Rockwell Automation 1779-KP5_KP5R ORD.1779-5.3 - Manual (Page 28)

Installing the 1779ĆKP5 Module
Chapter 3
3Ć15
To provide AC power isolation between the 1779-KP5 and other
equipment, connect a separate transformer between the module’s power
supply and the AC power source. Connect the:
Transformer primary to the AC source.
High side of the transformer secondary to the L1 terminal of the power
supply.
Low side of the transformer secondary to the L2/N terminal of the
power supply.
The 1779-KP5 consumes 50 watts of power. To determine the required
rating of the transformer, multiply the power requirements of the
Allen-Bradley power supplies by 2.5 and add all other power
requirements (input circuits, output circuits). Take into consideration the
surge currents of devices controlled by the controller when determining
power requirements. The minimum transformer rating requirement for
the 1779-KP5 interface is 125 VA.
The 115V AC power supplies on Allen-Bradley modules are designed to
shut down whenever the AC line voltage drops below 85V. The power
supply allows the interface to resume operation when the line voltage
reaches 85V again. The 230V AC power supplies on Allen-Bradley
modules shut down at 170V AC.
If the transformer is too small, it clips the peak of the sine wave before the
voltage drops below 85 volts. The power supply senses this as a low
voltage and shuts down the interface prematurely.
Connecting Power and Ground to the Terminal Strip
1. Make sure that you remove all power to the enclosure. Usually, you
remove power by locking open the main disconnect switch on your
enclosure.
WARNING: Do not connect power to the power terminals
without first removing power from the enclosure. Otherwise,
you may be injured by electrical shock.