Siemens Simovert Masterdrives Compendium page 235

Functions
NOTE
Rated speed (U856)
Rated acceleration
(U857)
7-26
The AVWF, which is entered in P169 for the figured before the decimal
point and in P170 for the figures after the decimal point, can be entered
as a decimal with a maximum of 8 figures. Alternatively, the AVWF
parameters can be entered as a gearbox factor (fraction)
numerator/denominator, P180.1, P180.2 of the motor encoder.
The rated speed is a reference value used to represent speed.
The AVWF is also used to calculate the rated speed U656 which, in the
factory setting, is 12288.00 [1000 LU/Min]. If this value is changed, the
basic unit parameter P205 (rated V) must also be set to the same
value, ignoring the figures after the decimal point.
Rated V = resolution x AVWF factor x reference speed x 10
Rated V: U856
Resolution: P171 [FD 330.3]
AVW factor: P169, P170 or P180, P181 [FD 330.3]
Reference speed: P353 [FD 20.5]
The rated V is specified in 1000 LU/min and the reference speed in
rpm.
In the factory setting, the resolution of 2
an AVWF = 1.0 and 3000 rpm results in a rated speed of 12 288 000
LU/min. This speed then corresponds to 100% in the equipment.
In the example, the rated V derived from:
131 072 [LU/rev.], an AVWF of 0.71905288 [AVWF] and 3000 rpm
rated motor speed results in a rated speed of 282743097 [LU/min].
17
U856 = rated V = 2
= 282743.096 in 1000 LU/min
The value is entered in 1000 LU/min with 2 decimal places
= 282743.09 in 1000 LU/min
The acceleration represents the change of speed (LU/min) within a time
unit.
The rated acceleration is defined as the rate at which the drive
accelerates from v = 0 to the rated speed (rated V) in t = 1 sec.
The following equation is used to calculate this:
Rated acceleration = U857 (in 1000 LU/s
Rated speed = U856 (in 1000 LU/min)
U ( 857 r ) ated accelerati
12
= 4096 increments/revolution,
x 0.71905288 [IBF] x 3000 [rpm] x 10
2
)
rated speed U ( 856
=
on
×
60 t
6SE7087-6QX70 (Version AK)
Compendium Motion Control
09.2008
-3
-3
)
Siemens AG
SIMOVERT MASTERDRIVES