Section 2: Installation
Capacitance limits
An increase in capacitance on the Corbus affects data transmission and causes the system to slow down. Capacitance
increases for every foot of wire added to the Corbus. The capacitance rating of the wire used will determine the maximum
length of the Corbus.
For example, 22-gauge, non-shielded, 4-conductor wire has a typical capacitance rating of 20 picofarads per foot (which is
20 nF/1000 ft). For every 1000 feet of wire added – regardless of where it is run – the capacitance of the Corbus increases
by 20 nF.
The following table indicates the total wire distance allowed for the capacitance rating of the wire used:
Table 2-3 Wire capacitance
Wire Capacitance per 1000 ft (300 m)
Total Corbus Wire Length
15 nF
5300 ft/1616 m
20 nF
4000 ft/1220 m
25 nF
3200 ft/976 m
30 nF
2666 ft/810 m
35 nF
2280 ft/693 m
40 nF
2000 ft/608 m
2.4 Installing modules
Remove all power from the system while connecting modules to the alarm controller.
Zone expanders
The main alarm controller has connection terminals for zones 1 to 8. Additional HSM2108 and HSM3408 zone expanders
may be added to increase the number of zones on the system. Each zone expander consists of one group of 8 zones. At
enrollment, the zone expander is automatically assigned to the next available 8-zone expander slot/Corbus expander slot.
Connect the RED, BLK, YEL and GRN terminals to the Corbus terminals on the alarm panel. Board current draw: 30 mA.
Figure 2-20 HSM2108 zone expander
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