A transformer neutral point overvoltage protection gas insulated combination electrical apparatus

Abstract

The application provides a transformer neutral point overvoltage protection gas insulated combined electric appliance. The application forms a sealed cavity by a metal shell to accommodate a movable contact, a movable side ball head and a static side ball head, and provides gas insulation for the movable contact, the movable side ball head and the static side ball head. Thus, an induction coil arranged at the periphery of the conductive structure of the movable contact or the movable side ball head can induce the ground current of the transformer neutral point passing through the conductive structure. Thus, the application can integrate the transformer neutral point overvoltage protection grounding isolating switch, the discharge gap and the corresponding current transformer into one by the integrated independent electric appliance structure, reduce the component size, reduce the insulation distance, and thus provide higher safety performance while reducing the installation space occupied by the electric appliance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of transformer protection equipment, in particular to a transformer neutral point overvoltage protection gas insulated combined electrical apparatus. BACKGROUND

[0002] The combined electrical apparatus for transformer neutral point overvoltage protection is electrically connected with the discharge gap, current transformer, grounding isolating switch and arrester, etc. after leading out the transformer neutral point signal, and is used as the neutral point overvoltage comprehensive protection device of the ungrounded transformer in the effective grounding network. The electrical schematic diagram can be seen in the attached Figure 4 The grounding isolating switch and discharge gap are part of the combined electrical apparatus, and realize the direct grounding of the transformer neutral point. The discharge gap or arrester in the combined electrical apparatus is used to realize the electric energy release of the transformer neutral point overvoltage. The current transformer can be connected in series in the loop of the combined electrical apparatus to measure the current through the loop.

[0003] The existing combined electrical apparatus for transformer neutral point overvoltage protection often adopts open air insulation technology, so it needs a large safety distance, increases the land occupation area, is not conducive to the demand of building intensive substation, and is easily affected by external environment such as humidity, altitude, etc. and needs to maintain a safety distance according to the requirements of the corresponding voltage level regulations during operation.

[0004] In addition, the existing isolating switch and discharge gap for transformer neutral point overvoltage protection using air insulation technology cannot be integrated with the current transformer using solid insulation medium, the parts occupy a large space, and are not conducive to the demand of building intensive substation. SUMMARY

[0005] The application aims at the deficiencies of the prior art, and provides a transformer neutral point overvoltage protection gas insulated combined electric appliance, which is used as a transformer neutral point overvoltage comprehensive protection device, adopts SF6 gas insulation technology as a whole, and can realize transformer neutral point overvoltage protection and simultaneously integrate a current transformer. The application can simplify the structure of the transformer neutral point overvoltage protection device and realize the function of measuring the ground current in an integrated manner. The application specifically adopts the following technical scheme. First, to achieve the above purpose, a transformer neutral point overvoltage protection gas insulated combined electric appliance is provided, which comprises: a common end conductor arranged in a gas insulated tank body and electrically connected to a transformer neutral point; a metal shell sealedly connected with the gas insulated tank body and commonly grounded; a switch mechanism arranged in the metal shell, having a switch ground current path connected from the common end conductor to the metal shell, and a switch side induction coil surrounding the periphery of the switch ground current path and used for sensing the ground current passing through the switch ground current path; a gap mechanism arranged in the metal shell, having a gap discharge current path connected to the metal shell, and a gap side induction coil arranged at the periphery of the gap discharge current path and used for sensing the discharge current between the common end conductor and the gap discharge current path; and a tank type surge arrester sealedly connected with the gas insulated tank body and commonly grounded.

[0006] Optionally, the transformer neutral point overvoltage protection gas insulated combined electric appliance as claimed in any one of the above, wherein the metal shell comprises a switch side ground cavity, a gap side ground cavity and a gas insulated tank body, the switch side ground cavity and the gap side ground cavity are respectively communicated with the gas insulated tank body, and the switch side ground cavity and the gap side ground cavity respectively independently accommodate the switch mechanism and the gap mechanism in the interiors thereof; and the switch mechanism and the gap mechanism are independently electrically connected with the common end conductor or disconnected.

[0007] Optionally, the transformer neutral point overvoltage protection gas insulated combined electric appliance as claimed in any one of the above, wherein the switch ground current path comprises: a static contact fixedly connected with the common end conductor; and a dynamic contact, the upper portion of which is slidably electrically connected between the metal shell, the bottom end of the dynamic contact is electrically connected with the static contact when the dynamic contact slides to a lower limit position of the metal shell, and the bottom end of the dynamic contact is electrically disconnected with the static contact when the dynamic contact slides to an upper limit position of the metal shell.

[0008] Optionally, the transformer neutral point overvoltage protection gas insulated combined electric appliance as claimed in any one of the above, wherein the switch side induction coil is arranged at the periphery of the dynamic contact, the dynamic contact penetrates through the switch side induction coil, and the switch side induction coil is used for sensing the unidirectional ground current passing through the dynamic contact.

