Power protection information including how to design a secure power protection plan using uninterruptible power systems, generators and power distribution units.
Most modern transformerless uninterruptible power supplies can run up to 96% or more in terms of energy efficiency in full online mode if they have an IGBT-based rectifier and inverter. Some transformer-based UPS can achieved up to 96% if they use a high efficiency design transformer. The higher the efficiency the lower the running costs and addition to cooling load in the server room or datacentre environment.
In a centralised uninterruptible power supply installation, a single UPS system is used to power all the critical loads. The loads connect to an electrical circuit via sockets or PDUs connected to sub-distribution board and LV panels which are supplied with uninterruptible power. In a decentralised power protection plan, a number of individual uninterruptible power supplies are distributed into the server room or datacentre environment to power specific loads or areas. The UPS may be installed within a server rack or at the end of a server row.
In this scenario, the uninterruptible power supply is part of the critical power installation in order to provide a filtered, clean and stable electrical supply to the connected loads when mains power is present. When the mains power supply fails or fluctuates outside preset thresholds, the UPS uses its battery set to provide power via its inverter. At the same time the generator receives a signal via the automatic mains failure (AMF) panel to start. A standby generator will start-up and be up to full power within 1-2 minutes. Most UPS systems are installed with 10-30 minute battery sets to cover any delay in generator start-up and allow a short time for investigation and corrective actions. If the generator cannot start and the UPS exhausts its battery before the mains power supply returns, the connected loads are dropped. This is why monthly generator testing is recommended alongside regular maintenance for both the generator and uninterruptible power supply by manufacturer certified service engineers.