Fire-Lite ABF-1F, Руководство пользователя

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15390 Rev D 8/2/96 P/N 15390:D
Figure 2: Terminating the Shield
The EIA-485 circuit must be wired using a twisted-shielded pair cable having a Charac-
teristic Impedance of 120 ohms, +/- 20%. Do not run cable adjacent to, or in the same
conduit as, 120-volt AC service, noisy electrical circuits that are powering mechanical
bells or horns, audio circuits above 25 V
RMS
, motor control circuits, or SCR power circuits.
All enclosures, including the FACP backbox, must be connected to earth ground! Never
use the shield for grounding purposes. Terminate the EIA-485 shield at the Fire Alarm
Control Panel only.
When the EIA-485 shield is in conduit: connect it to system reference ( system common).
The shield can enter the cabinet, but must be insulated from the cabinet (not electrical
contact). Between annunciators, wire-nut multiple shields together (which can be inside
of the respective enclosure, but can not contact the enclosure.)
When the EIA-485 shield is not in conduit: Terminate the shield at the outside of the FACP
backbox (ground). Do not allow the shield to enter or even touch the cabinet. Between
annunciators, wire-nut multiple shields together
outside of the respective enclosures.
Enclosure
Annunciator
Figure 1:
Installing the Enclosure
Mount the backbox or cabinet and pull all annun-
ciator wiring into the enclosure.