Sinamics Error Code F07900 / F07901 / F07902 Explained

Sinamics Error Code 7900 Series: What It Means and How to Fix It

The F07900 fault family is one of the most common alarm clusters you will see on a Siemens SINAMICS drive. These codes all point to the same subsystem: the drive's motor protection and current monitoring logic. Understanding which code fired — and what hardware or parameter condition triggered it — is the difference between a 15-minute fix and a wasted day of parts-swapping.

What Each Code Means

Siemens groups these faults tightly, but each has a distinct trigger. Knowing the difference saves diagnostic time.

F07900 — Motor Overload (I²t)

The drive's thermal model calculated that the motor has been running above its rated current long enough to threaten winding insulation. This is a software-model fault, not a hardware sensor trip. The drive integrates (current² × time) and compares it against the motor's thermal time constant, both of which come from your parameter settings. If the nameplate data is entered incorrectly — especially rated current — the model will be wrong and can false-trip or fail to protect.

F07901 — Motor Overcurrent

The measured phase current exceeded the instantaneous overcurrent threshold. This is a hardware-detected event: the drive's current sensors saw a spike above the programmed limit. Common causes are a short in the motor cable, a winding fault, a bearing-seized load that stalls the motor, or an incorrect current limit parameter that is set too low for the application.

F07902 — Motor Phase Current Asymmetry / Imbalance

The drive detected a significant imbalance between phase currents. One or more phases is carrying materially more or less current than the others. This almost always means a wiring problem (loose terminal, damaged cable, blown fuse on one phase) or a motor winding fault. It can also appear after a connector is re-landed incorrectly following maintenance. Note that exact fault text wording for F07902 varies by SINAMICS series — consult the parameter manual for your specific platform.

F07490 — Motor Data Identification Failed

When you run the SINAMICS motor data identification routine, the drive applies controlled test signals and measures actual motor parameters. F07490 fires when that identification run fails or produces results outside expected bounds. Causes include incorrect nameplate data entered before the ID run, a motor that is not properly coupled or is under mechanical load during the ID test, or a cable/connection fault preventing valid measurements. Fault code availability and exact descriptions vary by SINAMICS platform — verify against the parameter manual for your specific variant (G120, S120, etc.).

Diagnostic Procedure

Work through these steps in order. Most F07900-series faults resolve at step 3 or 4 without touching hardware.

1. Read the fault buffer, not just the active fault. On the operator panel or via STARTER/Startdrive software, navigate to the fault history buffer. The fault value stored alongside the fault code often encodes which phase or which threshold was exceeded — the exact parameter number varies by SINAMICS variant and firmware version; consult the parameter manual for your platform. Write this down — it narrows the search significantly.
2. Compare motor nameplate to entered parameters. Pull up the motor data parameter group. Check rated current, rated voltage, rated frequency, rated speed, and rated power factor against the physical nameplate. A single transposed digit in rated current will throw off every protection calculation. This is the single most common cause of false F07900 trips on surplus or replacement motors.
3. Check for mechanical overload. Disconnect the motor from the load mechanically if possible. Jog the motor uncoupled. If the fault clears, the problem is downstream — seized bearings, jammed conveyor, over-tensioned belt, hydraulic pump cavitation, or similar.
4. Inspect motor cables and terminals. With power off and DC bus discharged, check all three output phases at the drive output terminals, any intermediate junction boxes, and the motor terminal box. Look for loose lugs, discoloration from heat, corrosion, or signs of tracking between phases. Measure insulation resistance phase-to-phase and phase-to-ground with a megohmmeter — a degraded motor or cable will show up here before it shows up visually.

5. For F07902 specifically: verify phase rotation and terminal assignments. Re-check that U/V/W at the drive output lands on U/V/W at the motor. A swapped phase does not always cause rotation reversal in every topology — but it will cause current asymmetry.
6. For F07490: re-run motor ID under correct conditions. The motor must be at rest, uncoupled from the load (or at minimum unloaded), and at roughly ambient temperature. Re-enter nameplate data carefully, then trigger the identification routine. The exact menu path and commissioning parameter required to enable motor ID differs between SINAMICS platforms (G120, S120, and others use different commissioning workflows) — refer to the commissioning manual for your specific variant.
7. Check current limit parameters. If nameplate data looks correct and there is no mechanical issue, review the current limit parameters. An integrator who commissioned the drive may have set current limits conservatively for a different motor. Compare the set limit against the motor's rated current and service factor. Specific parameter numbers for current limits differ between SINAMICS variants and firmware versions — consult the parameter manual for your platform.
8. Evaluate the drive output stage. If all of the above check out and faults persist — especially F07901 with no apparent overload — the drive's output IGBTs or current sensing circuit may be damaged. This typically shows up as a fault that trips immediately at enable, even with the motor disconnected. If the fault trips with output terminals open, the drive is the problem.

Common Problems and What They Actually Look Like

When to Replace the Drive

Most F07900-series faults are application or parameter problems — not dead drives. But there are clear signs that the drive hardware is the issue:

• F07901 trips instantly with all output terminals disconnected (motor and cable completely removed).
• Fault value in the buffer points consistently to the same phase, and that phase checks out perfectly on the motor and cable side.
• Drive trips on F07901 at very low commanded current — well below what the motor or load could possibly draw.
• Physical evidence: burn marks, component damage on the power board, or a current sensor that reads non-zero with no motor connected.

At that point, continuing to troubleshoot the application wastes time. The output IGBT module or current measurement circuit is damaged, and the drive needs to be replaced.

Summary

F07900, F07901, F07902, and F07490 are all symptoms of the same question: does the drive's measured or modeled current match what the motor and parameters say it should be? In the majority of field cases the answer is wrong motor data, a mechanical overload, or a single bad terminal. Work through the diagnostic steps methodically before ordering parts. When the drive output stage itself is the culprit, the test is clear — fault with no motor connected — and replacement is straightforward.

For deeper parameter documentation, Siemens maintains the full SINAMICS parameter manual on their industry support portal at support.industry.siemens.com. Search your specific drive variant (G120, S120, G130, etc.) plus "parameter manual" to get the correct document for your firmware version.

Disclaimer: This guide is provided for general information only. Procedures vary by model, series, and firmware version. Industrial equipment can cause serious injury, equipment damage, or downtime if serviced incorrectly. Always consult the manufacturer's official documentation and a qualified professional before performing work, and follow your facility's lockout/tagout and safety procedures. PLC Department is an independent surplus supplier and is not affiliated with or endorsed by the manufacturers referenced. Use this information at your own discretion.