Current transformer for electrified railway
By adopting a current transformer with epoxy resin vacuum casting and external shielding, the problems of flashover and temperature rise of current transformers in electrified railway substations have been solved, the insulation stability and pollution resistance of the equipment have been improved, and the safety and reliability of the equipment have been enhanced.
Patent Information
- Application Number
- CN202423021069.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-09
- Publication Date
- 2025-12-30
- Estimated Expiration
- 2034-12-09
AI Technical Summary
Current transformers in existing electrified railway substations are prone to faults such as flashover, excessive temperature rise, and insulation breakdown discharge under high voltage conditions, resulting in poor equipment reliability.
The current transformer is made of epoxy resin vacuum casting into a single structure. It features a compact casting body and a uniform skirt structure, combined with an external shielding wrapping scheme to enhance insulation performance, and a primary equalizing network to prevent tip discharge.
It improves the insulation stability and pollution resistance of current transformers, reduces temperature rise, enhances equipment safety and reliability, and avoids failures caused by dust and dirt.
Smart Images
Figure CN223743391U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to power supply system high pressure measurement or relay protection equipment, concretely is a current transformer for electrified railway. BACKGROUND
[0002] The electrified railway traction substation is to transform three-phase 110kV (or 220kV) high voltage alternating current into two single-phase 27.5kV alternating current, then delivers power to the railway contact net, supplies power for traction, and the current transformer in the substation is the electrical equipment connected with the primary circuit and secondary device, mainly as current measurement, monitoring and realizing the function of relay protection, and its design level is in the 70s in China, and the structure is the semi-closed structure with exposed core, and the product has small creepage distance, high temperature rise and poor insulation reliability, and based on the working condition of railway substation, there are many faults such as pollution, moisture, condensation, grounding fault, large overcurrent, high operating overvoltage, frequent overvoltage, frequent pollution flashover, high temperature rise and insulation breakdown, so in order to further improve the reliability of railway traction power supply, a current transformer suitable for railway traction substation must be developed to comprehensively improve the safe and reliable operation level of railway substation equipment. SUMMARY
[0003] In view of the above problems, the utility model aims at providing a current transformer for electrified railway to solve the problems of pollution flashover, high temperature rise and insulation breakdown of high voltage current transformer in existing railway traction substation due to special environment.
[0004] In order to achieve the above purpose, the utility model adopts the following technical scheme:
[0005] The utility model provides a current transformer for electrified railway, which comprises a casting body and a coil body enclosed in the casting body, the coil body comprises a secondary winding, a primary winding wound outside the secondary winding and a secondary winding support for supporting the secondary winding, wherein the secondary winding comprises a plurality of secondary winding units, the plurality of secondary winding units are arranged side by side and form an integral structure by wrapping a secondary winding outer shielding layer outside; the secondary connection terminal of the secondary winding is arranged at the bottom of the side surface of the casting body, the primary connection terminal of the primary winding is arranged at the top of the casting body, and the bottom of the casting body is provided with a plurality of mounting inserts.
[0006] The secondary winding unit comprises a core, a core insulation layer, an enameled round copper wire and a secondary winding outer wrapping layer, wherein the core is wrapped with the core insulation layer outside, the enameled round copper wire is wound outside the core insulation layer, and the secondary winding outer wrapping layer is wrapped outside the enameled round copper wire.
[0007] The iron core insulation layer is wrapped from inside to outside by 0.5mm paperboard angle ring one layer, half-lap plain weave cloth tape one layer, half-lap double-layer corrugated paper one layer, half-lap polyester film two layers and half-lap insulation self-adhesive tape one layer.
[0008] The secondary winding outer wrapping layer comprises half-lap double-layer corrugated paper one layer and half-lap polyester film two layers wrapped from inside to outside.
[0009] The secondary winding outer shielding layer is semi-conductive corrugated paper.
[0010] The secondary winding is connected with the secondary wiring terminal through a secondary winding lead, and a primary voltage-sharing net is arranged between the primary winding and the secondary winding lead, the primary voltage-sharing net is in a circular arc structure, and two legs of the primary voltage-sharing net are connected with two mounting inserts close to the secondary wiring terminal.
[0011] The pouring body is an integral structure in the shape of a rectangular parallelepiped poured by epoxy resin, and the four corners are in the form of missing corners, and the transition is provided with a transition round corner; and umbrella skirt structures are arranged at the outer side of the pouring body in the height direction at equal intervals.
