Set Points; Cascade Control - ABB COMMANDER 1900 Series Programming Manual

...4 CONTROL CONFIGURATION LEVEL

...4.1 Set Points

Information.
• Cascade control – comprises two series-connected controllers (master and slave), each containing a complete
measuring and controlling system operating on a single regulating device. Cascade control is only available when two
control front panels are fitted (channel 1 and channel 2) and channel 2 has no Remote set point facility. Channel 1 is the
'Master' controller and channel 2 is the 'Slave' controller.
• Cascade control with output tracking – ensures bumpless transfer when switching between auto/manual modes, i.e.
when the slave is switched to Manual it switches the Master to Manual, automatically .
• Cascade control with set point tracking – ensures bumpless transfer when switching between local/cascade set points
modes.
4.1.1 Cascade Control (without output tracking)
Controller 1
Master
PV
RSP
LSP
Master
PV
RSP
LSP
Master
PV
RSP
LSP
30
Controller 2
Auto
PV
P.I.D.
CAS
O/P
Software Link
LSP
Slave Switched to
Manual Mode
Local Set Point
Selected on Slave
Auto
PV
P.I.D. O/P CAS
Software Link
LSP
Slave Switched to
Set Point Tracking
Automatic Mode
Auto
PV
P.I.D. O/P CAS
Software Link
LSP
Cascade Set Point
Selected on Slave
Slave
Full Automatic Cascade Control Mode
Auto
A ratio and bias can be applied to the
cascade set point (derived from the master
P.I.D. output) to give the required slave set point.
O/P
To switch to
switch to select manual mode on the slave.
To switch to
local set point in
Slave
Manual Mode
Man
If the slave is switched from automatic
control to manual control, with cascade set
P.I.D. point
O/P
automatically reverts to local, irrespective of
the output tracking setting.
(optional)
Slave
Local Set Point Mode
Auto
If local set point is selected on the slave
when in
operation of the master is not affected.
P.I.D.
O/P
To return to
Press the
mode on the slave and select cascade set
point in
, press the
Manual Mode
Local Set Point Mode
of the slave.
Operating Page
selected, the set point
Full Automatic Cascade Mode,
Full Automatic Cascade Mode:
switch to select automatic
of the slave.
Operating Page
, select
type