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.
Here are the most common failure paths on the Yaskawa Sigma-7 when servo overcurrent is the reported condition. Frequency reflects real field reports; First Check is the remote step to take before sending us your 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: "Repair Yaskawa SGD7S (Sigma-7) Servo Drive — Overcurrent Alarm" by Jess Technology — embedded from YouTube; loads only after you 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 us the error code, a photo of the screen and what you already tried — an independent specialist reviews your case and replies with an evaluation, typically within 24 hours.
Submit Your CaseSend 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.
Before changing drive parameters or replacing parts, verify against the official documentation from Yaskawa:
Tip: for simple issues, a general-purpose AI assistant can help you interpret a fault code — but always cross-check any corrective action against the official manual before applying it.
A servo fault on a CNC platform with a similar remote path.
Another controller-side fault needing config review.
Full machinery controller troubleshooting collection.