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The performance specifications are nominal and conform to acceptable industry standards. For applications at conditions beyond these specifications, consult the local Johnson Controls office.
Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or misuse of its products. © 2015 Johnson Controls, Inc. www.johnsoncontrols.com
R-105
P28 Series Lube Oil Pressure Cutout Control with Time Delay
P28AA Lube Oil Pressure Cutout
Control
Description
The P28 series provides dependable lube oil
protection on pressure of lubricated
refrigeration compressors by sensing low
lube oil pressure. A built-in time delay
switch, accurately compensated for ambient
temperature, allows for pressure pick up on
start and avoids nuisance shutdowns on
pressure drops of short duration during the
running cycle.
Refer to the P28 and P128 Series Lube Oil
Controls with Built-in Time Delay Relay
Product Bulletin (LIT-125420) for important
product application information.
Features
• direct-reading scale indication
• adjustable setpoint
• trip-free manual reset
• replacement timing relays available
• dust-protected switch
Applications
• semi-hermetic compressors
• P28 Control measures pressure available
to circulate oil though the lubrication
system (Net oil pressure is the difference
between oil gauge and crankcase
pressure.)
Accessories
• all models listed on this page include a
universal mounting bracket
• replacement timing relays— refer to
Replacement Timing Relays for P28 and
P29 Lube Oil Controls Catalog Page
(LIT-1927395)
Repair Information
If the P28 Series Lube Oil Pressure Cutout
Control with Time Delay fails to operate within
its specifications, replace the unit. For a
replacement control, contact the nearest
Johnson
Controls® representative.
Selection Chart
Technical Specifications
The maximum bellows pressure is 180 psig (2,241 kPa).
Product Code
Number
Time
Delay
Time Delay
Heater Circuit VAC
Type of
Reset
Range
1
psi (kPa)
1. Switch differential approximately 5 psig (34 kPa). Time delay relay energizes at 9 psig (61 kPa) pressure difference, de-energized at 14 psig (97 kPa) difference
Refrigerant
(R)
Pressure
Connection
P28AA-1C
2
2. Replaces Ranco® P30-3701
90 seconds 120/240 Manual 8 to 70 (55 to 483) Non-corrosive
3
3. Non-corrosive refrigerants include R-12, R-22, R-134A, R-500, R-502 (R)
36 in. capillary with
1/4 in. flare nut
P28AA-2C
4
4. Replaces Ranco P30-3601
60 seconds
P28AA-17C
5
5. Replaces Ranco P30-3801
120 seconds
P28AA-18C 45 seconds
P28AN-1C 90 seconds 120/240 Manual 8 to 70 (55 to 483) Ammonia 1/4 in. internal NPT
P28DN-1C 90 seconds
With Runlight and
Alarm Terminals
P28DA-1C 120/240 Manual 8 to 70 (55 to 483) Non-corrosive
3
36 in. capillary with
1/4 in. flare nut
P28GA-2C 90 seconds Automatic
P28NA-5C 120 seconds 24 VAC
or VDC
Manual
Electrical Ratings - Pilot Duty
Time Delay
Heater Circuit
Pilot Circuit Alarm Circuit
(must be same voltage
as pilot circuit)
P28DA-1 Contact Rating 2 to 1: 2 to 3
(must be same voltage as time delay circuit)
Crankcase Heater: Term 2 to 1 Runlight: Term 2 to 3
120/240 VAC 750 VA, 120/240 VAC 125 VA, 120/240 VAC 10 A 120 VAC, 5 A 240 VAC 10 W
24 VAC or VDC 125 VA, 24 VAC
57.5 VA, 24 VDC
125 VA, 24 VAC
57.5 VA, 24 VDC
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Electromechanical Lube Oil and Differential Pressure Controls
Code No. LIT-1927185