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• General-purpose motor and inverter motor
Induction motors are classified as general-purpose motors (limited speed range) or
inverter motors (wide speed range), based on their cooling capabilities. Therefore,
the motor overload function operates differently between these two motor types.
Example of 200V class motor
Cooling Effect Torque Characteristics
Electronic Thermal
overload
General-purpose Motor
Effective when operated
at 50/60Hz from
commercial power
supply
Base Frequency 60Hz
(V/f for 60Hz, 220V Input Voltage)
For low-speed operation, torque must be
limited in order to stop motor temperature
rise.
error (motor
overload protection)
occurs when
continuously operated at
50/60Hz or less at 100%
load.
Inverter Duty Motor
Effective even when
operated at low speed
(approx. 6Hz)
Base Frequency 60Hz
(V/f for 60Hz, 220V Input Voltage)
Use an inverter duty motor for continuous
operation at low speed.
Electronic thermal
overload protection not
activated even when
continuously operated at
50/60Hz or less at 100%
load.
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