Notes On Motor Operation - YASKAWA T1000A Technical Manual

i.2 General Safety
u Notes on Motor Operation
n
Using a Standard Motor
Low Speed Range
The cooling fan of a standard motor is usually designed to sufficiently cool the motor at the rated speed. As the self-
cooling capability of such a motor reduces with the speed, applying full torque at low speed will possibly damage the
motor. To prevent motor damage from overheat, reduce the load torque as the motor slows.
Insulation Tolerance
Consider voltage tolerance levels and insulation in applications with an input voltage of over 440 V or particularly long
wiring distances. Contact Yaskawa or your Yaskawa agent for consultation.
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
T1000A lets the user 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 resonance occurs shock-absorbing rubber should be installed around the base of the motor.
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
• Contact Yaskawa or your Yaskawa agent if you plan to use any other synchronous motor not endorsed by Yaskawa.
• 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 rotor position.
• 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.
• 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.
• 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.
• 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.
• 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.
20 YASKAWA ELECTRIC SIEP C710616 30B YASKAWA AC Drive T1000A Technical Manual