Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 96)

Drive Overload
96 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
The lower curve in Figure 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.
Again, if fold back of current limit is not enabled in the [Drive OL Mode], 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.
Figure 19 Heavy Duty Boundary of Operation
Current
Lev
el (
P
er Normal)
Time (Seconds)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
1.00 10.00 100.00 1000.00 10000.00