AS 7240.4:2018 pdf free.Fire detection and alarm systems Part 4: Power supply equipment (ISO 7240-4:2017, MOD).
5.3 Power sources
5.3.1 General
5.3.1.1 There shall be at least two power sources for the power supply of the FDAS: the main power source and the standby power source.
5.3.1.2 Each power source, on its own, shall be capable of meeting the PSE manufacturer’s output specification or, in the case of an integrated the PSE, shall be capable of operating the equipment in which it is integrated within its specifications.
5.3.1.3 Switching from one power source to the other shall not cause any change in status or indications within other equipment of the FDAS, other than those relating to the power supply.
5.3.1.4 Failure of one of the power sources shall not cause the failure of any other power source or the failure of the supply of power to the FDAS.
NOTE The compatibility of the separated PSE with the other equipment, for example, FDCIE, is dealt with in
ISO 7240-13.
5.3.2 Main power source
5.3.2.1 ‘l’he main power source shall be designed to operate trom the public electricity supply or equivalent system.
5.3.2.2 When the main power source is available, it shall be the exclusive source of power to the FDAS, except for currents associated with battery monitoring.
5.3.2.3 If the main power source fails, then the PSE shall automatically switch over to a standby power source. When the main power source is restored, the PSE shall automatically switch back to the main power source.
5.3.2.4 When operated from the main power source, the following shall apply.
a) The PSE shall be capable of operating in accordance with its specification given in the manufacturer’s data, irrespective of the condition of the standby power source. This includes any charge condition of the standby power source, or open circuit or short circuit of the connection to the standby power source.
b) The PSE shall be capable of continuously supplying Pa, max and simultaneously charging a battery discharged to its final voltage.
c) It may allow battery charging to be limited or interrupted when the PSE is delivering power greater than a, max (see note to Table 1).
5.3.3 Standby power source
5.3.3.1 At least one standby power source shall be a rechargeable battery.
5.3.3.2 When operated from the standby power source, the PSE shall be capable of operating in accordance with the specification given in the manufacturer’s data. The PSE shall be capable of supplying Pc, max irrespective of the condition of the main power source, and with an internal resistance of the battery and its associated circuitry, e.g. connections, fuses (see 6.4) equal to R,
NOTE Standby periods and alarm periods for specific applications are specified in ISO 7240-14 and ISO 7240-19, or other national design and installation standards where they take precedence.AS 7240.4 pdf download.