[0012] The primary wiring terminal is a flat plate type wiring board embedded in the pouring body and partially exposed, and provided with a threaded hole.
[0013] The secondary wiring terminal is provided with a transparent secondary wiring cover outside.
[0014] The mounting insert at the bottom of the pouring body is connected with a bottom plate through a countersunk screw, and the bottom plate is provided with a grounding bolt.
[0015] The utility model has the advantages and beneficial effects that:
[0016] 1. Small volume, flexible installation: the utility model optimizes the structure design, the structure is more compact, two primary wiring terminals are embedded flat wiring boards with threaded holes, can be flexibly connected with the main bus for electrical and mechanical pressure connection, and is installed in the switch cabinet in a matched mode.
[0017] 2. Stable insulation, high anti-pollution grade: the utility model is integrally formed in a structure by vacuum pouring of epoxy resin, is stable and reliable in insulation, and is uniformly distributed with umbrella skirts at equal intervals from top to bottom, effectively increases the surface creepage distance of the product, and does not occur arc flash, discharge and insulation breakdown failure due to dust and dirt in long-term operation, and the insulation is more stable.
[0018] 3. High dynamic thermal stability current, low temperature rise: the primary winding in the utility model is wound by wires with increased wire diameter, effectively increases the product primary winding flow cross section, improves the primary dynamic thermal stability current, effectively avoids overcurrent caused by system grounding fault, and the product has lower temperature rise.
[0019] 4. The primary high-voltage winding and the secondary winding low-voltage winding of the utility model, when bandaging, all adopt the outer shielding bandaging scheme, making the coil external electric field uniform, without the hidden danger of sharp end discharge, greatly improving the product partial discharge level. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 It is the internal structure schematic view of the current transformer for electrified railway of the utility model;
[0021] Figure 2 It is the left view of the utility model; Figure 1
[0022] Figure 3 It is the plan view of the utility model; Figure 1
[0023] Figure 4 It is the K direction schematic diagram without bottom of the utility model; Figure 1
[0024] Figure 5 It is the partial enlarged view of A in the utility model; Figure 1
[0025] Figure 6 It is the overall structure schematic view of the current transformer for electrified railway of the utility model;
[0026] Figure 7 It is the left view of the utility model. Figure 6
[0027] In the drawing: 1-pouring body; 2-primary winding; 3-iron core; 4-iron core insulation layer; 5-enamel round copper wire; 6-secondary winding outer bandaging layer; 7-primary winding bandaging layer; 8-mounting insert; 9-bottom plate; 10-secondary winding support; 11-secondary winding; 12-secondary winding lead; 13-primary voltage-sharing net; 14-secondary wiring terminal; 15-secondary wiring cover; 16-grounding bolt; 17-primary wiring terminal; 18-secondary winding outer shielding layer. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model is described in detail below by combining with the drawings and specific embodiments.
[0029] Referring to Figures 1 to 7 As shown in the utility model provides a kind of current transformer for electrified railway, including casting body 1 and coil body enclosed in casting body 1, coil body includes secondary winding 11, primary winding 2 wound on the outside of secondary winding 11 and the secondary winding support 10 for supporting secondary winding 11, wherein secondary winding 11 includes multiple secondary winding units, multiple secondary winding units are arranged side by side and outside is formed by the outer shielding layer 18 of binding secondary winding One integral structure;Secondary connection terminal 14 of secondary winding 11 is arranged at the side bottom of casting body 1, primary connection terminal 17 of primary winding 2 is arranged at the top of casting body 1, and the bottom of casting body 1 is provided with multiple mounting inserts 8.
[0030] Referring to Figure 1 、 Figure 2 As shown in the utility model embodiment, the mounting insert 8 of the bottom of casting body 1 is connected with the bottom plate 9 with mounting hole by countersunk screw, the bottom plate 9 is provided with grounding bolt 16, to improve the safety of system.
[0031] Referring to Figure 1 、 Figure 5 As shown in the utility model embodiment, secondary winding unit includes core 3, core insulation layer 4, enameled round copper wire 5 and secondary winding outer binding layer 6, wherein the outside of core 3 is bound with core insulation layer 4, enameled round copper wire 5 is wound on the outside of core insulation layer 4, and secondary winding outer binding layer 6 is bound on the outside of enameled round copper wire 5.
