Relay protection testers for low-frequency applications provide multi-phase current and voltage outputs, low-level input simulation, and precise waveform generation for testing both traditional and modern protection relays.Key Features of Low-Frequency Relay Testers
Multi-Phase Outputs: Modern testers, such as the LND-802 and HVTestPro systems, offer up to six-phase current and four-phase voltage outputs, enabling comprehensive testing of transformer differential protection, overcurrent, and distance relays (LND-802, HVTestPro) . Low-Level Input Simulation: Devices like the SVERKER900 LPIT101 adapter simulate low-level outputs from Rogowski coils and LPVTs, accurately reproducing frequency variations, harmonics, and transient conditions for relays with low-level inputs (SVERKER900 LPIT101) . High Accuracy and Waveform Quality: Testers employ DSP and FPGA-based control with high-resolution DACs to generate high-fidelity sine waves, ensuring precise current and voltage outputs even at small amplitudes, which is critical for low-frequency testing (LND-802, HVTestPro) . Software and Automation: Advanced software platforms, such as OMICRON's Test Universe, allow automated testing, relay simulation, fault playback, and parameter verification independent of relay type or manufacturer. This facilitates efficient low-frequency testing and system-based protection verification (CMC 356) . Field and Laboratory Use: Many testers are portable and can be connected directly to laptops or industrial PCs, making them suitable for both on-site commissioning and laboratory testing. They often include self-diagnosis, heat dissipation, and soft-start features for safe operation (HVTestPro, LND-802) . Primary Injection Capability: Some testers, like the CMC 356, support high-current primary injection, which is useful for testing high-burden electromechanical relays and verifying current transformer wiring and plausibility (CMC 356) .
Examples of Low-Frequency Relay Testers
- LND-802 Microcomputer Relay Protection Tester: Offers four-phase voltage and three-phase current outputs, DSP + FPGA control, high-fidelity waveform generation, and Windows XP-based interface for intuitive operation .
- CMC 356 (OMICRON): Universal six-phase tester with high dynamic range, low-level outputs for LPCT/LPVT simulation, and modular software for automated system-based testing .
- SVERKER900 LPIT101 Adapter (Megger): Specialized for low-level input relays, simulating LPCT and LPVT signals with harmonics and transient conditions .
- HVTestPro Relay Protection Tester: Supports six-phase outputs, high-fidelity linear amplifiers, automated calibration, fault playback, and three-phase differential protection testing .
Conclusion
For low-frequency relay protection testing, the ideal tester should combine multi-phase output capability, low-level input simulation, high waveform fidelity, and advanced software automation. Devices like the LND-802, CMC 356, SVERKER900 LPIT101, and HVTestPro provide versatile solutions for both field and laboratory applications, ensuring accurate and reliable testing of modern and traditional protection relays.
