User Guide

4 System 350 P352P Electronic Proportional Plus Integral Static Pressure Controls
C2 (Switch 3 to On position, all others Off) selects a
five minute integration constant. If the rate of system
recovery to setpoint is sluggish with the control set to
C3 and it is determined that the system has enough
capacity to drive the process to setpoint at a faster rate,
the C2 setting may be used.
C1 (Switch 4 to On position, all others Off) is the
fastest integration constant (equal to 2.5 min.). C1
should be used only in instances where the rate of
change at the transmitter is extremely rapid and system
capacity can compensate for that rapid change.
Proportional Only Control
Proportional Plus Integral Control
Load Change
System Load
Integration adjusts the
proportional output to
bring the process to
setpoint regardless of load.
Load Change
System Load
Control Point
Follows the Load
Pressure
Pressure
Setpoint
Time
Time
Setpoint
Throttling
Range
Error
Proportional
Offset
Error
Proportional
Offset = 0
Figure 4: Operation of Proportional Only vs. Proportional Plus Integral Control
Mode of Operation (Direct or Reverse)
The RA/DA mode is selected by the jumper blocks located
on the lower circuit board just to the right of the integration
constant DIP switch block. Position the jumper blocks
vertically for reverse action and horizontally for direct
action.
With the jumper blocks in the RA position, the analog
output increases as the pressure drops (see Figure 5).
With the jumper blocks in the DA position, the
proportional output will increase as the pressure rises.
As shipped from the factory, the RA/DA jumper blocks are
installed in the reverse acting mode.
0
5
VDC
0
10
mA
Throttling Range
(in. W.C.)
Setpoint
Setpoint
20 10
RA
DA
Output
Throttling Range
(in. W.C.)
Maximum
Throttling
Range
Maximum
Throttling
Range
Figure 5: Direct or Reverse Acting Proportional Bands
Shown in “Proportional Only” Mode
(Shaded Area Shows Throttling Range Possibilities from
Minimum to Maximum)