear (10), the method comprising: opening (1210) an interrupter (140) by rotating an interrupter switch handle (142), opening (1220) a disconnect switch (100) by rotating a disconnect switch handle (132), looking (1230) through a clear window (160) and insulating optically transmissive cover (112), determining (1240) whether electric contacts (107) are disengaged from electrical terminals (104), and locking (1250) a disconnect lock bar (147) with a switch gear lock bar (149) to ensure safety and that the electric switchgear (10) is inactive or nonconductive.20241886217. The method (1200) of claim 16, wherein the safety interlock system is configured to prevent the visible disconnect switch (100) from being opened unless the interrupter (140) is opened and prevent the interrupter (140) from being closed unless the visible disconnect switch (100) is closed.

18. The method (1200) of claim 16 or 17, wherein the disconnect switch (100) comprises a disconnect switch handle (132) and the interrupter (140) comprises an interrupter switch handle (142), and wherein, when in a closed state, the disconnect switch handle (132) and the interrupter switch handle (142) are arranged in a substantially parallel manner.

19. The method (1200) of claim 16, 17 or 18, wherein the visible disconnect switch (100) is configured as a single-phase or multi-phase switch, wherein each phase structure (102) comprises an individual compartment (110) housing electric terminals (104) and movable contact bars (105) including electric contacts (107) for connecting or disconnecting with electrical terminals (104), and wherein the individual compartment (110) includes a first insulating shed (108) disposed inside the compartment (110) and a second insulating shed (152, 152’) disposed outside the compartment (110), thereby increasing dielectric strength of the visible disconnect switch (100).

20. The method (1200) of claim 16, 17, 18 or 19, wherein the interrupter (140) comprises a vacuum fault interrupter or a load breaker.

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