Siemens Drive Fault Code 7902 Jun 2026

If the actual speed remains below p2179 while the setpoint is above that threshold for longer than p2177 , the drive trips with F07902.

Siemens Drive Fault Code 7902 is fundamentally a . While alarming, it is rarely a "ghost fault." In 80% of field cases, the culprit is a failing mains contactor or an incorrectly set mains voltage parameter. By methodically isolating the power path—from the incoming line through the contactor, precharge resistor, and DC link to the motor—you can resolve the issue without unnecessary component replacement. Siemens Drive Fault Code 7902

Siemens Drive Fault Code 7902 is your drive’s way of saying: “I want to move, but something is holding me back.” The vast majority of cases are purely mechanical or application-related. By following the structured diagnostic approach above—starting with manual rotation and ending with parameter optimization—you can quickly restore operation and implement permanent fixes. If the actual speed remains below p2179 while

All Siemens Power Modules contain a precharge resistor (or a PTC thermistor) that limits inrush current. If this resistor fails open-circuit, the DC link capacitors cannot charge at all, triggering an immediate 7902. A failed resistor often smells burnt or shows visible cracking. By methodically isolating the power path—from the incoming

In rare cases, the internal ADC (Analog-to-Digital Converter) on the Control Unit that measures the DC link voltage drifts out of calibration. The drive may physically have a good DC link, but the CU "sees" a low voltage and triggers 7902.