Code ov (Fault): Overvoltage

Code type: Fault Manual section: Yaskawa A1000 Troubleshooting Deceleration time is too short and regenerative energy is flowing from the motor into the drive. - Increase the deceleration time (C1-02, C1-04, C1-06, C1-08). - Install a dynamic braking option. - Enable stall prevention during deceleration (L3-04 = 1). Stall Prevention is enabled as the default setting. Fast acceleration time causes the motor to overshoot the speed reference. - Check if sudden drive acceleration triggers an overvoltage alarm. - Increase the acceleration time. - Use longer S-curve acceleration and deceleration times. - Enable the Overvoltage Suppression function (L3-11 = 1). - Lengthen the S-curve at acceleration end. Excessive braking load. The braking torque was too high, causing regenerative energy to charge the DC bus. Reduce the braking torque, use a dynamic braking option, or lengthen decel time. Surge voltage entering from the drive input power. Install a DC reactor. Note: Voltage surge can result from a thyristor convertor and phase advancing capacitor using the same input power supply. Ground fault in the output circuit causing the DC bus capacitor to overcharge. - Check the motor wiring for ground faults. - Correct grounding shorts and turn the power back on. Improper Setting of Speed Search related parameters. (Includes Speed Search after a momentary power loss and after a fault restart.) - Check the settings for Speed Search-related parameters. - Enable Speed Search restart function (b3-19 greater than or equal to 1, up to 10). - Adjust the current level during Speed Search and the deceleration time (b3-02 and b3-03 respectively). - Perform Stationary Auto-Tuning for line-to-line resistance and then enable Speed Estimation Speed Search (b3-24 = 1). Drive input power voltage is too high. - Check the voltage. - Lower drive input power voltage within the limits listed in the specifications. The braking transistor is wired incorrectly. - Check braking transistor wiring for errors. - Properly rewire the braking resistor device. PG cable is disconnected. Reconnect the cable. PG cable wiring is wrong. Correct the wiring. Electrical signal interference along the PG encoder wiring. Separate the wiring from the source of the noise (often the output lines from the drive). Drive fails to operate properly due to electrical signal interference. - Review the list of possible solutions provided for controlling noise. - Review the section on handling electrical signal interference and check the control circuit lines, main circuit lines, and ground wiring. Load inertia has been set incorrectly. - Check the load inertia settings when using KEB, overvoltage suppression, or Stall Prevention during deceleration. - Adjust the load inertia ratio in L3-25 to better match the load. Braking function is being used in OLV/PM. Connect a braking resistor. Motor hunting occurs. - Adjust the parameters that control hunting. - Set the gain for Hunting Prevention (n1-02). - Adjust the AFR time constant (n2-02 and n2-03). - Adjust the speed feedback detection suppression gain for PM motors (n8-45) and the time constant for pull-in current (n8-47).