The Reyrolle Duobias-M is a sophisticated numerical biased differential protection relay engineered for high-speed, selective protection of power transformers, reactors, and generators. The DU3-201-LA-60 model is specifically configured for high-reliability utility and industrial power systems, providing sensitive fault detection while maintaining stability during external disturbances and magnetizing inrush conditions. Its advanced signal processing ensures rapid isolation of faulted equipment to protect critical infrastructure.
⚙️ Technical Parameters and Specifications
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Rated Voltage: 110V AC/DC auxiliary supply
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Protection Functions: Biased differential protection with unrestrained high-set feature
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Mounting Type: Horizontal or vertical rack-mount (standard draw-out case)
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Dimensions: 177 mm (Height) x 212 mm (Width) x 250 mm (Depth)
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Weight: Approximately 5.0 kg
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Country of Origin: United Kingdom
🏭 Application Areas
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Transformer Protection: Ideal for two-winding power transformers, providing fast clearing of internal phase-to-phase and phase-to-ground faults.
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Generator Protection: Suitable for differential protection of small to medium-sized generators.
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Industrial Substations: Designed for use in environments where precise, high-speed fault isolation is required to minimize process downtime.
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Retrofit Projects: Frequently utilized in existing infrastructure upgrades due to its reliable historical performance and standardized physical footprint.
📖 Product User Guide
For effective operation, the Reyrolle Duobias-M should be installed in a clean, vibration-controlled environment. Connect the CT secondary circuits to the rear terminals, ensuring correct polarity for differential stability. The unit is typically configured via front-panel settings or communication software to define CT ratios, bias characteristics, and pickup thresholds. Before commissioning, perform a comprehensive secondary injection test to verify the differential characteristic curve and ensure that stability is maintained during simulated external fault conditions. Always ensure the 110V auxiliary power supply is within specified tolerances to avoid nuisance alarms.
❓ Frequently Asked Questions (Q&A)
What is the significance of the “Biased” feature in this relay? The biased feature allows the relay to become less sensitive as the through-fault current increases, preventing incorrect tripping due to CT saturation or small mismatch errors during high-current external faults.
Is this relay suitable for protecting transformers with different voltage levels? Yes, the relay compensates for current magnitude differences caused by transformation ratios and vector group shifts via programmable internal settings and CT ratio adjustments.
How do I check the health status of the relay? The relay incorporates a “Healthy” LED indicator on the front fascia. If this LED is illuminated, the internal self-monitoring routines have confirmed that the hardware, power supply, and software processes are operating within normal parameters.
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