Emerson AC4 Manuale Utente

The common alarm relay, found in the top right corner of the 

Liebert AC4, permits the user to connect auxiliary notification 

equipment, such as lights, horns and sirens, to the Liebert AC4. 

To determine the proper wire size, see Table 4 Wiring 

specifications.
There are two connectors for the common alarm output. However, 

the connectors are not individual relay outputs. The connectors 

should be treated as a double-pole, double-throw (DPDT) relay.
The common alarm relay is energized whenever an alarm occurs.
To connect an output:
1. Turn OFF electrical power to the Liebert AC4.
2. If necessary, remove a conduit knockout to permit wire entry into the Liebert AC4 enclosure.
3. Bring the wire(s) into the Liebert AC4 enclosure through a conduit knockout or access slot.
4. Loosen the appropriate screw and slip the stripped end of the wire into the terminal block.
5. Tighten the screw until it holds the wire snugly.

The Liebert AC4’s Service Terminal Interface offers 

full configuration and monitoring capability via the 

RS232 port (see A.2 - Connecting to the Service 

Terminal Interface).
The RS232 port requires a null modem cable. Connect 

one end of the cable to the Liebert AC4’s RS232 port, 

shown at right, and the other end to the COM1 port of 

a laptop computer or video terminal.