CN201234132Y

CN201234132Y - Neutral point protection apparatus for 110kV-220kV transformer

Info

Publication number: CN201234132Y
Application number: CNU200820122337XU
Authority: CN
Inventors: 杨文波
Original assignee: QUZHOU SUNRISE ELECTRIC CO Ltd
Current assignee: QUZHOU SUNRISE ELECTRIC CO Ltd
Priority date: 2008-07-30
Filing date: 2008-07-30
Publication date: 2009-05-06
Anticipated expiration: 2018-07-30

Abstract

A neutral point protection device for 110 to 220 kV transformer comprises a grounding electrode, a non-grounding electrode, a terminal box and a mounting chassis, wherein the grounding electrode comprises an electrode bar and a current transformer; the primary coil of the current transformer has an upper incoming terminal and a lower outgoing terminal; an insulating layer is arranged outside the electrode bar of the primary coil of the current transformer; the secondary coil of the current transformer is arranged to surround the insulating layer; and an outdoor epoxy resin layer is cast outside the secondary coil. Compared with the prior art, the neutral point protection device obviates the assembly process of the current transformer and the electrode bar and simplifies the assembly process of the outgoing terminal of the current transformer and the mounting chassis. The parts, such as the current transformer, are wrapped by the outdoor epoxy resin layer by one-step hermetically casting formation, so as to prevent metal parts from being corroded by environment factors, such as wind and rain, thereby ensuring the mechanical and electrical performances of the product and ensuring the safe operation of the power grid. In addition, the wiring connection is more convenient after the parts are reduced.

Description

The neutral point protection device of 110kV-220kV transformer

[technical field]

The utility model relates to a kind of protection equipment for transformer, relates in particular to a kind of neutral point protection device of the 110kV-220kV of being used for transformer.

[background technology]

China 110kV and above electric power system are system with effectively earthed neutral, employed transformer is the graded insulation structure, the insulation level that is the Transformer Winding neutral point is lower than the winding overhang insulation level, its neutral point insulation has 35kV, 44kV, 60kV electric pressure, and stipulate by standard GB 311 " insulation coordination of high-tension power transmission and transformation equipment " and industry standard DL/T620 " overvoltage protection of alternating-current electric device and insulation coordination ": lightning impulse withstand voltage (peak value) is respectively 185kV, 250kV, 325kV; 1min power-frequency withstand voltage (effective value) is respectively 85kV, 95kV, 140kV in short-term.In effectively earthed system,,, form local isolated neutral system with the directly ground connection operation of part transformer neutral point in order to limit the single-line to ground fault electric current, prevent Communication Jamming and to satisfy requirement such as relay protection setting configuration.

For the transformer of isolated neutral, must take overvoltage protection.Its reason is: invade transformer station when lightning wave from circuit and arrive transformer neutral point and system's single-phase earthing, open-phase operation, when particularly supervening static exciter inductance and line mutual-ground capacitor resonance, can produce higher lightning overvoltage or Frequency Transient Overvoltage, thereby the graded insulation transformer neutral point is constituted a threat to, even make insulation damages.

At present, the overvoltage protection to the transformer neutral point of local isolated neutral system generally adopts the gap protection device, when the over-voltage breakdown gap insulation apart from the time, short circuit current is imported the earth, thereby avoids sustained overvoltage to damage the transformer neutral point insulation.Described gap protection device is installed in the transformer edge; have grounding electrode and non-grounding electrode in the device; the end of two electrodes forms the gap; the current transformer of having connected in the primary circuit of grounding electrode; be used for the zero-sequenceprotection of isolated neutral transformer; the effect of current transformer is the current value of collection primary circuit and is transformed on the device of secondary relaying protection; thereby measure the current value behind the gap breakdown and provide the corresponding protection signal, to determine whether protective relaying device reaches operation condition.Terminal block on the non-grounding electrode is connected with transformer neutral point, makes transformer neutral point, non-grounding electrode, discharging gap, grounding electrode constitute an overvoltage protection loop.

The problem that existing gap protection device exists is: 1, the installation underframe of the leading-out terminal of being connected of the end of incoming cables of current transformer and grounding electrode, current transformer and ground connection is connected the structure that all adopts need to assemble bridging type; volume is big, complex structure and assembling and setting process are loaded down with trivial details; having more conduction in the structure is flexible coupling and securing member; parts are many, cause that production cost is higher, the assembling and setting qualification rate is on the low side and be connected wiring with the user to feel inconvenience very much.2, because device is arranged on the external world, the easy attack metal parts of environmental factors such as wind and rain make its corrosion, and then influence machinery, the electric property of product, make operation of power networks have potential safety hazard.

[summary of the invention]

For overcoming the problems referred to above that prior art exists; the utility model aims to provide the neutral point protection device of the novel 110kV-220kV transformer of a kind of structure; that this device has is simple in structure, overall performance good; production cost is low, assembling and setting qualification rate height is connected wiring and feels advantage easily very much with the user; device is arranged on the open air; environmental factors such as wind and rain are difficult for the attack metal parts, and then guarantee the safe operation of machinery, electric property and the electrical network of product.

