Trane Tracer UC400, Installation, Operation And Maintenance Manual

Page: 29 / 60

BAS-SVX065E-EN 29
Power Supply
Read the following Warnings, Cautions, and Notices before proceeding.
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N NO OT TIIC CE E
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IIm mp po orrtta an ntt:: After installation, ensure that the 24 Vac transformer is grounded through the
controller. Measure the voltage between chassis ground and any ground terminal on
the UC400 Controller. Expected measurement :Vac
£ 4.0 V
A separate transformer is recommended for each UC400 Controller. The line input to the
transformer must be equipped with a circuit breaker sized to handle the maximum transformer
line current. If a single transformer is shared by multiple UC400 Controllers:
• The transformer must have sufficient capacity.
• Polarity must be maintained for every controller powered by the transformer.
IIm mp po orrtta an ntt:: If the polarity is inadvertently reversed between two controllers powered by the
same transformer, a difference of 24 Vac occurs between the grounds of each
controller, which can result in:
– Partial or full loss of communication on the entire BACnet MS/TP link.
– Improper function of the UC400 Controller outputs.
– Damage to the transformer or a blown transformer fuse.
Transformer Recommendations
A 24 Vac power supply must be used for proper operation of the binary inputs, which requires 24
Vac detection. In addition, the spare 24 Vac outputs can be used to power relays and TRIACS:
• AC transformer requirements:
N No otte e:: The transformer must be sized to provide adequate power to the controller (12 VA) and
outputs (maximum 12 VA per binary output).
– UL listed, Class 2 power transformer.
– 24 Vac ±15%, device max load 24 VA.
• CE-compliant installations: The transformer must be CE marked and SELV compliant per IEC
standards.
Wiring Requirements
Install the power supply circuit in accordance with the following guidelines to ensure proper
operation of the UC400 Controller:
• 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.
• 18 AWG (0.823 mm 2 ) copper wire is recommended for the circuit between the transformer
and the controller.
W Wiirriin ng g IIn nsstta alllla attiio on n