Design Considerations
PN 15842:K 7/23/2002 23
Figure 3-2 Using Multiple Power Supplies With the EIA-485 Circuit
3.6 Annunciator Power Requirements & Electrical Ratings
Annunciators draw their power from the control panel and must be considered
when calculating the primary and secondary power supply requirements for the
system. Each annunciator module is accounted for in the power calculations
outlined in the respective installation manual. However, if the current draw
dedicated to the annunciators must be calculated as a separate figure, use the
equations in Table 3-1.
Electrical Ratings
Input Voltage: 24 VDC (must be power-limited and non-resettable).
Data Communications Port:
EIA-485 operating at 20 Kbps (must be power-limited).
EIA-485 Reference
Annunciators in a backbox,
powered from control panel
Fire Alarm
Control Panel
EIA-485 Circuit
caba3.wmf
Annunciators in a cabinet,
powered from remote supply
Two-wire
EIA-485
Circuit
Power Loop
A common reference connection must
be made between multiple power
supplies for the EIA-485 circuit to
function properly!
ACM-24ATface.cdr
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