CN114204475A - Transformer neutral point overvoltage protection gas insulation combined electrical apparatus - Google Patents

Abstract

The application provides a transformer neutral point overvoltage protection gas insulation combined electrical apparatus. This application utilizes metal casing to form seal chamber in order to hold moving contact, moving side bulb and quiet side bulb, moving side bulb to provide gas insulation to it. Therefore, the induction coil arranged on the periphery of the moving contact or moving side ball head conductive structure can induce the grounding current of the transformer neutral point passing through the conductive structure. From this, this application accessible independent electrical apparatus structure that integrates is integrated with transformer neutral point for overvoltage protection earthing isolator, discharge gap and corresponding current transformer as an organic whole, reduces the part size, thereby reduces insulating distance and provides higher security performance when reducing the shared installation space of electrical apparatus.

Description

Transformer neutral point overvoltage protection gas insulation combined electrical apparatus

Technical Field

The application relates to the field of transformer protection equipment, in particular to a transformer neutral point overvoltage protection gas insulation combined electrical apparatus.

Background

After the neutral point signal of the transformer is led out by the combined electrical appliance for neutral point overvoltage protection of the transformer, the neutral point lead-out wire is electrically connected with equipment such as a discharge gap, a current transformer, an isolating switch for grounding, a lightning arrester and the like respectively to be used as neutral point overvoltage comprehensive protection equipment of an ungrounded transformer in an effectively grounded power grid. The electrical schematic of which is shown in figure 4. The grounding isolating switch and the discharge gap are used as a part of the combined electrical apparatus to realize the direct grounding of the neutral point of the transformer, and the discharge gap or the lightning arrester in the combined electrical apparatus is used for realizing the electric energy release of the overvoltage of the neutral point of the transformer. A current transformer may be connected in series in the loop of the above-described combiner to measure the current through the loop.

The existing combined electrical apparatus for overvoltage protection of the neutral point of the transformer usually adopts an open type air insulation technology, so that the combined electrical apparatus needs a larger safety distance, increases the occupied area, is not beneficial to the requirement of building an intensive transformer substation, is also easily influenced by factors such as external environment, such as humidity, altitude and the like, and needs to keep the safety distance according to the regulation requirement of corresponding voltage grade during operation.

In addition, the existing isolating switch and the existing discharge gap for overvoltage protection of the neutral point of the transformer adopting the air insulation technology cannot be integrated with the current transformer adopting a solid insulation medium, the occupied space of parts is large, and the requirements for constructing an intensive transformer substation are not facilitated.

Disclosure of Invention

The application provides a transformer neutral point overvoltage protection gas insulation combined electrical apparatus to prior art's not enough, and it is as transformer neutral point overvoltage integrated protection equipment, wholly adopts SF6 gas insulation technique, can realize transformer neutral point overvoltage protection and simultaneously with current transformer integration together. The structure of neutral point overvoltage protection equipment of the transformer can be simplified, and the function of measuring the grounding current of the equipment is achieved in an integrated mode. The technical scheme is specifically adopted in the application. First, in order to achieve the above object, a transformer neutral point overvoltage protection gas insulated switchgear is provided, which includes: a common terminal conductor disposed in the gas-insulated tank and electrically connected to the neutral point of the transformer; the metal shell is hermetically connected with the gas insulation tank body and is commonly grounded; a switching mechanism provided in the metal case, having a switch ground circuit connected to the metal case by a common terminal conductor, and a switch side induction coil surrounding an outer periphery of the switch ground circuit, for inducing a ground current passing through the switch ground circuit; the gap mechanism is arranged in the metal shell, is provided with a gap discharge electric path connected to the metal shell, and is provided with a gap side induction coil arranged on the periphery of the gap discharge electric path and used for inducing discharge current between the gap discharge electric path and a common end conductor; and the tank-type lightning arrester is hermetically connected with the gas insulation tank body and is commonly grounded.

Optionally, the transformer neutral point overvoltage protection gas-insulated switchgear as described in any of the above, wherein the metal housing includes a switch-side grounding cavity, a gap-side grounding cavity, and a gas-insulated tank, the switch-side grounding cavity and the gap-side grounding cavity are respectively communicated with the gas-insulated tank, and the switch-side grounding cavity and the gap-side grounding cavity respectively accommodate the switch mechanism and the gap mechanism therein separately; the switching mechanism and the gap mechanism are independent of each other to form an electrical path or break an electrical path with the common terminal conductor.

Optionally, the transformer neutral point overvoltage protection gas-insulated switchgear as described in any of the above, wherein the switch ground circuit includes: the static contact is fixedly connected with the common end conductor; the upper part of the moving contact is in sliding electrical connection with the metal shell, the bottom end of the moving contact is in electrical contact with the static contact when the moving contact slides to the lower end limit position along the metal shell, and the bottom end of the moving contact is separated from the static contact when the moving contact slides to the upper end limit position along the metal shell.

