Wiring and Connections

3.2.3 Setting the Digital Output Jumpers

Digital output jumpers (four)

Each digital output has an associated jumper to define its operation when power is interrupted. This puts the AC4

in a fail-safe mode and ensures proper functioning when the board has no power.

The 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 (nor- mally closed). The settings are shown in Table 5.

Table 5

Digital output jumper settings

 

 

 

Output status

Setting

(power loss)

OFF

Normally open

 

 

ON

Normally closed

 

 

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.

3.3 Connecting Common Alarm Outputs

The common alarm relay, found in the top right corner of the AC4, permits the user to connect auxiliary notification equip- ment, such as lights, horns and sirens, to the 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:

Common alarm outputs

 

1.Turn OFF electrical power to the AC4.

2.If necessary, remove a conduit knockout to permit wire entry into the AC4 enclosure.

3.Bring the wire(s) into the 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.

3.4RS232 Connector

The AC4’s Service Terminal Interface offers full con- figuration and monitoring capability via the RS232 port (see A.2 - Connecting to the Service Termi- nal Interface).

The RS232 port requires a null modem cable. Connect one end of the cable to the AC4’s RS232 port, shown at right, and the other end to the COM1 port of a lap- top computer or video terminal.

Serial interface connector (RS232/ EIA574)

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Liebert AC4 user manual Connecting Common Alarm Outputs, RS232 Connector, Setting the Digital Output Jumpers
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AC4 specifications

The Liebert AC4 is a highly advanced cooling solution designed for critical environments, such as data centers and telecommunications facilities. As data demands rise and IT equipment generates significant heat, an effective cooling system is paramount to maintaining optimal performance and reliability. The Liebert AC4 stands out in this space, offering a blend of efficiency, flexibility, and innovative technology.

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Furthermore, the system is designed to be easy to install and maintain, reducing downtime during setup and upkeep. The modular design allows for scalability, enabling organizations to expand their cooling capabilities as their needs grow.

The Liebert AC4 also features a robust construction that enhances reliability and durability, making it an ideal choice for environments where equipment uptime is critical. Its streamlined design not only optimizes airflow and cooling distribution but also contributes to aesthetic considerations in professional settings.

In conclusion, the Liebert AC4 combines efficiency, versatility, and advanced technologies to deliver a reliable cooling solution for modern data centers and critical facilities. Its variable-speed fans, flexible configurations, and advanced monitoring capabilities position it as a leader in the competitive field of cooling solutions, ensuring that critical equipment remains operational and efficient. Organizations looking to enhance their cooling strategies will find the Liebert AC4 to be an invaluable asset in today’s fast-paced digital landscape.
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