Parameter Description              MD280/MD280N User Manual 
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1˖S-curve speed-up/speed-down A 
The output frequency increases or decreases along the straight line. S 
curve is generally used in the applications where start and stop processes 
are relatively flat, such as elevator and conveyor belt.As shown in 
Fig.6 .The speed-up/speed-down time is consistent with the straight 
speed-up/speed-down time.Function code of F4-08 and F4-09 can be 
respectively defined the time proportion  between the S-curve 
starting-segment and finishing-segment for S-curve speed-up/speed-down 
A. 
2˖  S-curve speed-up/speed-down B 
In the speed-up/speed-down curve, the motor rated frequency 
b
 is 
always the point of inflexion on S-curve.As shown in 6-14. S curve is 
generally used in the applications where the high-speed area above the 
rated frequency and short-time speed-up/speed-down. 
When setup frequency is above the rated frequency, 
speed-up/speed-down time is: 
2
45
(() )
99
b
f
tT
f
 u u
. 
Where, 
  Refers to setup frequency, 
b
  Refers to motor rated frequency, 
T
  Refers to the time speed-up from 0 to rated frequency 
b
 
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