The protection and maintenance of oil-immersed power transformers have always been urgent concerns for many transformer users. Although dry-type transformers have their advantages, properly protected and maintained oil-immersed power transformers also possess unique strengths. So, what measures should be noted when protecting and maintaining oil-immersed power transformers? Tianhong Power Technology is here to offer professional advice!
Transformers are high-voltage equipment that requires excellent insulation performance. Oil-immersed transformers are prone to moisture absorption, so moisture prevention is one of the key measures for transformer protection and maintenance. To this end, users should pay attention to the following:
- After purchasing the transformer, promptly request the power supply bureau to conduct acceptance tests.
- Install a breather immediately. Transformers with a capacity of 100kVA and above must be equipped with a breather. Once the transformer arrives at the site, install the breather without delay to prevent internal moisture accumulation.
- Monitor the silica gel in the breather and replace it immediately if it becomes damp. Silica gel in the breather absorbs moisture to protect the transformer; its color changes when saturated with moisture, indicating the need for replacement with new dry silica gel.
The tank of an oil-immersed transformer is filled with transformer oil, and oil-resistant rubber components are sealed with fasteners during assembly. Poor sealing is the main cause of transformer oil leakage, which requires special attention during protection and maintenance:
- Check if small bolts are loose due to vibration; tighten them if necessary. The tightening torque should be appropriate and consistent across all bolts.
- Inspect rubber components for cracks or deformation. When replacing recycled rubber parts, ensure their model and specifications match the original, and keep the sealing surface clean.
During the operation of the oil-immersed power transformer, constantly monitor changes in oil level, oil temperature, voltage, and current. Analyze and handle any abnormalities in a timely manner.
During the installation of oil-immersed power transformers, it is strictly prohibited to connect aluminum stranded wires, aluminum bars, etc., to the transformer’s copper busbars to prevent corrosion of the busbars.
If the transformer is idle for too long, operated for an extended period, or affected by other natural and man-made factors, its insulation may degrade, internal water ingress may occur, or oil quality may deteriorate. In such cases, the transformer oil must be replaced and the transformer dried.
- First, hoist out the transformer core, drain all contaminated oil, and clean the tank. Rinse the core if it is contaminated with oil stains.
- After the tank is dried, inject new oil and replace all oil-resistant rubber seals.
- The transformer can be connected to the power grid for operation only after passing relevant tests.
There are various methods for drying the transformer core, such as the zero-sequence drying method, eddy current drying method, short-circuit drying method, and oven drying method. For transformers with large capacity (35kV and above), it is recommended to send them to local power equipment manufacturers for vacuum drying. This ensures the transformer insulation is dry and intact without causing insulation aging.
The above are the protection and maintenance methods for oil-immersed transformers. If you want to learn more about oil-immersed transformers, feel free to consult us at any time!
