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Power Supply Calculations
6.4 Calculating the Battery Size
Use Table 6.3 to calculate the total Standby and Alarm load in ampere hours (AH). This total load
determines the battery size (in AH), required to support the ACC-25/50 Series under the loss of AC
power. Complete Table 6.3 as follows:
1.
Enter the totals from Table 6.2 on page 99 Calculation Columns 1 and 2 where shown.
2.
Enter the NFPA Standby and Alarm times (refer to Section 6.4.1, "NFPA Battery
Requirements").
3.
Calculate the ampere hours for Standby and Alarm, then sum the Standby and Alarm ampere
hours.
4.
Multiply the sum by the derating factor of 1.2 to get the proper battery size (in AH).
5.
Write the ampere hour requirements on the Protected Premises label located inside the cabinet
door.
Secondary Standby Load
(total from Table 6.2 Calculation Column 1)
[
]
Secondary Alarm Load
(total from Table 6.2 Calculation Column 2)
[
]
Sum of Standby and Alarm Ampere Hours
Multiply by the Derating Factor
Battery Size, Total Ampere Hours Required
Table 6.3 Total Secondary Power Requirements at 24 VDC
6.4.1 NFPA Battery Requirements
NFPA requires 24 hours of standby plus 15 minutes activation for audio systems. The total ampere
hours required cannot exceed 18 AH with an internal charger. An external charger can be used to
increase the total ampere hours (internal charger must be disabled).
6.4.2 Selecting and Locating Batteries
Select batteries that meet or exceed the total ampere hours calculated in Table 6.3. The audio panel
can charge batteries in the 7 AH to 18 AH range. The ACC-25/50 Series can house up to 18 AH
batteries.
100
Required Standby Time
(24 or 60 hours)
[
]
Required Alarm Time
(for 5 min., enter 0.084,
for 10 min., enter 0.168,
for 15 min., enter 0.250)
[
]
Audio Command Center Series Manual — P/N 51889:E1 6/8/2010
Calculating the Battery Size
=
AH
=
AH
=
AH
X 1.2
=
AH
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