[0032] Specifically, core insulation layer 4 is 0.5mm paperboard corner ring one layer, plain cloth tape half-lap one layer, double-layer corrugated paper half-lap one layer, polyester film half-lap two layers and insulation self-adhesive tape half-lap one layer, which are bound from inside to outside. Core insulation layer 4 increases the buffering degree, so that the entire secondary winding has better electrical safety performance.
[0033] Specifically, secondary winding outer binding layer 6 includes double-layer corrugated paper half-lap one layer and polyester film half-lap two layers, which are bound from inside to outside.
[0034] Preferably, secondary winding outer shielding layer 18 is half-lap one layer of semi-conductive corrugated paper. Primary winding 2 is bound with primary winding binding layer 7 on the outside, and primary winding 2 and secondary winding 11 both adopt outer shielding binding scheme, which provides strong guarantee for uniform mutual inductor internal electric field.
[0035] Referring to Figure 1As shown, in the embodiment of the utility model, the secondary winding 11 is connected with the secondary wiring terminal 14 through the secondary winding lead 12, the primary voltage-sharing net 13 is arranged between the primary winding 2 and the secondary winding lead 12, the primary voltage-sharing net 13 is of circular arc structure, and the primary voltage-sharing net 13 is connected with the two mounting inserts 8 close to the secondary wiring terminal 14 through two legs. In the embodiment, the bottom of the pouring body 1 is provided with four mounting inserts 8. The primary voltage-sharing net 13 effectively prevents the tip discharge phenomenon under high voltage, and has good guarantee for improving the partial discharge level of the product.
[0036] In the embodiment of the utility model, the pouring body 1 is an integral structure of rectangular parallelepiped shape poured by epoxy resin, and the four corners are in the form of missing corners, and the transition has a transition round corner, the structure is optimized, and the uniform and sufficient insulation distance around the internal primary and secondary coils is guaranteed; the pouring body 1 is provided with an umbrella skirt structure at the outer four sides along the height direction at equal intervals, so that the product has a large surface creepage distance between high voltage and ground, the insulation is more reliable, and the optimized shape design will not accumulate too much dust and dirt in the running process.
[0037] Specifically, the primary wiring terminal 17 is a flat plate type wiring board embedded in the pouring body 1 and partially exposed, and has a threaded hole, which effectively guarantees the electrical and mechanical pressure connection with the busbar inlet and outlet line in the main busbar chamber, increases the effective contact area, and the overall structure is made of epoxy resin vacuum pouring, and the structure is more compact.
[0038] Further, the outer side of the secondary wiring terminal 14 is provided with a secondary wiring cover 15 made of transparent material, the secondary wiring cover 15 is provided with a lead seal screw, has good dustproof and anti-theft effect, and will not cause secondary short circuit and monitoring failure in the use process due to environmental condensation and moisture. The secondary winding support 10 is of bridge type structure, the bridge surface is of circular arc shape, there are two round through holes on the bottom foot, and the secondary winding support 10 supports the secondary winding in the pouring body 1.
[0039] The current transformer for electrified railway provided by the utility model has the manufacturing process that:
[0040] The plurality of secondary winding units are integrally packaged to form a secondary winding 11, the primary winding 2 is wound by using a special tool, and the primary winding is wrapped by a primary winding wrapping layer 7 of an auxiliary wrapping insulation material, after the secondary winding 11 is bound and cushioned by using the secondary winding support 10, a coil body with a primary connection terminal 17, the primary winding 2, the secondary winding 11 and a secondary connection terminal 14 is formed; the secondary winding 11 is fixed on a mold by using the secondary winding support 10, the primary winding 2 is positioned and fixed on the mold by using the primary connection terminal 17, and after the distance is adjusted, the primary winding 2 is formed into an integrated structure by using epoxy resin vacuum casting and solidification. The integrated structure is uniformly distributed with equal-interval umbrella skirts from top to bottom, so that the product has a larger surface creepage distance between high voltage and ground, and the insulation is more reliable; the pouring body 1 has a cuboid shape, corners of the pouring body 1 are in a form of a missing angle, the structure is optimized, the internal coil has a uniform and sufficient insulation distance around the coil, and the pouring body 1 will not accumulate too much dust and dirt during use; the two primary connection terminals 17 are flat connection plates with threaded holes embedded in the pouring body 1 and partially exposed, so that the primary connection terminals 17 can be effectively electrically and mechanically pressed with busbar in and out line rows in a busbar room, and the integrated structure is formed by using epoxy resin vacuum casting, so that the structure is more compact. A primary voltage equalizing net 13 is arranged between the primary winding 2 and the secondary winding lead 12, so that the sharp end discharge phenomenon during high voltage is effectively eliminated. The secondary connection terminal 14 is located at the lower part of the front side of the integrated structure, the secondary connection cover 15 is made of transparent flame-retardant material, the secondary connection cover 15 has a lead seal screw, and the secondary connection cover 15 has the functions of dustproof and waterproof, so that the secondary connection cover 15 will not cause secondary short circuit and monitoring failure due to environmental condensation and moisture during use. The outer shielding wrapping scheme is used when the primary winding 2 and the secondary winding 11 are wrapped, so that the electric field outside the coil is uniform, there is no risk of sharp end discharge, and the local discharge level of the product is greatly improved.
