In this article, Alex Emms, Operations Manager at Kohler Uninterruptible Power (KUP) explains the important role of the UPS during network presence and in the event of power outages and shows how important the selection of online systems is.
Most IT staff are aware that UPS batteries use batteries to seamlessly take on the critical load should the incoming utility power fail. While fulfilling this role, a UPS also performs an equally important protective function when utility power is available. Although electricity can be delivered, despite the total blackout, it is still subject to many types of interference. These fluctuations in the supply can damage or destroy unprotected sensitive loads.
Data center loads are usually described as critical, both in terms of their availability for the application that depends on them and their own dependence on high quality power supply at all times.
The immediate effect of an excess power supply can be to cause equipment failure due to component damage. Even if the supply problem just halts the load rather than damaging it, the consequences can still be severe. An unexpected hardware stop will result in a software crash, which will result in data loss or corruption. Business transactions are interrupted and lost, exposing the company to wider financial and reputational impacts.
In a manufacturing environment, the results could be equally if not more severe. For example, control systems could be placed in an inappropriate state. Both production equipment and the product can be damaged, requiring both cleaning and repairing time.
How serious is the threat to your particular installation and what can you do to mitigate it?
The answer depends on three factors; the type of power disturbances your power supply may experience, the types of devices you want to protect and how susceptible they are to these problems, and the steps you can take to provide protection.
Spikes are rapid voltage transitions of short duration that are superimposed on the network waveform. They can cause both positive and negative voltage fluctuations, damage or destroy electrical and electronic components, and damage software. It can be especially difficult to track down and fix software problems because they may not show up until some time after the damage occurs.
Spikes are typically caused by devices that switch high electrical currents or load switching by utility companies.
Overvoltages are voltage increases above normal grid levels that exceed one cycle. They usually occur after switching off a large load or after switching loads on substations.
Sags are drops in the mains supply that can last several cycles. They are generated similarly to negative spikes, but have a much longer duration. Sags are very common events, usually caused by turning on large loads such as air conditioners or starting rotating machinery. Sags can cause the computer to restart if the mains voltage is so low that the computer thinks it is turned off.
Brownouts are identical to sags, but are of much longer duration and generally more serious. They arise when the grid supply cannot cover the current load requirement and the generating company lowers the entire grid voltage. Brownouts can last several hours in extreme circumstances.
Power outages are complete power outages in which the mains supply fails completely. Caused by utility line failures, accidents, thunderstorms, and a host of other conditions, they have an obvious, sometimes devastating effect.
Computers usually have upper and lower limits for slow averaged rms voltage fluctuations in steady-state between ± 5% and ± 10%, depending on the manufacturer, but tolerate short-term mains voltage fluctuations outside these limits. The shorter the duration of the excursion, the larger the tolerable excursion. The ability of computer equipment to withstand network disturbances is very limited. Protection from the power supply at all times is essential.
The DPA control unit MF1500 from Kohler Uninterruptible Power with 6 modules
Choosing a UPS with an online double conversion topology protects against frequency fluctuations and voltage problems. This provides the highest level of power protection as the rectifier and inverter are positioned as barriers between the supply and the load. Removal of network-related noises and transient voltages. It is important that the inverter maintains its supply regulation even if it is operated with the UPS battery during a power failure.
The UPS not only filters out events such as peaks, but also protects against deflections outside a preset voltage range. In the event of overvoltages or sags, the UPS switches to battery power, as it would in the event of a complete power failure.
Critical loads can be threatened by both power issues and power outages. To ensure true UPS protection against all potential utility problems, it is essential to select a system with a dual online topology. Users then enjoy both protection against mains failures and battery autonomy in the event of a power failure.