Mains undervoltage
Lenze · SHB4800/4900
What does LU mean?
This fault indicates that the incoming mains voltage has dropped below the permissible operating threshold for the drive. By default, this condition is configured as a Warning, meaning it alerts the operator and is entered into the history buffer, but it does not immediately inhibit pulses. Continued operation under undervoltage can lead to reduced motor performance or potential damage if not resolved promptly.
Complete Troubleshooting Guide
- 1
Measure incoming mains voltage: Use a multimeter to check the voltage at the drive's input terminals and compare it to the drive's minimum operating voltage.
- 2
Check for voltage sags: Monitor the mains supply for temporary voltage drops that might trigger this warning.
- 3
Verify upstream power supply capacity: Ensure the electrical network feeding the drive has sufficient capacity and is not overloaded.
- 4
Inspect power wiring: Check for loose connections or undersized cables that could lead to voltage drop under load.
- 5
Consult with facility electricians: Investigate if there are other heavy loads or issues on the power grid causing voltage fluctuations.