User Manual Instruction Manual

Application Notes 13-71
current as shown on the upper curve, current limit may fold back to 100% of the drive
rating until the 10/90 or 5/95 duty cycle has been achieved. For example, 60 seconds
at 110% will be followed by 9 minutes at 100%, and 3 seconds at 150% will be
followed by 57 seconds at 100%. With the threshold for where to take action slightly
above the rated level the drive will only fold back when drive ratings are exceeded.
If fold back of current limit is not enabled in Drive OL Mode (150), the drive will
generate a fault when operation exceeds the rated levels. This fault can not be
disabled. If current limit fold back is enabled then a fault is generated when current
limit is reduced.
The lower curve in Figure 13-19 shows the boundary of heavy duty operation. In
heavy duty, the drive is rated to produce 150% of rated current for 60 seconds, 200%
for three seconds, and 220% for 100 milliseconds. The maximum value for current
limit is 200% so the limit of 220% for 100 milliseconds should never be crossed. If the
load on the drive exceeds the level of current as shown on the upper curve, current
limit may fold back to 100% of the drive rating until the 10/90 or 5/95 duty cycle has
been achieved. For example, 60 seconds at 150% will be followed by 9 minutes at
100%, and 3 seconds at 200% will be followed by 57 seconds at 100%. With the
threshold for where to take action slightly above the rated level the drive will only fold
back when drive ratings are exceeded.
Figure 13.18 – Normal Duty Boundary of Operation
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Current Level (Per Normal)
Time (Seconds)