: The default delay time for stall detection is too short for high-inertia loads. siemens drive fault 7902 - Click2Electro
. This critical protection fault occurs when the drive detects that the difference between the set speed and actual speed has exceeded a defined tolerance for too long, often because the motor cannot generate enough torque to overcome the load. Siemens SiePortal 1. Primary Causes of F7902 Mechanical Overload:
Siemens drive systems are industry standards for precision motor control. However, like all sophisticated automation hardware, they occasionally trigger faults to protect the equipment from catastrophic failure. One common error encountered by automation engineers and maintenance technicians using SINAMICS drives (such as the G120, S120, or V90 series) is , which stands for "Motor stalled."
A stalled motor fault rarely stems from a single isolated issue. It is typically triggered by a combination of mechanical resistance, incorrect electrical parameters, or hardware degradation. The root causes generally fall into four categories: 1. Mechanical Blockages and Overload
Line 4 was the heart of the factory, a massive Siemens-driven servo press responsible for churning out the chassis plates for the new electric vehicle contract. If it was down, the morning shift would start with a disaster, and the plant manager would be breathing down everyone's necks before sunrise.
[F07902 Motor Stalled Fault] │ ┌────────────────┼────────────────┐ ▼ ▼ ▼ Mechanical Electrical Software & Obstructions Failures Parameters ├─ Jammed load ├─ Bad phases ├─ Missing Motor ID ├─ Seized brg ├─ Brake issue ├─ Low current limits └─ Overload └─ Loose wire └─ Strict tolerances 1. Mechanical Jamming and Overload
Motor cables (U, V, W) are connected improperly, or the encoder signal is reversed (if applicable). Premature Startup: Motor excitation time ( p0346p 0346
When encountering fault code 7902, follow these steps to troubleshoot and potentially resolve the issue:
If the drive is in closed-loop control (p1300 = 21) and the encoder signal is faulty, the drive may get conflicting data.
The drive lacks accurate motor nameplate parameters (e.g., rated power, current, or power factor), leading to inefficient torque calculation. Incomplete Commissioning: Skipping the Motor Data Identification
Based on Siemens technical support forums and real-world case studies, the F07902 fault rarely has a single cause. It typically falls into one of the following categories:
: The drive is unable to provide enough torque to move the load because limits (p0640) are set too low.
