20 VAV-SVX07B-EN
Wiring Installation
Wiring Requirements
To ensure proper operation of the UC400 controller, install the power supply circuit in accordance
with the following guidelines:
• The controller must receive AC power from a dedicated power circuit.
Important: Failure to comply may cause the controller to malfunction.
• A dedicated power circuit disconnect switch must be near the controller, easily accessible by
the operator, and marked as the disconnecting device for the controller.
•DO NOT run AC power wires in the same wire bundle with input/output wires.
Important: Failure to comply may cause the controller to malfunction due to electrical noise.
• 18 AWG (0.823 mm
2
) copper wire is recommended for the circuit between the transformer and
the controller.
Connecting the Wires
Referring to Figure 2:
1. Disconnect power to the transformer.
2. Connect the 24 Vac secondary wires from the transformer to the 24 Vac and terminals on
the UC400 controller.
3. Choose one of the following options to ensure the controller is adequately grounded:
• Connect a grounding pigtail at some point along the secondary wire that runs between the
controller terminal and the transformer.
• Ground one of the terminals on the controller to the enclosure (if the enclosure is
adequately grounded) or to an alternate earth ground.
Figure 2. Connecting 24 Vac transformer and ground
VAC
24
XFRM
VAC
24
VAC
24
BI
1
BI
2
BI
3
LINK
IMC
+
24
VDC
BI4
AO1
BI
5
AO2
UI
1
UI
2
AI
3
AI
2
AI
1
AI
4
AI
5
P
1
P
2
CNCNO
BO3
CNCNO
BO2
CNCNO
BO1
RELAYS
ADDRESS
TRIAC SUPPLY TRIACS
A
BO9BO8BO7BO6BO5
BO4
ABB
TX
RX
LINK
IMC
SERVI
C
E
SERVICE TOOL
CONNECT AC POWER TO THE TRAIC SUPPLY TO POWER THE TRIACS
BO1 BO2 BO3 BO4 BO5 BO6 BO7 BO8 BO9
1
2
3
4
5
6
7
8
9
IM
C
1
IM
C
1
3
4
5
6
7
1
2
3
4
5
6
7
8
9
8
9
x1
A pigtail connection may be
necessary between earth ground
and/or enclosure ground if the device
is not grounded through one leg of
the transformer wiring.
Alternate earth ground method.
24 Vac
transformer
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