Johnson Controls System 350 P352AB Series, System 350 P352AB-2, System 350 P352AB-3, System 350 P352AB-4 Product Manual
System 350 Product Guide 930
Basic Controls Section
Product/Technical Bulletin P352AB
Issue Date 0200
System 350
P352AB Electronic Pressure Control Series
The P352AB controls are On/Off electronic pressure
controls with Single-Pole, Double-Throw (SPDT) relay
output and Light-Emitting Diode (LED) indication. The
P352AB controls are designed with Reverse or Direct
Acting mode of operation, adjustable differential, and
an interchangeable pressure transducer. The P352AB
control will accept S352A Stage Modules to control
stages of Heating, Ventilating, and Air Conditioning
(HVAC) and/or refrigeration equipment.
Three models cover the ranges of 0-100 psi,
90-250 psi, and 240-600 psi, covering most common
refrigeration and air conditioning applications.
As are all System 350™ products, the P352AB control
is housed in a NEMA 1 high-impact thermoplastic
enclosure. The modular design provides easy,
snap-together connections for quick installation and
future expandability.
Figure 1: P352AB Electronic Pressure Control
Modular Design
❑
Plug-together Connectors
❑
and 35 mm DIN Rail
Mounting
Three Models Available
❑
with Adjustable Setpoint
Ranges of 0-100 psi,
90-250 psi, and 240-600 psi
Models Available with
❑
Adjustable Differential from
2-50 psi and 10-100 psi
Field-selectable Direct or
❑
Reverse Acting Mode
Interchangeable Pressure
❑
Transducer
Features and Benefits
Provides the flexibility to add S352A Stage
Modules, D352 Display Module, and Y350R
Power Module
Eliminates wiring between modules and
reduces installation costs
Handles pressures required for most fan
cycling and compressor unloading
applications
Enables user to match the equipment cycle
rate and/or sequencing for a given application
Energizes relay output on either an increase
or a decrease in pressure
Increases versatility and serviceability
© 2000 Johnson Controls, Inc.
Part No. 24-7664-1903, Rev. — www.johnsoncontrols.com
Code No. LIT-930038
1
pplication
A
The P352AB Electronic Pressure Control can be used
as a standalone device or in conjunction with
System 350 plug-together accessory modules for
single or multiple stage refrigeration and HVAC
pressure control applications. Typical applications
include:
●
condenser fan cycling
●
compressor cycling and unloading
IMPORTANT: The System 350 controls are
intended to control equipment under
normal operating conditions. Where
failure or malfunction of the
System 350 controls could lead to an
abnormal operating condition that
could cause personal injury or
damage to the equipment or other
property, other devices (limit or
safety controls) or systems (alarm or
supervisory systems) intended to
warn of, or protect against, failure or
malfunction of the System 350
controls must be incorporated into
and maintained as part of the control
system.
A typical System 350 pressure control setup includes
the following:
●
P352AB Electronic Pressure Control
●
S352A Stage Modules
●
D352 Digital Display Module
●
Y350R Power Module (or 24 VAC transformer)
●
P399 Electronic Pressure Transducer
IMPORTANT: The P352AB controls use an input
signal from the P399 Electronic
Pressure Transducer to determine
pressure in psi (pounds per square
inch). The P399 transducer uses a
sealed-reference of one atmosphere
to determine 0 psi. For more
information on interpreting control
pressure readings, refer to the
P399 Electronic Pressure Transducer
Product/Technical Bulletin,
LIT-125515
.
Setpoint
Setpoint is defined as the pressure at which the relay
de-energizes. The setpoint is adjustable between
0 to 100, 90 to 250, and 240 to 600 psi, depending on
the model ordered. (See Table 1.)
Table 1: Setpoint Adjustment Range
P352AB Model No. Setpoint Range
P352AB-2
P352AB-3
P352AB-4
0 to 100 psi
90 to 250 psi
240 to 600 psi
Differential
Differential is defined as the difference in pressure
between energization and de-energization of the
output relay. The differential is adjustable between
2 to 50 and 10 to 100 psi, depending on the control
model. (See Table 2.)
Table 2: Differential Adjustment Range
peration
O
The P352AB Electronic Pressure Control operates on
24 VAC and has an SPDT relay output. A front panel
LED lights to indicate when the relay is energized.
P352AB Model No. Differential Range
P352AB-2
P352AB-3
P352AB-4
2 to 50 psi
10 to 100 psi
10 to 100 psi
The P352AB controls are used with the P399
Electronic Pressure Transducers, which are available
in several pressure ranges, and provide a ratiometric
analog signal (0.5 to 4.5 VDC), based on the sensed
pressure.
