72 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
Motor Overload
The overload capability applies to the rated speed range.
Normal Duty
After continuous operation at the rated output current, overload may be 110%
rated output current (I
L
) for 1 minute as long as it is followed by a period of load
less than the rated current so that the output current over the duty cycle does not
exceed the rated output current (I
L
).
Example:
If the duty cycle requires 110% rated output current for 1 minute of every 10
minutes, the remaining 9 minutes must be at approximately 98% rated current or
less to maintain output current less than 100%. If the requirement is 1 minute out
of 60 minutes, the remaining 59 minutes must be at approximately 99% rated
current or less.
Figure 17 - Illustration of I
L
Heavy Duty
After continuous operation at the rated output current, overload may be 150%
rated output current (I
H
) for 1 minute as long as it is followed by a period of load
less than the rated current so that the output current over the duty cycle does not
exceed the rated output current (I
H
).
Example:
If the duty cycle requires 150% rated output current for 1 minute of every 10
minutes, the remaining 9 minutes must be at approximately 92% rated current or
less to maintain output current less than 100%. If the requirement is 1 minute out
1 minute
9 minutes
1.1 x I
L
Time
Current
I
L
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