Siemens Drive Fault Code 7902 _verified_ May 2026

By following a logical, step-by-step diagnostic process—visual inspection, continuity testing, megger testing, and swap tests—you can pinpoint the cause within an hour. Remember: do not simply reset the fault and restart. Find the physical root cause, or it will return, often with more severe damage (including a burnt motor or drive).

Keywords: Siemens drive fault 7902, F07902 Sinamics, phase failure in motor cable, Siemens drive troubleshooting, motor phase loss detection.

This fault triggers the drive’s built-in monitoring function, which compares the current in all three phases (U, V, W) at the drive’s output. If the current in one phase falls below a specific threshold relative to the others, the drive assumes a cable break or motor winding failure and shuts down to prevent damage. Siemens drives do not rely solely on external sensors. They use internal current measurement at the inverter’s output stage. When the motor is running, the drive expects balanced currents. If one phase deviates by more than a programmable tolerance (typically set via parameter p3230 in Sinamics), the drive triggers fault 7902. siemens drive fault code 7902

Replaced contactor and implemented weekly starter torque check. Fault 7902 eliminated. Conclusion Siemens drive fault code 7902 is unequivocally a power delivery warning . In 95% of cases, the problem is external to the drive: a loose wire, a failing contactor, a damaged cable, or a motor winding opening. Only in about 5% of cases is the drive’s own output stage at fault.

Lastly, document your findings. Keeping a log of recurring 7902 faults can reveal systemic issues like undersized cables, excessive vibration, or environmental contamination (dust, moisture) in the motor terminal box. Consult the official Siemens manual for your specific drive model (function diagrams 8010–8020 for output monitoring). For hands-on help, Siemens Technical Support can provide remote diagnostic assistance using Starter or STARTER software to trace current waveforms in real time. Keywords: Siemens drive fault 7902, F07902 Sinamics, phase

The official Siemens description: “Phase failure in the motor feeder cable.”

If you are staring at a panel displaying “F07902” or “Fault 7902,” you know production has stopped. This article provides a deep dive into what this fault means, why it occurs, and—most importantly—a step-by-step guide to getting your machinery back online. In the Siemens drive ecosystem, fault code 7902 is universally associated with a motor lead or power cable phase failure . Specifically, it indicates that the drive has detected an asymmetry or interruption in the motor’s supply voltage (usually one of the three phases is missing). Siemens drives do not rely solely on external sensors

In the complex world of industrial automation, Siemens drives (ranging from the venerable Masterdrives to the modern Sinamics S120, G120, and S150 families) are known for their robustness. However, like any precision electronic equipment, they occasionally halt production with an error code. Among the more cryptic and frustrating alarms for maintenance technicians is Siemens drive fault code 7902 .