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1. The operation of power transformers must comply with all the technical requirements specified in the \"Transformer Operation Regulations\". II. Before putting a newly installed or repaired transformer into operation, the following checks should be carried out: 1. Verify the nameplate to ensure that the voltage rating indicated on it matches the voltage level of the circuit. 2. Check whether the transformer insulation is satisfactory by using a 1000 or 2500-volt megohmmeter; the testing time should be no less than 1 minute until the pointer stabilizes. The insulation resistance should be no less than 1 megohm per kilovolt. The order of measurement is high voltage to ground, low voltage to ground, and high and low voltages together. 3. Check for any oil leaks or seepages in the fuel tank, ensure that the oil level is within the range indicated by the gauge, verify that the fuel gauge is functioning properly, confirm that the breather hole is unobstructed, and that the silica gel inside the breather is blue in color. 4. Is the tap switch in the correct position and is the contact good? 5. The porcelain bushing should be clean and free from looseness. III. Power transformers should be regularly inspected externally. The transformers in substations where there is regular personnel on duty should be inspected at least once a day, with a night inspection required once a week. IV. For unattended transformers with a capacity of 3200 kVA or more, inspections must be carried out at least once every 10 days, as well as before and after each time they are put into use. For capacities greater than 320 kVA but less than 3200 kVA, inspections shall be carried out at least once a month, as well as before each time it is put into use and after it is taken out of use. V. Within 48 hours after the major repair or once the installed transformer starts operating, inspections shall be conducted twice per shift. VI. When the transformer is operating under abnormal conditions (such as high oil temperature, abnormal noises, oil leakage, etc.), monitoring should be intensified and the frequency of inspections increased. VII. When operating a transformer, the following items should be inspected and monitored: 1. Check whether the sound is normal; during normal operation, there should be a uniform \"humming\" sound. 2. The temperature of the oil in the upper layer should not exceed 85°C. 3. Check for any oil seepage or leakage, and ensure that the oil color and level indicators are normal. 4. Whether the bushing is clean, and whether there are any damages, cracks, discharge marks, or other abnormalities. 5. The explosion-proof tube membrane is free of cracks and oil leakage. 6. Check whether the oil level inside the gas relay window is normal and whether there is any gas present. VIII. Permissible operating modes of the transformer 1. The upper oil temperature during operation should not frequently exceed 85°C, and the maximum allowable value is 95°C. 2. The voltage applied to the voltage tap shall not exceed 5% of the rated value. 3. The transformer can operate under normal overload and fault overload conditions. Normal overload can be used frequently, and its allowable value is determined by the unit’s technical supervisors based on the transformer’s load curve, the temperature of the cooling medium, and the load carried by the transformer before the overload occurs. In the event of an accident, operation at 30% overload is permitted for two hours, but the upper oil temperature must not exceed 85°C. IX. Transformers can be operated in parallel, but the following conditions must be met: 1. The coil connection groups must be the same. 2. The voltage ratios are equal, with an error not exceeding 0.5%. 3. The short-circuit voltages are equal, with an error not exceeding 10%. 4. The transformer capacity ratio shall not be greater than 3:1. 5. The phase sequence is the same. 10. Phase sequence verification must be carried out before the transformer is connected in parallel for the first time. 11. Transformers without on-load tap-changer devices shall not have their taps changed while under voltage. For transformers of 320 kVA and above, the DC resistance should be measured before and after tap changing, in order to check the integrity of the circuit and the uniformity of the three-phase resistances. XII. The following procedures must be followed when bringing a transformer online or taking it offline: 1. For transformers equipped with oil switches and isolating switches on both the high-voltage and low-voltage sides, all isolating switches on both sides of the transformer should be closed first; thereafter, the oil switch on the high-voltage side should be turned on to charge the transformer, followed by turning on the oil switch on the low-voltage side to charge the low-voltage busbar. The reverse order is applied when shutting down the transformer. 2. When a transformer with an oil-free switch on the low-voltage side is put into operation, first engage the isolator on the high-voltage oil switch side, then turn on the oil switch on the high-voltage side to charge the transformer; after that, engage the disconnectors and circuit breakers on the low-voltage side to supply power to the low-voltage busbar. The order is reversed during a power outage. 13. In the event of any of the following abnormal conditions during transformer operation, report to the management immediately and prepare to switch to the backup transformer. 1. The temperature of the oil in the upper layer exceeds 85°C. 2. Oil leakage from the housing, changes in oil level, and drop in oil level. 3. Cracks have appeared in the sleeve, with discharge phenomena occurring. 14. In the following situations involving the transformer, it is necessary to contact the power supply provider immediately to cut off the power: 1. There is a loud noise inside the transformer, along with discharge sounds. 2. The temperature of the transformer rises sharply. 3. Severe oil leakage, with the oil level dropping rapidly. 15. In the event of the following serious accidents involving the transformer, power supply should be cut off immediately. 1. The explosion-proof valve of the transformer sprays oil and fire, and the transformer itself catches fire. 2. Explosion of the transformer bushing. 3. The iron casing of the transformer itself cracked, causing oil to spill out in large quantities. 16. When a transformer catches fire, the oil valve should be opened first to allow the oil to flow into the oil tank, while simultaneously using carbon dioxide or carbon tetrachloride fire extinguishers to put out the fire. After cutting off the transformer and all surrounding power supplies, use a foam fire extinguisher to put out the fire; water must not be used for extinguishing the fire. 17. When a mild gas signal is detected, the transformer should be inspected. If the oil level drops and the oil reservoir is empty, oil should be added. If there is gas inside the gas relay, its color should be observed and reported promptly, along with taking appropriate action. 18. The oil in operating transformers and standby transformers shall undergo dielectric strength tests and simplified tests as specified. 19. The standby transformer must be in good condition and ready to be put into operation at any time