Yaskawa drive alarm no R91, should be A910. A910, A710 and A720 all have overload alarm, among which A710 is an instantaneous overload alarm and A720 is a continuous overload alarm. Alarm reason: power line phase sequence error; Servo drive failure; Motor power mismatch; Mechanical part stuck;
Solution: Confirm the power wire wiring is correct; Confirm that the drive is normal; Confirm that the mechanical part is not stuck; Re-study the load and calculate the motor power.