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Winding Wire, the industry’s general scientific name magnet wire, is a special insulated wire with high conductivity, high strength insulation protection, and can be tightly wound into coils. It is the core basic component of all magnet induction equipment. From the structural point of view, winding wire consists of two core parts: high-purity metal conductor core + multi-layer composite insulation protective layer, which is different from ordinary power wires and signal wires. The core design goal of winding wire is not long-distance transmission, but winding coil, gathering magnetic field and realizing efficient two-way conversion of electric energy and magnetic energy.
The core requirements of ordinary wires are low transmission loss, outdoor aging resistance, and long-distance transmission stability; while the core requirements of winding wires are more stringent, and four core performance indicators need to be met at the same time: extreme conductivity uniformity, stable insulation voltage resistance, accurate heat aging resistance, and excellent mechanical winding adaptability. In the tightly wound coil structure, the spacing between turns and turns, layers and layers of windings is very small, the potential difference distribution is complex, and it is easy to have problems such as inter-turn short circuit, partial discharge, insulation breakdown, high temperature aging, etc., which also determines the production process, material standard and inspection standard of winding wire.
From the perspective of industry standards, winding wire is a special magnet wire produced in accordance with IEC 60317, GB/T 6109, NEMA MW and other international and domestic authoritative standards, widely adapted to low frequency, power frequency, high frequency, high temperature, high voltage, strong vibration, frequent start and stop and other complex electrical conditions. Its core value runs through the whole life cycle of the equipment: the quality of the wire directly determines the motor efficiency, transformer loss, equipment temperature rise, insulation life, short-circuit resistance and operation stability. It is the core basic material for upgrading the performance of electrical equipment, saving energy and reducing carbon and improving reliability.
With the rapid development of new energy power, intelligent manufacturing, ultra-high voltage transmission and rail transit industries, traditional ordinary winding wires can no longer meet the needs of high-end equipment. Various types of subdivided special winding wires have emerged, including flat enameled wires, high-frequency SST litz wires, CTC continuous transposition wires, etc., forming a winding wire product system with perfect categories, clear gradients and accurate matching of working conditions, covering all scenarios of civil, industrial and high-end special equipment.
| Material English Chinese abbreviation | Heat resistance Class | core advantages | AI-based solutions across |
| Polyurethane (PU) polyurethane insulating paint | 130℃ Class B | 1. It can be directly welded without scraping paint, greatly improving the automatic welding capacity 2. The paint film is thin and light, and the high-frequency dielectric loss is extremely low 3. Material parity, good insulation uniformity | Small household appliances motor, precision instrument coil, ordinary switching power supply, low frequency solenoid valve, civil small transformer |
| Polyester (PE) polyester insulating paint | 155℃ Class F | 1. High mechanical strength, tensile resistance, wear resistance, strong adhesion of paint film, bending without cracking 2. Moisture resistance, chemical corrosion resistance, frequency long-term operation aging slow 3. Comprehensive cost-effective, versatile | Industrial general motor, power frequency transformer, common reactor, water pump/fan motor, conventional industrial coil |
| Polyesterimide (PEI) polyesterimide insulating paint | 180℃ Class H | 1. Optimized high temperature resistance, thermal stability, aging resistance, partial discharge resistance far superior to ordinary polyester 2. Excellent thermal shock performance, long-term continuous operation at 180℃ 3. Oil and moisture resistance, high adaptability to oil immersed/sealed high temperature equipment 4. Excellent balance of performance and cost | High-power industrial motor, oil-immersed transformer, energy storage reactor, inverter winding, long-term full-load industrial electrical equipment |
| Polyamide imide (PAI) insulating paint | 200℃ Class N | 1. High temperature resistance, overload resistance, corona resistance, partial discharge resistance outstanding 2. Withstand high frequency pulse voltage, frequent load fluctuation 3. High film hardness, abrasion resistance, scratch resistance, winding is not easy to damage | New energy vehicle drive motor, variable frequency speed motor, high frequency high power reactor, aviation general electric, high-end automation industrial motor |
| Polyimide (PI) Polyimide insulating paint | C grade above 220℃ | 1. Organic insulation system top comprehensive performance, high temperature resistance, low temperature resistance, radiation resistance, corona resistance, corrosion resistance 2. Strong short-term temperature tolerance, suitable for vacuum, extreme high and low temperature environment | Aerospace motor, nuclear power winding, military special electrical, ultra-high vacuum equipment, extreme temperature change special magnet equipment |
| Kraft Paper | 105℃/120℃/155℃ gradient | 1. Fiber dense insulation stability, excellent compatibility with transformer mineral oil, long-term immersion does not decompose 2. Strong mechanical toughness, tear resistance, good heat dissipation and air permeability 3. Mature technology, low cost, decades of industry proven reliability | Oil-immersed power transformer, high-voltage reactor, large-capacity oil-immersed equipment winding interlayer, outer coating insulation |
