Excessive Top Oil Temperature
-The oil temperature is more than 10°C higher than usual under normal load and cooling conditions;
-The oil temperature continues to rise under constant load.
*The transformer should be shut down immediately to prevent more serious failures.
Abnormal Oil Color
Under normal circumstances, the transformer oil should be transparent and light yellow.
-The oil suddenly becomes very dark;
-Abnormal phenomena such as carbon particles are found in the oil.
*The power supply should be cut off for inspection to prevent further damage to the transformer.
Abnormal Oil Level
-When the oil level is too high or overflows, first check if the load and temperature are normal. If they are normal, it may be that the breathing device or oil level indicator tube is blocked, causing a false oil level.
-Low oil level may trigger a light gas alarm. It is necessary to promptly perform vacuum oil filling. If there is a significant oil leakage, the transformer should be immediately shut down.
Overload Operation
-Check whether the current exceeds the standard limit and report the situation;
-Verify if the oil level and oil temperature are normal, and activate the cooling system;
-Adjust the operation mode and put the backup transformer into service;
-Coordinate with the dispatcher to optimize load distribution;
-During normal overload, determine the operating time based on the overload multiple, and closely monitor the oil temperature and oil level;
-During accidental overload, reduce the load according to the manufacturer's specifications.
Cooling System Failure
-Immediately confirm whether the backup cooling device has been properly activated;
-Investigate the cause of the power interruption and restore the cooling system to normal operation as soon as possible;
-Strengthen the monitoring of the top oil temperature and oil level to ensure that the transformer is not damaged by overheating;
-If the cooling system cannot be restored within a short period, request to reduce the transformer's load or or shut it down.
Gas Protection
-Minor faults occur inside the transformer, causing slow gas generation;
-Air enters the interior of the transformer;
-The oil level drops too low;
-Secondary circuit issues such as DC system grounding lead to maloperation.
*After the gas protection signal appears, operators should check the oil level and oil color in the oil conservator, as well as the gas volume and color in the gas relay. Then, inspect the transformer body and oil circulation system for any signs of oil leakage.
Common Heating Issues During Operation and Their Causes
-Poor contact in the tap changer;
-Inter-turn short circuit between windings;
-Short-circuit loop of the iron core;
-Poor contact in other components;
*Closely monitor the temperature changes in the overheated parts, analyze the cause of overheating, coordinate with dispatchers, and conduct power-off inspection when necessary.