Optionally, the transformer neutral point overvoltage protection gas-insulated switchgear as described in any of the above, wherein the switch-side induction coil is disposed at an outer periphery of the moving contact, the moving contact penetrates through the switch-side induction coil, and the switch-side induction coil is configured to induce a ground current passing through the unidirectional driven contact.

Optionally, the transformer neutral point overvoltage protection gas insulated switchgear as described in any above, wherein the gap discharge electrical path includes: the static side ball head is fixedly connected with the common end conductor; the movable-side ball head is positioned in the metal shell and is positioned above the static-side ball head; the bottom of the conducting rod is fixedly connected with the movable-side ball head, the upper part of the conducting rod is electrically connected with the metal shell in a sliding manner, and the movable-side ball head and the static-side ball head are both arranged in insulating gas; when the conducting rod slides downwards along the metal shell, the gap distance between the ball head on the movable side and the ball head on the static side is reduced, and the discharge voltage threshold between the ball heads is reduced; when the conducting rod slides downwards along the metal shell, the gap distance between the ball head on the movable side and the ball head on the static side is increased, and the discharge voltage threshold value between the ball heads is increased; when the voltage between the ball heads exceeds the discharge voltage threshold value, the insulating gas is broken down, and the discharge current is conducted to the conducting rod through the moving-side ball head and is discharged to the grounding loop.

Optionally, the transformer neutral point overvoltage protection gas insulated switchgear as described in any of the above, wherein the gap side induction coil is disposed at an outer periphery of the conducting rod, the conducting rod penetrates through the gap side induction coil, and the gap side induction coil is configured to induce a discharge current passing through the conducting rod in a single direction.

Optionally, the transformer neutral point overvoltage protection gas insulated switchgear as described in any of the above, wherein the metal housing forms a ground loop only outside the switch-side induction coil and the gap-side induction coil; the grounding loop is formed by connecting the following conductive components: the upper flange is arranged on the periphery of the middle part of the moving contact and/or the conducting rod and is hermetically arranged on the top of the switch side induction coil and/or the gap side induction coil; the lower flange is hermetically connected with the gas insulation tank body and arranged below the switch side induction coil and/or the gap side induction coil; and the metal connecting piece is simultaneously and stably electrically connected with the upper flange and the lower flange.

Optionally, the transformer neutral point overvoltage protection gas insulated switchgear as described in any of the above, wherein the metal connecting member is a bridging metal bar having upper and lower sides electrically connected to the upper and lower flanges, respectively, and a coil cover is further disposed on the outer periphery of the switch side induction coil and/or the gap side induction coil, and the coil cover is optionally disposed on the inner side or the outer side of the bridging metal bar; the inner side of the upper flange extends downwards to form a shielding cylinder surrounding the periphery of the moving contact and/or the conducting rod, the bottom of the shielding cylinder and the lower flange are sealed by an insulating connecting piece, the top of the insulating connecting piece is abutted to the bottom end of the shielding cylinder, and the bottom of the insulating connecting piece is abutted to the upper surface of the lower flange.

Optionally, the transformer neutral point overvoltage protection gas-insulated switchgear as described in any of the above, wherein the metal connecting member is a metal cylinder hermetically connected to the peripheries of the upper flange and the lower flange; the inner side of the upper flange extends towards the lower flange to form a shielding cylinder surrounding the periphery of the moving contact and/or the conducting rod, an insulating gap is arranged between the bottom of the shielding cylinder and the lower flange, and insulating gas is filled in the insulating gap.

Optionally, the transformer neutral point overvoltage protection gas insulation combined electrical apparatus as described in any one of the above, wherein the gas insulation tank is hermetically connected to the neutral point outgoing line oil-gas casing, and the common end conductor is electrically connected to the neutral point of the transformer through an oil-gas casing connection conductor in the neutral point outgoing line oil-gas casing.

Advantageous effects

First, this application utilizes metal casing to form sealed cavity in order to hold moving contact, move side bulb and enclose the induction coil at its conducting structure periphery respectively to provide gas insulation to it. When the moving contact and the static contact are contacted, or the distance between the moving side ball head and the static side ball head is lower than the discharge gap, the voltage of the neutral point of the transformer in the common end conductor can be correspondingly released through the electric contact or the discharge process. Therefore, the induction coil arranged on the periphery of the moving contact or moving side ball head conductive structure can correspondingly induce the grounding current of the neutral point of the transformer passing through the contact or the ball head conductive structure. From this, this application accessible independent electrical apparatus structure that integrates is integrated with transformer neutral point for overvoltage protection earthing isolator, discharge gap and corresponding current transformer as an organic whole, reduces the part size, thereby reduces insulating distance and provides higher security performance when reducing the shared installation space of electrical apparatus.

Secondly, this application realizes the isolation protection to transformer neutral point for overvoltage protection isolator and discharge gap through gas insulation technique in the sealed cavity that metal casing formed. By adopting SF6 as an insulating medium, the insulation distance of the transformer can be effectively reduced, and the discharge gap and the isolation gap between the contacts are not influenced by the surrounding atmospheric conditions, so that the floor area of the transformer equipment and the requirement on the installation space are reduced, and the equipment floor area and the installation cost are saved.

