ABB ACS 400 User Manual page 123

Code Description
8121 REG BYPASS CTRL
Regulator by-pass control provides a simple control mechanism without a PID regulator. By-pass control is
needed in special applications only. Example is given in Figure 59 and Figure 60.
0 =
NO
Process PID regulator is in use.
1 =
YES
The process PID regulator is bypassed. The signal connected to the PID Controller actual value pin
(parameter 4006
constant speed motors is referred to this actual value signal instead of the output of the PID regulator.
Mains 3 ~
Figure 59 Regulator bypass control. The capacity of the pumping station (outlet flow) follows the measured
inlet flow.
Output Frequency
Maximum
frequency
Start freq 2
Start freq 1
Low freq 2
Low freq 1
Minimum
frequency
a: No auxiliary motors running
b: One auxiliary motor running
c: Two auxiliary motors running
Figure 60 The relation between the control signal and the frequency of the controlled motor in a three-
motor system.
ACS 400 User's Manual
) is used as the PFC frequency reference. The automatic start and stop of
ACTUAL VAL SEL
Measured Inlet Flow = Reference for the Pumping Station
P1
P2
P3
ACS 400
3 3
3
a
3
Outlet
Pipe 1
3
Outlet
Pipe 2
3
Outlet
Pipe 3
Contactors
b c
M
3~
P1
M
3~
P2
Sewage
Tank
M
3~
P3
Control Signal %
Inlet
Pipe
113