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Basic Controls—System 350 P352AB Electronic Pressure Control Series Product/Technical Bulletin
A
pplication
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
O
peration
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.
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.
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
0 to 100 psi
P352AB-3
90 to 250 psi
P352AB-4
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
P352AB Model No.
Differential Range
P352AB-2
2 to 50 psi
P352AB-3
10 to 100 psi
P352AB-4
10 to 100 psi