Particularly, the grounding circuit in the metal shell is optimized, and the insulating medium can be used for isolating and blocking the electric path in the inner periphery of the induction coil, so that the induction coil is ensured to only induce the grounding current of the moving contact or the conducting rod when the isolation switch for neutral point overvoltage protection of the transformer is grounded or the discharging gap discharges, and the grounding current is not interfered by the signal of the return current path. From this, when being integrated as an organic whole with isolator, discharge gap and gas-insulated current transformer, self when improving space utilization, can also guarantee that induction coil can effectively induced-current signal, compression equipment installation space satisfies the installation demand of intensification transformer substation.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application.

Drawings

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 and not limit the application. In the drawings:

fig. 1 is a sectional view of a transformer neutral overvoltage protection gas insulated switchgear of the present application in an off state;

FIG. 2 is a cross-sectional view of another isolator switch configuration of the present application in an on state;

FIG. 3 is a cross-sectional view of another discharge gap structure of the present application in a discharged state

FIG. 4 is a schematic diagram of the circuit applied to the neutral point of the transformer to realize overvoltage protection;

in the figure, 1 represents a neutral point outlet oil gas casing; 2 represents an oil and gas casing connecting conductor; 3 denotes a common terminal conductor; 31 denotes a gas-insulated can body; 32 denotes a hand hole; 4 denotes a dead-side ball head; 5 represents a moving-side ball head; 6 denotes a conductive rod; a gap-side induction coil 7; 8 denotes a gap distance adjusting member; 9 represents a switch state operating mechanism; 91 denotes a switch control motor; 92 denotes an actuator housing; 93 denotes a switch drive gear; 10 denotes a switch-side induction coil; 11 denotes a movable contact; 12 denotes a contact guide member; 121 denotes an insulating connector; 122 denotes a moving contact shield; 13 denotes a stationary contact; a can-type arrester is indicated at 14; 23 denotes a switch dead side portion; 24 denotes a gap dead side portion; 110 denotes a switch-side ground cavity; 111, a switch side end cap; 112 denotes a movable contact block; 113 switch side upper flange; 114 proud view switch side lower flange; 210 denotes a gap-side ground cavity; 211, a gap side end cap; 212, a conductive rod base; 213 denotes a gap-side upper flange; 214 denotes a gap-side lower flange; and 16 denotes a ball head guide on the movable side.

Detailed Description

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 clearly and completely described below with reference to the drawings of the embodiments of the present application. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the application without any inventive step, are within the scope of protection of the application.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical 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 will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The meaning of "and/or" as used herein is intended to include both the individual components or both.

The meaning of "inside and outside" in the application refers to that relative to the transformer neutral point overvoltage protection combined electrical apparatus, the direction from the outside of the metal shell to the center of the internal induction coil is inside, and vice versa; and not as a specific limitation on the mechanism of the device of the present application.

The term "connected" as used herein may mean either a direct connection between components or an indirect connection between components via other components.

The meaning of "up and down" in this application means that when a user is facing the combined electrical system for overvoltage protection of the neutral point of the transformer, the direction from the common terminal conductor to the operating mechanism is up, and vice versa is down, and is not a specific limitation on the device mechanism of this application.

Fig. 1 shows a transformer neutral overvoltage protection gas-insulated switchgear according to the present application, which is installed outside a transformer tank and electrically connected to a neutral outlet oil-gas bushing 1 led out from a neutral point in a transformer 30, and all the components are insulated by SF6 gas to reduce the insulation distance and the space occupied by the compression components, and to ensure that the electrical components are not affected by external meteorological conditions.

The combination comprises a gas-insulated gap arrangement 24 to provide a discharge gap, a switching arrangement 23 and a lightning arrester 14 as part of the combination. One or more combinations of the three structures can be flexibly configured according to actual needs. The gap mechanism or the grounding isolation switch mechanism is respectively compounded with the current transformer induction coils 23 and 24 so as to measure the gap discharge current or the direct grounding current. The specific structure can be seen in fig. 1, and it can be configured to include:

the common end conductor 3 is arranged in the gas insulation tank body 31 and is electrically connected with a neutral point of the transformer through the neutral point outgoing oil gas sleeve 1, wherein the end part of the gas insulation tank body 31 can be specifically arranged to be hermetically connected with the neutral point outgoing oil gas sleeve 1, and the common end conductor 3 in the gas insulation tank body can be electrically connected with the neutral point of the transformer through the oil gas sleeve connecting conductor 2 in the neutral point outgoing oil gas sleeve 1;

a metal shell hermetically connected to the gas-insulated can 31 filled with an insulating gas such as SF6 to provide gas insulation, and commonly grounded through the shells hermetically connected to each other, the metal shell being in communication with the inside of the gas-insulated can 31 to commonly provide ground protection and insulation isolation;

