Emerson AC4 Manuale Utente

The four digital outputs are found on the lower right side of the Liebert AC4 just above the input 

terminal blocks, as shown at right. These outputs are numbered 1 through 4.
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.

Each digital output has an associated jumper to define its 

operation when power is interrupted. This puts the 

Liebert AC4 in a fail-safe mode and ensures proper 

functioning when the board has no power.
The Liebert AC4 comes from the factory with all digital 

output jumpers in the OFF position (normally open). The 

jumper setting for each digital output can be changed to 

ON (normally closed). The settings are shown in Table 5.

To change the output jumper setting:
1. Find the respective loss-of-power jumper on the 

circuit board, as shown above. See Table 1 Controller board components for more 

information.

2. Decide whether your configuration requires the jumper to be OFF or ON.
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.

To reduce the risk of fire or electric shock, do not interconnect the outputs of different class 2 

circuits.

OFF

Normally open

ON

Normally closed