[0009] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the preceding claims, wherein the gap discharge electric path comprises: a static side ball head fixedly connected with the common terminal conductor; a dynamic side ball head located in the metal shell and above the static side ball head; and a conductive rod having a bottom fixedly connected with the dynamic side ball head and an upper portion slidably connected with the metal shell, and the dynamic side ball head and the static side ball head are both arranged in the insulating gas; when the conductive rod slides downward along the metal shell, the gap distance between the dynamic side ball head and the static side ball head decreases, and the ball-to-ball discharge voltage threshold decreases; when the conductive rod slides downward along the metal shell, the gap distance between the dynamic side ball head and the static side ball head increases, and the ball-to-ball discharge voltage threshold increases; when the ball-to-ball voltage exceeds the discharge voltage threshold, the insulating gas is broken down, and the discharge current is conducted to the conductive rod through the dynamic side ball head and discharged to the grounding loop.

[0010] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the preceding claims, wherein the gap side induction coil is arranged on the outer periphery of the conductive rod, and the conductive rod penetrates through the gap side induction coil, and the gap side induction coil is used for inducing the discharge current unidirectionally passing through the conductive rod.

[0011] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the preceding claims, wherein the metal shell is only provided with a grounding loop outside the switch side induction coil and the gap side induction coil; the grounding loop is formed by connecting the following conductive components: an upper flange arranged on the outer periphery of the middle part of the dynamic contact and / or the conductive rod, and sealingly arranged on the top of the switch side induction coil and / or the gap side induction coil; a lower flange sealingly connected with the gas insulated tank body and arranged below the switch side induction coil and / or the gap side induction coil; and a metal connecting piece stably electrically connected with the upper flange and the lower flange.

[0012] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the preceding claims, wherein the metal connecting piece is a cross-over metal row having upper and lower sides electrically connected with the upper and lower flanges, respectively, and the outer periphery of the switch side induction coil and / or the gap side induction coil is further provided with a coil outer cover, which is optionally arranged on the inner side or the outer side of the cross-over metal row; the inner side of the upper flange extends to the lower flange to form a shielding cylinder surrounding the outer periphery of the dynamic contact and / or the conductive rod, and the bottom of the shielding cylinder is sealed by an insulating connecting piece from the lower flange, the top of the insulating connecting piece abuts against the bottom end of the shielding cylinder, and the bottom of the insulating connecting piece abuts against the upper surface of the lower flange.

[0013] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the above, wherein the metal connecting member is a metal cylinder sealingly connected to the outer periphery of the upper flange and the lower flange; the inner side of the upper flange extends downward to form a shielding cylinder surrounding the outer periphery of the moving contact and / or the conductive rod, and an insulating gap is provided between the bottom of the shielding cylinder and the lower flange, and the insulating gap is filled with insulating gas.

[0014] Optionally, the transformer neutral point overvoltage protection gas insulated combined electrical apparatus as claimed in any one of the above, wherein the gas insulated tank is sealingly connected to the neutral point outgoing oil and gas sleeve, and the common terminal conductor is electrically connected to the transformer neutral point through an oil and gas sleeve connecting conductor in the neutral point outgoing oil and gas sleeve.

[0015] Advantages

[0016] Firstly, the sealed cavity formed by the metal shell is used to accommodate the moving contact, the moving side ball head, and the induction coil surrounding the outer periphery of the conductive structure thereof, and to provide gas insulation therefor. When the moving contact and the stationary contact are in contact, or when the distance between the moving side ball head and the stationary side ball head is less than the discharge gap, the transformer neutral point voltage in the common terminal conductor can be released through electrical contact or discharge process accordingly. Thus, the induction coil provided around the outer periphery of the conductive structure of the moving contact or the moving side ball head can correspondingly induce the grounding current of the transformer neutral point passing through the conductive structure of the contact or the ball head. Thus, the transformer neutral point overvoltage protection disconnector, the discharge gap, and the corresponding current transformer can be integrated into one through the integrated independent electrical apparatus structure, thereby reducing the size of the components, reducing the insulation distance, and providing higher safety performance while reducing the installation space occupied by the electrical apparatus.

[0017] Secondly, the sealed cavity formed by the metal shell is used to accommodate the moving contact, the moving side ball head, and the induction coil surrounding the outer periphery of the conductive structure thereof, and to provide gas insulation therefor. When the moving contact and the stationary contact are in contact, or when the distance between the moving side ball head and the stationary side ball head is less than the discharge gap, the transformer neutral point voltage in the common terminal conductor can be released through electrical contact or discharge process accordingly. Thus, the induction coil provided around the outer periphery of the conductive structure of the moving contact or the moving side ball head can correspondingly induce the grounding current of the transformer neutral point passing through the conductive structure of the contact or the ball head. Thus, the transformer neutral point overvoltage protection disconnector, the discharge gap, and the corresponding current transformer can be integrated into one through the integrated independent electrical apparatus structure, thereby reducing the size of the components, reducing the insulation distance, and providing higher safety performance while reducing the installation space occupied by the electrical apparatus.

