ABB ACS280, Firmware Manual, Page: 56 / 430

56 Program features
The simplified block diagram below illustrates the process PID control.
The drive contains two complete sets of process PID controller settings that
can be alternated whenever necessary.
Note: Process PID control is only available in external control; see section
Local
and external control locations
on page
26
.
Sleep and boost functions for process PID control
The sleep function is suitable for PID control applications where the
consumption varies, such as clean water pumping systems. When used, it stops
the pump completely during low demand, instead of running the pump slowly
below its efficient operating range. The following example visualizes the
operation of the function.
Example: The drive controls a pressure boost pump. The water consumption
falls at night. As a consequence, the process PID 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 would never stop 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 resumes when the pressure falls under the predefined
minimum level and the wake-up delay has passed.
Process
PID
AI1
Process
actual
values
AI2
• • •
EFB
Setpoint
Speed, torque or
frequency
reference chain
Filter
Limitation