Siemens Drive Fault Code 7902

Use a digital multimeter and, if available, a megohmmeter.

If the above points pass but the fault persists, suspect drive hardware:

Before diving into causes, it helps to recognize how this fault manifests: siemens drive fault code 7902

In some applications, immediate trip on overtemperature is too aggressive. You can modify the response:

Warning: Delaying trip can destroy motor winding insulation. Only do this if you have secondary protection (e.g., external thermal switch). Use a digital multimeter and, if available, a megohmmeter

Yes, by setting p0600 = 0 (disable temperature monitoring). However, this removes overtemperature protection – emergency use only.

| Cause | Description | |-------|-------------| | PLC stop | Controller switched to STOP mode, stopped sending cyclic data | | Cable issue | PROFIBUS/PROFINET cable disconnected, damaged, or poorly terminated | | Connector fault | Loose or broken fieldbus connector (especially PROFIBUS 9-pin D-sub) | | Configuration mismatch | Telegram configuration (e.g., telegram type, length) differs between drive and PLC | | Bus overload | Excessive bus cycle time or high bus load causing intermittent telegrams | | Parameter error | p2040 (telegram monitoring time) set too low | | Master failure | Fieldbus master (PLC) power cycle or hardware fault | | Interference | Electromagnetic interference (EMI) on bus cable | In some applications, immediate trip on overtemperature is

| Drive Family | Fault Code | Notes | |--------------|------------|-------| | Sinamics S120 | F07902 | Also logs additional info in r0949 (phase affected: 1=U, 2=V, 3=W) | | Sinamics G120 (CU240E) | F07902 | Can be temporarily inhibited via p2118/p2119 (not recommended for permanent fix) | | Masterdrives (6SE70) | F023 or F024 (older codes) | 7902 appears as “Phase failure output” in newer software versions | | Simotion / Sinamics S150 | F7902 | Same root cause; check also motor holding brake wiring |