[0018] Especially noteworthy is that, through the optimization of the internal grounding loop of the metal shell, the present patent can use the insulating medium to isolate and block the electrical path around the induction coil, thereby ensuring that the induction coil only induces the grounding current passing through the moving contact or the conductive rod in one direction when the transformer neutral point overvoltage protection disconnector is grounded or when the discharge gap discharges, and is not disturbed by the return current path signal. Thus, while integrating the disconnector, the discharge gap, and the gas insulated current transformer to improve the space utilization, the induction coil can also effectively induce the current signal, thereby compressing the installation space of the equipment and meeting the installation needs of intensive substations.

[0019] Other features and advantages of the present application will be set forth in the following specification, and in part will become apparent to those skilled in the art upon exercise of the disclosure herein, or by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0021] Figure 1 is a sectional view of the off state of the transformer neutral point overvoltage protection gas insulated combined apparatus of the present application;

[0022] Figure 2 is a sectional view of the on state of another disconnector structure in the present application;

[0023] Figure 3 is a sectional view of the discharging state of another discharge gap structure in the present application

[0024] Figure 4 is a circuit schematic diagram of the present application applied to the transformer neutral point to achieve overvoltage protection;

[0025] In the figure, 1 represents the neutral point outgoing oil gas bushing; 2 represents the oil gas bushing connecting conductor; 3 represents the common end conductor; 31 represents the gas insulated tank; 32 represents the hand hole; 4 represents the static side ball head; 5 represents the dynamic side ball head; 6 represents the conducting rod; 7 represents the gap side induction coil; 8 represents the gap distance adjusting component; 9 represents the switch state operating mechanism; 91 represents the switch control motor; 92 represents the operating mechanism shell; 93 represents the switch drive gear; 10 represents the switch side induction coil; 11 represents the moving contact; 12 represents the contact guide component; 121 represents the insulation connecting piece; 122 represents the moving contact shielding cover; 13 represents the static contact; 14 represents the tank type surge arrester; 23 represents the switch static side part; 24 represents the gap static side part; 110 represents the switch side grounding cavity; 111 represents the switch side end cover; 112 represents the moving contact seat; 113 represents the switch side upper flange; 114 represents the switch side lower flange; 210 represents the gap side grounding cavity; 211 represents the gap side end cover; 212 represents the conducting rod seat; 213 represents the gap side upper flange; 214 represents the gap side lower flange; 16 represents the dynamic side ball head guide seat. DETAILED DESCRIPTION

[0026] In order to make the purpose and technical solutions of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without any inventive effort fall within the scope of protection of the present application.

[0027] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with meanings in the context of the prior art, and should not be interpreted to have idealized or overly formal meanings unless defined as such herein.

[0028] The meaning of "and / or" described in the present application means that each single existence or both existences are included.

[0029] The meaning of "inner, outer" described in the present application means that, with respect to the combined electrical apparatus itself for transformer neutral point overvoltage protection, the direction from the outer metal shell to the center of the internal induction coil is inner, and vice versa; and is not a specific limitation on the device mechanism of the present application.

[0030] The meaning of "connection" described in the present application can be a direct connection between components or an indirect connection between components through other components.

[0031] The meaning of "upper, lower" described in the present application means that, when facing the combined electrical apparatus for transformer neutral point overvoltage protection, the direction from the public end conductor to the operating mechanism is upper, and vice versa; and is not a specific limitation on the device mechanism of the present application.

[0032] Figure 1 In order to be a transformer neutral point overvoltage protection gas insulated combined electrical apparatus according to the present application, it is installed outside the transformer tank, and is electrically connected with the neutral point outgoing line oil gas sleeve 1 led out from the neutral point in the transformer 30. All elements are insulated by SF6 gas to reduce the insulation distance, compress the space occupied by the components, and ensure that the operation of the electrical components is not affected by external meteorological conditions.

[0033] The combined electric appliance comprises a gas-insulated gap mechanism 24 for providing a discharge gap, a switch mechanism 23, and a lightning arrester 14 as a part of the combined electric appliance. According to actual needs, one or more of the three structures can be flexibly configured in combination. The gap mechanism or the grounding isolating switch mechanism is respectively compounded with the current transformer induction coil 23, 24, so as to measure the discharge current of the gap or the direct grounding current. The specific structure can be referred to Figure 1 As shown, it can be provided to include:

[0034] A common terminal conductor 3 is arranged in a gas-insulated tank 31 and electrically connected to the neutral point of the transformer through the neutral point outgoing oil gas sleeve 1. The end of the gas-insulated tank 31 can be specifically arranged in sealing connection with the neutral point outgoing oil gas sleeve 1, and the internal common terminal conductor 3 can be electrically connected to the neutral point of the transformer through the oil gas sleeve connecting conductor 2 in the neutral point outgoing oil gas sleeve 1.

[0035] A metal shell is sealingly connected with the gas-insulated tank 31 filled with SF6 or other insulating gas to provide gas insulation, and is commonly grounded through the mutually sealingly connected shells. The metal shell is in communication with the inside of the gas-insulated tank 31, and commonly provides grounding protection and insulation isolation.

