Acceptance before commissioning of new equipment: Verify that the wiring of newly installed protection devices is correct, the settings are accurate, and the logic meets design requirements. Periodic preventive tests: According to regulations (e.g., every 1-3 years), calibrate protection devices in operation to prevent misoperation or failure to operate due to component aging. Fault analysis: When a power grid accident causes protection to operate (or not operate), use the tester to reproduce the fault waveform and analyze whether the protection behavior is correct. Research and teaching: Used in university laboratories or research institutions to study new protection algorithms. 3. Technical characteristics and development trends High precision and high stability: Modern testers typically use DSP (Digital Signal Processing) or FPGA technology, with extremely low output waveform distortion (<0.2%) and phase accuracy up to 0.1°. Multi-phase output capability: Mainstream devices provide six-phase voltage and six-phase current outputs, which can not only test conventional protection but also easily handle complex differential protection (requiring independent multi-side current sources) and automatic transfer switch (ATS) device testing. GPS synchronization: High-end models support GPS/Beidou timing, enabling multiple testers to synchronize remotely for traveling wave protection or longitudinal differential protection testing of long-distance transmission lines. Digital interface (IEC 61850): With the popularity of smart substations, the new generation of testers not only outputs analog quantities (hard wiring) but also has fiber optic Ethernet ports, capable of directly sending and parsing SV (Sampled Values) and GOOSE (Generic Object Oriented Substation Event) messages, achieving closed-loop testing of digital protection devices. Portable design: High integration, light weight, built-in large-capacity lithium battery, suitable for field operations without power supply. 4. Examples of common test items Overcurrent protection test: Gradually increase the current until the protection operates, record the operating value and operating time. Low voltage protection test: Gradually reduce the voltage to verify undervoltage blocking or undervoltage tripping logic. Distance protection test: Change the amplitude and phase of voltage and current to simulate short-circuit points at different distances, plot the R-X impedance diagram. Reclosing test: Simulate transient faults, check the full process time coordination of "trip -> delay -> reclose -> post-accelerate". Automatic transfer switch (ATS) test: Simulate loss of voltage on the main power supply, verify the logic and time limit for automatic switching to the backup power supply. 5. Operation precautions Anti-open circuit/anti-short circuit: Although the tester has internal protection, the current loop is strictly prohibited from being open (may generate high voltage), and the voltage loop is strictly prohibited from being short-circuited (may burn out the power amplifier). Grounding safety: The tester casing and the tested protection panel cabinet must be reliably grounded together to prevent potential difference from interfering with test results or damaging equipment. Wiring verification: Before testing, be sure to verify the wiring of the binary inputs (normally open/normally closed contacts), otherwise it may cause time measurement errors or logic judgment failures. Exit pressure plates: When performing tests that may cause misoperation of running circuit breakers, relevant exit pressure plates must be withdrawn as required (unless performing a full group transmission test with safety measures in place). 6. Mainstream brands and market International brands: Omicron (Austria, industry benchmark, expensive, extremely powerful), Doble (USA). Domestic brands: PONOVO, ONLLY, Jidian, Huatian, etc. Domestic equipment has high cost performance and mature functions, fully meeting the needs of the domestic power system. If you need specific test wiring diagrams, test steps for a specific protection (such as transformer differential), or how to interpret test reports, please let me know, and I can provide you with detailed operating instructions.
