SEC1000 FIRE ALARM CONTROL PANEL
Page
21
of 24
6. Battery Capacity Calculation
The standby time of the fire alarm control panel after the main power source has failed depends
on the quiescent load of the panel, the alarm load of the panel, and the capacity of the batteries.
To determine the capacity of batteries required in a system, the following formula is used:
Battery capacity (Ah) = 1.25 x ( T
1
x ( I
Fq
+ I
Lq
) + T
2
x ( I
Fmax
+ I
Lmax
+ I
Rout
) )
In which,
The multiplier 1.25 is present to account for loss of capacity over the life of the battery.
I
Fq
= 0.15A, which is the quiescent current of the fire alarm control panel in the event of the
loss of the mains supply;
I
Lq
is the quiescent current of the loop load, which is determined by the number of loads. The
quiescent current of a smoke detector, a heat detector, or a manual call point is typically
0.0002A (or 200μA), while that of a module/sounder strobe is 0.002A (or 2mA);
I
Fmax
= 0.16A, which is the alarm current of the fire alarm control panel;
I
Lmax
is the maximum loop current. The alarm current of a smoke detector, a heat detector, or a
manual call point is typically 0.001A (or 1mA), while that of a input/output modules or
Intelligent Sounder Beacon is 0.008A (or 8mA) ;
I
Rout
is the alarm output current of the panel’s three relays, which is determined by the number
of loads they connect;
T
1
is the amount of standby hours required (most commonly being 24 hours);
T
2
is the amount of alarm hours required (most commonly being half an hour).
Take the system of 120 points as an example: there are 104 addressable detectors, 8 input/output
modules, 8 intelligent Sounder Beacon, 8 loop isolators and 3 full loaded relay output.
Thus,
I
Lq
= 0.0002 x 104 + 0.002 x 16 = 0.0528A,
I
Lmax
= 0.001 x 104+0.008 x 16 = 0.232A,
I
Rout
= 1 x 0.1 = 1.1A,
Battery capacity = 1.25 x (24 x (0.15+0.0528) + 0.5 x (0.16+0.232+1.1) )
= 1.25 x (4.8672 + 0.746)
= 7.0165Ah
Note: The final interpretation right belongs to the company.
7. Maintenance and Troubleshooting
7.1 Maintenance
Periodic maintenance should be carried out on the system as prescribed in the local design,
maintenance and installation regulations.
The key to the panel shall be kept by specially assigned maintenance personnel.
The standby batteries should be periodically checked for integrity of the connections. And a period
of 5 years is recommended to replace the correct type of battery.
Summary of Contents for SEC1000
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