the gap mechanism is arranged in the metal shell and is provided with a gap discharge electric path connected to the metal shell through the common end conductor 3 and a gap side induction coil 7 arranged on the periphery of a conducting rod in the gap discharge electric path, the conducting 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 through the gap side induction coil 7;

the switch mechanism can be selectively and independently arranged in a cavity formed by independent metal shells, can also be sealed and grounded by the same shell together with the gap mechanism, a switch grounding electric path which can be connected to the metal shells through a common end conductor 3 is arranged in the switch mechanism, in addition, a switch side induction coil 10 can be arranged on the periphery of a moving contact in the switch grounding electric path, and the moving contact penetrates through the inside of a current transformer, so that the switch side induction coil 10 can be ensured to induce the grounding current passing through the switch grounding electric path.

The tank-type lightning arrester 14 can be further arranged under the gas insulation tank 31 and is connected with the gas insulation tank 31 in a sealing mode and grounded together, and when the voltage of the neutral point of the transformer reaches a specified value, the overvoltage amplitude of the neutral point is limited through charges flowing through the lightning arrester, so that overvoltage protection is realized.

From this, the built-up electrical apparatus of this application accessible metal casing forms the gas insulation environment with transformer neutral point for overvoltage protection isolator contact structure, bulb discharge gap, integrated as an organic whole with current transformer, through metal casing and the inside SF6 gas that fills of gas insulation jar body 31 provide gas insulation. The integration mode not only saves the space occupied by the device, but also can reduce the insulation distance required by the device by adopting SF6 as an insulation medium, ensure that the gap distance value is not limited by the surrounding atmospheric conditions, and further reduce the space occupied by the whole transformer system.

As an example of the implementation shown in fig. 1, the transformer neutral overvoltage protection gas-insulated switchgear may be configured such that the metal housing is divided to include a switch-side grounding cavity 110 and a gap-side grounding cavity 210. The switch-side ground cavity 110 and the gap-side ground cavity 210 are respectively communicated with both ends of the gas-insulated can 31 or respectively communicated with two sections of gas-insulated cans 31 electrically connected with each other. The switching mechanism can be accommodated in the switching-side ground cavity 110 and the gap mechanism can be accommodated in the gap-side ground cavity 210, and the switching mechanism and the gap mechanism are separated from each other by two independent gas insulation cavities, so that the switching mechanism and the gap mechanism can be connected with or disconnected from the common terminal conductor 3 independently from each other.

The switch grounding electrical path in the switch-side grounding cavity 110 may specifically include:

a static contact 13 which is fixedly and electrically connected with the common end conductor 3;

the upper portion of the movable contact 11 is in sliding electrical connection with the isolating switch shell in the metal shell through the movable contact seat 112, that is, the electrical connection with the metal shell is realized through sliding contact, and the lower portion of the movable contact 11 can be limited to slide up and down relative to the fixed contact only in the vertical direction through the guiding of the contact guiding component 12. When the moving contact 11 slides to the bottom limit position along the metal shell, the bottom end of the moving contact is electrically contacted with the static contact 13, and at the moment, the switch side induction coil 10 is sleeved on the periphery of the moving contact 11, so that the moving contact can induce the grounding current passing through the inside of the one-way driven contact 11; when the moving contact 11 slides to the top limit position along the metal shell, the bottom end thereof is separated from the static contact 13, and no induced current passes through the switch side induction coil 10.

Similarly, the gap discharge path in the gap-side grounding cavity 210 may be specifically configured to include:

a static side bulb 4 which is fixedly and electrically connected with the common end conductor 3;

the moving-side ball head 5 is arranged in the metal shell and is positioned above the static-side ball head 4;

the bottom of the conducting rod 6 is fixedly connected with the movable-side ball 5 to form a conducting path, the conducting path is limited to be over against the upper part of the static-side ball through the movable-side ball guide seat, and the upper part of the conducting rod 6 is in sliding contact with a gap side end cover 211 arranged in the metal shell through a conducting rod seat 212 to realize electric connection;

therefore, when the conducting rod 6 slides downwards along the metal shell, the movable-side ball 5 and the static-side ball 4 approach each other to reach a discharge distance, an electric field between the balls breaks through an insulating gas gap to discharge, the discharge current is conducted to the conducting rod 6 through the movable-side ball 5 to form a discharge current, and at the moment, the gap-side induction coil 7 is sleeved on the periphery of the conducting rod 6, so that the discharge current passing through the conducting rod 6 in a single direction can be induced;

when the conducting rod 6 slides upwards along the metal shell, the distance between the movable-side ball 5 and the static-side ball 4 exceeds the discharging distance, the two balls are insulated by insulating gas in the cavity, and no induced current passes through the gap-side induction coil 7.

