Johnson Controls P352PN-3 User Manual

4
Basic Controls—P352PN Electronic Proportional Plus Integral Pressure Controls for PSI Applications
Proportional
Offset
Setpoint
Load Change
System Load
Control Point
Follows the Load
Temperature
Time
Throttling
Range
Error
Proportional Only Control
Temperature
Proportional
Offset = 0
Setpoint
Load Change
System Load
Integration adjusts the
proportional output to
bring the process to
setpoint regardless of load.
Time
Error
Proportional Plus Integral Control
Figure 3: Operation of Proportional Only vs. Proportional Plus Integral Control
Minimum Output Adjustment and LED Bar
Graph Output Indicator
The minimum output adjustment sets the minimum
signal output (in VDC or mA) that the P352PN control
provides to the controlled device. The minimum output
can be set between 0 and 60% of the output range
(up to 6 VDC or 12 mA).
Example: For a controlled device that responds to a
4 to 20 mA output signal, the minimum output must be
4 mA or 20% of the 0 to 20 mA range. (See Figure 4.)
Adjust the MIN OUTPUT potentiometer located in the
center of the circuit board. The LED bar graph will
advance one LED segment for each 10% increase in
output range. The first segment lights at 10%, the
second segment at 20% and so on, until the tenth
segment lights at 100%.
Minimum
Output
Setting (20%)
Throttling Range (psi)
Setpoint
Pressure
(Range for
P352PN-2)
(Range for
P352PN-3 or
P352PN-4)
Minimum Output Set to 20% (4 mA) and
Throttling Range Set to 50 psi for P352PN-2
or 100 psi for P352PN-3 and P352PN-4.
Output
Range
(in mAs)
20
10
0
4
50
100
25
50
Figure 4: Minimum Output and Throttling Ranges for
the P352PN Controls
Throttling Range (Proportional Band)
On controls set for proportional only, the throttling
range or proportional band setting establishes how far
the system pressure must deviate from the P352PN
control setpoint to generate a 100% output signal from
the control.
Thus, on a proportional only control with a throttling
range setting of 25 psi, the output signal (VDC or mA)
is 0% when the system pressure equals the setpoint
pressure. The output signal increases to 100%
(10 VDC or 20 mA) when the system pressure rises
25 psi above the setpoint in DA mode, or drops 25 psi
below the setpoint in RA mode.
When setting up controls for proportional plus integral
operation, start with the integration constant OFF (in
the proportional only mode), and set the throttling
range (or proportional band) to a wide setting (60% or
more of the total range) to assure a stable control loop.
Then set the integration constant as slow as possible.
(Refer to
Integration Constant DIP Switch Settings.
)
Adjust the throttling range by turning the THROT
RANGE potentiometer located under the control cover
on the center of the circuit board.
The throttling range can be adjusted from 5-50 psi on
the P352PN-2 model and 10-100 psi on the P352PN-3
and P352PN-4 models. (See Figures 4 and 5.)

Johnson Controls P352PN-3 Specifications

General

Brand	Johnson Controls
Model	P352PN-3
Category	Control Unit
Language	English