Prevent the transformer from overloading:If the transformer is overloaded for a long time, the coil will heat up, the insulation will gradually age, and short circuits between boxes, phases or ground will occur, and the oil will decompose.
Ensure the quality of insulating oil:During the storage, transportation or operation and maintenance of the transformer insulating oil, if the oil quality is poor or there are too many impurities and water, the insulation strength will be reduced. When the insulation strength is reduced to a certain value, the transformer will short-circuit and cause electric sparks, arcs or dangerous temperatures. Therefore, the oil quality of the transformer should be tested regularly during operation, and unqualified oil should be replaced in time.
Prevent the transformer core insulation from aging and damage:Aging of the core insulation or damage to the clamping bolt sleeve will cause a large eddy current to the core, causing long-term heating of the core and aging of the insulation.
Prevent inadvertent damage to insulation during maintenance:When the transformer is repaired and the core is suspended, attention should be paid to protecting the coil or insulating sleeve. If scratches or damage are found, they should be handled in time.
Ensure good contact of the wires：Poor contact of the internal joints of the coils, poor contact of the connection points between the coils, the connection points leading to the high and low voltage side bushings, and the various supporting points on the tap changer will cause local overheating, damage insulation, and cause short circuits or open circuits. The high-temperature arc generated at this time will decompose the insulating oil, produce a large amount of gas, and increase the pressure inside the transformer. When the pressure exceeds the protection setting of the gas breaker without tripping, an explosion will occur.
Prevent electric shock：The power supply of the power transformer generally comes from the overhead line, which is easily struck by lightning, and the transformer will burn due to insulation breakdown.
Short-circuit protection must be reliable：If the transformer coil or load is short-circuited, the transformer will bear a considerable short-circuit current. If the protection system fails or the protection setting is too large, the transformer may burn. For this reason, a reliable short-circuit protection device must be installed.
Maintain good grounding：For low-voltage systems using protective grounding, 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. When this current is too large and the contact resistance is large, the grounding point will have a high temperature, igniting the surrounding combustible materials.
Prevent overheating：The temperature change should be monitored when the transformer is running. If the transformer coil wire is Class A insulation, its insulation is mainly paper and cotton yarn. The temperature has a great impact on the insulation and service life. For every 8°C increase in temperature, the insulation life will be reduced by about 50%.
Therefore, when the transformer is running, it must maintain good ventilation and cooling. If necessary, forced ventilation can be adopted to achieve the purpose of reducing the temperature rise of the transformer.
