ODES WY-35 Undervoltage Relay: Reliable PT Failure Supervision
- TonyZhang
- Sep 27, 2025
- 2 min read
In secondary systems, when the potential transformer (PT) secondary supply fails, measurement, protection, and metering all lose their reference—leaving the system effectively “blind.”
The ODES WY-35 undervoltage relay is purpose-built for PT supply supervision. It supports both secondary PT cabinets and primary switchgear PT cabinets. When the PT secondary voltage falls below the set threshold for longer than the set delay, the relay outputs an alarm or blocking contact—providing reliable input for PT transfer, synchronizing check, and automatic transfer logic. Configurations are available for both single-phase and three-phase PT monitoring.
Why Choose the ODES WY-35?
Wide auxiliary power range: DC 88–370 V / AC 85–265 V (50/60 Hz), one model compatible across substation supply systems.
Accurate and adjustable: Voltage setpoint 0.1–1.0 Un, delay adjustable 0–9999 ms or 0–9999 s, accuracy ±3%, customizable reset ratio (1.1 × pickup).
EMC robustness: Withstands ESD ±15 kV/±8 kV, EFT ±4 kV/±2 kV, surge common mode ±4 kV / differential mode ±2 kV—qualified for harsh substation environments.
Reliable outputs: Two DPDT contacts rated 6 A @ 250 VAC / 30 VDC, easy integration into blocking and permissive circuits.
Environmental resilience: −25 °C to +70 °C, ≤95 % RH (non-condensing), altitude ≤4500 m, V0 flame-retardant, 2 kV dielectric withstand, 100 MΩ insulation.
Standards compliance: Designed according to GB/T 50063, GB/T 13850, DL/T 1075, ensuring smooth project acceptance.
Typical Applications
Secondary PT Cabinets: WY-35 supervises operating-side PT undervoltage → sends alarm/blocking → triggers automatic dual-PT transfer or flags data invalid.
Primary Switchgear PT Cabinets: Provides pre-check for closing-voltage permissive and reclosing blocking → prevents dead-bus closing → enhances safety in synchronizing operations.
Proven Track Record
The WY-35 relay has been deployed for over 20 years in 110 kV / 220 kV and higher projects, serving every major domestic secondary protection integrator and supporting OEMs of high-voltage and medium-voltage switchgear.
Conclusion
Reliable PT undervoltage supervision is indispensable for safe power-system operation. The ODES WY-35 undervoltage relay delivers wide-range adaptability, EMC performance, and proven field reliability—trusted by integrators and OEMs across decades of critical projects.
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