The Sigma-7 drive trips an overcurrent alarm the moment the motor is enabled or under load, halting the axis while the controller logs a servo fault.
These are the failure paths we see most often on the Yaskawa Sigma-7 for a servo overcurrent condition. Likelihood reflects field frequency; First Check is what you can do remotely before sharing logs.
| Cause | Likelihood | First Check |
|---|---|---|
| Mechanical bind or overload raising phase current | High | Jog the axis slowly by hand with the drive off and feel for a hard stop |
| Tuning too aggressive (high gain / short settling) for the load | Medium | Compare the gain and filter settings to the machine's proven tuning |
| Motor or encoder cable short / contamination | Medium | Inspect the cable for damage and measure insulation at the connector |
| Wrong motor parameter or capacity mismatch | Low–Medium | Confirm the drive's motor ID and capacity setting matches the attached motor |
Work through these in order. Each step is something you can perform and report back on without opening the enclosure or swapping parts.
Record the exact Sigma-7 alarm code and when it trips — at enable, at speed, or under load. The trigger separates tuning from a hard fault.
With the drive disabled, move the axis by hand through its travel. A hard spot that appears only under power means mechanical load, not electronics.
Read the gain, filter and rigidity parameters and compare to the proven tuning. Over-aggressive gains spike current at enable and trip the drive.
Inspect the motor and encoder cables for damage or moisture and measure insulation at the connector. A partial short shows as overcurrent without a bind.
Verify the drive's motor ID and capacity match the attached motor. A mismatch makes the drive push wrong current and trip.
A Sigma-7 overcurrent is most often mechanical load or tuning, not a failed drive. The trip timing and a hand-jog comparison tell us whether to retune or look at the motor path. Cross-reference the broader collections: Overcurrent / overload alarm · Servo & drive control.
Video ID is a placeholder. Replace REPLACE_WITH_REAL_ID with the real YouTube video ID before publishing; the facade loads youtube-nocookie only after a click.
Rarely. We separate mechanical load, tuning and cable faults from a truly failed drive using the trip timing and insulation check.
Sometimes, but only after confirming there is no bind. Lowering gain to hide a mechanical fault can let it run damaged. We check load first.
An insulation check on the motor cable answers it. A short there trips overcurrent; a clean cable points to tuning or load.
Send the alarm code and the trip timing. We separate load, tuning and cable faults remotely so you avoid swapping a good drive.
Submit Your Case Connect With SpecialistsWe do not perform hardware repair, we do not replace parts, and we cannot promise a 100% resolution. Our role is limited to remote diagnostic and step-by-step guidance based on the information, photos and logs you share.
A servo fault on a CNC platform with a similar remote path.
Another controller-side fault needing config review.
Full machinery controller troubleshooting collection.