Transformer Knowledge Expansion

1. Role of oil pillow  

Oil pillow (oil reservoir) by storing and compensating for changes in the volume of transformer oil, reduce oil contact with air, delay the oxidation of oil, side oil level meter can be real-time monitoring of oil volume.

2. Iron core must be grounded

Iron core in the electric field will induce voltage, if not grounded may produce discharge. Grounding eliminates static buildup and avoids internal discharge accidents.

3. Comparison of cooling methods

Guided strong oil air-cooling device through the guided partition so that the oil flow directly flushing the winding and core, cooling efficiency is more than 30% higher than the unguided device.

4. Temperature monitoring three ways

Commonly used temperature measurement methods include: mercury thermometer (small), signal thermometer (with alarm function), resistance thermometer (remote monitoring) for monitoring the upper oil temperature.

5. Thermosiphon filter function  

By adsorbing the oxidation products and impurities in the oil, it prolongs the service life of the transformer oil, which can avoid frequent regeneration treatment, and the maintenance cycle can reach 5-8 years.

6. Unbalanced current limitation

Three-phase four-wire transformer requirements: phase-to-phase load imbalance ≤ 20%, neutral current ≤ 25% of the low-voltage rated current, exceeding the standard needs to be adjusted load distribution.

7. Installation slope standard

The gas relay side needs to ensure two slopes: 1%-1.5% slope of the big cover (to prevent gas accumulation), and 2%-4% slope of the oil pillow connecting pipe (to ensure that the gas enters the relay quickly).

8. Winding temperature distribution

Oil-immersed transformer hot spot is located in the winding height of 70% -75%, transverse inner diameter 1/3, the actual need to determine the specific location through the temperature rise test.

9. on-load voltage regulation failure reasons

Mainly includes power supply voltage loss, motor burnout (accounting for 60% of the failure), poor contact (caused by oxidation), mechanical parts off the buckle and other four types of problems.

10. respirator maintenance points  

Replacement of the moisture absorber needs to: ① heavy gas protection cut to the signal position ② blocking the connecting pipe to prevent the backflow of air ③ new moisture absorber needs to be submerged in the oil seal breathing port.