Siemens SIMATIC S5 Manual page 105

IP 267
The suitable interval for frequency increase and decrease (TI) must be calculated
specifically for each plant. The acceleration and deceleration values with which
the motor can be driven without losing steps are to be found in the docu-
mentation of the motor manufacturer. The values depend on the moment of
inertia of the drive and on the available torque of the motor (
example, frequency increase and decrease is fixed at 50 Hz/ms. The following
therefore applies for calculating the time interval:
50 Hz/ms =
The time interval may not be less than 7. This then corresponds to the following
acceleration ramp:
The value of TI is coded with bits 0 to 7 of byte 2 and written into QB 90 of the PIQ
( Table 6-2.).
The following applies for this example:
EWA 4NEB 812 6061-02a
BV * R
a =
4 * 0.032 ms * TI
40 * R
4 * 0.032 ms * TI
40 * 1
TI =
4 * 0.032 ms * 50 Hz/ms
TI = 6.25
BV * F
a =
4 * 0.032 ms * TI
40 * 1
a =
4 * 0.032 ms * 7
QB 90 =
Application Examples
5.6). In this
= 44.6 Hz/ms
00000111 = 07
H
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