Frequent alarms from the main transformer Buchholz relay, long oil sampling and testing cycles, and delayed data make it difficult to capture early latent faults—this is a common situation encountered by substation operation and maintenance personnel. When purchasing an oil chromatography online monitoring system, the following points can be checked one by one to determine whether the configuration matches on-site requirements.
The system should be able to detect dissolved characteristic gases in oil such as methane, ethane, ethylene, acetylene, hydrogen, carbon monoxide, and carbon dioxide. Among these, the minimum detection limit for acetylene is recommended to be no higher than 0.5 μL/L. During procurement, manufacturers can be asked to provide the detection range and repeatability indicators for each component, and whether they are sufficient can be judged based on the main transformer voltage level and previous oil sample data.
Common solutions include vacuum degassing, membrane separation, and polymer permeation. Vacuum degassing has a high degassing rate, but the vulnerable parts of the vacuum pump need to be replaced regularly; membrane separation has a simple structure, but the membrane module has an aging cycle. During procurement, the nominal service life and replacement cost of the degassing unit should be asked about to avoid later operation and maintenance costs exceeding the budget.
The monitoring device should be equipped with a 100M Ethernet interface to upload collected data to the server in the main control room. The background software needs to have functions such as historical curve query, threshold alarms, and three-ratio or Duval triangle fault analysis. Before procurement, it should be confirmed whether the software opens data interfaces to facilitate integration into the station's comprehensive online monitoring platform and avoid forming an information island.
The device is usually installed near the main transformer and needs to adapt to sunlight, rain, and electromagnetic interference environments. The enclosure protection rating is recommended to be no lower than IP55, and electromagnetic compatibility should meet the relevant requirements of GB/T 17626. For areas with strong electromagnetic fields, manufacturers can be asked to provide on-site anti-interference test records or case descriptions.
During procurement, the oil sampling port location, oil pipe routing, and whether power outage work is required must be clarified. Some models support access through a spare oil sampling valve, allowing installation to be completed while the main transformer is in operation. If on-site space is limited, customized brackets or extended oil pipe solutions should be discussed with the manufacturer in advance to reduce later modification costs.
