Liebert AC4 User Manual

3. Set the jumper as needed:
• Set the jumper to OFF by placing the loss-of-power jumper on the middle and top pins.
• Set the jumper to ON by placing the black jumper on the middle and bottom pins.
3.3 Connecting Common Alarm Outputs
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 Wiring and Connections on page21.
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.
3.4 RS232 Connector
The Liebert AC4’s Service Terminal Interface offers full
configuration and monitoring capability via the RS232 port
(see Connecting to the Service Terminal Interface on
page70).
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.
Vertiv | Liebert® AC4 User Manual | 24

Liebert AC4 Specifications

General

Brand	Liebert
Model	AC4
Category	Control Unit
Language	English