904
LOW LINE VOLTAGE FAULT
Otis · DSD 412 Elevator System
What does 904 mean?
The AC input power has dropped below 80% of the Nominal AC Line Voltage #9 for 3 consecutive cycles or lower than 50% for one cycle. This sets the Severe Fault flag and forces the DSD 412 current reference to zero, shutting down the drive.
Common Causes
- AC input power issues (voltage sag or prolonged low voltage).
Repair Steps & Checklist
Click steps to track your progress.
- 1
Measure the AC input power voltage to ensure it stays above 80% of Nominal AC Line Voltage #9.
- 2
Verify the stability of the AC input power supply.
Verified technical data. Last updated: March 2026
Related Faults
Source: Otis DSD 412 Elevator System