Preventing Reverse Rotation and Burnout: Practical Insights on Motor Phase‑Sequence Relays

TonyZhang
Oct 4
2 min read

Three‑phase motors are vulnerable to two high‑impact events: incorrect phase sequence (reverse rotation) and phase loss (overcurrent, overheating, potential burnout). These often occur after meter replacement, maintenance, or temporary hookups. Rapid detection and interlocking are required to prevent equipment damage and process upsets.

Operating Principle

The WX‑61 phase‑sequence relay supervises positive‑sequence order and phase presence. When wrong sequence or phase loss is detected, it:

provides clear LED status indication of the abnormal state, and
drives output contacts for interlocking with a contactor, PLC, or alarm circuit to block startup or command a controlled stop.

Core Features & Capabilities

Status visibility — Dual LEDs (RUN / FAULT) give immediate, unambiguous feedback for operators and maintenance staff.
Panel integration — 22.5 mm narrow DIN‑rail housing, IP20 touch‑safe, V0 flame‑retardant enclosure.
Wide electrical compatibility — Line‑to‑line input 187–528 VAC, 50/60 Hz auto‑sensing; suitable for domestic and overseas projects.
Time‑delayed supervision — Built‑in logic filters short‑duration fluctuations to avoid nuisance operations and repetitive trip–reclose cycles in frequent start/stop duties (cranes, fans, pumps).

Typical Applications

Distribution panels and motor control panels
Cranes and hoists
HVAC compressors and chillers
Elevators
Water / oil pumps (phase‑loss and reverse‑rotation prevention)

Field Case (Summary)

After a meter change at a chiller station, intermittent “abnormal at start” events were traced to a B‑phase fuse contact issue creating a pseudo three‑phase condition. With WX‑61 installed, the system performed a pre‑start phase‑sequence / phase‑loss self‑check; on detecting phase loss, the relay issued a fault output to stop the machine. Compressor failures dropped to zero, and maintenance shifted from emergency response to routine inspection.

Conclusion

By combining phase‑sequence verification, phase‑loss supervision, clear status indication, and interlock‑ready outputs, ODES WX‑61 prevents reverse rotation and phase‑loss damage—improving availability and safeguarding motors across demanding industrial sites.