Sensor Technology (Key Differentiators) The measurement accuracy of speed and travel depends on the sensor type, with three main types currently available: Linear Displacement Sensor (draw-wire/push-rod type): Principle: Directly connects to the circuit breaker's moving contact linkage, converting linear motion into electrical signals. Advantages: Most direct and accurate data, the preferred choice for arbitration-level testing. Disadvantages: Complex installation, requires finding suitable mounting points, difficult to fix on large circuit breakers. Angle Sensor (rotary type): Principle: Clamps onto the circuit breaker's main shaft, measures rotation angle, and converts to linear travel through software algorithms. Advantages: Extremely convenient installation (magnetic or clamp), strong applicability. Disadvantages: Relies on conversion model; errors may occur if the linkage mechanism wears or model parameters are set incorrectly. Acceleration Sensor (with built-in integration algorithm): Principle: Measures acceleration and integrates twice to obtain velocity and displacement. Advantages: Wireless, no wiring, fastest installation. Disadvantages: Significant low-frequency drift, relies on algorithms for zero-speed point determination, only suitable for trend analysis, not recommended for precise acceptance. 2026 Trend: High-end instruments typically come standard with high-precision draw-wire sensors, with optional wireless angle sensors to improve efficiency. 3. 2025-2026 New Technology Trends Multi-channel Synchronization and Expansion: Standard configuration supports 12 breaks (meeting testing requirements for 500kV and above circuit breakers). Supports modular expansion, allowing simultaneous testing of multiple circuit breakers or with GIS partial discharge testing. AI Waveform Diagnostic Expert System: No longer just displays waveforms but has a built-in fault feature library. Automatically analyzes coil current waveforms to identify typical faults such as “core not engaged”, “auxiliary switch switching too early”, “inter-turn short circuit in coil”, “mechanical jamming”, etc., and provides maintenance recommendations. Wireless Sensing and Bluetooth Connectivity: Industrial-grade wireless transmission between sensors and host (strong anti-interference capability), completely eliminating noise and wiring hassles from long signal cables. Supports tablet/smartphone APP control, allowing testers to operate away from high-voltage areas. True RMS and High-Frequency Sampling: Sampling rate increased to 100kHz - 1MHz, capturing millisecond-level action details and minor contact bounce. Misconnection Prevention and Self-Diagnosis: Automatically checks sensor status and circuit continuity at startup; graphical prompts on screen guide correct wiring when errors occur. 4. Key Selection Parameters Table Parameter Item Description and Recommendation Time Measurement Range 0 ~ 9999.9ms, resolution 0.01ms (even 0.001ms). Speed Measurement Range 0 ~ 20.00 m/s, resolution 0.01 m/s. Travel Measurement Range 0 ~ 1000mm (requires optional long-travel sensor), resolution 0.1mm. Number of Breaks At least 6 breaks (for 110kV/220kV), recommended 12 breaks (for 500kV/UHV). Control Power Output DC 0-300V adjustable (for low-voltage testing), current capacity > 20A. Sensor Interface Must support both linear displacement and angle rotation interfaces, with automatic recognition function. Anti-Interference Capability Under strong electromagnetic fields in substations (e.g., near operating equipment), data should not jump or freeze. Data Storage Built-in large-capacity storage, supports USB export, report formats compatible with Word/Excel/PDF. 5. Brief Operation Process Power Off and Safety Measures: Confirm the circuit breaker is de-energized, disconnect the operating power, and implement safety measures. Wiring: Break wires: Connect to both ends of each phase break (for time measurement). Control wires: Connect to the opening/closing coil terminals (for triggering and control). Sensors: Install linear or angle sensors, ensuring good tracking without slippage. Grounding: Reliable grounding of the instrument. Parameter Settings: Select circuit breaker type (vacuum/SF6/oil). Input rated voltage, rated speed standards (optional). Set sensor type and installation method (e.g., transmission ratio for angle sensors). Pre-operation Check: Perform manual opening/closing, observe if the sensor travel curve is smooth and free of dead zones. Formal Testing: Select “Closing”, “Opening”, or “Reclosing” mode. The instrument automatically outputs control signals and records the entire process data. Data Analysis: Check if time, speed, and travel exceed standards. Key analysis: Is the coil current waveform abnormal? Are there steps (sticking) in the travel curve? Is there severe rebound during closing? Restoration: Remove wiring and restore the circuit breaker to its original state. 6. Common Fault Diagnosis Cases Opening time too long: Possible causes include low opening coil voltage, core jamming, or overly tight buffer. Excessive closing rebound: Possible causes include contact spring fatigue, poor mechanism lubrication, or excessive closing energy. Low peak in coil current waveform: Inter-turn short circuit in coil or excessive power supply internal resistance. “Double peak” or distortion in coil current waveform: Core movement obstructed or auxiliary switch switching timing incorrect. Three-phase out-of-sync exceeding standards: Change in linkage length of a certain phase, moisture absorption and elongation of insulating pull rod, or uneven mechanism wear. 7. Market Mainstream Brand Reference International Brands: OMICRON (Austria, CIBANO series, highly integrated, expensive), Doble (USA). Leading Domestic Brands: Wuhan UHV Electric Power: Very high market share, comprehensive product line, rich sensor variety, high cost-performance. Wuhan Musen Electric: Outstanding in wireless sensing and intelligent diagnostics. Shanghai Siyuan Hongrui: Backed by Siyuan Electric, high compatibility with primary equipment. Baoding Tianwei/Xinnuo: Commonly used brands in northern power grids. 8. Special Notes Sensor installation is the key to success: 70% of testing errors originate from improper sensor installation (e.g., non-vertical draw-wire, angle sensor slipping). Ensure the sensor is rigidly connected or closely follows the circuit breaker's moving shaft. Anti-backfeed protection: Circuit breakers generate high back-EMF during opening/closing, so the instrument must have robust protection circuits to prevent damage to internal circuit boards. Standard Basis: Testing and interpretation should strictly follow GB 50150 (Standard for Handover Test of Electrical Equipment Installation Engineering) and DL/T 846.3 (General Technical Specifications for High-Voltage Switch Comprehensive Tester).
