167 
 
The motor is self-cooled so the overload tolerance falls when the motor speed is decreased. 
The Electrothermal relay trigger level changes according to the motor overload characteristics 
to protect the motor from overheat throughout the entire speed range.   
Overlaod Characteristics 
(when motor load is 100%) 
150
100
90
60
50
Torque
(%)
0
5 33 100
Speed(%)
(60Hz)
60 seconds
Continuous
Rated speed=100% speed 
Motor to operate from 
line power. 
Motor cooling is most 
effective when 
running at 50/60 Hz   
Running continuously at below 
50/60 Hz triggers an oL1 fault. 
A fault is output and the motor 
will coast to stop.   
2 : Drive Dedicated Motor (Constant Torque Range 1 : 10)     
The motor is allowed to run with 100% load from 10% to 100% speed. When the motor runs 
slower with 100% load, an overload fault will be triggered.   
Overlaod Characteristics 
(when motor load is 100%) 
150
100
90
55
50
Torque
(%)
0 1
10
100 Speed (%)
(60Hz)
60 seconds
Continuous
Rated speed=100% 
speed
Motor cools itself 
effectively even at low 
speeds (about 6 Hz) 
Continuous run from 6 Hz to   
60 Hz 
3 : Vector Motor (Constant Torque Range 1 : 100)   
The motor is allowed to run with 100% load from 1% to 100% speed. When the motor runs 
slower with 100% load, an overload fault will be triggered.