Hussmann Proto-Aire, Installation Manual

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Protocol™ Installation and
Service Manual
Terminal Connections
Protocol™ units carrying 5 and 6 compressors, or an oversized Control Panel, do not use a
single-phase bussbar. Wire number assignments and corresponding terminal number
assignments in the Power Distribution Box differ from the smaller panel arrangement.
120V Circuit Logic
The Protocol™ includes as standard the following 120V components:
Service Receptacle (5 Amp Max)
Cabinet Exhaust Fan
120V by 24V Transformer
Compressor Contactor Coils
Valve Solenoids
External Alarm Light
24V Circuits
The printed circuit control boards with attached relay coils are 24V. The
POWERLINKS™ are powered by a 24V DC supply (used to control electric defrost
heaters). Each POWERLINK™ power supply will drive up to 5 POWERLINKS™ at
once, and require 2 seconds to recharge an internal DC capacitor between operations. If the
POWERLINK™ power supply fails,
a transformer will NOT replace it.
Electronic Oil Level Control
A 24V transformer powers the electronic oil level control. All circuit logic including oil
solenoid control is 24 volt. Only the alarm contact is 120V. See next two pages for typical
wiring diagrams.
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