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Motor Application Precautions
îš‹ Using the Inverter for an Existing Standard Motor
Observe the following precautions when using an Inverter for an existing standard motor.
îš„Low Speed Ranges
If a standard cooled motor is used at low speed the cooling effects are diminished. If the motor is used in con-
stant torque applications in low speed area the motor may overheat. If full torque is required at low speed con-
tinuously an externally cooled motor must be used.
îš„Installation Withstand Voltage
If the inverter is used with an input voltage of 440 V or higher and long motor cables, voltage spikes at the
motor terminals may occur which can damage the motor windings. Please ensure that the motor insulation
class is sufficient.
îš„High-speed Operation
When using the motor at a speed higher than the motor rated frequency (usually 50 Hz), problems may arise in
dynamic balance and bearing durability.
îš„Acoustic Noise
The noise generated in the motor depends on the carrier frequency. The higher the setting the less the gener-
ated noise is.
îš‹ Using the Inverter for Special Motors
Observe the following precautions when using a special motor.
îš„Pole-changing Motor
The rated input current of pole-changing motors differs from that of standard motors. Select an appropriate
Inverter according to the maximum current of the motor.
îš„Submersible Motor
The rated input current of submersible motors is higher than that of standard motors. Therefore, always select
an appropriate Inverter according to the maximum current of the motor.
îš„Explosion-proof Motor
When an explosion-proof motor is used, it must be subjected to an explosion-proof test in conjunction with the
Inverter. This is also applicable when an existing explosion-proof motor is to be operated with the Inverter.
Since the Inverter itself is, however, not explosion-proof, always install it in a safe place.
îš„Gear motor
The speed range for continuous operation differs according to the lubrication method and motor manufacturer.
In particular, continuous operation of an oil-lubricated motor in the low speed range may result in damaging.
If the motor is to be operated at a speed higher than 50 Hz, consult the manufacturer.
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