During routine maintenance of vacuum switches at substation sites, O&M personnel often encounter the following situation: the withstand voltage test passes, but abnormal sounds occur during opening and closing operations or there are signs of reduced current-interrupting capability. It is difficult to clarify the actual vacuum state inside the arc-extinguishing chamber based solely on withstand voltage data. The withstand voltage test reflects the breakdown voltage level and is not sensitive enough to the slow deterioration of vacuum degree, while the arc-extinguishing chamber should not be frequently disassembled and sent for inspection. This contradiction is particularly common in on-site screening of 10kV to 35kV distribution switches.
The WDK-7500 Switch Vacuum Degree Tester adopts the magnetron discharge principle, applying a magnetic field outside the arc-extinguishing chamber and measuring the ion current to convert the vacuum degree inside the arc-extinguishing chamber. The measurement range covers 9.999×10⁻⁵ Pa to 1×10⁻¹ Pa, with a measurement error of no more than 10%. It can provide a quantitative judgment of the vacuum state of the arc-extinguishing chamber, making up for the limitation that the withstand voltage test only reflects breakdown voltage. The test process requires no disassembly of the arc-extinguishing chamber, making it suitable for rapid on-site screening of vacuum switches and reducing power outage time and disassembly workload for O&M teams.
The instrument panel layout is designed according to on-site usage habits. After wiring is completed, operate step by step according to the prompts, and the test results are displayed in numerical form, making it easy for O&M personnel to compare with historical data and judge deterioration trends. The unit is portable and suitable for use in switchgear sites, maintenance workshops, and other locations. Before use, confirm that the arc-extinguishing chamber has no visible damage, the wiring is reliable, and complete the calibration check as required by the manual.
The instrument can be used for vacuum degree testing of vacuum circuit breaker arc-extinguishing chambers in power system substations, industrial and mining enterprise distribution rooms, and electrical maintenance units. It can also serve as an auxiliary testing method for acceptance and condition-based maintenance of switchgear. Establishing regular test records for switches in operation helps to understand changes in the vacuum state of the arc-extinguishing chamber and provides data reference for maintenance decisions.
