110 kV transformer insulating oil filtration

Technical specifications and operation points for 110kV transformer insulating oil filtration

Preparation before filtration

1. Oil quality testing:

- Test items: moisture content (≤15ppm), breakdown voltage (≥50kV), dielectric loss factor (90℃≤0.02)

- Sampling specifications: According to the requirements of GB/T 7597, take a 500mL of oil sample for full analysis

2. Equipment selection:

- It is recommended to use a two-stage vacuum oil filter

- Technical parameter requirements:

Vacuum degree ≤5Pa (first-level vacuum chamber)

Heating temperature 60±5℃

Filtration accuracy ≤3μm

3. On-site preparation:

- Build a dustproof shed (humidity ≤60%)

- Prepare enough spare oil (20% of the processing volume)

Filtration process

1. Pretreatment stage:

- Coarse filtration: first remove large particles through a 20μm filter element

- Sedimentation separation: let it stand for 48 hours to discharge free water

2. Main treatment stage:

- Vacuum dehydration:

Temperature of first-level vacuum chamber 50-55℃

Temperature of second-level vacuum chamber 60-65℃

Cycle period ≥5 times

- Precision filtration:

Use a 3μm filter element with β≥200

Pressure difference controlled at 0.15-0.25MPa

3. Post-treatment stage:

- Vacuum oil injection: Keep vacuum degree ≤13Pa

- Standing time: ≥72 hours

Key control parameters

| Project | Control standard | Detection frequency |

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

| Vacuum degree | ≤5Pa (first level) | Real-time monitoring |

| Oil temperature | 60±5℃ | Every hour |

| Water content | ≤10ppm | Every 2 hours |

| Breakdown voltage | ≥60kV | Every 4 hours |

| Gas content | ≤0.5% | Every 8 hours |

Precautions

1. Safety control:

- Electrostatic grounding resistance of oil pipeline ≤4Ω

- Set combustible gas alarm (alarm value ≤ 10% LEL)

2. Quality assurance measures:

- The amount of oil processed in each batch does not exceed 10 tons

- Establish oil processing curve (water content-time curve)

- The final oil sample is sent to a third party for testing

3. Special treatment:

- For oil products with acid value > 0.05mgKOH/g:

Add white clay adsorption treatment

Extend the cycle time to 8-10 times

Acceptance criteria

1. Electrical performance:

- Breakdown voltage ≥60kV (DL/T 429.9)

- Dielectric loss factor ≤0.005 (90℃)

2. Physical and chemical indicators:

- Water content ≤8ppm

- Gas content ≤0.3%

- Particle size ≤NAS level 8

3. Compatibility test:

- Contact with solid insulating material for 72 hours without abnormality

Common Problems

1. The vacuum degree does not meet the standard:

- Check the oil level of the mechanical pump

- Check the sealing of the vacuum valve

- Check the connection of the bellows

2. Abnormal oil temperature:

- Clean the carbide on the surface of the heater

- Calibrate the PT100 temperature sensor

3. Low filtration efficiency:

- Check the saturation of the filter element

- Adjust the oil pump speed to the rated value

Note: The operation process must strictly follow the requirements of the "Preventive Test Procedures for Power Equipment" (DL/T 596), record key parameters throughout the process, and keep the treated oil sample for reference for 3 months. It is recommended to operate under the guidance of professional technicians, and contact the equipment manufacturer for technical support in complex situations.