Wiring Guide: ODES WY-31A4 Three-Phase Voltage Supervision Relay
- TonyZhang
- Sep 27, 2025
- 2 min read
In secondary circuits, proper wiring of three-phase voltage supervision relays is critical to ensure accurate monitoring and reliable protection logic. Recently, a design engineer raised a question:
With a PT output of ABCN (three-phase four-wire), and using the ODES WY-31A4 overvoltage relay, which has six input terminals (1–2, 4–5, 7–8 for Ua, Ub, Uc), how should the wiring be connected?
1 (Ua), 2 (Ua′): Phase A voltage input 4 (Ub), 5 (Ub′): Phase B voltage input 7 (Uc), 8 (Uc′): Phase C voltage input
OUT1, OUT2: Relay outputs
11/12 (+KM): Auxiliary power supply positive (+) 13/14 (GND): Auxiliary power supply ground (GND) 15/16 (−KM): Auxiliary power supply negative (−)
Wiring Method
The WY-31A4 relay uses paired input terminals for each phase:
Phase A → 1 (Ua), 2 (Ua’)
Phase B → 4 (Ub), 5 (Ub’)
Phase C → 7 (Uc), 8 (Uc’)
Terminals 2, 5, and 8 should be shorted together and connected to the neutral (N).
Phase wires connect to terminals 1, 4, 7.
Neutral wire connects to terminals 2, 5, 8 (shorted together).
This ensures each phase is measured independently, while maintaining compatibility with the ABCN three-phase four-wire PT secondary system.
Practical Engineering Note
All ODES WY-30 series relays are designed with terminal capacity supporting 2.5 mm² crimp lugs with double wiring, ensuring secure and convenient installation in protection panels.
Correct wiring of the ODES WY-31A4 three-phase voltage supervision relay guarantees reliable PT measurement, enabling accurate overvoltage protection and stable secondary circuit performance.
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