The moving contact can be driven by a switch state operating mechanism 9 arranged at the top end of the outer side of the switch side grounding cavity 110 to slide up and down; and the movable ball head can independently slide up and down by being driven by a gap distance adjusting component 8 arranged at the top end of the outer side of the gap side grounding cavity 210. The switch state operating mechanism 9 and the gap distance adjusting assembly 8 can drive a gear, a worm and other transmission mechanisms through a motor, so as to drive a moving contact or a conductive rod, the top of which is meshed with the gear, to move up and down linearly correspondingly.

For the combined electrical apparatus shown in fig. 1, the switch-side induction coil 10 and the gap-side induction coil 7 need to respectively form a grounding loop outside the coils through the switch-side metal shell 110 and the gap-side metal shell 210, so as to avoid forming a grounding loop inside the induction coils to affect the induction of the induction coils to the grounding current.

For the switch-side induction coil 10, the ground loop may be formed by connecting the following conductive members: the switch side upper flange 113 is arranged on the periphery of the middle part of the moving contact 11, the top of the switch side upper flange is sealed by a switch side end cover 111, and a conductive moving contact seat is arranged between the moving contact 11 and the switch side end cover 111 inside the switch side upper flange 113; a switch-side lower flange 114 hermetically connected to the gas-insulated tank 31 and disposed below the switch-side induction coil 10; a metal connecting member, which may be specifically configured to block external impurities through a coil housing surrounding the periphery of the switch-side induction coil 10, and to guide a ground current from the outside of the coil to the switch-side lower flange 114 through a movable contact holder, the disconnecting switch housing 111, the switch-side upper flange 113, and a jumper metal bar, which are simultaneously and stably electrically connected to the upper flange and the lower flange, to achieve grounding; or a metal cylinder is arranged at the periphery of the switch side induction coil 10, and grounding current is led to the switch side lower flange 114 from the outside of the coil through the movable contact seat, the isolating switch shell 111, the switch side upper flange 113 and the metal cylinder to realize grounding. Wherein, the bridging metal row can be optionally arranged at the inner side or the outer side of the coil housing.

And for the gap-side induction coil 7, the ground loop may be formed by connecting the following conductive members: a gap side upper flange 213 provided at the middle outer periphery of the conductive rod 6, the top of which is sealed by a gap side end cap 211, and a conductive rod seat 212 provided inside the gap side upper flange 213 between the conductive rod 6 and the gap side end cap 211; a gap-side lower flange 214 which is connected to the gas-insulated can 31 in a sealed manner and is provided below the gap-side induction coil 7; a metal connecting member, which may be specifically configured to block external foreign materials by a coil housing surrounding the periphery of the gap-side induction coil 7, and a jumper metal bar in which the upper flange and the lower flange are electrically connected stably, and to conduct a ground current from the outside of the coil to the gap-side lower flange 214 through the movable contact holder, the gap-side end cap 211, the gap-side upper flange 213, and the jumper metal bar to achieve grounding; or a metal cylinder arranged on the periphery of the switch side induction coil 7, and the grounding current is led to the gap side lower flange 214 from the outside of the coil through the movable contact seat, the gap side end cover 211, the gap side upper flange 213 and the metal cylinder to realize grounding. Wherein, the bridging metal row can be optionally arranged at the inner side or the outer side of the coil housing.

The movable contact seat in the structure can be arranged to surround the periphery of the upper part of the movable contact and is in sliding connection with the movable contact through a connecting structure such as a spiral spring, the movable contact seat is arranged to be made of metal materials at least at the position where the inner periphery of the movable contact is in direct contact with the movable contact so as to realize electrical connection through sliding contact, the movable contact can be generally fixed and keep the same potential with an end cover on the upper part of the metal shell through the metal connecting structure at the top, and therefore, the movable contact is kept at the grounding potential, and grounding protection is provided for the central point of the transformer.

Therefore, the combined electrical apparatus can measure the current amount of the inner conductor thereof through the grounding current or the discharge current passing through the corresponding induction moving contact of the induction coil or the inner part of the conducting rod respectively. The movable contact seat, the end cover and the upper flange of the current transformer are electrically connected through fixed contact.

The current transformer that induction coil constitutes, it can be prolonged the inside of upper flange downwards and form the shielding section of thick bamboo, and the coil is fixed around the realization of shielding section of thick bamboo outside, and the shielding section of thick bamboo provides the support for coil structure, and the shielding section of thick bamboo lower extreme sets up the slip guide part and provides spacing to moving contact or conducting rod slip direction, guides it to be close the public end conductor of below with the mode of sliding from top to bottom perpendicularly.

