3.17 Motor Application Precautions108 YASKAWA SIEPC71061753A GA500 Technical Manual■ Audible NoiseThe audible noise of the motor changes when the carrier frequency setting changes. When you use a high carrierfrequency, audible noise from the motor is equivalent to the motor noise generated when you operate from linepower. If you operate at speeds that are more than the rated rotation speed, the unwanted motor noise increases.◆ Precautions for PM Motors• Contact Yaskawa or your nearest sales representative to use a non-Yaskawa PM motor.• You cannot operate a PM motor from a commercial power supply. If you must operate from a commercialpower supply, use an induction motor.• You cannot operate more than one PM motor from one drive. Use an induction motor and a variable-speedcontrol drive.• In OLV/PM, the motor can operate in the reverse direction for 1/2 turn (electrical angle) at start up.• The quantity of generated starting torque changes when the control method and motor type change. Verify thestarting torque, permitted load characteristics, impact load tolerance, and speed control range before you set upthe motor with the drive. Contact Yaskawa or your nearest sales representative to use a motor that does not meetthese specifications.• In OLV/PM control, braking torque is always 125% or less when operating between 20% and 100% speed. Abraking resistor unit will not change the value. Braking torque is 50% or less when operating at 20% speed orless.• When you use a holding brake in OLV/PM control, release the brake before you start the motor. Failure to setthe correct timing can cause a decrease in speed. Do not use these configurations in applications with heavyloads, for example conveyors or elevators.• To restart a coasting motor that is rotating faster than 120 Hz, first use the Short Circuit Braking function to stopthe motor. A special braking resistor unit is necessary for Short Circuit Braking. Contact Yaskawa or yournearest sales representative for more information.To restart a coasting motor that is rotating slower than 120 Hz, use the Speed Search function.If the motor cable is long, use Short Circuit Braking to stop the motor.Note:The Short Circuit Braking function uses the drive to forcefully cause a short across the motor wires to stop the motor before it has timeto coast to a stop.• You can also use EZOLV to operate synchronous reluctance motors (SynRM). Contact Yaskawa or your nearestsales representative for more information.• If oC [Overcurrent], STPo [Motor Step-Out Detected], or LSo [Low Speed Motor Step-Out] occur duringrestart, try Speed Search again and use the Short Circuit Braking function when you start to adjust the motor.◆ Precautions for Specialized Motors■ Pole Change MotorsThe rated current of pole change motors is different than standard motors. Check the maximum current of themotor before you select a drive. Always stop the motor before you switch between the number of motor poles. Ifyou change the number of poles while the motor is rotating, the overvoltage from regeneration or the overcurrentprotection circuitry will make the motor coast to stop.■ Submersible MotorsThe rated current of a submersible motor is more than the rated current of a standard motor. Use a sufficientlylarge motor cable that will not let voltage drop decrease the maximum torque level.■ Explosion-Proof MotorsYou must test the motor and the drive together for explosion-proof certification. You must also test existinginstallations of explosion-proof motors. The drive is not designed for explosion-proof areas. Install the drive in asafe location.The encoder used with pressure-resistant explosion-proof motors is intrinsically safe. When wiring between thedrive and encoder, always connect through a specialized pulse coupler.
