1. Ensure regular and precise calibration of instruments

Instrument calibration is the foundation for avoiding false alarms and must be strictly executed according to cycles and standards.

Regular zero calibration: After each startup or continuous use for a period of time, use high-purity nitrogen gas (purity ≥ 99.999%) to perform zero calibration on the instrument, eliminating errors caused by baseline drift.

Carry out span calibration and single point calibration: at least use standard gases (such as mixed standard gases containing H ₂, CH ₄, C ₂ H ₂ and other components) for span calibration every month to ensure accurate detection range of each gas component; Single point calibration frequency can be increased for key components such as fault characteristic gas C ₂ H ₂.

Verification after calibration: After calibration is completed, another standard gas with a concentration close to the actual sample is used for verification to confirm that the detection result error is within the allowable range (usually requiring ≤± 5%).

2. Optimize the sample collection and preprocessing process

Oil sample contamination or improper handling is the main cause of false alarms, and operational details need to be standardized.

Strict sample collection: Use specialized sealed oil sample bottles (such as brown glass bottles with PTFE gaskets), and rinse the oil sample bottles at least 3 times before collection to avoid residual air or impurities inside the bottles; During the collection process, prevent prolonged contact between the oil sample and air to reduce the volatilization or dissolution of gas components.

Proper sample preparation: Before testing, the oil sample needs to be subjected to degassing treatment (such as vacuum degassing, oscillation degassing) to ensure that the dissolved gases in the oil are fully released; If the oil sample contains moisture or impurities, it needs to be removed through a filtering device (such as a 0.45 μ m organic phase filter membrane) to avoid blocking the instrument gas path or interfering with the detection sensor.

Control the timeliness of sample testing: The oil sample should be tested within 4 hours after collection. If timely testing is not possible, the oil sample should be sealed and stored in a dark environment at 0-4 ℃ for no more than 24 hours to prevent changes in gas composition.

3. Strengthen daily maintenance and status checks of instruments

Aging or contamination of instrument components can directly lead to detection deviations and require regular maintenance.

Clean key components: Clean the instrument's injection port, filter, and gas pipeline weekly, wipe off residual oil stains on the injection port with anhydrous ethanol, replace clogged filter cartridges (such as activated carbon cartridges), and avoid gas path blockage or cross contamination.

Check sensor performance: Check the response value and stability of the gas sensor every quarter. If the sensor shows slow response or excessive drift, it needs to be replaced in a timely manner (usually the sensor has a service life of 1-2 years, depending on the frequency of use).

Maintenance auxiliary system: Regularly check the purity and pressure of the instrument's carrier gas (such as nitrogen) to ensure compliance with requirements (carrier gas purity must be ≥ 99.999%, pressure stable at 0.4-0.6MPa); Ensure that the instrument cooling fan and temperature control module are working properly to avoid temperature fluctuations affecting detection accuracy.

4. Standardize operating procedures and data interpretation

Human error or misjudgment of data can also lead to false positives, and a standardized process needs to be established.

Unified operating standards: Develop a detailed operating manual, specifying the steps of preheating (usually 30-60 minutes, wait for the instrument temperature and pressure to stabilize before testing), sample injection volume (controlled according to the instrument manual, generally 5-10mL), cleaning after testing, etc., to avoid operational differences.

Combined with background data interpretation: The test results need to be comprehensively judged based on historical data (such as the trend of gas content in the previous oil of the transformer) and industry standards (such as GB/T7252 "Guidelines for Analysis and Determination of Dissolved Gases in Transformer Oil"). If a single data is abnormal but there is no obvious fault trend, resampling and testing can be carried out to avoid false alarms based solely on single data.

Recording and tracing: Detailed records of the instrument status, calibration status, sample information, and test results for each test. In case of false alarms, the cause of the problem can be identified through tracing records (such as calibration failure, sample contamination).