Primary power to the fire alarm system can be provided by the electric utility, an engine-driven generator (this is not a standby generator, however it is a site generator meeting the requirements in NFPA 72), and Stored-Energy Emergency Power Supply System (SEPSS), or a. Primary power to the fire alarm system can be provided by the electric utility, an engine-driven generator (this is not a standby generator, however it is a site generator meeting the requirements in NFPA 72), and Stored-Energy Emergency Power Supply System (SEPSS), or a. The new STV range of switch mode power supplies has been specifically designed for EN54 compliant fire systems and is NFS Approved. Available in either 1A, 2A or 5A versions they are certified to EN54-4, EN12101-10 and NF S 61-940 by AFNOR and VdS (EN54-4 only). The units include intelligent. To support firefighting operations, it is imperative that certain technical equipment is supplied with power for a sufficient period of time after a fire breaks out. For ex-ample, OBO systems for the maintenance ofelectrical functionto E60 and E90 ensure: Requirements regarding the length of the. There are a few different options when it comes to choosing a reliable power supply, as well as some calculations that are necessary to ensure that the fire alarm system is provided with sufficient backup power. The main power supply function is provided by connection to the AC mains. Circuits and equipment that provide.