Code ov (Alarm): DC Bus Overvoltage
Issue Description & Safety Warning
The Yaskawa A1000 AC Drive has triggered a critical DC Bus Overvoltage 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 Surge voltage present in the drive input power. - Install a DC reactor or an AC reactor. - Voltage surge can result from a thyristor convertor and a phase advancing capacitor operating on the same drive input power system. The motor is short-circuited. - Check the motor power cable, relay terminals and motor terminal box for short circuits. - Correct grounding shorts and turn the power back on. Ground current has over-charged the main circuit capacitors via the drive input power. Electrical signal interference causes the drive to operate incorrectly. - Review possible solutions for handling electrical signal interference. - Review section on handling electrical signal interference and check control circuit lines, main circuit lines and ground wiring. - If the magnetic contactor is identified as a source of noise, install a surge protector to the MC coil. Set number of fault restarts (L5-01) to a value other than 0. PG cable is disconnected. Reconnect the cable. PG cable wiring is wrong. Correct the wiring. Electrical signal interference along PG encoder wiring. Separate PG wiring from the source of the noise (often output wiring from the drive).
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 ov (Alarm) 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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