Oil filtration is an essential maintenance practice for transformers with oil-filled insulation systems. The primary purpose of oil filtration is to purify and rejuvenate the insulating oil, ensuring the transformer's continued reliable operation. Over time, oil can become contaminated with impurities, moisture, and by-products of the transformer's normal operation. Filtration helps remove these contaminants and enhances the dielectric strength and overall performance of the insulating oil. Here's a general guide on the oil filtration process for transformers:

1. Preparation:

• Ensure the transformer is de-energized and safely isolated.
• Set up a safe work area with proper ventilation.
• Have necessary personal protective equipment (PPE) for the operators.

2. Oil Sampling:

• Collect a representative oil sample for analysis before filtration.
• Perform tests such as dissolved gas analysis (DGA) to assess the condition of the oil.

3. Isolation and Drainage:

• Disconnect the transformer from the power source and allow it to cool if it has been recently in operation.
• Drain the oil from the transformer into a holding tank.

4. Filtration Equipment Setup:

• Set up the oil filtration equipment, which typically includes a filtration unit, pumps, hoses, and filters.
• Ensure that the filtration unit is clean and in good working condition.

5. Filtration Process:

• Pass the transformer oil through the filtration system, which usually includes one or more stages of filtration.
• Filtration techniques may include mechanical filtration, absorption, and vacuum dehydration.
• Filters with various levels of fineness are used to capture particles and contaminants.

6. Vacuum Dehydration:

• Apply vacuum dehydration to remove dissolved moisture from the oil.
• Moisture can significantly reduce the dielectric strength of the oil, leading to decreased transformer performance.