Installation manual

D9124 Operation & Installation Manual

Page 38

74-06799-000-D 2/96

Standby Battery and Current Rating Chart first:

You must calculate totals for columns

B and C in the

Auxiliary Current and Standby Battery Requirements

section,

Calculations

for 24VDC Devices

before you can complete the calculations below.

Calculating D9142 24VDC Battery Capacity Requirements for Initiating

and Indicating Devices

Central Stations or Local Systems Require 24 Hours Standby

For 24 hour standby battery capacity determination use the first three columns of Table

10. First determine your calculated total 24VDC current required, per page 36, Column B,

(AC power off). Next, from Table 10 in the 24 Hour Standby section, column labeled

Current (Amps), select the row where the current is equal to or larger than your

calculated total from page 36, Column B. To the left of this current value is the Battery

Amp Hour rating you need. This value already has factored in a five minute bell current of

3 Amps at the end of the 24 hour standby period. If your standby current is greater than 1

Amp, subtract the current greater than 1 Amp from the bell current. For example, if you

require 1.294 Amps of standby current you need a 38 AH battery. It will recharge in 17.1

hours and the maximum bell current is (4 Amps - 1.294 Amps) = 2.716 Amps of bell

current.

Remote Stations or Auxiliary Systems Require 60 Hours Standby

For 60 hour standby battery capacity determination use the first column and Columns 5

and 6 of Table 10. First determine your calculated total 24VDC current required per page

36, Column B (AC Power off). Next, from Table 10 in the 60 Hour Standby section,

column labeled Current (Amps), select the row where the current is equal to or larger

than your calculated total from page 36, Column B. To the left of this current value is the

Battery Amp rating you need. This value already has factored in a five minute bell current

of 3 Amps at the end of the 24 hours standby period. If your standby current is greater

than 1 Amp subtract the current greater than 1 Amp from the bell current. for the 60 and

71 hour standby required can always use 3 Amps for the battery capacities and currents

in the table.