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P78 Series Controls for Dual Pressure Applications
Installation Instructions
P78LCA, P78MCA
Applications
P78 Series Controls for Dual Pressure Applications provide combined high and low pressure control of
compressors on commercial refrigeration and air-conditioning applications.
IMPORTANT: Use this 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.
P78 control models with Single-Pole, Double-Throw (SPDT) switches allow users to install alarm devices or other
control circuits.
These controls are available in several pressure ranges and are compatible with most common refrigerants. They
may also be used on air, water, and other non-corrosive fluid applications.
Dual pressure P78MCA Type models with Manual Reset Lockout lock out when the Cut-out pressure is reached
and do not automatically reset after the control has cut out, providing shutdown capability for unmonitored
equipment. See Manual Reset Operation.
Type 1 enclosures are standard on most models.
Refer to the
P78 Series Controls for Dual Pressure Applications
Installation Instructions
Part No. 24-7664-3183, Rev. A
QuickLIT website
for the most up-to-date version of this document.
1
Issued September 2018
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Related Manuals for Penn P78 Series
Summary of Contents for Penn P78 Series
- Page 1 IMPORTANT: Use this 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.
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Page 2: Installation
Locate pressure-tap points on the topside of the refrigerant lines to reduce the possibility of oil, liquids, or sediment accumulating in the bellows, which could cause control malfunction. • Mount controls with Type 1 enclosures on horizontal or vertical flat surfaces. P78 Series Controls for Dual Pressure Applications Installation Instructions... - Page 3 électrique et de provoquer des blessures graves, voire mortelles. IMPORTANT: Use copper conductors only. Make all wiring connections in accordance with local, national, and regional regulations. Do not exceed the control’s electrical ratings. P78 Series Controls for Dual Pressure Applications Installation Instructions...
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Page 4: Refrigerant Connections
Éviter de former des coudes serrés avec les tubes capillaires. Les coudes serrés peuvent affaiblir les tubes capillaires ou engendrer des pliures, ce qui risque de provoquer des fuites de réfrigérant ou d'en gêner l'écoulement. P78 Series Controls for Dual Pressure Applications Installation Instructions... -
Page 5: Setup And Adjustments
Si nécessaire, réinitialiser la différence de pression d'ouverture sur les paramètres spécifiés par le fabricant. L'utilisation de paramètres de pression inappropriés risque d'endommager le dispositif de contrôle, le compresseur ou d'autres équipements contrôlés. P78 Series Controls for Dual Pressure Applications Installation Instructions... -
Page 6: Adjusting The P78 Dual Pressure Controls
3. Set the high side Cut-out setpoint. 4. Turn the high side range screw (5) clockwise to raise the Cut-out setpoint. 5. See Manual Reset Operation to restart controlled equipment (see Item 7). P78 Series Controls for Dual Pressure Applications Installation Instructions... -
Page 7: Manual Reset Operation
Full Load Amperes – Locked Rotor Amperes – 43.2 55.2 45.6 Resistive Amperes 16/8 Pilot Duty VA 125/125 Note: The Primary Contact is A–C; the Secondary Contacts are A–B and A–D. P78 Series Controls for Dual Pressure Applications Installation Instructions... - Page 8 CHINA www.penncontrols.com ® Johnson Controls and PENN are registered trademarks of Johnson Controls in the United States of America and/or other countries. All other trademarks used herein are the property of their respective owners. © Copyright 2018 by Johnson Controls. All rights reserved.