ODES Motor Phase‑Sequence Relay Application Guide

Three‑phase motors are exposed to two high‑impact risks during maintenance and temporary hookups: incorrect phase sequence (reverse rotation) and phase loss (overcurrent, overheating, potential burnout). A protection‑grade phase‑sequence relay prevents these conditions by verifying positive sequence (ABC) and supervising phase presence before permissive is issued.

1) Input Wiring — Three Equivalent Methods

Principle: parallel the motor/bus phases A, B, C—in the same rotation order as the site—to relay terminals 1, 2, 3 (often labeled L1, L2, L3). Any one of the following preserves positive sequence:

• A→1, B→2, C→3

• A→2, B→3, C→1

• A→3, B→1, C→2

If two phases are swapped, the relay indicates wrong sequence and drives the outputs to a safe state; correct by swapping any two input phases.

2) Indication & Contacts — Read the State at a Glance

Front‑panel LEDs and output contacts identify the operating condition:

• Normal (correct sequence, all phases present) – LEDs: RUN ON, ACT ON – Contacts: 11–14 and 21–24 closed; 11–12 and 21–22 open → permissive to downstream control

• Wrong sequence (A/B/C order abnormal) – LEDs: RUN ON, ACT OFF – Contacts return to safe: 11–12 and 21–22 closed; 11–14 and 21–24 open

• Phase loss (any phase absent/low) – LEDs indicate fault; contacts revert to safe state (same as wrong sequence)

This combination minimizes meter‑by‑meter probing and accelerates fault location.

3) Operating Modes — WORK vs TEST

A red selector on the front panel provides two modes:

• WORK: participates in sequence/phase‑loss supervision and drives outputs per logic.

• TEST: supervision bypassed; outputs do not operate—used for maintenance, commissioning, and demonstrations.

4) Commissioning Checklist

• Wiring verification: apply one of the positive‑sequence mappings above; confirm normal indication (RUN/ACT ON).

• Functional tests: simulate two faults—swap any two phases (wrong sequence) and open one phase (phase loss)—confirm LED and contact states.

• Timing settings: apply time‑delayed supervision to ride through brief transients and avoid nuisance operations in frequent‑start drives (cranes, fans, pumps).

5) Integration Notes

• Wire the relay output in series with the contactor permissive or feed it to PLC interlock logic to block start or command a controlled stop on fault.

• Use the LED state as a first‑line diagnostic before deeper inspection of fuses, terminals, and feeders.

6) Selection Highlights

• Narrow DIN‑rail housing (22.5 mm), IP20 touch‑safe, V0 enclosure for dense panels.

• Wide input window: 187–528 VAC, 50/60 Hz auto‑sensing.

• Adjustable pickup/reset and delays for coordinated permissive/blocking logic.

Conclusion

A phase‑sequence relay provides deterministic prevention of reverse rotation and single‑phasing damage. With clear indication, fail‑safe contact logic, and practical WORK/TEST modes, engineers gain faster commissioning, safer operation, and higher availability.

Need help mapping permissives or tuning delays for cranes, pumps, or compressors? 

Email: tonyzhang@odes.com.cn

or visit: https://www.odes-electric.com/

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