Why does transformer oil need a dedicated oil purifier?

It is crucial to use a dedicated oil purifier for transformer oil. This is crucial because it directly impacts the safe and stable operation of the power grid and can even prevent significant economic losses and power outages.

Transformer oil is not just any ordinary lubricant; it's the "blood" of the transformer. Its core function isn't lubrication, but insulation and cooling. If this "blood" fails, the transformer's "heart" is at risk.

Why does a dedicated oil purifier need to be used for transformer oil?

Transformer Oil's "Natural Enemies" and Their Dangers

While ordinary lubricants are most vulnerable to wear caused by particulate matter, transformer oil has three major "natural enemies" that require special measures to combat:

1. Moisture (especially dissolved water)

Existence: Not only is "free water" visible to the naked eye, but even more dangerous is "dissolved water" that is completely dissolved in the oil.

Danger: Water is a conductor (albeit a weak one). Even trace amounts of water can dramatically reduce the dielectric strength (breakdown voltage) of transformer oil. In high-voltage environments, this can easily lead to partial discharge or even insulation breakdown, resulting in serious accidents such as transformer explosion and burnout.

2. Gases (Dissolved Gases)

Forms: Primarily oxygen and nitrogen, dissolved in the oil.

Hazards:

Oxygen: Accelerates oil aging (oxidation), produces acids and sludge, corrodes equipment, and impairs heat dissipation and insulation.

Any gas: Reduces the dielectric strength of the oil, forms bubbles, and causes partial discharge under high electric fields.

3. Solid Particles

Forms: Metal shavings, fibers, carbides, etc.

Hazards: While not as direct a threat to insulation as the previous two, they can wear components and bridge the electric field, forming conductive pathways and reducing insulation performance.

Why Can't a Conventional Oil Purifier Be Used?

This is the core of the problem. Conventional pressure or centrifugal oil purifiers are incapable of dealing with transformer oil's natural enemies:

Conventional oil filter trucks/centrifuges: Can only remove free water and larger solid particles. They are virtually incapable of removing dissolved water and dissolved gases that are completely dissolved in the water. Using a conventional oil purifier to treat transformer oil is merely a temporary solution, not a permanent one, and the most dangerous hidden dangers remain.

The Secrets of a Specialized Oil Purifier (High Vacuum Oil Purifier)

A dedicated transformer oil purifier (high vacuum oil purifier) was designed to address the aforementioned issues. Its operating principle is a clever application of physics:

1. Heating: The oil is heated appropriately (usually between 50-65°C to prevent oil degradation) to reduce its viscosity and provide energy for the release of water and gas.

2. High Vacuum: 

This is the core technology. The oil is placed in a highly vacuumed container (a vacuum degassing tank) where the pressure inside is extremely low.

According to Dalton's law of partial pressures and Henry's law, under low pressure, the solubility of water and gas dissolved in oil decreases dramatically.

It's like shaking a bottle of Coke vigorously and then suddenly opening the cap: the dissolved CO₂ will burst out rapidly.

3. Large-area film spreading/atomization: 

Within a vacuum container, specialized devices (such as atomizers, packing layers, and thin-film evaporators) break the oil into extremely small droplets or spread it into a thin film. This significantly increases the surface area for evaporation, allowing dissolved water and gases ample space for instantaneous precipitation.

4. Extraction and filtration: 

The precipitated water vapor and gases are rapidly extracted by a vacuum pump. The deeply dehydrated and degassed oil then passes through a high-precision filter element (typically 1-3μm) to remove solid particles, ultimately yielding pure new oil.

Thus, using a dedicated oil purifier to treat transformer oil is not an option but a mandatory, standardized safety procedure. It is a critical component of preventive testing, inspection, and maintenance in the power industry, and is irreplaceable for extending transformer life and ensuring safe and reliable grid operation. Investing in a suitable dedicated oil purifier is far more valuable than the cost of a single transformer failure caused by insulating oil deterioration.