The abnormal operation of power transformer will lead to serious accident safety. If the daily maintenance work is done well, the safety and smooth operation of transformer will be ensured. Today we share tips on transformer maintenance.

I. Strengthen routine maintenance and regular testing

In accordance with the scope of division of labor of managers in Taiwan, in addition to carrying out transformer work regularly, I also require managers to strengthen their daily work and assign responsibilities. The key inspections include:

1. Observe the appearance. Mainly check whether there is oil seepage outside the transformer, whether there is smoke or discharge of parts. Due to improper welding or improper rubber pad, transformer oil leakage may occur. If the oil level is too low, insulation protection will be lost, resulting in discharges between conductive parts or between conductive parts and the outer shell, and transformer will be burnt down in serious cases. Therefore, it is necessary to eliminate faults and replenish oil in time to ensure that the oil level is maintained at 1/4-3/4 of the oil mark. For parts loosening, poor contact and even discharging, transformer fall insurance should be disconnected in time to eliminate hidden dangers.

2. Inspection of hygroscopics. When the volume of transformer oil expands and shrinks due to the change of load or ambient temperature, the gas in the oil storage tank is forced to breathe through the hygroscopicator to remove the impurities and moisture in the air and maintain the insulation strength of transformer oil in the transformer.

3. Regular inspection of casing. A bushing is a component insulator consisting of a conductive tube and a sleeve insulator. For a transformer, it is used to connect its internal winding lead wire with the power system or electrical equipment.

1) It is necessary to check whether the oil level of casing is normal.

2) Check whether the casing is clean, whether there are cracks, breakage and release point.

3) Check whether the connection between busbar and busbar is loose.

4) Check whether the oil level of oil-paper capacitive casing is normal.

5) Check whether the general cap of oil-paper capacitive sleeve is loose.

4. Listen to the voice. Normally Operating Transformers emit a uniform and subtle humming sound. When transformers fail of different properties, the sound will change. At this time, measures should be taken according to the site conditions to find out the causes of the failure.

5. Inspection of oil stain and dust on high and low pressure bushing of distribution transformer, timely cleaning and cleaning of oil stain and dust, in order to prevent pollution flashover and discharge in wet or rainy climate, resulting in short circuit between bushing, high voltage fuse fuse fuse, distribution transformer can not operate normally. I require people to clean it at least once every February.

6. Observing oil color and regularly detecting oil temperature, especially increasing times under the weather with large load variation, large temperature difference and bad weather, the top oil temperature of oil-immersed distribution transformer should not be higher than 95 C. In order to prevent winding and oil deterioration from speeding up, the temperature rise of top oil should not exceed 45 C frequently.

7. Shake the insulation resistance of the distribution transformer to check whether the leads are firm. Particular attention should be paid to whether the low-voltage outlet connection is in good contact and whether the temperature is abnormal.

8. Strengthen the measurement of electric load, strengthen the load measurement of each distribution transformer during peak period, increase the number of measurements when necessary, and timely adjust the distribution transformer with unbalanced three-phase current, so as to prevent excessive neutral line current from burning off the lead, causing damage to user equipment and distribution transformer. The three-phase load of the distribution transformer with Yyn0 connection group should be balanced as far as possible. It should not be supplied by only one or two phases. The current of the neutral line should not exceed 25% of the rated current of the low-voltage side, so as to make the distribution transformer run without overload and unbalanced load.

9. Regularly check and replace fuses once or twice. Aluminum fuses are strictly forbidden to replace fuses. It is well known that the primary fuse plays a protective role in the system, and the secondary fuse plays a protective role in the transformer. The selection of fuse must be compatible with the capacity of the transformer.

II. Preventing damage by external forces

1. Reasonable selection of installation location of distribution transformer, installation location as close as possible to the load center, and control the power supply radius within 0.5 km. At the same time, it should be avoided to install it in low-lying water areas which are easily struck by lightning. Because it is located in the county town, there are many transformers at the intersection. In order to reduce the accident of car crashing into the tower, all the anti-collision bar signs are pasted on the tower along the road.

2. Avoid installing low-voltage metering box on distribution transformer as far as possible. Due to long-term operation, glass damage of metering box or damage of low-voltage pile head of distribution transformer can not be replaced in time, resulting in damage of distribution transformer caused by burning down electric energy meter due to rainwater and other reasons. More than 95% of the public distribution transformers in our institute are equipped with JP cabinet, which plays a very good protective role for the safe operation of transformers.

3. It is not allowed to adjust tap-changer privately in order to prevent the tap-changer from burning out the distribution transformer due to the inter-phase short circuit when the tap-changer is not in place.

4. Insulation covers are installed at the high and low voltage ends of distribution transformers to prevent natural disasters and external damage, and high and low voltage insulation covers are installed in narrow roads and forest areas where animals frequently enter and exit, so as to prevent the distribution transformers from being short-circuited and burned by dropping things from the connection posts of distribution transformers.

5. Cut down the line passage regularly to prevent the low-voltage short-circuit from burning out the distribution transformer caused by the branches hitting the conductor.

III. Matters needing attention in use

1. Prevent transformer overload operation: If long-term overload operation, it will cause coil heating, aging insulation, inter-box short-circuit, inter-phase short-circuit or ground short-circuit and oil decomposition;

2. Prevent aging damage of transformer core insulation: aging of core insulation or damage of clamping bolt bushing will cause large eddy current of core, and aging of core insulation caused by long-term heating;

3. Prevent inadvertent damage to insulation during overhaul: When transformer overhauls suspension cores, attention should be paid to the protection coil or insulation bushing. If scratch damage is found, it should be handled in time.

4. The large unbalanced current of transformer low voltage Zui shall not exceed 25% of the rated value; the allowable range of transformer power supply voltage varies from positive to negative 5% of the rated voltage.

5. Guarantee good wire contact: poor contact between the internal joints of coils, poor contact between the joints of coils, bushings leading to the high and low voltage side, and the fulcrums on tap changers will cause local overheating, damage insulation, short circuit or circuit break. At this time, the high temperature arc will decompose the insulating oil, produce a large amount of gas, and increase the pressure in the transformer. When the pressure exceeds the set value of the gas breaker protection without tripping, explosion will occur.

6. Keep good grounding: For low voltage system with zero protection, (exam). The neutral point of the transformer's low voltage side should be grounded directly. When the three-phase load is unbalanced, current will appear on the zero line. When this current is too large and the contact resistance is too large, the ground point will be high temperature, igniting the surrounding flammable material.

7. Prevent over-temperature: When transformer is running, it should monitor the change of temperature. If the transformer coil conductor is class A insulation, its insulator is mainly paper and cotton yarn. The temperature has a great influence on insulation and service life. The insulation life will be reduced by about 50% when the temperature rises by 8 C. The transformer operates at normal temperature (90 C) and has a life of about 20 years. If the temperature rises to 105 C, the life of the transformer will be 7 years, 5 years and 120 C, with a life of only two years. Therefore, when transformer is running, it is necessary to maintain good ventilation and cooling. When necessary, forced ventilation can be adopted to reduce the temperature rise of transformer.