ABB ACS320 series, User Manual

Page: 126 / 442

126 Program features

Example
The time scheme below visualizes the operation of the sleep function.
Sleep function for a PID controlled pressure boost pump (when parameter 4022
SLEEP SELECTION is set to INTERNAL): The water consumption falls at night. As a
consequence, the PID process controller decreases the motor speed. However, due
to natural losses in the pipes and the low efficiency of the centrifugal pump at low
speeds, the motor does not stop but keeps rotating. The sleep function detects the
slow rotation, and stops the unnecessary pumping after the sleep delay has passed.
The drive shifts into sleep mode, still monitoring the pressure. The pumping restarts
when the pressure falls under the allowed minimum level and the wake-up delay has
passed.
Wake-up level deviation
(4025)
t < t
sd
Output frequency
Selected process
actual value
Stop
t
sd
= Sleep delay (4024)
Sleep level
(4023)
Start
Wake-up delay
(4026)
t
sd
Reference
Time
Sleep boost step (4031)
Control panel:
PID
SLEEP
Sleep boost time (4030)
Time
Time