Penn P78 Series User Manual

1
P78 Series Controls for Dual Pressure and Hazardous Location
Applications Installation Guide
Applications
P78 Series Controls for Dual Pressure and Hazardous Location Applications provide combined high and low
pressure control using a low energy signal from inside an explosive zone on commercial refrigeration and
air-conditioning applications. The controls have special dry circuit switches with gold-plated contacts for improved
contact characteristics that are required in circuits with low voltage and low current
.
These controls are available in several pressure ranges and are compatible with propane refrigerants. They are
designed to operate in
• Group II, Zone 2 environments, as defined in the ATEX Directive and UKEx regulation
s.
•
Class I, Division 2, Group D environments, as defined in NFPA 70 and CSA C22.
2.
Th
ey are equipped with fail-safe double bellows on the high side, and two 6 mm outer diameter copper tubes for
connecting to the refrigerant lines. Two adjustment lock plates are included with these models.
IP54 (Type 1 NEMA) enclosures are standard on these models.
P78 control models allow users to install alarm devices or other control circuits (see Figure 4).
Table 1 lists the standard models and features of P78 controls for dual pressure and hazardous location
applications. These standard models are available through most authorized Johnson Controls®/Penn distributors.
Table 1: Standard P78 Dual Pressure Controls for non-corrosive refrigerants
IMPORTANT: Use th
is P78 Series Control only as an operating control. 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 : Utiliser ce P78 Series Control uniquement en tant que dispositif de contrôle de fonctionnement.
Lorsqu'une défaillance ou un dysfonctionnement du contrôle 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 contrôle.
Model number Pack type Low pressure side High pressure side Maximum
bellows
pressure,
barg (psig)
Range,
barg (psig)
Differential,
bar (psi)
Range,
barg (psig)
Differential,
bar (psi)
P78XLCW-18000C Individual pack -0.5 to 7
(-7.25 to 102)
0.6 to 3
(9 to 44)
3 to 30
(44 to 435)
3 fixed
(44)
LP: 22 (319)
HP: 33 (479)
P78 Series Controls for Dual Pressure and Hazardous
Location Applications
Installation Guide
P78XLCW
Part No. 24-7664-3248, Rev. C
Issued June 2023

Penn P78 Series Specifications

General

Brand	Penn
Model	P78 Series
Category	Controller
Language	English

Summary

Applications Overview

P78 Series Control Applications

Controls provide high/low pressure control for commercial refrigeration and HVAC in hazardous locations.

Repair and Installation

Unit Replacement Procedure

Replace failed units and contact distributor for replacements.

Operating Temperature Limits

Limit media temp to 80°C (176°F) to prevent thermal ignition risk.

Physical Dimensions

Details the enclosure dimensions of the control unit.

General Mounting Guidelines

General instructions for safe and effective mounting of the control.

Mounting Instructions

Mounting to Vertical Surfaces

Specific instructions for attaching the control to vertical mounting surfaces.

Mounting to Horizontal Surfaces

Specific instructions for attaching the control to horizontal mounting surfaces.

Wiring and Safety

Explosion and Fire Safety Warning

Critical warning against disconnecting energized controls in hazardous areas.

Wiring Material and Compliance

Use copper conductors and adhere to local/national wiring regulations.

Terminal Screw Usage

Use specified terminal screws to maintain warranty and prevent damage.

Hazardous Area Wiring Precautions

Ensure ignition prevention by limiting energy supply outside hazardous zones.

Intrinsic Safety Information

Intrinsic Safety Protection Method

Explains the intrinsic safety method for hazardous location operation.

Entity Parameters

Lists the entity parameters for the P78 Pressure Control.

Associated Apparatus and Connections

Intrinsically Safe Entity Parameters for Associated Apparatus

Details intrinsic safety parameters for associated equipment.

Refrigerant Connections

How to connect the control to refrigerant lines, avoiding pulsations.

Adjusting the P78 Dual Pressure Controls

Dual Pressure Adjustment Procedure

Step-by-step guide for setting cut-in and cut-out points for low and high sides.

Technical Specifications and Compliance

Pressure Connection and Ambient Conditions

Specifies pressure connection type and ambient operating temperature/humidity.

Enclosure and Weight

Details enclosure type, dimensions, and approximate shipping weight.

Control Specifications Summary

Lists control purpose, construction, cycles, and mounting method.

Electrical and Pressure Ratings

Covers impulse voltage, over-voltage, ball pressure, and maximum working pressures.

Compliance and Certification

Lists certifications and compliance standards for US, Canada, Europe, and UK.