[0036] A gap mechanism is arranged in the metal shell and has a gap discharge electric path connected to the metal shell by the common terminal conductor 3, and a gap side induction coil 7 arranged on the outer periphery of the electrically conductive rod in the gap discharge electric path. The electrically conductive rod penetrates through the inside of the current transformer, and the discharge current passing through the discharge process in the gap discharge electric path can be induced by the gap side induction coil 7.

[0037] A switch mechanism can be independently arranged in a cavity formed by a separate metal shell, or can be sealingly and grounded by the same shell as the gap mechanism. The switch mechanism is arranged to have a switch grounding electric path connected to the metal shell by the common terminal conductor 3. In addition, the switch mechanism can be arranged to have a switch side induction coil 10 on the outer periphery of the moving contact in the switch grounding electric path, and the moving contact penetrates through the inside of the current transformer. Thus, the switch side induction coil 10 can induce the grounding current passing through the switch grounding electric path.

[0038] The application can further provide a tank-type lightning arrester 14 below the gas-insulated tank 31. The lightning arrester is sealingly connected with the gas-insulated tank 31 and commonly grounded. When the voltage at the neutral point of the transformer reaches a specified value, the charge flowing through the lightning arrester limits the amplitude of the overvoltage at the neutral point, thereby achieving overvoltage protection.

[0039] Thus, the combined electrical apparatus of the present application can protect the switch contact structure of the disconnector for transformer neutral point overvoltage, the ball head discharge gap, and the current transformer integrated as a whole through the gas insulation environment formed by the metal shell, and provide gas insulation through the metal shell and the SF6 gas filled in the gas insulation tank 31. This integrated mode not only saves the space occupied by the device itself, but also reduces the insulation distance required by the device by using SF6 as the insulation medium, ensures that the gap distance value is not limited by the surrounding atmospheric conditions, and further reduces the space occupied by the overall transformer system.

[0040] Figure 1 The implementation mode shown is an example. The above transformer neutral point overvoltage protection gas insulated combined electrical apparatus can separate the metal shell into a switch side ground cavity 110 and a gap side ground cavity 210. The switch side ground cavity 110 and the gap side ground cavity 210 are respectively communicated with both ends of the gas insulation tank 31 or are respectively communicated with the gas insulation tank 31 with two sections electrically connected to each other. Thus, the switch mechanism can be accommodated in the switch side ground cavity 110, and the gap mechanism can be accommodated in the gap side ground cavity 210. The switch mechanism and the gap mechanism are spaced apart from each other by two independent gas insulation cavities to ensure that the switch mechanism and the gap mechanism can be independently connected or disconnected with the common conductor 3.

[0041] The switch ground electrical path in the switch side ground cavity 110 can specifically include:

[0042] The static contact 13 is fixedly electrically connected with the common conductor 3.

[0043] The moving contact 11 is slidably electrically connected with the disconnector shell in the metal shell through the moving contact seat 112 on the upper part, that is, the electrical connection between the moving contact 11 and the metal shell is realized through sliding contact. The lower part of the moving contact 11 can be limited to only slide up and down relative to the static contact in the vertical direction through the guidance of the contact guide part 12. When the moving contact 11 slides to the bottom limit position of the metal shell, the bottom end of the moving contact 11 is electrically connected with the static contact 13. At this time, since the switch side induction coil 10 is sleeved on the outer periphery of the moving contact 11, the switch side induction coil 10 can induce the ground current passing through the moving contact 11 in one direction. When the moving contact 11 slides to the top limit position of the metal shell, the bottom end of the moving contact 11 is electrically disconnected with the static contact 13, and there is no induced current in the switch side induction coil 10.

[0044] Similarly, the gap discharge electrical path in the gap side ground cavity 210 can specifically include:

[0045] The static side ball head 4 is fixedly electrically connected with the common conductor 3.

[0046] The moving side ball head 5 is arranged in the metal shell and above the static side ball head 4.

[0047] The bottom of the conductive rod 6 is fixedly connected to the moving ball head 5 to form a conductive path and is restricted to facing the top of the stationary ball head by the moving ball head guide seat. Its upper part slides in contact with the gap side end cap 211 provided in the metal shell through the conductive rod seat 212 to achieve electrical connection.

[0048] Therefore, when the conductive rod 6 slides down along the metal shell, the moving side ball head 5 and the stationary side ball head 4 approach each other to reach the discharge distance. The electric field between the ball heads breaks down the insulating gas gap and discharges. The discharge current is conducted through the moving side ball head 5 to the conductive rod 6 to form a discharge current. At this time, since the gap side induction coil 7 is sleeved on the outer periphery of the conductive rod 6, it can sense the discharge current passing through the conductive rod 6 in one direction.

[0049] When the conductive rod 6 slides upward along the metal shell, the distance between the moving ball head 5 and the stationary ball head 4 exceeds the discharge distance. At this time, the two ball heads are kept insulated by the insulating gas inside the cavity, and no induced current flows through the gap-side induction coil 7.