| Nomex ® Paper | 200 deg C or higher | 1. High temperature resistance, flame retardant, breakdown resistance, anti-aging, dry and wet/oil immersion environment can be stable work 2. No water absorption defect, low insulation strength attenuation under high humidity conditions, partial discharge resistance 3. Good flexibility, special winding coating, bending processing is convenient | Dry-type transformer, high temperature reactor, new energy power equipment, high voltage special transformer, high temperature and high humidity electrical equipment |
| Fiberglass | 180℃~220℃ | 1. Inorganic non-combustible material, wide heat resistance range, strong mechanical protection ability, impact resistance and wear resistance 2. Aging resistance, insulation stability, suitable for vibration, inflammable and explosive scenarios 3. It can be combined with insulating paint to form double layer protection | High temperature industrial motor, crane motor, explosion-proof electrical, furnace supporting electrical, high temperature special winding equipment |
| Film Insulation (PET/PI/PPS) | Depending on the film material 155℃~220℃ | 1. Precise and controllable thickness, ultra-thin pinhole-free, extremely high dielectric strength 2. Moisture-proof corrosion resistance, high pressure breakdown resistance, significant improvement in tank fullness rate 3. It can be combined with paper and paint film to make a multi-layer composite insulation system | Compact high-end winding, high frequency precision coil, small high voltage transformer, high precision special magnet equipment |
The core of winding wire work completely depends on magnet induction law and ampere loop theorem, all the energy conversion logic of motor, transformer and inductance equipment depends on magnetic field concentration and magnet induction of winding wire coil. Simply put, the working process of winding wire is the complete process of “electrifying magnetism, magnetism and magnet energy two-way conversion”, which can be divided into three core operating mechanisms.
The high pure copper and aluminum conductor core inside the winding wire has extremely low resistivity, which can stably carry rated AC and DC currents and provide basic current carriers for magnet conversion. When the current passes through the winding coil, it will form a closed and concentrated magnetic field around the coil. Compared with the straight wire, the tightly wound winding wire can maximize the concentration of magnetic field lines and improve the magnetic field strength and magnetic field utilization. This is also the core reason why the coil of electrical equipment must adopt special winding wire.
This is the core key to distinguish winding wire from bare wire. After ordinary bare metal wire is wound into a coil, direct contact between turns and layers will cause a complete short circuit, and magnet work cannot be realized. The dense insulation layer (paint film, paper package, film, glass fiber, etc.) covered on the surface of the winding wire can realize the electrical isolation of each coil and each layer of coil, ensuring that the wires with different potentials and different currents are not conductive. At the same time, the outer insulation structure can realize the insulation of the coil, the iron core and the equipment shell to the ground, completely avoid the faults such as turn-to-turn short circuit, interlayer breakdown and leakage to the ground, and ensure the safe and stable operation of the equipment.
According to different equipment types, the magnet conversion function of winding wires is divided into two core modes. The first type is electro-magnetic mode: motor, reactor, electromagnet and other equipment, through winding line energization to generate stable controllable magnetic field, relying on magnetic field force to drive mechanical operation or achieve reactive power compensation, magnetic field regulation; The second type is magneto-electric mode: transformer, generator and other equipment, relying on external magnetic field changes, through winding line coil induction to generate induced electromotive force, to achieve voltage conversion, electrical energy transmission, mechanical energy to electrical energy functions.
In the whole working process, the material uniformity, insulation stability, section accuracy and heat resistance of the winding wire directly determine the operating performance of the equipment. Insufficient conductor purity will lead to increased DC loss and serious heating of equipment; uneven thickness of insulation layer and pinhole defects will cause partial discharge and insulation breakdown; insufficient heat resistance grade will lead to insulation aging failure under long-term high temperature operation and greatly shorten equipment life. It can be said that the quality of the winding wire directly determines the energy efficiency level, stability and service life of the magnet equipment.
In addition, under high frequency conditions, ordinary single winding wire will produce serious skin effect and proximity effect, and eddy current loss will increase sharply. At this time, special winding wire (litz wire, CTC wire) can effectively offset high frequency loss and balance current distribution through multi-wire twisting and continuous transposition structure optimization, so that winding wire can still maintain high efficiency and stable operation under high frequency and large capacity complex conditions. This is also the core working principle advantage of high-end winding wire.
