Emerson Autochangeover Controllers AC8 - Manual (Page 22)

Wiring and Connections
14
3.2 Connecting Digital Inputs and Digital Outputs
The digital inputs, digital outputs and control relay outputs are found on the right side of the AC8’s
printed wiring assembly board. Each set has two terminal blocks—one green, the other black:
• Digital inputs: two terminal blocks, with four inputs per block (8 inputs total)
• Digital outputs: two terminal blocks, with four outputs per block (8 outputs total)
• Control relay outputs: two terminal blocks, with one output per block (2 outputs total)
Each input is tied to an output with the same number:
• Input 1 is tied to Output 1 (default name: Device_1)
• Input 2 is tied to Output 2 (default name: Device_2)
• Input 3 is tied to Output 3 (default name: Device_3)
.
.
.
• Input 8 is tied to Output 8 (default name: Device_8)
Up to eight devices may be connected to the AC8. Each device must be connected to an input and an
output with the same number.
To determine the proper wire size, see Table 4 - Wiring specifications.
Connecting Liebert Environmental Units
For Liebert environmental units, follow these steps (be sure to connect the same device to inputs and
outputs with the same number—one device to Input 1 and Output 1, another to Input 2 and Output 2,
and so on):
• Connect a digital input from the AC8 to the Common Alarm Relay of the environmental unit:
terminals 75/76 or TB1-6, TB1-7.
• Connect a digital output (numbered the same as the input) from the AC8 to the Remote Shutdown
(Power Control) of the environmental unit: terminal 37/38 or TB1-4, TB1-5.
3.2.1 Connecting Digital Inputs
To connect a digital input:
1. Turn OFF electrical power to the AC8.
2. If necessary, remove a conduit knockout
to permit wire entry into the AC8
enclosure.
3. Bring the wire(s) into the AC8 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.
NOTE
Each terminal block is a removable, two-part assembly to permit easier connection of more
than one input at a time. If making multiple connections, grasp the upper portion of a block
and pull firmly to the right until the assembly pulls apart.
After making the connections, push the removed piece back into the portion attached to the
printed wiring assembly until the terminal block pieces lock together.
NOTE
Connect digital inputs to
nonpowered (dry) contacts only.
RELAY
OUTPUTS
TB2:
CONTACT
INPUTS ASS
EPOP INPUT
EPOP
TB1
REV
ONON
PFM5
OFF
(BOTTOM)
(TOP)
4
3
2
1
8
7
6
5
(BOTTOM)
(TOP)
4
3
2
1
8
7
6
5
ON
PFM2
OFF
DIGITAL INPUT
TERMINAL BLOCKS
NUMBERING KEYS -
Note numbering begins
with 1 at the bottom and
proceeds up to 4 (green);
and 5 up to 8 (black)