I. Fundamental Principle of Magnetic-Controlled Discharge Method
The magnetic-controlled discharge method is the core measurement principle of high-voltage switch vacuum degree testers. This technology leverages specific physical characteristics to achieve precise vacuum detection, with its fundamental basis being that, under the combined influence of electric and magnetic fields, residual gas molecules in a vacuum environment undergo ionization reactions. The resulting ion current intensity exhibits a stable, direct proportionality to gas density—i.e., the equipment’s vacuum level.
The implementation process follows a standardized procedure: first, the two contacts of the vacuum arc chamber are separated to their rated opening distance. Then, a high-voltage pulse electric field is applied between the contacts, while an external coil simultaneously generates a pulsed magnetic field synchronized with the high-voltage signal. Under the combined electromagnetic field, charged particles such as electrons and ions inside the arc chamber move in spiral trajectories, colliding with residual gas molecules and causing ionization. The instrument precisely captures the ion current generated during this ionization process and uses a pre-calibrated “ion current–vacuum degree” correlation curve to accurately convert it into real-time vacuum level values for the arc chamber.
II. Technological Evolution and Field Adaptability
Vacuum degree testing technology has undergone iterative improvements, significantly enhancing on-site adaptability and testing efficiency. Early methods involved cumbersome procedures and long durations, requiring disassembly of the vacuum arc chamber from the circuit breaker before placing it inside a solenoidal coil for measurement. This made the entire operation complex and unsuitable for rapid field testing.
Through technological optimization, modern vacuum testers now feature a new π-type excitation coil structure that can wrap around the arc chamber from the side, enabling non-invasive, on-site measurements without disassembling the equipment. This greatly simplifies operational procedures and improves field testing efficiency.
In terms of control and data processing, modern devices employ single-chip computers to manage synchronization, data acquisition, and computational processing. By performing two high-voltage activation cycles, environmental interference-induced leakage currents are effectively eliminated, significantly improving test accuracy. On-site sensitivity reaches 10⁻⁵ Pa. The device’s core technical parameters remain stable and well-suited to field conditions: typical measurement range spans 10⁻⁵ to 10⁻¹ Pa, measurement accuracy ranges from 5% to 10%, operating electric field voltage ranges from 20 kV to 30 kV, magnetic field voltage ranges from 1600 V to 1700 V, and the main unit weighs between 12 kg and 24 kg, balancing performance and portability.
III. Standardization Framework
(1) Core Standards and Specifications
The design, manufacturing, and inspection processes of vacuum switch vacuum degree testers strictly follow DL/T 846.9-2004, “General Technical Conditions for High-Voltage Testing Equipment—Part 9: Vacuum Switch Vacuum Degree Tester.” Issued by the National Development and Reform Commission, this standard specifically applies to vacuum degree testing equipment for vacuum circuit breakers in the power industry, clearly defining technical control requirements throughout the equipment lifecycle.
Key content includes basic technical specifications, standardized test methods, finished product inspection rules, and comprehensive regulations covering equipment labeling, tags, packaging, transportation, and storage. DL/T 846 is a complete series of standards for high-voltage testing equipment, comprising nine parts. In addition to the dedicated specification for vacuum degree testers, it covers technical standards for other high-voltage testing equipment such as high-voltage voltage dividers, impulse voltage measurement systems, high-voltage switch integrated testers, and partial discharge measuring instruments, forming a comprehensive regulatory framework for high-voltage testing equipment.
(2) Vacuum Degree Evaluation Criteria For the qualification assessment of vacuum interrupters, two widely adopted core standards are currently in use: the Ministry of Mechanical Industry standard JB/DQ2184—1986 “General Technical Conditions for Vacuum Interrupters Used in 3–35 kV Vacuum Circuit Breakers,” and the electric power industry standard DL403—1991 “Technical Specifications for Ordering Indoor 10–35 kV Vacuum Circuit Breakers.” Both standards uniformly specify that for 10–35 kV vacuum circuit breakers, the vacuum level must not be lower than 6.6×10⁻² Pa.
