Use With Pm Motors; Precautions Concerning Use Of Specialized Motors - YASKAWA GA700 Technical Manual

2.25 Motor Application Precautions
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Audible Noise
The audible noise of the motor varies based on the carrier frequency setting. When using a high carrier frequency,
audible noise from the motor is comparable to the motor noise generated when running from line power.
However, unpleasant motor noise is likely to increase when operating at speeds above the rated rotation speed.
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Use with PM Motors

• Contact Yaskawa or your nearest sales representative if intending to use a PM motor not manufactured by
Yaskawa.
• Motor cannot be operated using a commercial power supply. If it is necessary to achieve operation using
commercial power supply, use an induction motor.
• A multiple number of PM motors cannot be driven using one drive. When such operation is necessary, employ
an induction motor with a variable speed control drive.
• When starting with Open Loop Vector Control for PM motor, the motor may operate in the reverse direction for
up to half turn (electrical angle).
• The amount of generated starting torque differs depending on the control mode and motor type. Set up the
motor with the drive after verifying the starting torque, allowable load characteristics, impact load tolerance,
and speed control range. Contact Yaskawa or your nearest sales representative when planning to use a motor
that does not fall within these specifications.
• In Open Loop Vector Control for PM motors, braking torque is less than 125% when running between 20% and
100% speed, even with a braking resistor unit. Braking torque drops to less than 50% when running at less than
20% speed.
• In Open Loop Vector Control for PM motors, the allowable load inertia moment is approximately 50 times
higher than the motor inertia moment. Use the Closed Loop Vector Control for PM for applications with a larger
inertia moment.
• When using a holding brake in Open Loop Vector Control for PM motors, release the brake prior to starting the
motor. Failure to set the proper timing can cause speed loss. Note that such configurations must never be used
for applications where heavy loads are handled, such as for conveyors or elevators in particular.
• To restart a coasting motor rotating over 200 Hz while in V/f Control, first use the Short Circuit Braking
function to bring the motor to a stop. Short Circuit Braking requires a special braking resistor unit. Contact
Yaskawa or your nearest sales representative for details.
To restart a coasting motor rotating below 200 Hz, use the Speed Search function.
If the motor cable is relatively long, stop the motor using Short Circuit Braking.
Note:
The Short Circuit Braking function uses the drive to forcefully produce a short across the wires of the motor, causing it to stop before it
has time to coast to a stop.
• EZ open loop vector control can also be used to operate synchronous reluctance motors (SynRM). Contact
Yaskawa or your nearest sales representative for details.
• When replacing the encoder of a PM motor due to encoder failure, put the motor in the state where it can rotate
and execute Z Pulse Offset Tuning or PM Rotational Auto-Tuning.
• If oC [Overcurrent], STPo [Pull-Out Detection], or LSo [LSo Fault] occur during restart, retry Speed Search
and use the Short Circuit Braking function when starting to adjust the motor.
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Precautions Concerning Use of Specialized Motors

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Pole Change Motor
The rated current of pole change motors differs from that of standard motors. Check the maximum current of the
motor before selecting a drive. Always stop the motor before switching between the number of motor poles. If the
number of poles is changed while the motor is turning, the motor will coast to stop due to overvoltage from
regeneration or the overcurrent protection circuitry.
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Submersible Motors
The rated current of a submersible motor is greater than that of a standard motor, so select the drive accordingly.
Use a motor cable large enough to avoid decreasing the maximum torque level from voltage drop caused by a
long motor cable.
102 YASKAWA ELECTRIC SIEP C710617 01B YASKAWA AC Drive GA700 Technical Manual