Lowering TCO

Power protection is now an absolute must for modern IT systems, but implies investments that are on the increase daily. It is also true that predicting the development and growth of networks is becoming more and more difficult. As a result, defining in advance what economic impact a UPS system will have over time is not an easy exercise. For UPS systems in particular, in most cases assessment of the initial purchase cost seems to be the only parameter considered. On the other hand, operating and management costs (or TCO, Total Cost of Ownership) are also a factor that may condition the choice of an initial purchase. For example, the battery is one of the most problematic components in a UPS system because its operation depends on a series of variable factors that are often difficult to control, such as how it is used, the operating temperature and even where it is installed. It is well know that there are two main types of battery: lead acid and NiCad. The latter last longer and therefore have to support a higher number of charge and discharge cycles. Nor do they have leaks of gas or corrosive liquids. Another difference lies in storage: in the case of lead acid batteries, if a full discharge occurs, recharging may be difficult. NiCad batteries do not have this problem, but are subject to the well-known “memory effect” and are more expensive. In particular for lead acid batteries, a user wants to be able to count on guaranteed availability, on the reduction, or rather, on the prevention of failures and, last but not least, on low running costs limiting the consequent ageing of the batteries. Research carried out by Socomec Sicon UPS demonstrates that an increase in UPS power is proportional to the increase in battery costs. Assuming 100 to be cost of a 15 kVA UPS, the battery cost is around 20%, but this percentage rises to 40% for a unit with an 80 kVA power rating. Therefore attention needs to be paid to how the batteries are used, especially for high power units. There are three main causes of battery failure: insufficient charge (the sulphating phenomena occurs), positive grid corrosion caused by an overload, discharge and charge cycles (passivation). Another element to consider is the operating temperature. For a 10° C temperature increase, i.e. from 20° to 30° C, the battery life is halved; a further 10° C increase cuts battery life to a quarter. Finally any variation in “normal” operating voltage further reduces battery life. For example, assuming 100 to be the battery life, a slight fluctuation in voltage (up or down) causes a significant reduction in battery life. So careful management of the battery in terms of charging voltage and operating temperature will increase battery life and therefore lower system costs. However, the end user cannot be expected to take on these problems. This is where Socomec Sicon UPS comes in, offering an electronic system that provides an algorithm for intelligent battery charge management. By alternating intermittent recharge cycles with floating type recharges depending on the operating temperature and the recharge voltage, this system ensures that the voltage remains between two values close to the optimal operating voltage. In this way, keeping the values fluctuating in continual cycles between the maximum and minimum values, battery life is increased by a good 40%. Tests carried out show how a battery managed with electronics of this type lasts for 60 months, against the 36 months that are typical of a battery managed in the traditional way. Another solution for improving system performance is the so-called “double battery”. On a traditional UPS, the failure of one battery blocks the entire battery string and the UPS stops working. By arranging the batteries into two separate sections, should a failure occur on one section, the UPS can still guarantee 70% of the nominal charge even though with lower b

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