[0050] The aforementioned moving contact can be driven to slide up and down by the switch state operating mechanism 9 located at the top outer side of the grounding cavity 110 on the switch side; while the moving ball head can be driven to slide up and down independently by the gap distance adjusting component 8 located at the top outer side of the grounding cavity 210 on the gap side. The switch state operating mechanism 9 and the gap distance adjusting component 8 can typically be driven by a motor to drive a gear, worm gear, or other transmission mechanism, thereby driving the moving contact or conductive rod meshing with the gear at the top to move up and down linearly.

[0051] for Figure 1 In the case of the combined electrical appliance shown, the switching-side induction coil 10 and the gap-side induction coil 7 need to form grounding loops on the outside of the coils through the switching-side metal casing 110 and the gap-side metal casing 210, respectively, in order to avoid forming a grounding loop on the inside of the induction coil and affecting the induction coil's response to the grounding current.

[0052] For the switch side induction coil 10, the grounding circuit can be formed by connecting the following conductive components: a switch side upper flange 113 arranged on the outer periphery of the middle part of the movable contact 11, the top of which is sealed by a switch side end cover 111, and a conductive movable contact seat arranged inside the switch side upper flange 113 between the movable contact 11 and the switch side end cover 111; a switch side lower flange 114 sealingly connected with the gas insulation tank 31 and arranged below the switch side induction coil 10; and a metal connecting piece, which can be specifically arranged as a cross metal strip that blocks external impurities by surrounding the outer periphery of the switch side induction coil 10 and stably electrically connects the upper flange and the lower flange at the same time, so as to guide the grounding current from the outside of the coil to the switch side lower flange 114 through the movable contact seat, the disconnecting switch shell 111, the switch side upper flange 113, and the cross metal strip, thereby achieving grounding; or as a metal cylinder arranged on the outer periphery of the switch side induction coil 10, so as to guide the grounding current from the outside of the coil to the switch side lower flange 114 through the movable contact seat, the disconnecting switch shell 111, the switch side upper flange 113, and the metal cylinder, thereby achieving grounding. The cross metal strip can be optionally arranged on the inside or outside of the coil outer cover.

[0053] For the gap side induction coil 7, the grounding circuit can be formed by connecting the following conductive components: a gap side upper flange 213 arranged on the outer periphery of the middle part of the conductive rod 6, the top of which is sealed by a gap side end cover 211, and a conductive rod seat 212 arranged inside the gap side upper flange 213 between the conductive rod 6 and the gap side end cover 211; a gap side lower flange 214 sealingly connected with the gas insulation tank 31 and arranged below the gap side induction coil 7; and a metal connecting piece, which can be specifically arranged as a cross metal strip that blocks external impurities by surrounding the outer periphery of the gap side induction coil 7 and stably electrically connects the upper flange and the lower flange, so as to guide the grounding current from the outside of the coil to the gap side lower flange 214 through the movable contact seat, the gap side end cover 211, the gap side upper flange 213, and the cross metal strip, thereby achieving grounding; or as a metal cylinder arranged on the outer periphery of the switch side induction coil 7, so as to guide the grounding current from the outside of the coil to the gap side lower flange 214 through the movable contact seat, the gap side end cover 211, the gap side upper flange 213, and the metal cylinder, thereby achieving grounding. The cross metal strip can be optionally arranged on the inside or outside of the coil outer cover.

[0054] Taking the switch side as an example, the gap side is similar to the switch side. The movable contact seat in the above structure can be arranged to surround the upper part of the movable contact and be slidably connected with the movable contact through a connecting structure such as a coil spring. The movable contact seat is made of metal at least at the position where the inner periphery directly contacts the movable contact, so as to achieve electrical connection through sliding contact. The movable contact can also be fixed to the end cover on the upper part of the metal shell through a metal connecting structure at the top, so as to maintain the same potential and keep the movable contact at the ground potential, thereby providing grounding protection for the center point of the transformer.

[0055] Thus, the combined electrical device of the present application can measure the current of the internal conductor through the ground current or discharge current passing through the corresponding induction coil of the induction coil. The electrical connection between the moving contact seat, the end cover and the upper flange of the current transformer is achieved by fixed contact.

[0056] The current transformer composed of the induction coil can form a shielding cylinder by extending the inside of the upper flange downward, and the coil is fixed around the outside of the shielding cylinder to provide support for the coil structure. The lower end of the shielding cylinder is provided with a sliding guide component to limit the sliding direction of the moving contact or the conductive rod, guiding it to approach the lower common conductor in a vertical up-down sliding manner.

