The abnormal operation of the transformer will lead to serious safety accidents. If daily maintenance is done well, the safe and smooth operation of the transformer will be guaranteed. Then, the safe and smooth operation of the transformer mainly depends on regular and careful monitoring and maintenance. Today we will mainly share the tips on the daily maintenance of the transformer.

一、 Strengthen daily inspection, maintenance and regular testing
According to the division scope of work of the management personnel in the station area, in addition to regularly carrying out transformer inspection, we also require the management personnel to strengthen daily inspection and assign personnel and responsibilities. Key inspection contents include:
1. Observe the appearance. Mainly check whether there is oil leakage outside the transformer and whether there is smoke or discharge of parts. If the oil level is too low, the insulation protection will be lost, resulting in discharge between conductive parts or between conductive parts and shell, and the transformer will be burned in serious cases. Therefore, faults shall be eliminated and oil shall be supplemented in time to ensure that the oil level is maintained at 1 / 4-3 / 4 of the oil standard. For loose parts, poor contact and even discharge, the transformer drop fuse shall be disconnected in time to eliminate hidden dangers.
2. Inspection of moisture absorber. When the volume of transformer oil expands and contracts due to the change of load or ambient temperature, the gas in the oil conservator is forced to breathe through the moisture absorber to remove sundries and moisture in the air and maintain the insulation strength of transformer oil in the transformer.
3. Regular inspection of casing. A component insulator consisting of a conducting tube and a sleeve insulator. For the transformer, it is used to electrically connect its internal winding outgoing line with the power system or electrical equipment.
1) Check whether the oil level of the casing is normal
2) Check whether the casing surface is clean and whether there are cracks, damages and placing points.
3) Check whether the connection between bushing terminal and bus is loose.
4) Check whether the oil level of oil paper capacitive bushing is normal.
5) Check whether the cap of oil paper capacitive bushing is loose.
4. Listen to the sound. The transformer in normal operation will make a uniform and subtle buzzing sound. When the transformer has different faults, the sound will change. At this time, measures shall be taken according to the site conditions to find out the cause of the fault.
5. Check the oil stain on the distribution transformer and the dust on the high and low voltage bushing, and timely clean and erase the oil stain and dust, so as to prevent the pollution flashover and discharge in wet weather or rainy weather, resulting in the short circuit between bushings, the fusing of high-voltage fuse and the failure of normal operation of the distribution transformer. I require the inspectors to clean at least once every 2 months.
6. Observe the oil color and regularly detect the oil temperature, especially in the weather with large load change, large temperature difference and bad weather. The top oil temperature of oil immersed distribution transformer during operation shall not be higher than 95 ℃. In order to prevent excessive deterioration of winding and oil, the temperature rise of top oil shall not often exceed 45 ℃.
7. Shake the insulation resistance of the distribution transformer and check whether each lead is firm. Pay special attention to whether the connection of low-voltage outgoing line is in good contact and whether the temperature is abnormal.
8. Strengthen the measurement of power load. During the peak period of power consumption, strengthen the load measurement of each distribution transformer, increase the measurement times if necessary, and timely adjust the distribution transformer with unbalanced three-phase current to prevent excessive neutral line current from burning the lead, causing damage to user equipment and distribution transformer. For the distribution transformer with connection group Yyn0, the three-phase load shall be balanced as far as possible, and only one or two phases shall not be used for power supply. The neutral line current shall not exceed 25% of the rated current at the low-voltage side, so as to ensure that the distribution transformer does not operate under overload and unbalanced load.
9. Regularly check and replace the primary and secondary fuses. It is strictly prohibited to replace fuses with aluminum wires. As we all know, the primary fuse protects the system and the secondary fuse protects the transformer. The selection of fuse must adapt to the transformer capacity.
2、 Prevent external force damage
1. Reasonably select the installation location of distribution transformer, the installation location shall be close to the load center as far as possible, and the power supply radius shall be controlled within 0.5km. At the same time, try to avoid installing it in areas easy to be struck by lightning or low-lying ponding. As it is located in the county, there are many transformers at the intersection. In order to reduce the accident of car hitting the tower, all poles and towers along the road are pasted with anti-collision strip signs.
2. Try to avoid installing low-voltage metering box on the distribution transformer. Due to long-term operation, the glass of metering box is damaged or the low-voltage pile head of distribution transformer is damaged, which can not be replaced in time, resulting in the damage of distribution transformer caused by burning the electric energy meter due to rain and other reasons. More than 95% of the public distribution transformers in our institute are installed with JP cabinet, which plays a good role in protecting the safe operation of the transformer.
3. It is not allowed to adjust the tap changer without permission, so as to prevent phase to phase short circuit due to improper adjustment of the tap changer, resulting in burning out of the distribution transformer.
4. Install insulating covers at the high and low voltage ends of the distribution transformer to prevent natural disasters and damage by foreign objects. Install high and low voltage insulating covers in communities with narrow roads and forest areas with frequent animal access to prevent things from falling off the wiring pile of the distribution transformer, causing low-voltage short circuit and burning the distribution transformer.
5. Regularly inspect the line and cut down the line channel to prevent the accident of low-voltage short circuit burning out the distribution transformer caused by the branch touching the conductor.
3、 Precautions during use
1. Prevent overload operation of transformer: if overload operation for a long time, it will cause coil heating, gradual aging of insulation, short circuit between boxes, phase to phase short circuit or short circuit to ground and decomposition of oil;
2. Prevent aging and damage of transformer iron core insulation: aging of iron core insulation or damage of clamping bolt bushing will cause great eddy current in iron core, and long-term heating of iron core will cause insulation aging;
3. Prevent inadvertent damage to insulation during maintenance: when repairing the hanging core of transformer, pay attention to protecting the coil or insulating sleeve. If there is any scratch damage, deal with it in time.
4. The maximum unbalanced current of transformer low voltage shall not exceed 25% of the rated value; The allowable variation range of transformer power supply voltage is plus or minus 5% of rated voltage
5. Ensure good contact of wires: poor contact of internal connectors of coils, poor contact of connecting points between coils, contacts leading to bushings at high and low voltage sides, and poor contact of each fulcrum on tap changer will cause local overheating, damage insulation, short circuit or open circuit. At this time, the generated high-temperature arc will decompose the insulating oil and produce a large amount of gas, which will increase the pressure in the transformer. When the pressure exceeds the set value of gas breaker protection without tripping, explosion will occur.
6. Maintain good grounding: for the low-voltage system with protective zero connection, the neutral point at the low-voltage side of the (large) transformer shall be directly grounded. When the three-phase load is unbalanced, there will be current on the zero line. When the current is too large and the contact resistance is large, high temperature will appear at the grounding point and ignite the surrounding combustible materials.
7. Prevent overtemperature: monitor the temperature change during transformer operation. If the transformer coil conductor is class a insulation, its insulator is mainly paper and cotton yarn. The temperature has a great impact on the insulation and service life. For every 8 ℃ increase in temperature, the insulation life should be reduced by about 50%. The transformer operates at normal temperature (90 ℃), with a service life of about 20 years; If the temperature rises to 105 ℃, the service life is 7 years. 5. If the temperature rises to 120 ℃, the service life is only two years. Therefore, during the operation of the transformer, good ventilation and cooling must be maintained, and forced ventilation can be adopted when necessary, so as to reduce the temperature rise of the transformer.