The selection of an insulating oil chromatography analyzer is not merely a matter of purchasing an instrument; the core lies in establishing a reliable and sustainable system for analyzing dissolved gases in oil. The selection process should follow scientific steps and principles, as detailed below:
I. Clarifying Core Requirements and Objectives
The primary prerequisite for selection is to clearly define the core requirements and usage objectives based on the actual application scenarios. The key considerations include:
Detection purpose: It is necessary to clarify whether the instrument is used for preliminary fault screening or high-precision fault diagnosis and scientific research analysis. This positioning directly determines the accuracy level and configuration standards of the instrument.
Sample quantity: Statistics on the daily, weekly, or monthly analysis requirements of samples should be made. High sample volume detection scenarios require instruments with a higher degree of automation.
Detected gas components: The instrument must meet the national standard requirements and be capable of accurately detecting nine characteristic gases dissolved in oil, namely hydrogen (H₂), methane (CH₄), ethane (C₂H₆), ethylene (C₂H₄), acetylene (C₂H₂), carbon monoxide (CO), carbon dioxide (CO₂), oxygen (O₂), and nitrogen (N₂). Among them, acetylene (C₂H₂) is a key gas for judging discharge faults, and its detection sensitivity is a core consideration.
Budget range: The budget level directly determines the configuration specifications and automation level of the instrument. The selection range should be defined based on the actual financial planning.
II. Examination of Core Performance Indicators
Performance indicators are the technical core of the selection process. A comprehensive and detailed examination of key indicators is necessary to ensure that the instrument meets the detection requirements and industry standards:
(1) Detection sensitivity (minimum detectable concentration)
Industry standard: According to the DL/T 722 standard requirements, the detection limit for acetylene (C₂H₂) should not exceed 0.1 µL/L, and the detection limit for hydrogen (H₂) should not exceed 2 µL/L. High-quality instruments can achieve a C₂H₂ detection limit of 0.01 µL/L or even lower.
Indicator significance: High detection sensitivity can capture early fault signals within transformers earlier, providing a basis for equipment fault warning and operation and maintenance decisions.
(2) Resolution and chromatographic column system
Separation requirements: The instrument must achieve complete separation of key gas pairs, such as CH₄/C₂H₄ and C₂H₄/C₂H₆, to avoid quantitative analysis errors caused by incomplete separation.
Mainstream configuration: A mature configuration is a three-detector and three-chromatographic column system, with each detector having a clear division of labor: the TCD detector is used to detect O₂ and N₂; the FID detector is used to detect CH₄, C₂H₄, C₂H₆, and C₂H₂, among other hydrocarbon gases; the FID + nickel converter combination can convert CO and CO₂ into CH₄ for detection.
Key points for examination: Verify the chromatographic column model, aging process, and review typical chromatograms, focusing on whether the peak shapes are symmetrical and sharp and whether the baseline is stable.
(3) Repeatability and accuracy
Repeatability: For the same sample, multiple injections should be analyzed, and the relative standard deviation (RSD) of the results should meet the requirement of RSD < 3% for major components.
Accuracy: Use standard oil samples to test the instrument to ensure that the measurement values are within the allowable error range of the industry standards.
(4) Degree of automation
The degree of automation of the instrument directly affects the detection efficiency and control of human errors. Different configurations are suitable for different detection scenarios:
Manual injection: Lower cost but prone to human errors and low detection efficiency, suitable for scenarios with small sample volumes.
Headspace sampler (mechanical arm type): The mainstream configuration in the industry, which can automatically complete the entire process of oscillation, constant temperature, sampling, and injection, effectively improving the accuracy of the detection results and work efficiency.
Fully automatic sampler: Can be connected to dozens of sample trays, enabling unattended continuous analysis, suitable for professional testing centers with large sample volumes. (V) Data Processing and Diagnostic System
The software accompanying the instrument should have comprehensive functions, not only capable of data collection and concentration calculation, but also equipped with professional fault diagnosis tools, including the three-ratio method, David’s triangle method, and fault gas generation rate calculation, etc. It should be able to automatically generate diagnostic conclusions and standardized analysis reports, achieving the integration of detection and diagnosis.
III. Comprehensive Evaluation of Services and Partners
The long-term stable operation of the instrument cannot be separated from complete service support. A comprehensive evaluation of partners should be conducted from multiple dimensions:
Technical service capability: Assess the response speed and professional technical level of technical engineers to ensure that problems with the instrument can be resolved promptly and effectively.
Spare parts guarantee: Verify the supply cycle and price of spare parts to avoid long-term instrument downtime due to the lack of spare parts, which would affect the detection work.
Professional training support: Confirm whether systematic training on instrument operation, daily maintenance, and practical application can be provided to help operators quickly master the instrument usage skills and enhance the professionalism of the detection work.
IV. Summary of the Selection Process
To ensure the scientific and rational nature of the selection, a standardized selection process should be followed, with layer-by-layer screening and comprehensive evaluation:
Demand analysis: Based on the application positioning, clarify the core requirements of the detection work and define the basic scope of selection.
Market research: Collect technical data and parameter information of various instruments extensively, and complete the initial information screening and organization.
Technical communication: Conduct in-depth technical communication with relevant technical parties, requiring them to provide typical instrument spectra, detailed performance parameter tables, and actual application case information.
On-site inspection and demonstration: If conditions permit, visit the actual application units of the instrument for on-site inspection, or request the provision of sample machines for on-site demonstration to directly verify the separation effect, operational stability, and ease of operation of the instrument.
Comprehensive evaluation: Based on multiple factors such as the performance indicators, price positioning, and service guarantee of the instrument, conduct a comprehensive assessment and finally determine the selection plan.
Post time: Jan-20-2026