YASKAWA U1000 Series - Notes on Motor Operation

i.2 General Safety
YASKAWA ELECTRIC SIEP C710636 02B YASKAWA U1000 Technical Manual 25
◆ Notes on Motor Operation
■ 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 decreases 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.
Figure i.1 shows the allowable load characteristics for a Yaskawa standard motor. A motor designed specifically for
operation with a drive should be used when 100% continuous torque is needed at low speeds.
Figure i.1
Figure i.1 Allowable Load Characteristics for a Yaskawa Motor
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
The U1000 lets the user choose between high carrier PWM control. Selecting Closed Loop Vector Control 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 and
the Jump Frequency function should be enabled to prevent continuous operation in the resonant frequency range.
• Mechanical resonance can occur with long motor shafts and in applications such as turbines, blowers, and fans with
high inertia loads.
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 speed
can create unpleasant motor noise.
50
36
60
60
70
80
90
100
25% ED (or 15 min)
40% ED (or 20 min)
60% ED (or 40 min)
Frequency (Hz)
Continuous operation
Torque
(%)
20
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