Code Uv: Undervoltage
Issue Description & Safety Warning
The Yaskawa A1000 AC Drive has triggered a critical 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: Alarm / minor fault Manual section: Yaskawa A1000 Troubleshooting Phase loss in the drive input power. Check for wiring errors in the main circuit drive input power. Correct the wiring. Loose wiring in the drive input power terminals. - Ensure the terminals have been properly tightened. - Apply the tightening torque to the terminals as specified. Refer to Wire Gauges and Tightening Torque on page 76 There is a problem with the drive input power voltage. - Check the voltage. - Lower the voltage of the drive input power so that it is within the limits listed in the specifications. Drive internal circuitry is worn. - Check the maintenance time for the capacitors (U4-05). - Replace either the control board or the entire drive if U4-05 exceeds 90%. For instructions on replacing the control board, contact Yaskawa or your nearest sales representative. The drive input power transformer is too small and voltage drops when the power is switched on. - Check for an alarm when the magnetic contactor, line breaker, and leakage breaker are closed. - Check the capacity of the drive input power transformer. Air inside the drive is too hot. Check the temperature inside the drive. The CHARGE light is broken or disconnected. Replace either the control board or the entire drive. For instructions on replacing the control board, contact Yaskawa or your nearest sales representative.
Source: Yaskawa AC Drive A1000 High Performance Vector Control Drive Technical Manual (SIEP C710616 21H)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Yaskawa A1000 AC Drive Alarms
Yaskawa controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code Uv on the A1000 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: 280 Yaskawa A1000 AC Drive codes.
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