When mains power fails, an uninterruptible power supply (UPS) is designed to kick in almost instantly. This electrical set-up is commonly run by battery to give the user up to 15 minutes in which to restore the main energy supply or safely terminate ongoing processes, although fly wheel and diesel-powered systems are available. There are three main types of UPS: standby, online and line-interactive.
1. Standby or offline systems
The first is standby, also referred to as offline. When power drops, the DC-AV inverter is instigated to provide safety and back-up at a basic level. Run from the input power, this is a more cost-effective solution for systems under 1kVA.
For smaller spaces, the more recently-developed fuel cell UPS systems provide a contemporary solution without compromising the running time available. As reported by Digital Journal, the use of a fuel cell and hydrogen to form such a system is becoming an increasingly in-demand solution.
2. On-line or double conversion UPS systems
The second design type is online, whereby the UPS converts the AC to DC to take the power through a rechargeable battery before converting it back. The inverter and battery are constantly connected and the rectifier is temporarily dropped when there is a loss of power, meaning there is no break or switching required in the transfer process. Although this can be a more expensive option, it is more effective in larger scale operations and provides both a more substantial current and a continuously running inverter and rectifier; in addition, this system effectively provides a degree of insulation between the input power and the electrical devices, improving safety and reliability thanks to the static bypass.
Each element of any UPS system, such as the Eaton UPS systems, will vary depending on the manufacturer. A range of different elements are available from suppliers such as http://www.cppsales.com/Eaton_UPS_Systems___Accessories-catid17.
3. Line-interactive systems
The third design is a line-interactive system, which utilises autotransformers. By adjusting the power tap selected, this system is one of the cheaper options and can better handle long-running under voltage and over voltage surges; however, there may be a slight delay caused when the tap power is being redirected to the battery. Adapting this UPS to accommodate different voltages can become increasingly complex and costly.