A supplied standby-capacity exercise
A classroom fire-alarm power exercise supplies a standby current of 0.25 ampere for 24 hours and an alarm current of 1.5 amperes for five minutes. The exercise explicitly instructs learners to apply a multiplier of 1.2 to the summed charge requirement. These are supplied model assumptions, not a universal statement of the adopted code or a complete battery selection. A trainee multiplies the alarm current by five as though minutes were hours. Another selects a battery solely by its printed ampere-hour number without considering the equipment listing or operating conditions. Students must calculate the model consistently and explain what further information an actual approved system requires. No real battery chemistry, temperature, aging condition or manufacturer discharge curve is supplied.
1. Calculate the modeled capacity.
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Standby charge is 0.25 times 24 = 6 Ah. Alarm charge is 1.5 times 5/60 = 0.125 Ah. The stipulated multiplier gives (6 + 0.125) times 1.2 = 7.35 Ah.
2. Does 7.35 Ah alone select a battery?
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No. Real selection requires the listed system, applicable requirements, battery compatibility, discharge behavior and relevant aging and environmental conditions. The exercise multiplier and durations are explicitly supplied assumptions.