Based on actual operational requirements in the field, the industry has developed a mature grading evaluation system to accurately define equipment operating conditions: a vacuum level ≤10⁻² Pa indicates a qualified state; for newly commissioned switchgear, the vacuum level must be ≤10⁻³ Pa to ensure optimal initial performance; a vacuum level between 10⁻² and 10⁻¹ Pa represents a warning state, indicating potential performance degradation, requiring shortened inspection intervals and enhanced condition monitoring; a vacuum level ≥10⁻¹ Pa is considered unqualified, meaning insulation and arc-quenching performance do not meet requirements, necessitating immediate shutdown and replacement to eliminate operational safety risks.
(3) Related Reference Standards
In addition to specialized standards, vacuum degree testing for vacuum switches also relies on a general standard framework to ensure standardized, professional, and universally applicable testing practices. GB/T 11022-2020 “Common Technical Requirements for High-Voltage Switchgear and Control Equipment” establishes fundamental criteria for insulation performance and general test methods, serving as the foundational reference for testing. DL/T 596-2021 “Preventive Test Regulations for Electric Power Equipment” standardizes test cycles, inspection items, and condition assessment criteria for field testing, providing guidance for routine maintenance and inspection. IEC 62271-100 “High-Voltage Switchgear and Control Gear – Part 100: Alternating-Current Circuit-breakers” provides international support through common standards, meeting diverse testing needs across various application scenarios.
IV. Field Application of High-Voltage Switch Vacuum Degree Testers
(1) Main Application Scenarios
The application scenarios of high-voltage switch vacuum degree testers can be categorized into two main types, covering the entire lifecycle from manufacturing to operation and maintenance.
The first category involves production quality control, primarily used in final product inspections of vacuum interrupters and incoming quality checks for interrupters paired with circuit breakers, ensuring that new equipment meets required vacuum specifications at the source.
The second category covers preventive field testing, widely applied in routine maintenance, capacity performance testing of vacuum switches, and comprehensive assessments of equipment operating conditions within the power industry. Currently, this testing equipment is widely deployed across industries such as power, steel, petrochemicals, textiles, coal, and railways—sectors with extensive installations of vacuum switches—and has become one of the essential diagnostic tools for high-voltage electrical equipment maintenance.
(2) On-Site Operation Procedure
On-site vacuum degree testing follows a standardized procedure with clear, practical steps:
Step 1: Wiring Preparation. Place the vacuum switch under test in the open position and complete connections: connect the magnetic control coil to the magnetic current output terminal on the instrument panel, and place the coil around the outer side of the vacuum interrupter; separately connect the high-voltage lead and signal input cable to the moving and fixed contacts of the interrupter. Throughout the wiring process, ensure the high-voltage lead remains suspended and maintain a safe distance between the magnetic control coil and the high-voltage output terminal to avoid interference and safety hazards.
Step 2: Selection of Tube Parameters. Based on the specific model of the vacuum interrupter being tested, select the corresponding tube parameters in the instrument system. If no matching parameters are available, direct measurement of the ionization current can be performed instead. Under normal conditions, the vacuum level value is approximately two orders of magnitude smaller than the ionization current value, allowing for conversion and judgment accordingly.
Step 3: Automatic Measurement by Device. After parameter settings are completed, start the instrument. The device will automatically carry out the entire testing procedure: first, activate the high-voltage module to measure ambient leakage current; then automatically turn off the high voltage and connect the charging switch. Once the voltage reaches the rated standard value, restart the high-voltage module and simultaneously enable the magnetron current output. Accurately measure the combined value of leakage current and ionization current. The system automatically subtracts the leakage current caused by environmental interference and converts the pure ionization current data into a precise vacuum level reading. Finally, display the results, store them, and print the output, completing a single test cycle.
Post time: Jun-11-2026