Emerson Liebert MC Microchannel Outdoor Condenser 28 - 220kW User Manual

1. Three-Phase Electrical Service—Terminals are on the top of the disconnect switch for one-fan 

and two-fan units. Terminals are on the bottom of the disconnect switch for three-fan and four-fan 

units. Three-phase service not by Emerson. See 4.1.1 - Wye vs. Delta Connection Power 

2. Earth Ground—Field lug terminal for earth ground connection. Ground terminal strip for fan 

motor ground connection.

3. Primary High-Voltage Entrance—Three 7/8" (22.2mm) diameter knockouts located at the 

bottom of the enclosure.

4. SPD Field Connection Terminals—High-voltage surge protection device (SPD) terminals. 

SPD is an optional device.

5. CANbus Terminal Connections—Field terminals for CANbus cable connection.

• 5A is the CANbus connectors.

• TB49-1 is the input terminal for CANbus high.
• TB49-3 is the input terminal for CANbus low.
• TB50-1 is the output terminal for CANbus high.
• TB50-3 is the output terminal for CANbus low.
• Each CANbus cable shield is connected to terminal “SH;” see 9 below.

• 5B is the “END OF LINE” jumper.
• 5C is the CANbus “DEVICE ADDRESS DIP SWITCH.” CANbus cable not by Liebert. See 

requirements in 4.2 - Low-Voltage Control Wiring—Premium Efficiency Control 

6. Remote Unit Shutdown—Replace exiting jumper between Terminals TB38-1 and TB38-2 with 

field-supplied normally closed switch having a minimum 75VA 24VAC rating. Use field-supplied 

Class 1 wiring.

a. Common Alarm Relay indicates when any type of alarm occurs. TB74-1 is common, TB74-2 is 

normally open, and TB74-3 is normally closed. 1 Amp 24VAC is the maximum load. Use 

field-supplied Class 1 wiring.

b. Shutdown Alarm Relay indicates when condenser loses power, or when a critical alarm has 

occurred that shuts down the condenser unit. TB74-4 is common; TB74-5 is normally open;, 

and TB74-6 is normally closed. 1 Amp 24VAC is the maximum load. Use field-supplied 

Class 1 wiring.

a. On any call for compressor operation, normally open contact is closed across Terminals 70 and 

71 for Circuit 1, and normally open contact is closed across Terminals 70 and 230 for Circuit 2 

from indoor room unit.

b. During SPD alarm, normally open contact is closed across Terminals 12 and 13. SPD is an 

optional device.

9. CANbus Shield Terminal—Terminal for field shield connection of the CANbus field-supplied 

cables. The shield of CANbus field-supplied cables must not be connected to ground at the 

condenser.

10. Primary Low-Voltage Entrance—One 7/8” (22.2mm) diameter knockout that is free for 

customer low-voltage wiring.