Completely prevent inter-turn short circuits to ensure uninterrupted power supply for the transformer

        In critical scenarios such as fire emergency power supply, security monitoring systems, industrial automation control, building power distribution, and communication base stations, transformers need to meet the demanding conditions of continuous operation for 8,760 hours throughout the year. The continuity of power supply directly determines the operational reliability and safety baseline of the entire equipment. Among various types of transformer faults, inter-turn local short circuits have the highest occurrence rate, the strongest concealment, the greatest destructive power, and are the core hidden hazard that most easily leads to power outages. According to statistics on power equipment failures, 50% to 60% of transformer winding faults are inter-turn short circuit faults. Most sudden shutdowns, equipment burnouts, and power outages problems gradually evolve from initial minor inter-turn local short circuits. 

        Unlike obvious faults such as inter-phase short circuits and ground faults, inter-turn local short circuits do not cause immediate tripping, no obvious abnormal sounds, or significant temperature rise in the early stage. They only involve a few line turns having insulation damage and conducting, forming a local circulation. The equipment can continue to operate with faults, and the operation and maintenance detection is difficult to detect. However, during long-term operation, local high temperatures, insulation carbonization, and magnetic flux disorder will continuously exacerbate the fault, eventually rapidly evolving into inter-layer short circuits, inter-phase breakdown, and complete machine burnout, directly causing a forced interruption of the all-weather power supply system, triggering equipment paralysis, project acceptance failure, and a sharp increase in operation and maintenance costs, and causing a series of serious problems. Therefore, from the design, material selection, process, and structure dimensions, to completely prevent inter-turn local short circuits, is the core key to ensuring the long-term continuous power supply of transformers and eliminating sudden shutdown faults. It is also the necessary technical barrier for high-reliability and uninterrupted power supply equipment.

        The insulation of transformer windings' inter-turns is the core protective barrier for isolating adjacent enameled wire turns. The insulation layer thickness is only a few millimeters, and it is the weakest insulation link in the entire electrical system. The core essence of inter-turn local short circuits is that the insulation layers between adjacent windings of the winding break irreversibly, age, and break down, causing the originally insulated wires to conduct, forming a closed short-circuit circulation fault phenomenon. This fault has strong progressive, concealment, and destructive properties. It is divided into three development stages, gradually eroding the stability of equipment's power supply, and ultimately completely interrupting the power supply. 

The first stage is a latent minor short circuit. A few individual or a few adjacent turns of the coil insulation have minor damage, resulting in a weak local circulation. The number of short-circuited turns is small and the fault current is low. At this time, the transformer's no-load voltage, load parameters, and temperature rise indicators are basically normal. Conventional detection equipment cannot capture the fault signal, and the equipment can operate normally and start and stop. This is a typical "latent faulty condition with no obvious symptoms". However, the local circulation will continuously generate concentrated hotspots. The local temperature of the coil turns is much higher than the average temperature of the winding, slowly carbonizing the surrounding insulation material, forming a vicious cycle. 

The second stage is the acceleration of fault spread. Local high temperatures continuously burn the insulation between windings, the damaged area gradually expands, the number of short-circuited windings continues to increase, and the short-circuit current multiplier rises sharply. The problem of local winding overheating becomes prominent, and the equipment shows phenomena such as slight excessive temperature rise, output voltage drift, increased electromagnetic noise, and waveform distortion. At this time, the equipment's load-bearing capacity decreases, the power supply accuracy deteriorates, intermittent soft faults occur frequently, and if it continues to operate without interruption, the fault will quickly enter the explosive stage. 

The third stage is complete insulation breakdown during shutdown. The inter-turn short circuit continues to deteriorate, the insulation undergoes extensive carbonization failure, and eventually leads to inter-layer short circuit, phase-to-phase short circuit or ground breakdown. The short circuit current surges instantly, exceeding the equipment's tolerance threshold, directly causing the transformer to trip, burn out, and catch fire on the winding, resulting in a complete interruption of the all-weather power supply system. For critical equipment without continuous monitoring, sudden power supply interruption will directly lead to system paralysis, triggering safety accidents, data loss, and functional failure, which are irreversible consequences. 

        Compared to other faults, the greatest hazard of inter-turn local short circuit lies in "no warning in the early stage, rapid outbreak in the later stage, and wide damage range". It remains latent in continuously operating equipment and is the greatest safety hazard in high-reliability power supply scenarios. At the same time, inter-turn faults will disrupt the magnetic field balance of the winding, causing magnetic circuit disorder, increased loss, and accelerated aging of insulation, significantly shortening the service life of the transformer as a whole, and increasing the cost of equipment operation and replacement.

        Inter-turn local short circuit does not occur randomly; it is a systematic problem caused by multiple factors such as material defects, unreasonable structural design, loose production processes, environmental erosion, and long-term operation aging. There are five core inducing causes in the industry, which are also the main reasons for the high incidence of faults in uninterrupted power supply equipment.

