94 UNT Controller—Unitary Controller (UNT)
In some OEM systems, the contactor solenoid coils driven by the UNT
may also be earth grounded. This also disrupts the isolation required for
N2 communication integrity.
Note: The Troubleshooting section of this technical bulletin contains a
detailed process that will reduce installation errors by ensuring
proper isolation.
If the secondary of the power transformer is grounded, you must use a
separate 24 VAC to 24 VAC isolation transformer such as the Y65G13
(see Figure 42).
If UNT output loads, such as driven contactor or solenoid coils, are
grounded, you must use a separate isolation relay for each load
(see Figure 42).
The binary inputs on the UNT100/101 series controllers are inactive when
open or a 5 VDC logical high is supplied. They are active when a contact
closure to UNT common or a logical low is applied. BI 4 may be used as
an accumulator input for frequencies less than 100 Hz.
Each UNT100 series controller’s binary outputs must be connected
between the BO terminal and 24 VAC terminal since it is low side
switching.
Power
Transformer
Isolation
UNT100/101
Load Isolation
UNT100/101
Binary Inputs
Binary Outputs
Summary of Contents for UNT Series
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