6.10 Troubleshooting without Fault DisplayYASKAWA ELECTRIC SIEP C710616 27C YASKAWA AC Drive A1000 Technical Manual 341Troubleshooting6◆ Motor Rotates After the Drive Output is Shut Off (Motor Rotates During DC InjectionBraking)◆ Output Frequency is not as High as Frequency Reference◆ Buzzing Sound from Motor at 2 kHz◆ Unstable Motor Speed when Using PM◆ Motor Does Not Restart after Power LossCause Possible SolutionsDC Injection Braking is set too low and the drive cannot decelerateproperly.• Adjust the DC Injection braking settings.• Increase the current level for DC Injection Braking (b2-02).• Increase the DC Injection Braking time at stop (b2-04).The stopping method is set so that the drive coasts to stop. Set b1-03 (Stopping Method Selection) to 0 or 2.Cause Possible SolutionsFrequency reference is set within the range of the Jump frequency. • Adjust the parameters used for the Jump frequency function (d3-01, d3-02, d3-03).• Enabling the Jump frequency prevents the drive from outputting the frequencies specified in the Jump range.Upper limit for the frequency reference has been exceeded.• Set the maximum output frequency and the upper limit for the frequency reference to more appropriate values (E1-04, d2-01).• The following calculation yields the upper value for the output frequency = E1-04 x d2-01 / 100Large load triggered Stall Prevention function during acceleration. • Reduce the load.• Adjust the Stall Prevention level during acceleration (L3-02).Cause Possible SolutionsExceeded 110% of the rated output current of the drive whileoperating at low speeds.• If the output current rises too high at low speeds, the carrier frequency is automatically reduced and causes a whiningor buzzing sound.• If the sound is coming from the motor, disable carrier frequency derating (L8-38 = 0).• Disabling the automatic carrier frequency derating increases the chances of an overload fault (oL2). Switch to a largercapacity motor if oL2 faults occur too frequently.Cause Possible SolutionsThe motor code for the PM motor (E5-01 or T2-02) is setincorrectly (Yaskawa motors only). Refer to Motor Performance Fine-Tuning on page 296 for details.Drive is attempting to operate the motor beyond the speed controlrange listed in the specifications. Check the speed control range and adjust the speed accordingly.Motor hunting occurs. Refer to Motor Performance Fine-Tuning on page 296 for details.Hunting occurs at start. Increase the S-curve time at the start of acceleration (C2-01).Too much current is flowing through the drive.• Enter the correct motor code for the PM motor being used into E5-01.• For special-purpose motors, enter the correct data to all E5 parameters according to the test report provided for themotor.Cause Possible SolutionsThe Run command was not issued again when power was restored. • Check the sequence and wiring that has been set up to enter the Run command.• A relay should be set up to make sure the Run command remains enabled throughout any power loss.The relay that is supposed to maintain the Run command has beenswitched off. Check wiring and circuitry for the relay intended to keep the Run command enabled.
