Watson-Marlow MM440 - Manual (Page 246)

3 Functions Issue 10/06
MICROMASTER 440 Operating Instructions
246 6SE6400-5AW00-0BP0
¾ Closed-loop controlled operation down to ≈ 1 Hz
¾ Can start in the closed-loop controlled mode (immediately after the drive has
been energized)
¾ The low frequency range (0 Hz) is passed-through in closed-loop controlled
operation
f
t
P1755
Closed loop
Open loop
Start f
t
Closed loop
Open loop
Zero crossing
P1755
P1755
Fig. 3-103 Starting and passing-through 0 Hz in closed-loop controlled operation
The following advantages are obtained as a result of closed-loop controlled
operation down to approx. 1 Hz (this can be selected using parameter P1755) as
well as also the possibility to immediately start closed-loop controlled at 0 Hz or to
reverse closed-loop controlled (this can be set using parameter P1750):
¾
No changeover operation is required within the closed-loop control
(smooth behavior – no frequency dips)
¾ Continuous closed-loop speed-torque control is possible down to approx. 1 Hz.
NOTE
For closed-loop controlled reversing or closed-loop controlled starting from 0 Hz it
must be taken into account that when staying too long (> 2 s or > P1758) in the
range around 0 Hz, that the closed-loop control automatically changes-over from
closed-loop into the open-loop controlled mode.