YASKAWA CIMR-VU BA0001 Technical Manual page 21

High Speed Operation
Problems may occur with the motor bearings and dynamic balance of the machine when operating a motor beyond its rated
speed. Contact the motor or machine manufacturer.
Torque Characteristics
Torque characteristics differ compared to operating the motor directly from line power. The user should have a full
understanding of the load torque characteristics for the application.
Vibration and Shock
The drive settings allow the user to choose between high carrier PWM control and low carrier PWM. Selecting high carrier
PWM can help reduce motor oscillation.
Take particular caution when using a variable speed drive for an application that is conventionally run from line power at a
constant speed. If mechanical resonance occurs, install shock-absorbing rubber around the base of the motor and enable the
Jump frequency selection parameter to prevent continuous operation in the resonant frequency range.
Audible Noise
Noise created during run varies by 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. Operating above the rated r/min, however,
can create unpleasant motor noise.
n Using a Synchronous Motor
• Synchronous motors cannot be started directly from line power. Applications requiring line power to start should use an
induction motor with the drive.
• A single drive is not capable of running multiple synchronous motors at the same time. Use a standard induction motor for
such setups.
• At start, a synchronous motor may rotate slightly in the opposite direction of the Run command depending on parameter
settings and motor type.
• The amount of starting torque that can be generated differs by each control mode and by the type of motor being used. 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 Yaskawa agent if you plan to use a motor that does not fall within these specifications.
• Braking Torque: In Open Loop Vector Control for PM motors, braking torque is less than 125% when running between
20% to 100% speed, even with a braking resistor. Braking torque drops to less than half when running at less than 20%
speed.
• Load Inertia: In Open Loop Vector Control for PM motors, the allowable load inertia moment is approximately 50 times
higher than the motor inertia moment or less. Contact Yaskawa or your Yaskawa agent concerning applications with a larger
inertia moment.
• Holding Brake: 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 result in speed loss. Not for use with conveyor, transport, or hoist type
applications.
• Restarting a Coasting Motor: To restart a coasting motor rotating at over 200 Hz while in the V/f control mode, use the Short
Circuit Braking function to first bring the motor to a stop. Short Circuit Braking requires a special braking resistor. Contact
Yaskawa or your Yaskawa agent for details.
Speed Search can be used to restart a coasting motor rotating slower than 200 Hz. If the motor cable is relatively long,
however, the motor should instead be stopped using Short Circuit Braking, which forces the motor to stop by creating a
short-circuit in the motor windings.
n
Applications with Specialized Motors
Multi-Pole Motor
Because the rated current will differ from a standard motor, be sure to check the maximum current when selecting a drive.
Always stop the motor before switching between the number of motor poles. If a regen overvoltage (oV) fault occurs or if
overcurrent protection (oC) is triggered, the motor will coast to stop.
Submersible Motor
Because motor rated current is greater than a standard motor, select the drive capacity accordingly. Be sure to use a large
enough gauge motor cable to avoid decreasing the maximum torque level on account of voltage drop caused by a long motor
cable.
YASKAWA ELECTRIC SIEP C710606 18F YASKAWA AC Drive – V1000 Technical Manual
i.3 Application Precautions
21