What is transformer oil dielectric loss filter?

Transformer Oil Dielectric Loss Filter Introduction

Transformer oil dielectric loss (abbreviated as dielectric loss, tanδ or DDF) is a key indicator to measure the electrical performance of insulating oil, reflecting the impact of polar impurities, moisture, oxidation products, etc., in the oil on the insulation efficiency. A dielectric loss filter is a purification device specially used to reduce the dielectric loss value of transformer oil. It removes pollutants that cause increased dielectric loss through multi-stage treatment and restores the insulation performance of the oil.

1. Working principle of dielectric loss filter

- Core goal: reduce the dielectric loss factor (tanδ) of oil and improve insulation strength.

- Key technologies:

- Vacuum dehydration and degassing: remove moisture and dissolved gas (moisture is the main cause of increased dielectric loss).

- Precision filtration: multi-layer filter element (1-5μm) removes particulate matter, colloids, and carbides.

- Adsorption regeneration: use silica gel, activated alumina or ion exchange resin to adsorb polar substances (such as organic acids and oxides).

- Electrostatic purification (optional): Separate colloidal impurities through an electrostatic field.

2. Main components of the equipment

| Module | Function |

|--------------------|-------------------------------------------------------------------------|

| Vacuum pump system | Create a negative pressure environment to evaporate water and light hydrocarbons. |

| Heating system | Control oil temperature (usually 60-70℃) to improve dehydration efficiency. |

| Filtration system | Multi-stage filter element (mechanical + adsorption) removes particles and chemical pollutants. |

| Adsorption tower | Filled with silica gel or activated alumina, adsorbs acids and polar compounds. |

| Control system | PLC automatically adjusts temperature, vacuum degree, flow rate, and some equipment has online dielectric loss monitoring. |

3. Applicable scenarios

- Dielectric loss value exceeds the standard: When the transformer oil tanδ > 0.5% (20℃), it needs to be processed.

- Oil aging: The insulation performance is reduced due to oxidation to generates organic acids and sludge.

- Wet oil: Water content exceeds 50 ppm, affecting dielectric strength.

- Preventive maintenance: Regular purification delays oil aging.

Well-known brands:

- GlobeCore (Germany/Ukraine): Expertise in oil regeneration, precise dielectric loss control.

- Pall Corporation (USA): High-precision filtration, military-grade reliability.

- YUNENG (China): High cost-effectiveness, suitable for emerging markets.

5. Dielectric loss filtration vs. ordinary oil filter

| Comparison items | Dielectric loss filter | Ordinary oil filter |

|------------------|--------------------------------|------------------------------|

| Core functions | Reduce tanδ and repair insulation performance | Remove only moisture and particulate matter |

| Technical complexity | Multi-stage adsorption + vacuum dehydration | Mechanical filtration or simple vacuum dehydration |

| Cost | High (adsorption material required) | Low |

| Applicable oils | Oils with severe aging and excessive dielectric loss | Oils with slight contamination |

6. Precautions for use

1. Adsorbent replacement: Silica gel/alumina needs to be regenerated or replaced after saturation (otherwise it will reverse contaminate the oil).

2. Temperature control: Avoid overheating (>80℃) to aggravate oil oxidation.

3. Dielectric loss test: A Dielectric loss tester (such as OMICRON Dirana) needs to be used to verify the effect before and after treatment.

4. Environmental requirements: Waste adsorbents may be hazardous waste and must be disposed of in compliance with regulations.

The transformer oil dielectric loss filter is a high-end oil regeneration equipment that solves the problem of excessive dielectric loss through deep purification. It is suitable for power systems, large substations and other scenarios with strict requirements on insulation performance. When choosing, it is necessary to weigh the degree of automation and adsorption technology based on the degree of oil pollution, processing volume and budget.