[0057] For Figure 1 As shown in the implementation, an insulating connecting piece 121 can also be provided between the shielding cylinder and the lower flange, with the top of the insulating connecting piece 121 abutting the bottom end of the shielding cylinder and the bottom of the insulating connecting piece 121 abutting the upper surface of the lower flange. The shielding cylinder is prevented from forming a shell backflow downward by the barrier of the insulating connecting piece, so that the coil inside only has the current passing through the moving contact of the disconnecting switch or the conductive rod. The insulating connecting piece 121 can also form a sealed insulating gas chamber between the flange and the shielding cylinder, ensuring that the SF6 gas is enclosed in the shielding cylinder, protecting the contact structure in an insulating medium with reliable insulation distance. On the outside of the coil, a coil cover and a cross-connection metal strip can be further provided between the upper flange and the lower flange to protect the coil from being directly exposed to the atmosphere, and the cross-connection metal strip provides a ground connection between the upper and lower flanges to form a ground loop on the outside of the coil. The lower flange and the lower tank are electrically connected by a fixed contact structure such as welding or sealing bolts. A metal moving contact shield 122 can also be provided outside the moving contact bottom guide component to cooperate with the electric field strength on both sides of the upper moving side and the neutral point lead-out end of the static side of the switch, shielding the electric field between the moving contact and the shielding cylinder to prevent the moving contact from discharging due to the bottom burr. If the outer surface of the moving contact bottom guide component is smooth enough, the above-mentioned moving contact shield can be omitted without affecting the performance of the device.

[0058] In other implementations, as shown in the Figure 2 ground switch or Figure 3 gap side structure, to ensure that the metal shell only forms a ground loop on the outside of the induction coil, and cannot form a ground loop between the induction coil and the moving contact or the internal conductive rod to affect the induction of the induction coil on the ground current. The above-mentioned ground loop can also be formed by connecting the following conductive components:

[0059] The upper flange 6 is arranged on the outer periphery of the middle part of the moving contact 11 and is sealingly arranged on the top of the induction coil 7;

[0060] a lower flange 11, which is sealingly connected with the lead-out shell of the transformer neutral point and is arranged below the induction coil 7;

[0061] a sealing metal cylinder, which is sealingly connected between the upper flange and the lower flange through a metal cylinder structure, can be stably electrically connected with the upper flange and the lower flange, provides ground protection, and has sufficient sealing performance to ensure that the SF6 gas in which the coil is located is not leaked;

[0062] In the implementation mode of the metal cylinder, the inner side of the upper flange can still extend downward to form a shielding cylinder surrounding the outer periphery of the moving contact or the conductive rod. The bottom of the shielding cylinder is electrically isolated from the lower flange by the insulating gas sealed in the metal shell and the lead-out shell of the neutral point. As long as the distance between the two meets the requirement of electric field strength, the insulating connecting piece 121 structure in the previous implementation mode can be omitted.

[0063] Thus, when the transformer neutral point needs to be directly grounded, the switch control motor 91 operates to drive the switch driving gear inside the operating mechanism shell 92 to rotate, thereby engaging and driving the moving contact to move downward. Figure 2 The moving contact can penetrate the moving contact seat and the moving contact guide seat, and is guided by the moving contact guide seat to be inserted into the disconnecting switch static contact connected with the common conductor, and during the sliding process, the moving contact 11 is guided by the moving contact guide seat to have its bottom end opposite to the upper side of the common conductor 15, thereby realizing electrical connection with the moving contact seat, the metal shell, and the upper flange of the current transformer, and then connecting with the grounding network through the metal cylinder, the lower flange of the current transformer, and the gas insulation tank, thereby realizing direct grounding of the transformer neutral point gas insulation combined electric appliance. Since only the moving contact structure inside the induction coil has a single-direction ground current, the current value passing through the disconnecting switch moving contact can be detected through the induced current triggered by the ground current.

[0064] In addition to the above gas insulation or insulating connecting piece mode, to avoid the influence of the moving contact bottom guide seat burr on the electric field distribution and to avoid the insulation gas near the burr being broken down, the moving contact shielding cover 122 can be further arranged outside the lower end of the moving contact guide part in the above switch structure. The moving contact shielding cover 122 is generally made of metal material with a smooth surface and can further provide signal shielding for the moving contact.

[0065] The switch static side part 23 and the gap static side part, which are connected to the neutral point leading-out end of the lower part of the switch side and the gap side, can realize the electrical connection between the transformer neutral point and the moving contact and the moving side ball head through the static contact 14 and the static side ball head connecting the common conductor 15. Taking the disconnector as an example, the gap side structure is similar to it. The static side contact is installed on the common conductor led out by the transformer neutral point oil gas sleeve and is located inside the gas insulation tank formed by the transformer neutral point leading-out end shell. The tank can further be provided with a hand hole 32 at the lower part of the tank near the static side, i.e. the bottom of the leading-out end shell of the transformer neutral point, and the hand hole is arranged in a direction facing the common conductor 15 below the moving contact 11 to facilitate the observation and maintenance of the contact structure.

