Paper-insulated self-bonding/acetaldenide-enameled transposed conductor
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Product Description
1.1 Paper-Insulated Acetal-Enamelled Transposed Conductor
To this end, a certain number of acetal-insulated copper flat wires are arranged in two parallel columns with their wide faces in mutual contact. On the upper and lower surfaces of these two columns, the wires are transposed in the same direction along their narrow faces, and the winding is then formed by multiple layers of continuous, tight wrapping with electrical insulating paper tape.
Replacing a single large-cross-section conductor with transposed conductors for winding the coil facilitates the winding process and, due to the reduced cross-sectional thickness of the conductors, lowers eddy-current losses within the windings.
In transposed conductors, the insulation between parallel conductors is thinner, resulting in a smaller footprint compared with windings formed by paralleling conventional insulated conductors; thus, the spatial utilization of the winding can be improved.
When using transposed winding, no transposition is required, which simplifies the winding process and saves labor time.
This product is widely used in the windings of large oil-immersed transformers and reactors.
1.2 Paper-Insulated Self-Adhesive Acetal Enamel Transposed Conductor
The difference between self-adhesive alkyd-enameled transposed conductors with paper insulation and conventionally alkyd-enameled transposed conductors with paper insulation lies in the fact that the self-adhesive enameled copper flat wire is produced by coating conventional alkyd-enameled copper flat wire with a self-adhesive enamel whose main component is epoxy resin. During the drying process after the windings have been formed, the partially polymerized epoxy resin reacts, thereby causing the individual conductors to bond to one another.
In addition to the advantages of paper-insulated, self-bonding alkyd-enameled, transposed conductors, the use of self-bonding alkyd-enameled flat wire enables the enameled strands to adhere to one another during drying and heating, thereby forming a more rigid winding that can withstand greater bending stresses. This prevents internal slippage of the winding conductors and avoids blockage of oil passages due to thermal expansion, which in turn facilitates winding cooling and enhances transformer operational reliability. Moreover, the improved mechanical properties of the windings enhance the transformer’s short-circuit withstand capability.
This product is widely used in the windings of large oil-immersed transformers and reactors.
1.3 Main Technical Specifications of Paper-Insulated Self-Adhesive/Aldehyde-Resin Varnished Transposed Conductors:
Number of individual enameled flat wires in the transposed conductor: 5 to 87.
Single-conductor dimensions (mm): side a: 0.80–3.00; side b: 3.00–13.00. For transposed conductors with more than 55 strands, to better ensure the winding processability of the conductor, it is recommended that side a be 1.30–1.70 mm and side b be 5.3–7.5 mm, and that semi-rigid conductors be used.
The width-to-thickness ratio of a single conductor is: b/a ≤ 7.
Core dimensions of the transposed conductor (mm): W1 ≤ 28; H1 ≤ 90.
Aspect ratio of the transposed conductors: ≤6.
Acetal layer coating thickness (mm): 0.08–0.15. (Customizable per customer requirements.)
Epoxy adhesive layer thickness (mm): 0.02–0.08. (Customizable upon customer request.)
Insulation types: cable paper, high-density paper, Denison paper, heat-resistant paper, Nomex paper, and mesh belt (customizable per customer requirements).
Paper insulation thickness (mm): 0.30; 0.45; 0.60; 0.75; 0.95; 1.35; 1.60; 1.95; 2.45; 2.95; 3.45; 3.95; 4.25; 4.80. (If the customer has specific requirements, processing shall be carried out in accordance with those requirements.)
Number of paper layers: As per customer requirements.
Mesh belt thickness (mm): 0.28; 0.40; (custom processing available upon customer request).
Pitch for pitch exchange (mm): S ≤ π × d/n. Typically 8–18 b; in special cases, the parties shall negotiate. The pitch for pitch exchange may be less than 8 b. (Minimum pitch: 30 mm.)
Bonding strength (120°C for 24 hours, MPa): ≥ 5.
Resistivity ρ20 (Ω·mm²/m): ≤0.017241.
Specified non-proportional extension strength Rp0.2 (MPa): 80–300. (Wire with a strength exceeding 100 MPa is classified as semi-hard wire; if the customer has special requirements, processing shall be carried out in accordance with those requirements.)
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Product Advantages
Leveraging more than two decades of technological expertise and industry-leading manufacturing capabilities, the company has developed core product advantages characterized by high electrical conductivity, low loss, corona resistance, and exceptional reliability. By employing high-purity oxygen-free copper and state-of-the-art insulation processes, the products deliver outstanding mechanical and electrical performance, meeting the stringent requirements of high-voltage transmission and transformation applications as well as emerging sectors such as new-energy vehicles. This comprehensive approach enhances equipment operational efficiency, extends service life, reduces overall energy consumption, and provides customers with a stable, efficient, and secure one-stop electromagnetic wire solution.
Higher electrical conductivity
● Excellent electrical conductivity and low copper losses, enhancing motor efficiency and service life.
● Hongyuan Company Standard: Copper purity ≥ 99.99%, resistivity at 20°C ≤ 0.01710 Ω·mm²/m.
Control measures: High-purity Class A copper plates are self-cast to ensure excellent electrical performance.
Lower oxygen content
● Low oxygen content ensures high welding quality, thereby extending the service life of the motor.
● Hongyuan Company Standard: Oxygen content < 8 ppm.
Control measures: High-quality Grade A copper plates are self-drawn and cast, and process technical requirements are established for the charging frequency of electrolytic copper plates, smelting temperature, cooling rate, and protective measures during the melting process in the upward-drawing production process, to ensure that the copper rods have high purity and low oxygen content.
Smaller fillet radius
● A smaller fillet radius results in a higher packing density and higher motor efficiency.
● Hongyuan Company Standard: Minimum corner radius of 0.30 mm.
Control measures: Molds are manufactured using precision CNC technology and inspected with a projector, ensuring that the round-corner radius deviation is within ±10%.
Smaller coating film eccentricity
● The smaller the eccentricity, the more uniform the coating film and the better its electrical properties, such as corona resistance.
● Hongyuan Company Standard: Coating film eccentricity: maximum thickness/minimum thickness ≤ 1.3.
Control measures: Maintain optimal baking temperature, varnish bath temperature, and viscosity; conduct projection inspection on both bare-wire molds and coating molds to ensure that the fillet radii are properly matched, thereby guaranteeing uniform coating.
Better film flexibility and adhesion
● Excellent flexibility and adhesion to prevent cracking of the coating at the ends during bending.
● Hongyuan Company Standard:
Film flexibility: The coating film shall not crack when rolled up to twice its original thickness and twice its original width.
Coating adhesion: After cutting and stretching by 15%, the distance at which the coating loses adhesion shall be no greater than 0.5 times the conductor width.
Control measures: Employ the optimal painting process and precisely control the thickness of each paint layer.
Higher partial discharge inception voltage (PDIV)
● The higher the PDIV value of the winding, the longer the insulation system’s service life under aging conditions.
● Hongyuan Company Standard: Single-coat film thickness of 0.13 mm, PDIV (Vp) ≥ 1900 V.
Control measures: use PI varnish with a low dielectric constant, increase the varnish film thickness, and enhance the degree of varnish curing.
Higher corona resistance
● Enhancing corona resistance can reduce partial-discharge-induced coating degradation, thereby extending the service life of electric motors.
● Hongyuan Company Standard: Single-coat film thickness of 0.12 mm, corona resistance life ≥ 500 hours.
Control measures: modify the properties of the insulating varnish, increase the coating thickness, reduce coating eccentricity, and enhance coating cure.
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