User guide

Digital Designer’s Guide
AN0604D Revision B
Tips for connecting 24-volt power
Connecting to controllers
1–17
Connecting to
controllers
KMC Controls recommends supplying power to each controller from a
transformer dedicated to the controller.
Illustration 3 is a typical connection of a
KMC XEE–6000 series transformer connected to a KMC controller. The usual
practice is to connect the phase (usually blue) wire of the transformer secondary
to the phase or ~
terminal and the common (usually brown) wire connected to the
– or ground terminal. Other transformers may use a different color scheme.
Unless required by an electrical code requirement, do not ground either lead of
the secondary.

24 VAC120 VAC
Connecting several controllers to a single transformer
When more than one controller must be powered from a common transformer,
connect as shown in
Illustration 3. In addition, observe the following
requirements:
◆ Connect the phase (~) terminals in parallel with other phase terminals and
the commons (–) in parallel with the other common terminals. See
Illustration 4.
◆ If the secondary must be grounded, ground it at only one location. See
Grounded secondary connections
on page 1-18.
◆ Connect only controllers with the same type of power supply. Controllers
with half-wave power supplies and full-wave power supplies cannot be
powered directly by the same transformer. See Grounded secondary
connections on page 1-18.
◆ Choose a transformer with the correct VA rating. See Calculating transformer
size on page 1-21.
◆ Choose a wire size that limits the voltage drop to no more than 5%. See
Calculating voltage drop
on page 1-22.
Illustration 3 Connecting to a single controller