Power line phase error; confirm the mechanical part without blocking; servo driver failure; solution and A720 are overload alarm; should be A910; A720 for continuous overload alarm; confirm the drive is normal. A910 & A710: make sure the power line is properly wired. The cause of the alarm, where A710 is the instantaneous overload alarm; mechanical locked; motor power does not match; to study the load, motor power calculation of Yaskawa driving alarm without R91