KEB COMBIVERT F4-C - Page 133

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ANTRIEBSTECHNIK
6
417
KEB COMBIVERT F4-C
Name: Basis
28.01.98
6
© KEB Antriebstechnik, 1997
All Rights reserved
Functional DescriptionSet Value and Ramp Adjustment
Section
Page
Date
Chapter
Calculations The frequency change per raster scan delta_f (step size delta_f) for the mode constant
ascent is calculated from the ramp time t_ramp and the reference frequency (100
Hz) as follows:
100 Hz
delta_f = ————————-
t_ramp / delta_t
For different set values the real ramp time is calculated according to following formula:
f_set
t = t_ramp * ————
100 Hz
The actual step size for the mode constant time is calculated from the step size
delta_f and the actual set value f_set as follows:
f_set
delta_f(variable) = delta_f * ————-
100 Hz
To simplify the internal calculation the reference frequency 102.4 Hz is used:
f_set
delta_f(variable) = delta_f * —————
102.4 Hz
This results in an error of -2.4% for the real ramp time. If a specific real ramp time is
to be adjusted multiply the desired value with factor 1.024. Example:
desired ramp time = 10 s
adjusted ramp time = 10 s * 1.024 = 10.24 s