Code Uv1: DC Bus Undervoltage
Issue Description & Safety Warning
The Yaskawa V1000 AC Drive has triggered a critical DC Bus Undervoltage alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Code type: Fault Manual section: Yaskawa V1000 Troubleshooting Input power phase loss. - The main circuit drive input power is wired incorrectly. - Correct the wiring. One of the drive input power wiring terminals is loose. - Ensure there are no loose terminals. - Apply the tightening torque specified in this manual to fasten the terminals. Refer to Wire Gauges and Tightening Torques on page 56 for details. There is a problem with the voltage from the drive input power. - Check the voltage. - Correct the voltage to within range listed in drive input power specifications. The power has been interrupted. Correct the drive input power. Drive internal circuitry has become worn. - Check the maintenance time for the capacitors (U4-05). - Replace the drive if U4-05 exceeds 90%. The drive input power transformer is not large enough and voltage drops after switching on power. Check the capacity of the drive input power transformer.
Source: Yaskawa AC Drive V1000 Compact Vector Control Drive Technical Manual (SIEP C710606 19D)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Yaskawa V1000 AC Drive Alarms
Yaskawa controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code Uv1 on the V1000 AC Drive identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Yaskawa's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 153 Yaskawa V1000 AC Drive codes.
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