Thread: UPS Selector for example APC products

Uninterruptible power supplies (UPS) - is an automatic device whose primary function - the power to the connected load from the energy storage batteries when the mains voltage disappears or its output parameters (voltage, frequency) beyond the permissible limits. In addition, some UPS can adjust the parameters of power when working from the mains, ie serve as a filter and stabilizer.

In this article, choose the UPS is illustrated by the company's products APC (American Power Conversion), founded in 1981 by three electrical engineer, have completed the Massachusetts Institute of Technology (MIT). The first was published by UPS in 1984 and in 2007, APC is a subsidiary of Schneider Electric and is currently the market leader in uninterruptible power supply and the winner of numerous awards.

In early 2010, APC has released a new model series RS - Back-UPS RS 550 (BR500GI) This device has a new interesting feature of energy saving. It is implemented as a "dependent" output Outlets UPS, which is de-energized, if you turn off the computer connected to the "mainstream" outlet on the device.

So you can save energy by automatically turning off equipment such as hubs, modems, routers and other peripherals, are usually unnecessary when not operating computer. Another important innovation that makes it more convenient to use UPS, is the presence of liquid crystal display that displays detailed information about the UPS status and power.

For reference: In Russia the standard domestic power supply is as follows: operating voltage - 220 V ± 10%, 50 Hz ± 1%, the coefficient of non-sinusoidal - lasting up to 8%, short term up to 12%. Thus, the voltage should change its value a sine curve with period 1 / 49 - 1 / 51 sec, located within 196 V - 242 V, and vary in shape from the ideal sine wave is not more than 8%.

Uninterruptible power supply indicated in volt-amperes (VA), and the power in a more familiar in watts (W) can be found by multiplying the power in volt-amperes by a factor of 0.6. For example, UPS power characteristics 700VA protects uninterrupted power supply equipment with a maximum consumption of 420 Tues

Calculate the power to the connected load can summing power for all connected to the UPS consumers for personal computers, this power is always less than the rated capacity of power supply (as a rule - one and a half times) and depends on the particular configuration, it can be roughly calculated example, using the FAQ on the selection of the required power supply.
Example: a computer system with power supply denomination 350Vatt consumes 250 watts + monitor 45W = 295 W, dividing this figure by 0.6, we obtain 491VA, ie for this configuration, the minimum suitable power UPS - 500VA.

Estimated time of the UPS for a given load level, the easiest way to find out, see the documentation provided by the manufacturer. This article further refers to the time chart of all families referred UPS APC. Typically, the maximum load the battery life is measured by several minutes, which is usually enough to retain user data and the correct equipment off.

Remember also that the dependence of battery life on the power of the connected load has a nonlinear form of the drop in converter efficiency while reducing the load on the face, for example, UPS series BackES this dependence has the form shown in the chart on the left.Understanding this fact can save you from buying too powerful UPS for a long service life of connected equipment - such an idea is unlikely to end well, because when running on battery power operation, in times less than the nominal UPS, their resources will be mainly spent an inverter, and not load.

Another factor that reduces the battery of the UPS is a drop in battery capacity. Battery capacity decreases during the term of operation, this must be borne in mind, if the batteries in the UPS is operated by a substantial part of their life cycle (typically it ranges from two to four years).