NFS2-640/E Installation Manual —
P/N 52741:P2 7/10/14
67
Calculating the System Current Draws
Power Supply Calculations
Results taken from Table A.3 below assume that, while in a fire alarm condition, batteries must
feed the main power supply (and any additional supplies such as the APS-6R and AA-30) with the
maximum rated power each supply can provide.
Device
Quantity
Current
(in amps)
Total Current/Type
Alarm Current, from Table A.2, col 2
=
APS-6R
*
* Actual load current may be used in place of maximum rated supply
current. To calculate actual load current, sum the current draws for each
appliance connected to APS-6R supplies.
[
]
X
6
=
APS2-6R
[
]
6
=
AA-30
†
† Exclude Amplifiers that are employed for backup.
[
]
X
3
=
AA-120
[
]
X
7.3
=
Sum Column for Secondary Fire Alarm Load
=
Table A.3 Maximum Secondary Power Fire Alarm Current Draw
NOTE:
The Secondary Fire Alarm Load cannot exceed the following:
12 A with BAT-12260 batteries (12 V, 26 AH).
20 A with BAT-12550 batteries (12 V, 55 AH).
