KEB COMBIVERT F5 BASIC Applications Manual page 167

Set Value and Ramp Adjustment
Calculations
© KEB Antriebstechnik, 2002
All rights reserved
Fig. 6.4.9.c Graph with ramp modes
f_soll
f_soll
f_2
f_2
100 Hz
100 Hz
delta_f_2
delta_f_2
variabel
variabel
delta_f
delta_f
konstant konstant
f_1
f_1
delta_f
delta_f
konstant konstant
delta_t
The frequency change per raster scan delta_t (step size delta_f) for the mode
constant ascent is calculated from the ramp time t_ramp and the reference frequency
(100 Hz dependend on ud.2) as follows:
100 Hz
delta_f = —————————
t_rampe / 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:
delta_f(variabel) = delta_f *
For the simplification of the internal calculation as frequency reference 102.4 Hz
(e.g. 204.8 Hz or 409.6 Hz dependend on ud.2) is used :
delta_f(variabel) = delta_f * —————
As a result an error of -2,4 % for the real ramp time occurs. If a certain real ramp
time has to be adjusted, the desired value must be divided by 1.024.
Example:
desired ramp time = 10 s
adjusted ramp time = 10 s / 1.024 = 9.77 s
Name: Basis
KEB COMBIVERT F5-G / B
Functional Description
delta_t delta_f
delta_f
konstant konstant
delta_t
delta_t
delta_f_1
delta_f_1
delta_t
variabel variabel
t_1
f_set
———
100 Hz
f_set
102.4 Hz
Date
06.02.02
t_2
t
t_rampe
Chapter Section Page
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