For the implementation mode shown in fig. 1, an insulating connector 121 may also be generally disposed between the shielding cylinder and the lower flange, such that the top of the insulating connector 121 abuts against the bottom end of the shielding cylinder, and the bottom of the insulating connector 121 abuts against the upper surface of the lower flange, and the shielding cylinder is ensured to be downward and not to form a housing backflow through the obstruction of the insulating connector, so as to ensure that only a current passing through a moving contact or a conducting rod of the disconnector exists inside the coil, and the insulating connector 121 may further form a sealed insulating air chamber between the flange and the shielding cylinder, so as to ensure that SF6 gas is enclosed in the shielding cylinder, and the protection contact structure is in an insulating medium, and has a reliable insulating distance; a coil outer cover and a bridging metal row are further arranged between the upper flange and the lower flange on the outer side of the coil to protect the coil from being directly exposed in the atmosphere, the bridging metal row provides grounding electric connection between the upper flange and the lower flange, and a grounding loop can be formed on the outer side of the coil; the lower flange and the lower tank body are electrically connected through fixed contact structures such as welding or sealing bolts. The moving contact bottom guiding component can be provided with a moving contact shielding cover 122 made of metal so as to be matched with the electric field intensity on the two sides of the moving side of the switch upper part and the static side of the neutral point leading-out end, an electric field between the moving contact and the shielding cylinder is shielded, and the moving contact is prevented from discharging due to bottom burrs. If the outer surface of the guide part at the bottom of the moving contact is smooth enough, the moving contact shielding case can be omitted, and the performance of the device can not be influenced.

In other implementation manners, taking the grounding switch shown in fig. 2 or the gap-side structure shown in fig. 3 as an example, in order to ensure that the metal shell forms a grounding loop only outside the induction coil, and a grounding loop cannot be formed between the induction coil and the movable contact or the inner conductive rod to affect the induction of the induction coil to the grounding current, the grounding loop may be formed by connecting the following conductive components:

the upper flange 6 is arranged on the periphery of the middle part of the moving contact 11 and is hermetically arranged at the top of the induction coil 7;

the lower flange 11 is hermetically connected with a leading-out end shell of a neutral point of the transformer and is arranged below the induction coil 7;

the sealing metal cylinder is hermetically connected between the upper flange and the lower flange through a metal cylinder structure, can be stably and electrically connected with the upper flange and the lower flange at the same time, provides grounding protection, and has enough sealing performance to ensure that SF6 gas at the coil is not leaked;

in the implementation mode of the metal cylinder, the inner side of the upper flange can still extend towards the lower flange to form a shielding cylinder surrounding the periphery of the moving contact or the conducting rod, the bottom of the shielding cylinder and the lower flange are electrically isolated by using insulating gas sealed in the metal shell and the leading-out end shell of the neutral point as an insulating medium, and the insulating connecting piece 121 structure in the previous implementation mode can be omitted as long as the distance between the bottom of the shielding cylinder and the lower flange meets the requirement of electric field intensity.

Therefore, when the neutral point of the transformer 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, so that the moving contact is driven to move downwards by meshing. In fig. 2, the moving contact can penetrate through the moving contact seat and the moving contact guide seat, is guided by the moving contact guide seat to be inserted downwards into a static side contact of the isolating switch connected with the common end conductor, and guides the moving contact 11 through the moving contact guide seat in the sliding process to enable the bottom end of the moving contact to be over against the common end conductor 15, so that the moving contact is electrically connected with the moving contact seat, the metal shell and an upper flange of the current transformer, and then the moving contact is connected with a grounding net through a metal cylinder, a lower flange of the current transformer and a gas insulation tank body, so that the direct grounding of the transformer neutral point gas insulation combined electrical appliance is realized. Because only the moving contact structure in the induction coil has grounding current in a single direction, the current value of the moving contact of the isolating switch can be detected through the induced current triggered by the grounding current.

Except the above-mentioned gas insulation or insulating connecting piece mode, in order to avoid moving contact bottom guide bar burr to influence electric field distribution, avoid contact position insulating gas to be punctured near the burr, still can further set up moving contact shield 122 in the outside of moving contact guide part lower extreme among the above-mentioned switch structure, moving contact shield 122 generally selects the metal material to have smooth surface still can further provide signal shielding for the moving contact.

The switch static side part 23 and the gap static side part which are matched with the movable side part and the current transformer part and the lower parts of the switch side and the gap side are connected with a neutral point leading-out end of the transformer can be connected with a common end conductor 15 through a static contact 14 and a static ball head to realize the electric connection between the neutral point of the transformer and the movable contact and the movable ball head. Taking the isolating switch as an example, the gap side structure is similar, and the static side contact is arranged on a common end conductor led out from a transformer neutral point oil gas sleeve and is positioned in a gas insulation tank formed by a transformer neutral point leading-out end shell. The tank body can be further provided with a hand hole 32 at the lower part of the tank body close to the static side, namely the bottom of a leading-out end shell of a neutral point of the transformer, and the opening direction of the hand hole can be over against the common end conductor 15 and is positioned below the movable contact 11 so as to be convenient for observing and overhauling the contact structure.

