Penn A28PA Series Installation Manual

A28PA and A28PJ Series Two-Stage Temperature Controls

Application

Important: A28PA and A28PJ Series Two-Stage
Temperature Controls with Type 4X Raintight
Enclosures are intended to provide an input to
equipment under normal operating conditions.
Where failure or malfunction of the control could lead
to personal injury or property damage to the
controlled equipment or other property, additional
precautions must be designed into the control
system. Incorporate and maintain other devices,
such as supervisory or alarm systems or safety or
limit controls, intended to warn of or protect against
failure or malfunction of the control.
Important : Le A28PA and A28PJ Series Two-Stage
Temperature Controls with Type 4X Raintight
Enclosures est destiné à transmettre des données
entrantes à un équipement dans des conditions
normales de fonctionnement. Lorsqu'une défaillance
ou un dysfonctionnement du control risque de
provoquer des blessures ou d'endommager
l'équipement contrôlé ou un autre équipement, la
conception du système de contrôle doit intégrer des
dispositifs de protection supplémentaires. Veiller
dans ce cas à intégrer de façon permanente d'autres
dispositifs, tels que des systèmes de supervision ou
d'alarme, ou des dispositifs de sécurité ou de
limitation, ayant une fonction d'avertissement ou de
protection en cas de défaillance ou de
dysfonctionnement du control.
You can use A28PA and A28PJ series two-stage
electromechanical temperature controls in many
agricultural applications. The A28PA and A28PJ
controls have rugged polycarbonate enclosures and
are UL listed as Type 4X. A28PA and A28PJ controls
are also UL listed for use in National Electrical Code
(NEC) Article 547 Agricultural Environments
(ANSI/NFPA 70).
Two single-pole, double-throw (SPDT) switches
provide independent stage control circuits. You can
wire each switch for open-high or close-high action,
which provides automatic changeover on heating or
cooling applications. The temperature controls include
a jumper across the switches' red common terminals.
Adjustable A28PA and A28PJ series temperature
controls have O-ring sealed external set point
adjustment knobs and range scales with oversized
markings for easy readability in low light.
©
2022 Johnson Controls
Part No. 996-545, Rev. H
with Type 4X Raintight Enclosures
Installation Guide
Issue Date
Important: Do not dent, bend, uncoil, or otherwise
alter the position of the sensing element, also known
as the coil, mounted on the base of the A28PA and
A28PJ series controls. If you damage the sensing
element, you could change the control calibration
and you void any warranties on the control.

Operation

The circuit between R and Y of the low stage switch
(RY ) closes, and R and B (RB
L
temperature increase to the setpoint, which you can
view on the dial setting. On a further temperature
increase, the high stage switch closes RY
RB . The reverse sequence occurs on a temperature
H
decrease.

Dimensions

Figure 1: A28PA and A28PJ dimensions, in. (mm)
December 2022
) opens on
L
and opens
H
1
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