14
UNT Controller—Unitary (UNT) Controller
The UNT must be installed more than 9 meters (30 feet) from electrical
distribution panels or major bus and feeder systems in industrial plants,
when powered by standard transformers without MOVs.
Without MOVs, the UNT meets the following surge levels:
IEEE-587 style Common Mode Pulse 3 kV
IEEE-587 style Normal Mode Pulse 1.5 kV
IEEE-472 style Common Mode Ringwave 1.5 kV
IEEE-472 style Normal Mode Ringwave 500 V
If the controller is installed within 9 meters (30 feet) of electrical
distribution panels or major bus and feeder systems in industrial plants,
you must take further precautions to prevent unwanted binary output
cycling, resetting, or other possible controller malfunctions.
To prevent electrical noise from adversely affecting the controller, use
a split-bobbin transformer (such as XFR50 or XFR100), or connect an
MOV (Metal Oxide Varistor) across the UNT supply transformer primary.
The MOV must be rated appropriately for the line voltage. Use the list in
Table 4 to select the correct MOV sold through your electronics parts
distributor.
The UNT meets the following power line surge/noise standards when you
correctly apply a split-bobbin transformer or MOV as described:
IEEE-587 Common Mode Pulse 1.5 kV
Normal Mode Pulse 6 kV
Normal Mode Ringwave 6 kV
IEEE-472 Common Mode Ringwave 1.5 kV
Normal Mode Ringwave 500 V
Note: The 50 VA split bobbin transformer in the EWC15 or -101 model
UNT provides additional surge/noise immunity.
For more information on noise prevention, refer to Appendix A:
Precautions for Rooftop Installations in this technical bulletin.
Power Line
Wiring
Transient Noise
Precautions
Surge Levels
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