Therefore, the gap control conducting rod penetrates through the inside of the current transformer; a gap distance adjusting part is arranged at the upper part of the gap control conducting rod, and a gap movable side ball head is arranged at the lower part of the gap control conducting rod; the gap static side ball head is arranged on the common end conductor and is in clearance fit with the gap movable side ball head, and when overvoltage protection is required according to a specified voltage value, the gap distance adjusting part is utilized to drive the conducting rod and the movable side ball head to move up and down so as to control the gap distance and realize overvoltage protection of different voltage values. When the voltage at the neutral point is greater than a specified voltage value, the movable side bulb and the static side bulb discharge through an insulating gas gap, the current sequentially passes through the common end conductor, the static side bulb, the movable side bulb, the conducting rod and the conducting rod seat, and then the conducting rod seat is grounded through the metal shell, so that the overvoltage protection of the transformer neutral point gas-insulated combined electrical appliance is realized, and the current transformer measures the gap discharge current value passing through the conducting rod.

For the switch side, the moving contact of the isolating switch penetrates through the inside of the current transformer; the upper part of the moving contact is provided with an isolating switch operating component, and the lower part of the moving contact is provided with a moving side shielding and guiding component; mounting a static side contact of the isolating switch on a common end conductor; when the isolating switch is switched off, the movable side shielding cylinder is arranged to be in insulation fit with the static side contact, so that when the operating mechanism drives the movable contact to move linearly through the guide component, the movable contact can be inserted into the static side contact, and the direct grounding of a neutral point is realized. Therefore, if the voltage in the common end conductor is larger than zero, the common end conductor can be switched on through the switch side structure to enable the current to sequentially pass through the common end conductor, the static side contact, the moving contact and the moving contact seat, and then the moving contact seat is grounded through the shell, so that the direct grounding protection of the transformer neutral point gas insulated switchgear is realized, and the current value passing through the moving contact is measured by the current transformer.

In summary, the above-mentioned combined electrical apparatus of the present application has the following advantages:

the combined electricity integrates a movable side, a static side and a current transformer of a switch structure and a gap discharge structure into an integrated structure, and the integrated structure is placed in SF6 insulating gas, so that the direct grounding or discharge protection can be realized, the grounding current or the discharge current can be measured, the occupied space is smaller, the insulation performance is not influenced by external weather, and the combined electricity is safer and more stable;

2, the isolator's for ground connection moving contact, movable contact seat, isolator shell, last flange that this application provided form the ground connection current route in current transformer coil is inside, again by last flange, metal connecting piece, lower flange at the outside ground connection route that forms of current transformer coil, insert the ground net by the gas-insulated tank body at last to guarantee the security that the metal casing of this application can stable ground connection in order to improve whole isolator structure. The moving contact is adjusted to move downwards to be inserted into the static side contact, so that the direct grounding of the transformer neutral point gas insulation combined electrical appliance can be realized, and the overvoltage protection is realized;

3, the movable side bulb, the conducting 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, and then the upper flange, the metal connecting piece and the lower flange form a grounding path outside the current transformer coil, and finally the grounding network is accessed by the gas insulation tank body, so that the metal shell can be stably grounded to improve the safety of the whole discharge gap structure. By adjusting the gap distance between the movable-side ball head and the static-side ball head, the overvoltage discharge protection of the transformer neutral point gas-insulated combined electrical appliance under a specified voltage value can be realized;

4, the moving contact guide seat and the moving side ball head guide seat of the isolating switch for grounding provided by the application are arranged on a shielding cylinder of a current transformer, and can guide a moving contact or a conducting rod with longer length to linearly move and extend into the gas insulation tank body to accurately abut against a static contact or trigger the static side ball head to discharge so as to form a grounding path of a neutral point of a transformer;

5, the moving contact shielding case of the grounding isolating switch provided by the application is arranged on the moving contact guide seat, so that the matching effect of the electric field intensity of the moving side and the static side can be realized conveniently;

6, isolator and clearance discharge structure's for ground connection quiet side that this application provided is installed on the public end conductor that transformer neutral point oil gas sleeve pipe was drawn forth, and the jar body lower part of mounted position still sets up the access hand hole. This application is through separately arranging the side of moving and quiet side with switch structure and clearance discharge structure, and the access hand hole of usable quiet side lower part conveniently observes, maintains upper portion switch structure or discharge structure.

The above are merely embodiments of the present application, and the description is specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the protection scope of the present application.

Claims (10)

1. A transformer neutral point overvoltage protection gas insulated switchgear, comprising:

a common terminal conductor (3) which is provided in the gas-insulated tank (31) and electrically connected to the neutral point of the transformer;

a metal housing hermetically connected to the gas-insulated tank (31) and commonly grounded;

a switch mechanism provided in the metal case, having a switch ground electric path connected to the metal case by a common terminal conductor (3), and a switch side induction coil (10) surrounding the outer periphery of the switch ground electric path, for inducing a ground current passing through the switch ground electric path;

the gap mechanism is arranged in the metal shell, is provided with a gap discharge electric path connected to the metal shell, and is provided with a gap side induction coil (7) arranged on the periphery of the gap discharge electric path and used for inducing discharge current between the gap discharge electric path and a common end conductor;

and the tank-type lightning arrester (14) is hermetically connected with the gas insulation tank body (31) and is commonly grounded.

