Degassing Oscillation Test for Transformer Insulating Oil

Overview

Transformer insulating oil is the core liquid medium inside oil-filled power transformers. Refined from petroleum fractions, it features excellent insulation and thermal conductivity, and undertakes three core functions during equipment operation: insulation protection, heat dissipation and cooling, and arc extinguishing and buffering. It is a critical material to ensure the stable operation of transformers.

During long-term operation of transformers, insulating oil will gradually age under the action of high temperature, electric field and oxidation. On the one hand, it will decompose and produce dissolved gases such as hydrocarbons, carbon monoxide and carbon dioxide, and abnormal components of these gases often indicate latent faults such as overheating and discharge inside the equipment. On the other hand, it will generate water-soluble acidic substances. Excessive acidic substances will corrode metal components and insulating materials, accelerate equipment aging, and even cause insulation breakdown accidents in severe cases. Therefore, dissolved gases and water-soluble acids are the core indicators of insulating oil testing, and constant-temperature oscillation degassing is an essential pretreatment step for both tests.

Experimental Purpose

The degassing of dissolved gases in insulating oil and the dissolution of water-soluble acids are completed through constant-temperature oscillation treatment, to provide qualified samples for subsequent testing, so as to determine the aging degree of insulating oil and the operation status of transformers. The experiment strictly complies with GB/T 17623-1998 Determination of Components of Dissolved Gases in Insulating Oil by Gas Chromatography and DL 429.4-91 Quantitative Determination of Water-Soluble Acids. The SH121 Degassing Oscillator used in this test is developed and manufactured in accordance with the method requirements of the two standards.

Experimental Samples and Instruments

• Experimental sample: In-service transformer insulating oil
• Experimental instruments and consumables:

1. SH121 Degassing Oscillator
2. 100mL glass syringes, sealing rubber caps
3. Calibration glass thermometer
4. Cleaning and wiping consumables

Operation Procedures

1. Chromatographic Degassing Oscillation (Corresponding to GB/T 17623-1998)

Slowly inject the insulating oil sample to be tested into a 100mL glass syringe, expel all air bubbles and seal it. Place the syringes steadily on the double-layer sample carrier inside the instrument in turn, and close the upper cover.

Turn on the power supply, and select the chromatographic degassing oscillation mode on the main interface of the 5-inch color touch screen. The instrument has pre-set parameters in accordance with the standard: constant temperature of 50℃, oscillation for 20 minutes, and constant-temperature standing for 10 minutes.

After clicking start, the instrument automatically completes the whole process of temperature rise, oscillation and standing without manual attendance throughout the process. The screen displays the current temperature and operation status in real time.

At the end of the experiment, the instrument gives a buzzer prompt. Take out the samples for subsequent gas chromatography component detection. The operation can be stopped or returned to the main interface at any time during the process.

2. Water-Soluble Acid Oscillation (Corresponding to DL 429.4-91)

Prepare the oil sample and extractant according to standard requirements, put them into the syringe and seal it, fix it on the sample carrier, and close the upper cover of the instrument.

Select the water-soluble acid oscillation mode on the main interface. The instrument pre-sets a constant temperature of 75℃ and oscillation for 5 minutes in accordance with the standard.

After clicking start, the instrument runs automatically and gives a buzzer reminder when finished. Take out the samples for quantitative titration of water-soluble acids.

3. Custom Oscillation Mode

For personalized oscillation pretreatment requirements of other oil products, the custom oscillation mode can be selected. The target temperature can be freely set within the range from room temperature to 100℃, and the oscillation duration and constant-temperature standing duration can be adjusted within 0-99 minutes, to adapt to different experimental requirements.

Data Analysis and Result Evaluation

Parallel test verification was carried out on multiple groups of standard insulating oil samples, and the test results of samples treated by the SH121 Degassing Oscillator are stable and reliable:

1. Temperature control accuracy meets standard requirements: the temperature control accuracy reaches ±0.2℃ in the range of room temperature to 50℃, and ±0.3℃ in the range of 50℃ to 100℃. The constant temperature state is stable without obvious temperature fluctuation, and the degassing and dissolution effects will not be affected by temperature deviation.
2. Excellent consistency of treatment effect: with 35mm oscillation amplitude and stable oscillation frequency of 275±3 times per minute, it can fully separate dissolved gases in oil, and also ensure the complete dissolution of water-soluble acidic substances. The detection deviation of parallel samples is within the allowable range of the standard, with good repeatability.
3. Adaptable to laboratory batch testing needs: it can hold 8 pieces of 100mL syringes at the same time in a single run, supporting synchronous pretreatment of batch samples, which greatly improves detection efficiency. The low-noise transmission design and compact body can also well adapt to the layout of conventional laboratory benches.