Installing the 1779KFM Interface
Chapter 4
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Power supplies that are set up for 115V AC operation are designed to
generate a shutdown whenever the AC line voltage drops below 85 volts
and to allow the interface to resume operation when the line voltage
reaches 85 volts again. For power supplies that are set up for 230V AC
operation, the shutdown level is 170V AC.
If the transformer is too small, it will clip the peak of the sine wave before
the voltage drops below 85 volts. The power supply will sense this as a
low voltage and shut down the interface prematurely.
Allen-Bradley power supplies have circuits which suppress
electromagnetic interference from other equipment. For installations near
particularly bad electrical noise generators, an isolation transformer can
provide further suppression of electromagnetic interference from other
equipment.
In applications where the AC power source is especially “soft” and
subject to unusual variations, a constant-voltage transformer can stabilize
the AC power source to the interface, thereby minimizing shutdowns.
Now that you have installed the 1779-KFM interface, connecting it
between a host device and a dropline on the Data Highway II link, you are
ready to read about how to operate and troubleshoot your 1779-KFM
interface.
Summary