1. Weak insulation material of enameled wire, insufficient inherent protection
Some manufacturers, in an effort to reduce material costs, use low-grade thin enamel enameled wire, which has poor adhesion of the insulation paint, low temperature resistance, and weak impact resistance. During winding, bending, and close contact, the enameled wire is prone to micro cracks, local peeling of the paint, and pinhole defects, forming inherent insulation hazards. After the equipment is continuously powered on and the temperature changes cyclically, the small defects gradually expand and eventually cause inter-turn conduction short circuit, which is the primary inducement of inter-turn faults in mass-produced equipment.

2. Loose winding winding process, cumulative mechanical damage
Manual winding and aging equipment winding have problems such as disordered wiring, squeezing of overlapping wires, uneven tension, and misaligned wire turns. When the winding is closely stacked and compressed, the wires rub against each other, squeeze, and bend, causing hidden damage to the insulation paint; the uneven spacing of the wiring leads to local stress concentration, and under long-term electromagnetic vibration, the insulation layer is continuously worn and damaged, eventually causing local inter-turn short circuit. This kind of mechanical damage is a congenital defect in the process and cannot be detected initially; it only gradually exposes during long-term uninterrupted operation.

3. Overvoltage and impulse current break insulation
Grid lightning surges, instantaneous voltage spikes, and frequent start-stop of loads will generate instantaneous overvoltages far exceeding the rated value, with an electric field intensity that can reach 10-20 times that of normal operating conditions. The weak inter-turn insulation cannot withstand the instantaneous high voltage impact, resulting in local breakdown and micro-conduction faults. For equipment that operates continuously without interruption, the cumulative voltage impact over the years will continuously damage the insulation, eventually causing inter-turn short circuit faults, resulting in power supply interruption.

4. Poor heat dissipation and high-temperature aging, insulation performance degradation
Defects in heat dissipation structure design, dense stacking of windings without ventilation, and severe local heat accumulation will cause the transformer to operate at high temperatures for a long time. The inter-turn insulation paint and insulation paper are organic polymer materials that will gradually become brittle, carbonize, and lose insulation toughness under high-temperature conditions, with the insulation resistance continuously decreasing. For every 10°C increase in temperature, the insulation aging rate doubles. The cumulative effect of heat on uninterrupted operation equipment is particularly obvious, easily causing inter-turn insulation failure and local short circuit problems. At the same time, high temperatures will accelerate the aging and cracking of the paint layer, significantly increasing the failure probability.

5. Moisture and dust environment erosion, forming conductive channels
Most outdoor, machine rooms, and building equipment are in a humid, dusty, and slightly oily working environment. Water vapor, dust, and oil in the air will adhere to the surface of the windings and inter-turn gaps, forming weak conductive channels. Over time, this will reduce the insulation performance of the inter-turn insulation, causing leakage, micro-conduction, and gradually developing into inter-turn local short circuit, disrupting the continuity of power supply. In a high-humidity environment with a humidity greater than 85%, the occurrence rate of such faults will significantly increase.

       To ensure uninterrupted power supply of transformers, a "material selection to prevent defects, structure to prevent compression, process to prevent damage, insulation to prevent breakdown, heat dissipation to prevent aging, and environment to prevent erosion" full-chain prevention system must be constructed. This will completely eliminate the hidden hazard of inter-turn local short circuit and completely eliminate the risk of power supply interruption from the source.

1. High-grade insulation materials are selected to lay a solid foundation for inherent protection.
All low-grade thin-coated wires are completely abandoned, and 180-level and 200-level high-temperature-resistant thick-coated pure copper enameled wires are uniformly adopted. The enamel coating has high adhesion, high flexibility, high voltage resistance, resistance to aging, and resistance to wear, which can effectively avoid damage to the enamel coating caused by winding and bending, as well as long-term vibration. The insulation materials between turns are selected as high-density composite insulation paper and temperature-resistant insulating paint, with high breakdown voltage and strong anti-aging ability. In the temperature range of -20℃ to 120℃, the insulation performance is stable, eliminating insulation failure caused by material aging and eliminating the hidden short-circuit hazard between turns from the source of materials.

2. Precise symmetrical winding process, eliminating mechanical stress damage.
Using fully automatic precise winding equipment, the entire process is constant tension, uniform speed, and tight winding to ensure that the windings are flat layer by layer, with uniform density, no overlapping lines, no over-winding, no misalignment, and no stress concentration. The regular winding structure can completely avoid hidden paint coating damage caused by mutual compression and friction of the wire turns, ensuring that each layer of the conductor insulation layer is intact and evenly stressed. At the same time, the winding end processing is optimized to reduce the bending angle of the wire, eliminating the cracking and damage of the end insulation, and comprehensively avoiding process-related turn-to-turn defects.

3. Layered isolation insulation structure, strengthening turn-to-turn withstand voltage protection.
Optimizing the winding structure design, a layered and zoned insulation isolation scheme is adopted. After each layer of winding is wound, a high-strength insulation isolation layer is laid to prevent direct contact and squeezing between layers and turns. For high-voltage windings and impact load conditions, an additional turn-to-turn reinforcement insulation process is added to enhance the instantaneous overvoltage tolerance, effectively resisting high-voltage breakdown risks caused by grid surges and load impacts, and completely eliminating turn-to-turn micro-short circuits caused by instantaneous voltage disturbances.

