How to choose transformer oil chromatography online monitoring system? Six core indicators comparison guide
Date: May 15, 2026 10:11:26
- Detecting gas type: the number of gases that can be detected simultaneously is a core indication of the system's capability, and should cover at least five key gases: H₂, CO, CH₄, C₂H₄, and C₂H₂.
- sampling period: from 1 hour to 24 hours, the shorter the cycle time the better the ability to capture fast-moving faults, balanced against the consumption of consumables.
- Data diagnostic capabilities: Whether standard diagnostic models (Triple Ratio, David's Triangle, etc.) are built-in, and whether diagnostic conclusions and trend analyses can be output automatically
- Communication compatibilityWhether it supports Modbus, IEC61850 and other mainstream power communication protocols, and whether it can be seamlessly connected to the existing SCADA system.
- Ease of Installation: Whether it supports non-power installation, how much installation work is required, and what are the requirements for space and power supply at the site
- Long-term operation and maintenance costs: Replacement cycle and cost of consumables such as carrier gas and chromatographic columns, manufacturer's after-sales response speed
1. Selection overview: six core indicators
| Indicator dimension | weights | fundamental requirement | Preferred Criteria |
|---|---|---|---|
| Detecting gas type | ★★★★★ | ≥ 5 (H₂, CO, CH₄, C₂H₄, C₂H₂) | More than 7 types + microwater content |
| Sampling and analysis cycle | ★★★★ | ≤24 hours/session | ≤4 hours/times and adjustable |
| Diagnostic and analytical functions | ★★★★★ | Trend graph + overrun alarm | Triple Ratio + David's Triangle + Expert Pool |
| Communication Protocol Support | ★★★★ | Modbus RTU | Modbus+IEC61850+TCP/IP |
| Data storage and querying | ★★★★★ | ≥ 1 year of local storage | ≥10 years + remote backup |
| Environmental adaptation and protection | ★★★★★ | Temperature -20~60℃, IP54 | -40~70℃, IP55 or above |
2. Indicators in detail
2.1 Detecting gas types - determining fault coverage
The more gases detected, the more comprehensive the fault types that can be covered. A minimum of 5 gases is required to complete a basic triple ratio diagnosis. Adding CO and CO₂ assesses the state of the solid insulation, and adding microwater detection determines moisture problems. For critical transformers, a full-featured configuration of seven gases plus microwater is recommended.
2.2 Sampling Period - Determining Response Speed
The shorter the sampling period, the more timely the capture of rapidly developing faults. However, a shorter period also means faster carrier gas consumption and a larger amount of data. It is recommended that the main transformer be set to once every 2~4 hours, and the general distribution transformer can be set to once every 12~24 hours. The system should support flexible cycle adjustment.
2.3 Diagnostic and analytical capabilities - determining value in use
Data alone without diagnostics is the same as giving a lab sheet without a diagnostic report. A good system should have a variety of standard diagnostic models built-in, automatic output failure type judgment and confidence level. Trend analysis function is particularly important - the absolute value of a single point of data may be disturbed by a variety of factors, but the direction of the continuous trend is the most reliable basis for judgment.
2.4 Communication Compatibility - Determining Integration Difficulty
If the system cannot communicate with the existing monitoring backend in the station, the data cannot be effectively utilized. Before selecting a system, it is necessary to check the type and protocol version of the existing communication network in the substation to make sure that the selected system is natively supported.IEC61850 has become the standard protocol for new intelligent substations.
2.5 Data storage and querying
Historical data is the basis for trend analysis and fault retrospective. The system should provide at least 1 year of local data storage capacity, and support querying and exporting reports by time period. A system with remote data backup function can better protect data security.
2.6 Environmental adaptation and protection classes
Outdoor installations require adequate levels of protection and a wide temperature range. Low-temperature start-up capability is a concern in northern regions, and corrosion and condensation-resistant designs are needed in coastal and high humidity areas.
3. Selection focus for different scenarios
3.1 500kV/220kV Hub Substation
The focus of the selection is on the fullest possible range of gases to be detected, the deepest possible diagnostics, and the use of IEC 61850 communication protocols. this type of substation has the highest safety requirements and a relatively large budget, so the highest configuration should be chosen.
3.2 110kV urban substations
Selection focus: balancing performance and cost. Detect more than six gases, support Modbus protocol, sampling period 4~8 hours. Focus on trend analysis and alarm linkage.
3.3 Distribution transformers for industrial users
Selection focus: cost-effectiveness. You can choose a less-component or single-hydrogen monitoring program that meets basic failure warning needs. Ease of installation is more important - most do not have specialized O&M personnel.
4. Frequently Asked Questions FAQ
4.1 Q. Is there a gap between imported and domestic equipment in terms of core indicators?
A: In terms of testing accuracy and reliability, domestic mainstream brands have made significant progress in recent years, and the core indicators have been close to imports. Domestic equipment in the after-sales response speed, spare parts supply and customized services are often more advantageous.
4.2 Q. Is it necessary to choose the model that detects the most gases?
A: Not necessarily. The more types of gas the higher the price and the greater the consumption of consumables. Requirements should be determined according to the transformer's voltage level, importance and operational risk. Choose full-featured for critical transformers and adequate for general transformers.
4.3 Q: Modbus or IEC61850 for communication protocol?
A: Modbus is usually the most compatible solution for retrofitting old stations; IEC61850 should be chosen directly for new intelligent substations; some systems support both protocols, which is the most compatible solution.
4.4 Q: How long does carrier gas last? Does the frequency of replacement have a significant impact on O&M costs?
A: Carrier gas consumption is positively correlated with the sampling period. A bottle of carrier gas can be used for 3 to 6 months for 2 tests per day. Carrier gas is a routine consumable and is not costly. More attention should be paid to column replacement cycles and costs.
4.5 Q. How long does the installation process take?
A: Standard installation is usually completed in 1~2 days, including equipment positioning, oil pipe connection, electrical wiring and communication debugging. The entire process does not require a power outage and can be carried out using natural intervals during transformer operation.
5. Recommendations for the selection process
5.1 Define monitoring needs - Make a list of transformers, labeling them with voltage level, capacity, years of operation, and importance, and determine the level of monitoring configuration for each piece of equipment.
5.2 Gather site information - Confirm the space dimensions of the installation location, power pickup method, and the type of existing communication network to avoid the inability to install the equipment when it arrives.
5.3 Comparison of multiple programs - from the technical parameters, engineering cases, after-sales protection of three dimensions of a comprehensive assessment, to choose the overall optimal supplier.
Disclaimer: The content of this article is for technical exchanges and reference only, and does not constitute any form of procurement commitment or contract offer. Product technical parameters, configuration programs and prices are subject to the actual signed contracts and technical agreements. The technical data and cases involved in this article are from public information and engineering practice, if updated without notice.
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