[0066] Therefore, the gap control conductive rod passes through the inside of the current transformer. The gap distance adjusting part is installed on the upper part of the gap control conductive rod, and the gap moving side ball head is installed on the lower part. The gap static side ball head is installed on the common conductor and realizes the gap cooperation with the gap moving side ball head. When the overvoltage protection is needed according to the specified voltage value, the gap distance adjusting part drives the conductive rod and the moving side ball head to move up and down to control the gap distance, so as to realize the overvoltage protection of different voltage values. When the voltage at the neutral point is greater than the specified voltage value, the moving side and the static side ball head discharge through the insulating gas gap. The current passes through the common conductor, the static side ball head, the moving side ball head, the conductive rod, the conductive rod seat, and then is grounded through the metal shell, so as to realize the overvoltage protection of the transformer neutral point gas insulation combined electric appliance, and the current transformer measures the gap discharge current value through the conductive rod.

[0067] For the switch side, the disconnector moving contact passes through the inside of the current transformer. The disconnector operating part is installed on the upper part of the moving contact, and the moving side shielding and guiding part is installed on the lower part. The disconnector static side contact is installed on the common conductor. When the disconnector is opened, the moving side shielding cylinder and the static side contact are insulated and cooperated, so that when the operating mechanism drives the moving contact to realize the linear motion through the guiding part, the moving contact can be inserted into the static side contact, and the direct grounding of the neutral point is realized. Therefore, if the voltage in the common conductor is greater than zero, the switch side structure can be closed to make the current pass through the common conductor, the static side contact, the moving contact, the moving contact seat, and then be grounded through the shell, so as to realize the direct grounding protection of the transformer neutral point gas insulation combined electric appliance, and the current transformer measures the current value through the moving contact.

[0068] In summary, the above-mentioned combined electric appliance has the following advantages:

[0069] 1. The combined electrical switch structure and gap discharge structure provided by the application integrates the moving side and the static side of the switch structure and the gap discharge structure and the current transformer into an integrated structure, which is placed in SF6 insulation gas, can measure the grounding current or discharge current while achieving direct grounding or discharge protection, occupies less space, and the insulation performance is not affected by external climate, and is more safe and stable;

[0070] 2. The moving contact, the moving contact seat, the disconnecting switch shell and the upper flange of the disconnecting switch for grounding form a grounding current path inside the current transformer coil, then the upper flange, the metal connecting piece and the lower flange form a grounding path outside the current transformer coil, and finally the gas insulation tank is connected to the grounding net to ensure that the metal shell of the application can be stably grounded to improve the safety of the overall disconnecting switch structure. By adjusting the downward movement of the moving contact to insert the static side contact, the direct grounding of the transformer neutral point gas insulated combined electrical apparatus can be achieved, and overvoltage protection can be achieved.

[0071] 3. The moving side ball head, the conductive rod, the conductive rod seat, the gap side end cover and the upper flange of the discharge gap form a discharge current path inside the current transformer coil, then the upper flange, the metal connecting piece and the lower flange form a grounding path outside the current transformer coil, and finally the gas insulation tank is connected to the grounding net to ensure that the metal shell of the application can be stably grounded to improve the safety of the overall discharge gap structure. By adjusting the gap distance between the moving side ball head and the static side ball head, the transformer neutral point gas insulated combined electrical apparatus can achieve overvoltage discharge protection at a specified voltage value.

[0072] 4. The moving contact guide seat and the moving side ball head guide seat of the disconnecting switch for grounding are installed on the shielding cylinder of the current transformer, which can guide the linear movement of the long moving contact or conductive rod into the gas insulation tank to accurately abut the static contact or trigger the static side ball head discharge to form a grounding path for the transformer neutral point. During the conduction or discharge process, the metal shell of the application can be connected to the grounding net through the sealed metal cylinder or the cross-over metal row, so that the external part of the device is not electrified, and the safety performance of the device is improved.

[0073] 5. The moving contact shielding cover of the disconnecting switch for grounding is installed on the moving contact guide seat, which can facilitate the cooperation of the electric field intensity of the moving side and the static side.

[0074] 6. The static side of the disconnecting switch for grounding and the gap discharge structure provided by the application is installed on the common end conductor led out by the transformer neutral point oil gas sleeve, and a maintenance hand hole is also arranged at the lower part of the tank at the installation position. The moving side and the static side of the switch structure and the gap discharge structure are arranged separately in the application, which can facilitate observation and maintenance of the upper switch structure or discharge structure through the maintenance hand hole at the lower part of the static side.

