38 900 Series V5.0: Installation Guide, April 1999
6.2.4. Calculation
Table 8: Calculation formula
Calculation for minimum device voltage (v
min
) under worst case
conditions:
Total current: I (sum of quiescent and alarm current)
Total resistance: R
Loop voltage: V ( e.g. FP1100/1200/2000 : 27.6 V )
V
min
= V — (I x R)
V
min
> = 17V — no zone monitoring units
V
min
> = 20V — with zone monitoring units