ABB VFD Fault 5010 — What It Means
Fault 5010 on ABB ACS drives (ACS580, ACS880, ACH580) indicates that the Safe Torque Off (STO) function has been activated. STO is a safety function per IEC 61800-5-2 that removes the gate drive signals from the output IGBTs, preventing the drive from producing torque — without removing main power from the drive. Fault 5010 means the STO circuit has interrupted motor output, either intentionally (safety system request) or due to a wiring or component problem.
Common Causes
- Safety relay or safety PLC opened the STO circuit — The most common cause is intentional. An e-stop button, light curtain, safety mat, or safety relay opened the STO input circuit as designed.
- Loose or broken STO wiring — The STO inputs on ABB drives (terminals STO1+ / STO1- and STO2+ / STO2- on ACS880, or the STO connector on smaller drives) are 24VDC logic signals. A loose wire or connector vibration causes an unintended STO trip.
- Failed safety relay or STO card — The safety relay supplying the STO signal can fail in the open state, permanently activating STO. On ACS880 drives with an STO option card, the card itself can fail.
- Power supply to STO circuit lost — The 24VDC supply powering the safety relay or STO logic is required; loss of this supply removes the STO enable signal.
Step-by-Step Fix {#fix}
- Identify why the STO was activated — Check the machine’s safety system. If an e-stop or guard door is open, close it and reset the safety relay before attempting to restart the drive.
- Check STO input wiring — With drive control power on (main power off), verify 24VDC is present on the STO input terminals (STO1+ and STO2+ on ACS880). No voltage = safety relay de-energized or wiring fault.
- Inspect STO circuit wiring — Trace the wiring from the safety relay output to the drive STO inputs. Look for broken conductors, damaged insulation, or loose terminal connections.
- Test the 24VDC safety supply — Confirm the 24VDC power supply feeding the safety relay is operational. Replace if output voltage is absent or out of tolerance (should be 22–26VDC).
- Reset the drive — After correcting the STO condition, perform a fault reset on the drive (via keypad or digital input). If STO has cleared, the drive should be ready to run.
Parts Often Needed
| Part | Notes |
|---|---|
| Safety relay (24VDC) | Amazon | Match safety relay series (Pilz, Schmersal, Sick, etc.) |
| ABB STO option card (FSIO) | Amazon | ACS880 drives with separate STO option module |
| 24VDC control power supply | Amazon | Replace if STO supply is failed |
| STO wiring (24VDC, shielded) | Amazon | Replace any damaged conductors in the STO circuit |
When to Call a Pro
Modifying or bypassing STO safety circuits is a machinery safety violation and must never be done to get a machine running. Fault 5010 without an obvious safety trigger requires a certified safety engineer and/or ABB service technician to diagnose the STO circuit.