What are the factors affecting the operation of transformers? The six protection methods for power transformers.

Power transformers are electrical devices that convert the AC voltage and current of one system into the voltage and current of another system through electromagnetic induction, consisting of a core and two or more windings wrapped around it. The main functions include: voltage transformation, current transformation, impedance transformation, isolation, and voltage stabilization (magnetic saturation transformers), etc. Next, let's follow Ameya360 electronic components procurement network to see what factors affect the operation of transformers?
What are the factors affecting the operation of transformers? The explanation is as follows:
1. Prevent transformer overload operation. If the transformer operates under overload for a long time, it will cause the coil to heat up, leading to gradual aging of the insulation, resulting in inter-winding short circuits, phase-to-phase short circuits, or ground short circuits, as well as oil decomposition.
2. Ensure the quality of insulating oil. If the insulating oil of the transformer is of poor quality or contains excessive impurities and moisture during storage, transportation, or maintenance, it will reduce the insulation strength. When the insulation strength drops to a certain value, the transformer will short circuit, causing electric sparks, arcs, or dangerous temperatures. Therefore, the transformer should regularly test the oil quality during operation, and unqualified oil should be replaced in a timely manner.
3. Prevent aging damage of the transformer core insulation. Aging of the core insulation or damage to the clamping bolt sleeve can cause large eddy currents in the core, leading to long-term heating of the core and causing insulation aging.
4. Prevent accidental damage to insulation during maintenance. When lifting the core for transformer maintenance, care should be taken to protect the coils or insulating sleeves. If any scratches or damages are found, they should be dealt with promptly.
5. Ensure good contact of wires. Poor contact at internal joints of the coil, connection points between coils, connections to high and low voltage side sleeves, and contact points on the tap switch can cause local overheating, damaging insulation, and resulting in short circuits or open circuits. The high-temperature arcs generated at this time can decompose the insulating oil, producing a large amount of gas, increasing the pressure inside the transformer. If the pressure exceeds the protection set value of the gas relay without tripping, an explosion may occur.
6. Prevent electric shock. The power supply of power transformers generally comes from overhead lines, which are easily struck by lightning, causing the transformer to burn out due to insulation breakdown.
7. Short circuit protection must be reliable. If a short circuit occurs in the transformer coil or load, the transformer will endure a considerable short circuit current. If the protection system fails or the protection set value is too large, the transformer may burn out. Therefore, reliable short circuit protection devices must be installed.
8. Maintain good grounding. For low-voltage systems using protective earthing, the neutral point on the low-voltage side of the transformer should be directly grounded. When the three-phase load is unbalanced, current will appear on the neutral line. If this current is too large and the contact resistance is also high, the grounding point will become hot, igniting surrounding combustible materials.
9. Prevent overheating. The temperature changes of the transformer should be monitored during operation. If the coil wire of the transformer has Class A insulation, primarily made of paper and cotton yarn, the temperature significantly affects insulation and service life. The transformer has an insulation aging "six-degree rule"; when the insulation temperature of the transformer winding is in the range of 90 to 130°C, for every 6°C increase in temperature, the insulation aging rate will double, meaning that for every 6°C increase, the insulation life is halved. Therefore, during transformer operation, good ventilation and cooling must be maintained, and forced ventilation may be implemented if necessary to reduce the temperature rise of the transformer.
Introduction to the six protection methods of power transformers:
Power transformer protection method one: For main transformers in 6-10kV workshop substations, overcurrent protection with a time limit is generally installed. If the overcurrent protection action time exceeds 0.5-0.7s, current instantaneous protection should also be installed.
Power transformer protection method two: Gas protection: Oil-immersed transformers with a capacity of 800kVA and above should be equipped with gas protection as the main protection against internal faults and oil level drop.
Power transformer protection method three: Current instantaneous protection: In coordination with gas protection, it can quickly eliminate various faults on the high voltage side of the transformer and inside it, serving as the main protection for the transformer.
Power transformer protection method four: Overcurrent protection: This is installed to prevent overcurrent caused by external short circuits and serves as backup protection for the main transformer protection.
Power transformer protection method five: Temperature protection: This serves as a protection device for the rising oil temperature of the transformer and poor operation of the cooling system.
Power transformer protection method six: Single-phase grounding protection.
This concludes the introduction to transformer operation protection. To expand on related knowledge, the smaller the loss of a transformer, the higher the efficiency. A well-designed and well-manufactured transformer can achieve an efficiency of 90% or more. Large transformers are often immersed in insulating oil with good insulation properties to reduce heating and lower temperatures, allowing the transformer oil to dissipate heat into the air through radiators, thereby reducing the temperature rise and maintaining high efficiency. During the use of power transformers, regular maintenance is required to ensure the normal operation of the equipment and extend its service life!