4. Optimized heat dissipation structure, blocking the path of high-temperature aging
Using a layered air duct cooling system and a sparse winding arrangement structure, the traditional tightly piled winding arrangement defect of accumulated heat is broken. The winding inter-turns and inter-layer interstices have air circulation gaps, which can promptly discharge the operating heat and prevent the accumulation of local hot spots. Through scientific balance of copper loss and iron loss, the overall heat generation is reduced, allowing the transformer to operate at a low-temperature stable state for a long time, significantly delaying the aging and carbonization of insulation, and avoiding insulation failure caused by high temperatures, ensuring the persistent stability of insulation performance under uninterrupted operation conditions.

5. Vacuum impregnation for overall curing, moisture-proof and dust-proof to lock the insulation
Using a high-penetration vacuum pressure impregnation process, the insulating paint fully penetrates into every inter-turn gap and inter-layer gap, completely filling the internal cavities of the winding, solidifying the loose windings into a rigid whole. On the one hand, it isolates from the erosion of air moisture, dust, and oil stains, eliminating the conductive channels and insulation attenuation caused by external environmental factors; on the other hand, it locks the winding structure, eliminating the friction and insulation wear caused by long-term electromagnetic vibration, and at the same time, improving the overall insulation withstand voltage level, comprehensively eliminating the local short-circuit problems between turns.

6. Factory-wide strict testing, intercepting hidden faults
Establishing a special inspection standard for turn-to-turn insulation, each device must complete turn-to-turn withstand voltage testing, pulse turn-to-turn short-circuit detection, and DC resistance balance degree testing before leaving the factory. Precisely capture minor turn-to-turn defects and hidden insulation damage, and prevent faulty equipment from leaving the factory. Through high-frequency pulse comparison technology, accurately detect minor turn-to-turn hidden hazards that cannot be detected by conventional testing, ensuring that all equipment leaves the factory without defects and guaranteeing stable and uninterrupted power supply throughout the day.

       The thorough prevention of turn-to-turn short circuits is the core guarantee for the uninterrupted power supply of transformers, bringing multiple long-term benefits to key electrical systems, and completely solving the problem of power interruption.

Firstly, achieve zero-failure continuous operation of the equipment, eliminate sudden shutdowns and power outages, ensure that key systems such as fire protection, security, industrial control, and communication operate stably without interruption throughout the year, and avoid safety risks and functional failures caused by power outages. 

Secondly, significantly reduce the operating and maintenance costs of equipment. Inter-turn faults leading to equipment burnout, fault repairs, and batch replacements are the main cost expenditures in the operation and maintenance of electrical equipment. The full-chain prevention and control system can completely eliminate such faults, significantly reduce the equipment post-sale repair rate, on-site rectification frequency, and asset replacement costs, and achieve low-cost and highly reliable operation throughout the equipment's life cycle. 

Finally, it extends the overall service life of the equipment. By eliminating inter-turn insulation damage and local temperature accumulation, the windings, insulation system, and core magnetic circuit can remain in a stable working condition for a long time, significantly slowing down the aging process. This leads to a substantial extension of the equipment's service life. At the same time, it continuously ensures the accuracy and stability of power supply, avoiding problems such as parameter drift and performance deterioration in the later stage. 

        Inter-turn local short circuits are the core problem that restricts the all-weather, uninterrupted power supply of transformers. They have the characteristics of being highly concealed, gradually causing damage, suddenly erupting, and causing extremely great harm. Multiple factors such as material defects, rough processing, unreasonable structure, poor heat dissipation, environmental erosion, and voltage shock contribute to the frequent occurrence of inter-turn faults. Minor inter-turn hazards are initially difficult to detect, but they will continue to deteriorate over long periods of uninterrupted operation, eventually leading to equipment burnout, power supply interruption, and irreversible operational failures and economic losses. 

        Through a complete chain prevention system including high-grade insulation material selection, precise winding process, layered isolation structure, efficient heat dissipation design, vacuum curing protection, and factory-wide comprehensive testing, the potential risks of inter-turn local short circuits can be completely eliminated from multiple dimensions such as materials, processes, structure, operating conditions, and environment. This system builds a solid insulation safety defense line for transformers. This system does not require complex circuits and relies on pre-designed structures and process optimizations to eliminate fault risks at the source and ensure the stability of transformers under all operating conditions, including no-load, light-load, full-load, and impact load, achieving uninterrupted, zero interruption, and zero-fault long-term power supply throughout the year.

        In the industry context where key equipment operates around the clock and the reliability requirements for power supply are continuously upgraded, eliminating inter-turn local short circuits is not only a core necessity for transformer quality improvement but also a core technical support for ensuring the safety, stability, continuous operation, and cost reduction and quality improvement of electrical systems. It builds a solid operational foundation for various uninterrupted power supply equipment.