2. The transformer neutral overvoltage protection gas-insulated switchgear according to claim 1, wherein said metal housing comprises a switch-side grounding cavity (110), a gap-side grounding cavity (210) and a gas-insulated tank (31), said switch-side grounding cavity (110) and said gap-side grounding cavity (210) are respectively in communication with said gas-insulated tank (31), and said switch-side grounding cavity (110) and said gap-side grounding cavity (210) respectively house said switching mechanism and said gap mechanism therein individually;

the switch mechanism and the gap mechanism are mutually independent to form an electric path or break an electric path with the common terminal conductor (3).

3. The transformer neutral overvoltage protection gas insulated switchgear of claim 1 wherein said switch ground electrical path comprises:

a static contact (13) which is fixedly connected with the common end conductor (3);

the upper portion of the moving contact (11) is in sliding electrical connection with the metal shell, the bottom end of the moving contact (11) is in electrical contact with the static contact (13) when the moving contact slides to the lower end limit position along the metal shell, and the bottom end of the moving contact (11) is separated from the static contact (13) when the moving contact slides to the upper end limit position along the metal shell.

4. The transformer neutral overvoltage protection gas insulated switchgear according to claim 3, wherein said switch side induction coil (10) is disposed at an outer periphery of a movable contact (11), the movable contact (11) penetrates through said switch side induction coil (10), and the switch side induction coil (10) is used for inducing a ground current passing through the inside of the unidirectional driven contact (11).

5. The transformer neutral overvoltage protection gas insulated switchgear of claim 1 wherein said gap discharge electrical path includes:

the static side bulb (4) is fixedly connected with the common end conductor (3);

the moving-side ball head (5) is positioned in the metal shell and is positioned above the static-side ball head (4);

the bottom of the conducting rod (6) is fixedly connected with the movable-side ball head (5), the upper part of the conducting rod is electrically connected with the metal shell in a sliding manner, and the movable-side ball head (5) and the static-side ball head (4) are both arranged in insulating gas;

when the conducting rod (6) slides downwards along the metal shell, the gap distance between the movable-side ball head (5) and the static-side ball head (4) is reduced, and the discharge voltage threshold between the ball heads is reduced;

when the conducting rod (6) slides upwards along the metal shell, the gap distance between the movable-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 value, the insulating gas is broken down, and the discharge current is conducted to the conducting rod (6) through the moving-side ball head (5) and is discharged to the grounding loop.

6. The transformer neutral overvoltage protection gas insulated switchgear according to claim 5, wherein said gap side induction coil (7) is provided at an outer periphery of said conducting rod (6), said conducting rod (6) penetrates said gap side induction coil (7), and said gap side induction coil (7) is adapted to induce a discharge current passing through said conducting rod (6) in one direction.

7. The transformer neutral overvoltage protection gas insulated switchgear of claim 1, characterized in that said metal enclosure is formed with a ground return path only outside of the switch side induction coil (10) and the gap side induction coil (7);

the grounding loop is formed by connecting the following conductive components:

the upper flange is arranged on the periphery of the middle part of the movable contact (11) and/or the conducting rod (6) and is hermetically arranged on the top of the switch side induction coil (10) and/or the gap side induction coil (7);

a lower flange hermetically connected to the gas-insulated tank (31) and disposed below the switch-side induction coil (10) and/or the gap-side induction coil (7);

and the metal connecting piece is simultaneously and stably electrically connected with the upper flange and the lower flange.

8. The transformer neutral overvoltage protection gas insulated switchgear of claim 7, wherein said metal connecting member is a jumper metal row electrically connected to the upper and lower flanges at the upper and lower sides, respectively, and the outer circumference of said switch side induction coil (10) and/or gap side induction coil (7) is further provided with a coil cover, said coil cover being optionally disposed inside or outside the jumper metal row;

the inner side of the upper flange extends downwards to form a shielding cylinder surrounding the periphery of the movable contact (11) and/or the conducting rod (6), the bottom of the shielding cylinder is sealed with the lower flange through an insulating connecting piece (121), the top of the insulating connecting piece (121) is abutted to the bottom end of the shielding cylinder, and the bottom of the insulating connecting piece (121) is abutted to the upper surface of the lower flange (11).

9. The transformer neutral overvoltage protection gas insulated switchgear of claim 7 wherein said metal connector is a metal cylinder sealingly connected to both the outer peripheries of said upper and lower flanges;

the inner side of the upper flange extends towards the lower flange to form a shielding cylinder surrounding the periphery of the movable contact (11) and/or the conducting rod (6), an insulating gap is arranged between the bottom of the shielding cylinder and the lower flange, and insulating gas is filled in the insulating gap.

10. The transformer neutral overvoltage protection gas-insulated switchgear of claim 1, wherein said gas-insulated tank (31) is hermetically connected to a neutral outlet oil gas bushing (1), and said common terminal conductor (3) is electrically connected to the transformer neutral through an oil gas bushing connection conductor (2) in the neutral outlet oil gas bushing (1).

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