When the vacuum degree of a vacuum switch interrupter drops below the order of 10⁻¹ Pa, its breaking capacity will decline significantly. For technical engineers, selecting a vacuum degree tester mainly depends on the lower limit of the range, measurement error, resolution, and on-site power supply compatibility, rather than a single indicator. The following comparison is developed according to six key points.
Point 1: The lower limit of the range determines the degree of deterioration that can be measured. The measurement lower limit of common equipment can cover down to the order of 10⁻⁷ Pa. The lower the range lower limit, the more capable it is of identifying early slow leakage in the interrupter. If the lower limit is too high, the instrument may already be unable to read when the vacuum degree has not yet severely deteriorated. During selection, the required lower limit should be back-calculated based on the allowable value given by the switch manufacturer.
Point 2: Error and resolution correspond respectively to accuracy and fineness. When the measurement error is better than 5%, the reading can be used for trend comparison; when the resolution reaches 10⁻⁵ Pa, it can present small changes between two adjacent measurements. Error and resolution need to be considered at the same time. If only the resolution is high but the error is large, the reference value of the data is limited.
Point 3: On-site environmental adaptability affects attendance rate. Models that allow an ambient temperature of -20℃～50℃ and air humidity ≤210 (mm) can adapt to the high and low temperature and high humidity conditions of outdoor substations and switch rooms. The on-site differences between northern winters and the plum rain season in the south are often variables ignored during selection.
Point 4: Non-disassembly measurement capability is a watershed in efficiency. Instruments with non-disassembly measurement capability can complete testing directly on the switch body, eliminating the procedures of disassembling the interrupter and re-evacuating, reducing power outage time and reassembly risks, and are suitable for distribution sites with tight maintenance windows.
Point 5: High-voltage output parameters are related to measurement stability. Models with a high-voltage output of pulsed 30kV and 15kHz establish measurement conditions through a pulsed electric field. Whether the output parameters are stable directly affects reading repeatability. During on-site comparison, three consecutive measurements can be made on the same switch to observe the degree of dispersion.
Point 6: Operation mode determines the personnel threshold. Instruments with liquid crystal display and menu-based operation have lower training requirements for on-site personnel; traditional analog meter methods rely more on empirical interpretation. For batch configuration, priority should be given to models with intuitive readings and convenient recording, so as to facilitate the establishment of vacuum degree ledgers.
Selection comparison is not about pursuing the highest value of a certain parameter, but about matching range, error, resolution, environmental adaptability, and on-site working methods with one another. It is recommended to use an interrupter with a known state for actual measurement verification before procurement, and then decide on the configuration model.
