UNT Controller—Unitary (UNT) Controller
17
Wiring Details
This section details the special precautions and grounding procedures you
must observe when installing the UNT.
!
WARNING: Possible Equipment Damage or Electrical Shock.
To avoid damaging equipment or suffering electrical
shock, ensure that all power supplies to the system
have been disconnected prior to wiring installation.
The Complementary Metal Oxide Semiconductor
(CMOS) circuits used in the controller are static
sensitive. Use static protection (anti-static) mats
and/or grounding straps when working on or near
internal circuitry.
The power transformer used must comply with:
•
CSA 22.2 No. 205
•
NEMA ICS 2, Part 2, 230
The power to each UNT must be limited to 3 amperes or less. However, if
you use one low voltage power trunk to power multiple controllers,
follow these precautions:
•
Ensure that polarity is maintained at each 24 VAC connection.
•
Enclose 24 VAC power trunks with greater than 4 amperes (100 VA)
in conduit as required by the National Electric Code (NEC).
•
Do not share a UNT’s power transformer with a Companion or
Facilitator Panel, or any other device with a full-wave rectifier in its
power supply. (UNTs use “half-wave” rectification. Half-wave
circuitry and full-wave circuitry must not share the same transformer.)
•
Consider all the actual loads as well as the basic load of the controller
when determining the system load.
Notes: Some local electrical codes and NEC 250 require that the
secondary common of the stepdown transformer be connected to
earth ground on units which are powered by greater than 150 VAC.
The M100 draws 20 VA if using common power for the controller
and the M100 actuator. It is recommended that each M100 use its
own 24 VAC isolation transformer.
Power Source
and Loads
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