For persistent cases, Siemens technical support can analyze a drive trace (via Startdrive recording function) to pinpoint whether the fault is load-related or hardware-related. Keep your motor parameters accurate, your cooling vents clean, and your sensor wiring intact—and fault 7902 will become a rare visitor in your maintenance log.
. This typically occurs when the drive loses synchronism with the motor, meaning the motor is unable to rotate at the speed commanded by the inverter. Common Causes Missing Motor Data Identification
If the fault occurs when trying to start a motor that is already spinning (coasting), enable the "Flying Restart" function ( Adjust Fault Limits:
The load on the motor is significantly higher than its rated capacity, preventing it from reaching the set speed. Incorrect Motor Data:
The actual motor speed has exceeded the p2162 (overspeed threshold) value for longer than the time set in p2163 .
| Solution | Action | |----------|--------| | Restart communication | Cycle PLC power or reinitialize bus from master | | Correct telegram mismatch | Set same telegram type (e.g., Standard Telegram 1) in both PLC hardware config and P0922 | | Adjust monitoring time | Increase P2040 to 200–500 ms to avoid nuisance trips | | Re-parameterize drive | Load factory defaults (p0010=30, p0970=1) and reconfigure fieldbus settings | | Replace/repair bus cable | Check continuity, shielding, and termination |
Use a digital multimeter and, if available, a megohmmeter.
For persistent cases, Siemens technical support can analyze a drive trace (via Startdrive recording function) to pinpoint whether the fault is load-related or hardware-related. Keep your motor parameters accurate, your cooling vents clean, and your sensor wiring intact—and fault 7902 will become a rare visitor in your maintenance log.
. This typically occurs when the drive loses synchronism with the motor, meaning the motor is unable to rotate at the speed commanded by the inverter. Common Causes Missing Motor Data Identification siemens drive fault code 7902
If the fault occurs when trying to start a motor that is already spinning (coasting), enable the "Flying Restart" function ( Adjust Fault Limits: For persistent cases, Siemens technical support can analyze
The load on the motor is significantly higher than its rated capacity, preventing it from reaching the set speed. Incorrect Motor Data: This typically occurs when the drive loses synchronism
The actual motor speed has exceeded the p2162 (overspeed threshold) value for longer than the time set in p2163 .
| Solution | Action | |----------|--------| | Restart communication | Cycle PLC power or reinitialize bus from master | | Correct telegram mismatch | Set same telegram type (e.g., Standard Telegram 1) in both PLC hardware config and P0922 | | Adjust monitoring time | Increase P2040 to 200–500 ms to avoid nuisance trips | | Re-parameterize drive | Load factory defaults (p0010=30, p0970=1) and reconfigure fieldbus settings | | Replace/repair bus cable | Check continuity, shielding, and termination |
Use a digital multimeter and, if available, a megohmmeter.