[0075] The above merely describes the embodiments of the present application, which are specific and detailed, but should not be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims

1. A gas-insulated composite electrical device for transformer neutral point overvoltage protection, characterized in that, The utility model relates to a kind of gas insulated switchgear, including: Common end conductor (3) is arranged in gas insulation tank (31), and is electrically connected with transformer neutral point; Metal shell, which is sealingly connected with the gas insulation tank (31) and is commonly grounded; Switch mechanism, which is arranged in the metal shell, has a switch ground electrical path connected to the metal shell by the common end conductor (3), and a switch side induction coil (10) surrounding the outer periphery of the switch ground electrical path for sensing the ground current passing through the switch ground electrical path; Gap mechanism, which is arranged in the metal shell, has a gap discharge electrical path connected to the metal shell, and a gap side induction coil (7) arranged at the outer periphery of the gap discharge electrical path for sensing the discharge current passing through the gap discharge electrical path between the common end conductor and the gap side induction coil (7); Tank-type surge arrester (14), which is sealingly connected with the gas insulation tank (31) and is commonly grounded; Wherein, the switch side induction coil (10) is arranged at the outer periphery of the moving contact (11) in the switch ground electrical path, the moving contact (11) penetrates the switch side induction coil (10), and the switch side induction coil (10) is used for sensing the ground current passing unidirectionally from the moving contact (11); The gap side induction coil (7) is arranged at the outer periphery of the conductive rod (6) in the gap discharge electrical path, the conductive rod (6) penetrates the gap side induction coil (7), and the gap side induction coil (7) is used for sensing the discharge current passing unidirectionally from the conductive rod (6); The metal shell is formed with a ground return only outside the switch side induction coil (10) and the gap side induction coil (7); The ground return is formed by connecting the following conductive components: Upper flange, which is arranged at the outer periphery of the middle part of the moving contact (11) and / or the conductive rod (6), is sealingly arranged at the top of the switch side induction coil (10) and / or the gap side induction coil (7); Lower flange, which is sealingly connected with the gas insulation tank (31), is arranged below the switch side induction coil (10) and / or the gap side induction coil (7); Metal connector, which is stably electrically connected with the upper flange and the lower flange at the same time.

2. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 1, characterized by, The metal shell includes a switch side ground cavity (110), a gap side ground cavity (210), and a gas insulation tank (31), the switch side ground cavity (110) and the gap side ground cavity (210) are respectively connected with the gas insulation tank (31), and the switch side ground cavity (110) and the gap side ground cavity (210) respectively contain the switch mechanism and the gap mechanism in the interiors thereof; The switch mechanism and the gap mechanism independently form an electrical path or are disconnected with the common end conductor (3).

3. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 1, wherein, The switch ground electrical path includes: Stationary contact (13), which is fixedly connected with the common end conductor (3); Moving contact (11), which is slidingly electrically connected between the upper part and the metal shell, the bottom end of the moving contact (11) is electrically connected with the stationary contact (13) when the moving contact (11) slides to the lower end limit position of the metal shell, and the bottom end of the moving contact (11) is disconnected from the stationary contact (13) when the moving contact (11) slides to the upper end limit position of the metal shell.

4. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 1, wherein, The gap discharge electrical path includes: A static side ball head (4) is fixedly connected with the common terminal conductor (3); A dynamic side ball head (5) is located in the metal shell and above the static side ball head (4); A conductive rod (6) is fixedly connected at the bottom with the dynamic side ball head (5) and is in sliding electrical connection between the upper part and the metal shell, and the dynamic side ball head (5) and the static side ball head (4) are both arranged in the insulating gas; When the conductive rod (6) slides downward along the metal shell, the gap distance between the dynamic side ball head (5) and the static side ball head (4) is reduced, and the discharge voltage threshold between the ball heads is lowered; When the conductive rod (6) slides upward along the metal shell, the gap distance between the dynamic side ball head (5) and the static side ball head (4) is increased, and the discharge voltage threshold between the ball heads is increased; When the voltage between the ball heads exceeds the discharge voltage threshold, the insulating gas is broken down, and the discharge current is conducted to the conductive rod (6) through the dynamic side ball head (5) and is discharged to the grounding circuit.

5. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 1, wherein, The metal connecting piece is a cross-over metal row electrically connected with the upper and lower flanges, the outer periphery of the switch side induction coil (10) and / or the gap side induction coil (7) is further provided with a coil outer cover, and the coil outer cover is optionally arranged on the inner side or the outer side of the cross-over metal row; The inner side of the upper flange extends downward to the lower flange to form a shielding cylinder surrounding the outer periphery of the moving contact (11) and / or the conductive rod (6), the bottom of the shielding cylinder is sealed between the lower flange by an insulating connecting piece (121), the top of the insulating connecting piece (121) abuts the bottom end of the shielding cylinder, and the bottom of the insulating connecting piece (121) abuts the upper surface of the lower flange (11).

6. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 5, wherein, The metal connecting piece is a metal cylinder sealedly connected with the outer periphery of the upper flange and the lower flange; The inner side of the upper flange extends downward to the lower flange to form a shielding cylinder surrounding the outer periphery of the moving contact (11) and / or the conductive rod (6), and an insulating gap is arranged between the bottom of the shielding cylinder and the lower flange, and the insulating gap is filled with insulating gas.

7. The transformer neutral overvoltage protection gas insulated combination electrical apparatus according to claim 1, wherein, The gas-insulated tank (31) is sealedly connected with the neutral point outgoing oil and gas sleeve (1), and the common terminal conductor (3) is electrically connected with the transformer neutral point through the oil and gas sleeve connecting conductor (2) in the neutral point outgoing oil and gas sleeve (1).

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