orange flexible conduit,black corrugated conduit,polyethylene flexible conduits,PA Corrugated tube,TPEE Corrugated tube,corrugated plastic tubing automotive,FEP Corrugated tube,corrugated electrical conduit Dongguan Zhonghe Electronics Co., Ltd. , https://www.zhonghesleeving.com
In the maintenance and installation of electrical equipment, it is essential to take insulating oil samples from transformers and reactors for testing. Once the test results are satisfactory, the equipment can be put into operation. However, improper sampling techniques, storage, transportation, or prolonged exposure can lead to failed test results, requiring repeated sampling and increasing operational costs.
To address this issue, a specialized negative pressure oil extraction device has been developed for transformers. This device ensures that the internal environment of the oil pipe and sampling bottle remains sealed, preventing exposure to atmospheric contaminants. This reduces the risk of secondary pollution, ensuring more accurate and reliable test results. The process is not only efficient but also safe and easy to operate, making it ideal for field use.
Currently, China's GB/T 7595-2008 "Standard for Operating Transformer Oil Quality" includes particle size increase as an inspection item for 500kV voltage grade oils. DL/T 1096-2008 "Particle Size Limits in Transformer Oil" specifies quality control standards for transformer and reactor oils at 500kV and above. For AC transformers of 500kV and above, the number of particles larger than 5μm in 100ml of oil should not exceed 2000 before operation (after hot oil circulation), and 3000 during operation. For DC commutation transformers, the limit is set at 1000 particles per 100ml before hot oil circulation. The PLD0201 oil particle size analyzer by Proudit is commonly used for such measurements.
Next, we introduce Proud’s method for measuring and controlling transformer oil. The following details the correct sampling method and device:
**Oil Sampling Requirements:**
1. **Sampling Container:** The container must be cleaned with distilled or deionized water, followed by isopropanol or high-purity ethanol. It should then be dried for future use. If rinsed with the sample itself, it should be used immediately, or a 250ml NAS16380 cleaning bottle can be purchased.
2. **Sampling Tube:** Use high-quality tubes resistant to insulating oil corrosion and non-reactive to it. Before use, they should be cleaned with distilled or deionized water, then isopropanol or high-purity ethanol, and dried thoroughly.
3. **New Oil Sampling:** Sample from the middle to the bottom of the oil drum using a clean tube. If free water is present, sample from the bottom. The tool must be cleaned with isopropanol or high-purity ethanol before use. Ensure the oil is well-mixed before sampling to avoid sedimentation.
4. **Running Oil Sampling:** Clean the sampling valve with isopropanol or high-purity ethanol before sampling. At least 1–2 liters of oil should be flushed out from the valve before taking the sample, and the valve should not be adjusted during flushing or sampling.
**Sampling Device:**
The oil sampling tool includes a negative pressure puller, NAS16380-grade hose, and a 250ml NAS16380 cleaning bottle. These components are pre-cleaned to NAS16380 standards, minimizing contamination risks. During sampling, the system operates under negative pressure, reducing exposure to airborne dust and improving measurement accuracy.
**Important Notes:**
Always take samples from the lower valve of the transformer, including sealed valves. Clean the valve with clean grade A cotton or gauze before sampling. Remove the nut, connect the oil-resistant tube, flush the pipeline, and collect the flushed oil instead of discharging it on-site. After flushing, take the sample and seal the bottle properly.
Avoid sampling when the oil temperature is below ambient temperature, or when humidity exceeds 75%. Do not sample in windy or rainy weather unless special precautions are taken.
Before measurement, check the oil for visible impurities, bubbles, or water droplets. Large particles (>500μm) may clog the sensor, while excessive moisture can cause inaccurate readings. In such cases, dehydration or oil replacement may be necessary.
Viscosity is another critical factor. The measured oil should generally not exceed 100 mm²/s for normal sampling and 500 mm²/s for high-pressure online measurements. If the oil is too viscous, dilution may be required before testing.