2
Basic Controls—System 350 P352AB Electronic Pressure Control Series Product/Technical Bulletin
Direct/Reverse Acting Mode
The P352AB controls utilize jumpers (at Jumper
Terminal J1) to select the operation mode. (See
Adjustments (P352AB Control)
When in
Direct Acting (DA) mode
section and Figure 3.)
, the relay
de-energizes when the pressure drops below the
setpoint. When the pressure rises above the setpoint
plus
the differential, the relay energizes and the “ON”
LED illuminates.
imensions
D
Mounting Slots
For No. 6 Screws
1/8 (4)
2-15/16 (75)
When in
Reverse Acting (RA) mode
, the relay
de-energizes when the sensed pressure rises above
the setpoint. When the pressure drops below the
setpoint
minus
the differential, the relay energizes and
the “ON” LED illuminates.
Note: The P352AB controls are configured for DA
mode at the factory.
Refer to Figure 5 for an example of a typical Direct
Acting/Reverse Acting application.
5 (127)
ON
JOHNSON
CONTROLS
CONTROLS
P352
O
O
1-1/2
(40)
Wiring Harness
6-1/2 ft
(2.0 m)
or
13 ft
(4.0 m)
7/16
(11)
2-1/4 (57)
P399 Transducer
Figure 2: P352AB Control Dimensions, in. (mm)
ounting
M
The P352AB Electronic Pressure Control is housed in
a compact NEMA 1 plastic enclosure designed for
standard 35 mm DIN-rail mounting. Four key-slot
mounting holes on the back of the control case are
provided for surface mounting. (See Figure 2.)
DIN Rail
Mount
1-3/16
2-3/8 (61)
7/8 (22)
2-3/8
(61)
Conduit
Hole
7/8 (22)
Note: When mounting the P352AB control (or any
System 350 Module) to rigid conduit, attach
the hub to the conduit before securing the hub
to the control enclosure.
Basic Controls—System 350 P352AB Electronic Pressure Control Series Product/Technical Bulletin
3
djustments (P352AB Control)
A
Perform the following steps to adjust the P352AB
control settings. (See Figure 3.) Refer to Figure 5 for
an example of the P352AB control in a typical Direct
Acting/Reverse Acting application.
!
WARNING:
Risk of Electrical Shock.
Disconnect power supply to
avoid possible electrical shock or
equipment damage. More than
one disconnect may be required
to completely de-energize
equipment.
1. Ensure all power to system is off.
Set the mode of operation
3.
by positioning the
jumpers (at Jumper Terminal J1) horizontally for
Direct Acting or vertically for Reverse Acting.
Note: The P352AB controls are configured in the
DA mode at the factory.
Adjust the differential
4.
using the potentiometer
marked DIFF ADJUST to the desired setting.
Clockwise rotation increases the differential.
Adjust the setpoint
5.
using the setpoint adjustment
dial to the desired setting.
After power is applied to the control, a more
accurate setting of the setpoint can be made by
utilizing the D352A Pressure Display Module.
2. Remove the P352AB control cover by loosening
the four captive cover screws.
Wire
Ter min al
Block
24V
COM
VDC
SEN
Differential
Potentiometer
Relay Energized
LED Indicator
Cover Screw
(One of Four)
Concealed Setpoint
Adjustment Dial
N.C.
Relay
Figure 3: Interior View and Typical Wiring of the P352AB Control
dd-On Modules
A
6. Replace the cover on the control and fasten in
place with screws.
7. Restore power to system.
Module
Connector
Jumper
Position at J1
Reverse Acting
Relay
COM
Output
N.O.
Terminals
Direct Acting
The Y350R Power Module, D352 Digital Pressure
Display, and S352A Stage Modules snap together and
plug into the P352AB Electronic Pressure Control via
connectors on both sides of each add-on module.
Y350R Power Module
The Y350R Power Module provides a convenient
The Y350R Power Module can be plugged into the
right side of the P352AB controls or any of the add-on
modules. The Y350R Power Module is capable of
providing power to a P352AB control, a D352 Display
Module, and up to five S352A Stage Modules. (Refer
System 350
to the
TM
Y350R Power Module
Product/Technical Bulletin, LIT-930090
information.)
method of powering System 350 modules from a
120 or 240 VAC power source.
4
Basic Controls—System 350 P352AB Electronic Pressure Control Series Product/Technical Bulletin
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