Watson-Marlow MM440 - Manual (Page 251)

Issue 10/06 3 Functions
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0 251
If the speed controller is pre-controlled, then the speed setpoint (r0062) is delayed
with the same smoothing (P1442 or P1452) as the actual value (r1445). This
ensures that when accelerating, there is no setpoint – actual value difference
(r0064) at the controller input which would have been exclusively caused by the
signal propagation time.
When the speed pre-control is activated, it must be ensured that the speed setpoint
is continuously entered and without any significant noise level (avoid torque
surges). An appropriate signal can be generated by smoothing the analog signal
P0753 (refer to Section 3.6.3) or by activating the rounding-off function of the ramp-
function generator P1130 – P1133 (refer to Section 3.12.2).
NOTE
¾
The ramp-up and ramp-down times (P1120; P1121) of the ramp-function
generator (refer to Section 3.12.2) in the setpoint channel should only be set so
fast that when accelerating and braking, the motor speed can follow the
setpoint. This then guarantees the optimum functioning of the speed controller
pre-control.
¾ The starting time r0345 is a measure for the overall moment of inertia of the
machine and describes that time in which the unloaded drive can accelerate
from standstill to the rated motor speed P0311 with the rated motor torque
r0333.
0333 r 60
0311 P 2
0342 P 0341 P
M 60
n 2
T r0345
rated , Mot
rated , Mot
starting
⋅
⋅ π ⋅
⋅ ⋅ =
⋅
⋅ π ⋅
⋅ Θ = =
If these secondary conditions match the particular application, then the starting
time can be used as the shortest value for the ramp-up and ramp-down times.