[0041] The current transformer for electrified railway is a new product designed according to standards and railway traction substation technology, adopts a rolled iron core, uses electromagnetic conversion principle, and can accurately reflect the change of primary current, and is used for current measurement and relay protection.
[0042] The current transformer for electrified railway is made of epoxy resin vacuum casting, has the characteristics of small volume, flexible installation, reliable insulation, high contamination resistance, high dynamic thermal stability current and low temperature rise, is completely suitable for railway traction substation environment, and improves the manufacturing level of railway substation equipment as a whole.
[0043] The above only describes the embodiments of the utility model, and is not used for limiting the protection scope of the utility model. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the utility model are included in the protection scope of the utility model.
Claims
1. A current transformer for electrified railways, comprising a cast body (1) and a coil former housed in the cast body (1), characterized in that, The coil body comprises a secondary winding (11), a primary winding (2) wound outside the secondary winding (11), and a secondary winding support (10) for supporting the secondary winding (11), wherein the secondary winding (11) comprises a plurality of secondary winding units arranged side by side and integrated by an outer shielding layer (18).
2. The current transformer for electrified railways according to claim 1, characterized in that, The secondary winding unit comprises a core (3), a core insulation layer (4), an enameled round copper wire (5), and a secondary winding outer wrapping layer (6), wherein the core (3) is wrapped with the core insulation layer (4) outside, the enameled round copper wire (5) is wound outside the core insulation layer (4), and the enameled round copper wire (5) is wrapped with the secondary winding outer wrapping layer (6) outside.
3. The current transformer for electrified railways according to claim 2, characterized in that, The core insulation layer (4) is wrapped with 0.5mm paperboard corner ring one layer, plain cloth tape half-lap one layer, double-layer corrugated paper half-lap one layer, polyester film half-lap two layers, and insulation self-adhesive tape half-lap one layer from inside to outside.
4. The current transformer for electrified railways according to claim 2, characterized in that, The secondary winding outer wrapping layer (6) comprises double-layer corrugated paper half-lap one layer and polyester film half-lap two layers wrapped from inside to outside.
5. The current transformer for electrified railways according to claim 1, characterized in that, The secondary winding outer shielding layer (18) is semi-conductive corrugated paper.
6. The current transformer for electrified railways according to claim 1, characterized in that, The secondary winding (11) is connected with the secondary wiring terminal (14) through a secondary winding lead (12), a primary voltage equalizing net (13) is arranged between the primary winding (2) and the secondary winding lead (12), the primary voltage equalizing net (13) is in a circular arc structure, and two legs of the primary voltage equalizing net (13) are connected with two mounting inserts (8) close to the secondary wiring terminal (14).
7. The current transformer for electrified railways according to claim 1, characterized in that, The pouring body (1) is an integrated structure in the shape of a rectangular parallelepiped poured with epoxy resin, and the four corners are in the form of missing corners, and the transition has a transition round corner; the pouring body (1) is provided with an umbrella skirt structure around the outside at equal intervals along the height direction.
8. The current transformer for electrified railways according to claim 1, characterized in that, The primary wiring terminal (17) is a flat plate type wiring board with threaded holes embedded in the pouring body (1) and partially exposed.
9. The current transformer for electrified railways according to claim 1, characterized in that, The outer side of the secondary wiring terminal (14) is covered with a transparent secondary wiring cover (15).
10. The current transformer for electrified railways according to claim 1, characterized in that, The mounting inserts (8) at the bottom of the pouring body (1) are connected with the bottom plate (9) through countersunk screws, and the bottom plate (9) is provided with grounding bolts (16).