As a core equipment in the power system, transformers undertake the key task of AC voltage conversion and energy transmission. Whether it is industrial production or daily life, the safe operation of transformers is crucial. JINSHANMEN TECHNOLOGY CO., LTD, as a professional manufacturer of power equipment, mainly produces oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, and other products, including high-quality oil immersed distribution transformer and 3 phase step down transformer. Based on years of production and on-site experience, this article analyzes the common faults of transformers, explores their causes, and provides targeted solutions to help industry peers reduce fault losses.
1. Winding Fault: The Core Hidden Danger Affecting Operation
Winding is the core component of transformers, and its faults mainly include turn-to-turn short circuit, winding grounding, phase-to-phase short circuit, disconnection and joint welding failure. For oil immersed distribution transformer, winding faults are often closely related to insulation oil quality and heat dissipation efficiency. The specific causes and treatment methods are as follows:
Causes of failure:
① Insulation damage left during manufacturing or maintenance;
② Poor heat dissipation or long-term overload during operation, leading to insulation aging;
③ Inferior manufacturing process, unable to withstand short-circuit impact, resulting in winding deformation;
④ Winding damp, insulation expansion blocking oil channels, causing local overheating;
⑤ Insulation oil deterioration due to water mixing, reducing insulation level.
Fault phenomenon: Transformer overheating, increased oil temperature, slight increase in power supply side current, unbalanced DC resistance of each phase. For 3 phase step down transformer, phase imbalance may be more obvious. Slight turn-to-turn short circuit will trigger gas protection action; severe cases will trigger differential protection or overcurrent protection.
Treatment measures: Once a winding fault is identified, the core should be lifted for inspection. First, measure the DC resistance of each phase winding for comparison; then check the insulation status. For minor insulation damage, replace the local insulation material; for serious deformation or short circuit, replace the winding and replace the insulation oil of the oil immersed distribution transformer.
2. Bushing Fault: Easily Ignored External Hazard
Bushing is the key component connecting the transformer internal and external circuits, and its common faults include explosion, flashover and oil leakage. This fault not only affects the insulation performance but also may cause secondary accidents. For 3 phase step down transformer used in industrial occasions, bushing fault is more likely to occur due to harsh working environment.
Causes of failure:
① Poor sealing leads to insulation damp and oil leakage;
② Improper configuration of breather or untimely treatment of inhaled moisture;
③ Porcelain defects such as sand holes or cracks in high-voltage capacitor bushings;
④ Defects in capacitor core manufacturing, leading to internal discharge;
⑤ Severe fouling on bushing surface.
Treatment measures: Regularly clean the bushing surface to remove fouling; check the sealing performance and replace the sealing ring in time. For bushings with porcelain defects or internal discharge, they should be replaced immediately to avoid explosion. For oil immersed distribution transformer, it is necessary to check the oil level in time after bushing replacement to prevent oil shortage.
3. Core Fault: Internal Overheating Trigger
The core is the magnetic circuit part of the transformer, and its insulation failure is the main cause of core faults. This kind of fault is hidden, and if it is not handled in time, it will cause local overheating and even melt the core. JINSHANMEN TECHNOLOGY strictly controls the core manufacturing process in the production of oil immersed distribution transformer and 3 phase step down transformer to reduce the occurrence of such faults.
Causes of failure:
① Insulation damage between silicon steel sheets causes local overheating and melting;
② Insulation damage of core clamping bolts forms a short circuit between bolts and silicon steel sheets;
③ Residual welding slag causes two-point grounding of the core;
④ Local magnetic flux leakage of core and winding clips causes overheating.
Treatment measures: When a core fault is suspected, the core should be lifted for inspection. First, conduct a visual inspection to check for welding slag residues and bolt insulation; then measure the insulation resistance between silicon steel sheets with DC voltage and ammeter method. For minor insulation damage, paint can be applied for repair; for serious damage, the silicon steel sheet or insulation parts should be replaced.
4. Gas Protection Fault: Safety Alarm Signal
Gas protection is the main protection of transformers, with light gas acting on signals and heavy gas acting on tripping. This protection device is particularly important for oil immersed distribution transformer, as it can timely detect internal faults such as oil decomposition.
Causes of action:
① Air enters due to poor sealing of oil filtering, oil filling and cooling systems;
② Oil level drops due to temperature decrease or oil leakage, or a small amount of gas is generated by minor faults;
③ Triggered by through short-circuit fault;
④ Secondary circuit failure of protection device.
Treatment measures: After light gas action, check the transformer status immediately and conduct gas sampling analysis if no abnormality is found. After heavy gas trips, first put in the standby transformer (such as the 3 phase step down transformer prepared by the user), then check the explosion-proof door, welding seam and shell deformation, and finally test the flammability of the gas. It is strictly prohibited to reclose without investigation.
5. Common Emergency Handling: Tripping and Fire
Transformer tripping and fire are urgent faults, and correct handling can minimize losses. JINSHANMEN TECHNOLOGY provides technical guidance for users while providing high-quality transformers, helping users deal with emergencies quickly.
Automatic tripping handling: After tripping, first adjust the operation mode by putting in the standby transformer; then check the protection action and system fault situation. For tripping caused by manual misoperation or obvious misprotection, trial power transmission can be carried out once with approval; for tripping caused by main protection such as differential and heavy gas, detailed inspection and insulation measurement are required before power transmission.
Fire handling: Immediately cut off the power supply and put in the standby transformer; stop the cooling device. If oil burns on the top cover, open the accident oil drain valve to an appropriate position; if internal fire occurs, do not drain oil to avoid explosion. Use dry powder or foam fire extinguishers to put out the fire, and call the fire department if necessary.
Conclusion
The safe operation of transformers is the cornerstone of the stable operation of the power system. Mastering the common fault analysis and handling methods of transformers such as oil immersed distribution transformer and 3 phase step down transformer is of great significance for improving the reliability of the power supply system. JINSHANMEN TECHNOLOGY CO., LTD has rich experience in the production of various transformers and transmission and distribution equipment. We are committed to providing users with high-quality products and professional technical services. If you have needs for transformers or technical consultation, please contact us.