The technical scheme scheme that realizes above-mentioned purpose is as follows: the neutral point protection device of this 110kV-220kV transformer; by grounding electrode; non-grounding electrode; terminal box and installation underframe are formed; grounding electrode is by electrode bar; current transformer constitutes; non-grounding electrode is by solid core post insulator and non-grounding electrode bar construction; it is characterized in that: the turnover line terminals of the primary winding of current transformer is to go out structure under enterprising; the electrode bar periphery of current transformer primary winding is provided with insulating barrier; the insulating barrier periphery is wound with the secondary coil of current transformer, and the secondary coil periphery is cast with outdoor epoxy resin layer.

Aforesaid protective device is characterized in that: Current Transformer Secondary lead-out wires of coil periphery is with the insulator of band full skirt.

Aforesaid protective device is characterized in that: electrode bar and non-electrode bar for grounding are the parts that stainless steel material is made.

Beneficial effect: compared with prior art, grounding electrode by electrode bar as the outer epoxy resin one-time cast-forming of the secondary coil user of the primary winding of current transformer and current transformer, thereby removed the assembling link of conventional current transformer and electrode bar from, and, because the turnover line terminals of the primary winding of current transformer is to go out structure under enterprising, grounding electrode adopts the standard bolt securing member just can directly be fixed to and installs on the underframe, the leading-out terminal of having removed conventional current transformer from need be flexible coupling to be connected to the assembling link that constitutes grounded circuit on the underframe is installed with conductive copper (aluminium) row or conduction, and, the outer epoxy resin layer of user is wrapped in inside with parts such as current transformers, device is arranged on the open air, environmental factors such as wind and rain are difficult for the attack metal parts, and then have guaranteed the machinery of product, the safe operation of electric property and electrical network.

The utility model is described in further detail below in conjunction with drawings and Examples.

[description of drawings]

Fig. 1 is the main TV structure schematic diagram of an embodiment of the utility model.

Fig. 2 is the plan structure schematic diagram of Fig. 1.

Among the figure: electrode bar 1, discharging gap 2, non-electrode bar for grounding 3, terminal board 4, solid core post insulator 5, terminal box 6 is installed underframe 7, insulator 8, insulating case 9, insulating case 10, earth terminal 11.

[embodiment]

Referring to Fig. 1, and in conjunction with Fig. 2.The turnover line terminals of the primary winding of current transformer is designed to the enterprising version that goes out down among the figure, earth terminal 11 only just can directly be fixed to two standard bolt securing members and install on the underframe 7, the leading-out terminal of having removed conventional current transformer from need be flexible coupling to be connected to the assembling link that constitutes grounded circuit on the underframe is installed with conductive copper (aluminium) row or conduction, non-electrode bar for grounding 3 is fixedly connected on the top of solid core post insulator 5, the top also is provided with terminal board 4, and the binding post on the terminal board 4 is connected with transformer neutral point through cable.Non-electrode bar for grounding 3 and electrode bar 1 be rectangular bending all, and level forms discharging gap 2 between in opposite directions, and the distance of discharging gap 2 can be set as required.The region of interest of non-electrode bar for grounding 3 and electrode bar 1 all is provided with the clearance distance adjusting mechanism, because being provided with of these mechanisms is same as the prior art, therefore, repeats no more.

At the hypomere of grounding electrode electrode bar 1, be provided with insulating barrier as electrode bar 1 periphery of current transformer primary winding, the insulating barrier periphery is wound with the secondary coil of current transformer, and the secondary coil periphery is cast with epoxy resin layer.Current Transformer Secondary lead-out wires of coil periphery is with the insulator 8 of band full skirt, and the parts that electrode bar 1 and non-electrode bar for grounding 3 are made for stainless steel material are to prevent rust corrosion.Insulating case 9, insulating case 10 are clipped in the middle the epoxy resin layer of secondary coil periphery, and the binding post of Current Transformer Secondary coil connects with binding post in the terminal box 6 through lead-out wire.Whole device is located on the installation underframe 7 of ground connection.

When system when the neutral point of 110kV-220kV transformer has overvoltage to produce; and when this superpotential amplitude reaches the discharge voltage value in gap; by 2 discharges of the discharging gap between electrode bar 1 and the non-electrode bar for grounding 3; electrical discharge arc is with transformer neutral point ground connection; make the neutral point of local earth-free 110kV-220kV transformer change effectively earthed system into by arcing ground; drop to the discharge voltage value in gap when following in superpotential amplitude; electric arc can be from horizontal blanking; current transformer exports the current value of measuring to protective relaying device, thereby realizes the superpotential automatic protection of transformer neutral point.

Claims

1; a kind of neutral point protection device of 110kV-220kV transformer; by grounding electrode; non-grounding electrode; terminal box and installation underframe (7) are formed; grounding electrode is by electrode bar (1); current transformer constitutes; non-grounding electrode is made of solid core post insulator (5) and non-electrode bar for grounding (3); it is characterized in that: the turnover line terminals of the primary winding of current transformer is to go out structure under enterprising; the electrode bar periphery of current transformer primary winding is provided with insulating barrier; the insulating barrier periphery is wound with the secondary coil of current transformer, and the secondary coil periphery is cast with outdoor epoxy resin layer.

2, protective device as claimed in claim 1 is characterized in that: Current Transformer Secondary lead-out wires of coil periphery is with the insulator (8) of band full skirt.

3, protective device as claimed in claim 1 is characterized in that: the parts that electrode bar (1) and non-electrode bar for grounding (3) are made for stainless steel material.