Uninterruptible power supplies (UPSs) are used in automation to provide continuous power in emergencies or disruptions. The main idea is to prevent equipment damage and to maintain operations during a power disruption or outage, which is important to save data.
Most automation systems will have a UPS available for protecting the control room but also to supply power to motor control centers (MCCs) or process control rooms for the purpose of protecting control cabinets and variable-speed drives and ensuring that data has time to be saved. Because automation systems have become extremely data-dependent, based on IT/OT convergence, the servers used in automation systems are also an asset in need of protection. Uninterruptible power supplies are used to provide battery or generator power during a power flicker or a brief outage to allow that safety critical systems may be cut over to backups or shut down in a safe manner. Automatic storage and retrieval systems (AS/RS), CNC machines and critical assembly lines are all assets that could benefit from a UPS.
The key benefit of a UPS is to provide power continuity, so devices do not short from surges. Other benefits are to ensure data integrity, improve safety and give a window to switch to generator support. Once on generator power, then the system may be controlled or fueled with a maintenance cycle. This means manning the equipment to make sure fuel is provided to keep systems running. Think data centers. Think safety systems.
Things to consider when choosing a UPS are sizing, high in-rush devices, matching the application, expandability and integration with other protection. For ratings, the common recommendation is to use a unit that is 1.2 times the total load. Yup, math is involved to calculate full load Amps.
High in-rush current surge can occur from devices like motor starters or high torque devices that require a boost of power on startup and then level out. This is also dependent on the application. Applications may need to consider three types of interfaces: standby, line interactive and double conversion. Double conversion systems offer the highest level of protection by continuously running the load through the inverter.
No system is an island to itself; thus, even if you calculate loads and set up the UPS for a specific application, you may need to expand in the future. Thus, when choosing a UPS, look at how more battery packs can be added or how UPS systems may be daisy-chained to allow for additional loads.
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Other protections include power quality components and surge protectors and line filters. These devices are used to ensure equipment is protected and reduce the possibility of damage to costly electronics. This is also key for data-center type applications because one way to cause problems is to break the power of a system as a cybersecurity threat. Data is either stored or in motion. Privacy of data is put into jeopardy when attackers can gain network access. One way of gaining network access is by physically faulting a system and intercepting on recovery.
Like many things, UPS systems may be networked. Providing a power solution may help prevent cybersecurity attacks, but you also must protect the UPS from attack using SNMP/HTTP security agent tactics. Examples of Various unplanned shutdowns in chemical plants, and hospital systems have caused chemical containment issues or imaging machines to shut down during critical times. Long-haul telecommunications systems normally use battery banks to ensure circuit stability. Failures on these fronts can cause government emergency systems to fail.
Failures of power systems in general are related to control-system fault, battery degradation, lack of maintenance, capacitor issue, overloading and environmental factors such as high temperatures, humidity and dust.
Remember that electrical components have a verified shelf life, but, when they are not traded out, maintained or tried, then they may fail unexpectedly. This is the reason that battery banks, UPS systems and generator tests are performed in a periodic maintenance cycle. If these maintenance cycles are neglected, then the UPS could fail when you need it most.
Uninterruptible power supplies may last five to eight years, but this is dependent on operating conditions. This is also dependent on battery quality and battery maintenance. Batteries should be replaced every three to five years. Other components that may fail in a typical UPS are the capacitors and the fan module. It’s important to test your UPS system a minimum of once per year. Once conditions of the UPS come to a variable state of uncertainty, then the UPS should be replaced. This would be normal service intervals for industrial, civil or information-technology (IT) environments.
