Control Techniques Commander SE Advanced User's Manual page 28

Since the ramp rate is defined in s/100Hz and the S ramp parameter is defined in s2/100Hz, the time T for the 'curved' part of
the S can be determined quite easily by dividing the two variables thus:
T = S-ramp rate of change / Ramp rate
Enabling S-ramp increases the total ramp time by the period T since an additional T/2 is added to each end of the ramp in
producing the S.
NOTE
Although the ramp rate can be set to 0.0, there is a minimum ramp time within the software of 0.1s/100Hz.
2.08 Standard ramp voltage
400V drive: 0 ~ 800
200V drive: 0 ~ 400
This voltage is used as the level for standard ramp modes. If it is set too low the machine will coast to rest, and if it is set too
high and no braking resistor is used it may trip on OV. The minimum level should be greater than the voltage produced on the
DC Bus by the highest supply voltage. Normally the DC Bus voltage will be approximately the rms supply voltage x √2.
Care should be taken in the setting of this parameter. It is recommended that the setting should be at least
50V higher than the maximum expected level of the DC Bus voltage. If this is ignored, the motor may fail to
decelerate on a STOP command.
CAUTION
2.09
2.10
This parameter is used to select acceleration ramp rates as follows:
0 Ramp rate selection by terminal input
1 Ramp rate 1 selected
2 Ramp rate 2 selected
3 Ramp rate 3 selected
4 Ramp rate 4 selected
5 Ramp rate 5 selected
6 Ramp rate 6 selected
7 Ramp rate 7 selected
8 Ramp rate 8 selected
9 Ramp rate selection by preset reference selection
When parameter 2.10 is set to 0 the acceleration ramp rate selected depends on the state of bit parameters 2.32, 2.33 &
2.34. These bits are for control by digital inputs such that ramp rates can be selected by external control. The ramp rate
selected depends on the binary code generated by these bits as follows:
28
Programmed
ramp rate
S ramp
acceleration
rate of change
T/2
400V drive: 750 (Eur)
200V drive: 390
Unused parameter
Acceleration ramp selector
0 ~ 9 0
Demanded Speed
Acceleration
Actual Speed
T/2 T/2
T
775 (USA) RW Uni
RW Uni
T/2 t
T
Commander SE Advanced User Guide
Issue Number: 4