Menu
Is free
check in
the main  /  Advice / Caring for uninterruptible power supply. Appointment of uninterruptible power supply (UPS), types of sources

Care of uninterruptible power supply. Appointment of uninterruptible power supply (UPS), types of sources

As a development, civilization begins to consume more and more energy, in particular, electric - machines, plants, electric pumps, lights on the streets, lamps in apartments ... The appearance of radio, televisions, telephones, computers gave humanity the opportunity to speed up the exchange of information, however, tied even more Its to sources of electricity, since now, in many cases, the disappearance of electricity is equivalent to the loss of information flow channel. This situation is most critical for a number of the most modern industries, in particular, where computer networks are the main tool.

It has long been calculated that through a couple of months of operation, the cost of information stored on the computer exceeds the cost of the PC itself. For a long time, the information has long been a type of product - it is created, assessed, sell, buy, accumulate, transformed ... and sometimes lose in a wide variety of reasons. Of course, up to half of the problems associated with the loss of information arise due to software or hardware failures. In all other cases, as a rule, problems are associated with poor-quality power supply of the computer.

Ensuring high-quality nutrition of PC components is the key to the stable operation of any computer system. From the form and qualitative characteristics of the network nutrition, the fate of the whole months of operation depends on the successful choice of nutritional components. Based on these considerations, the following methodology was developed below, designed to further become the basis for testing the qualitative characteristics of uninterrupted power supplies.

  1. Positions GOST
  2. UPS Classification (Description, Scheme)
    • Offline
    • Linear interactive
    • Online
    • Main types for facilities
  3. Physics
    • a. Power types, calculation formulas:
      • Instant
      • Active
      • Reactive
      • Full
  4. Testing:
    • Objective testing
    • General plan
    • Parameters for checking
  5. Equipment used in testing
  6. Bibliography
Positions GOST

All that is associated with electrical networks, in Russia is regulated by the provisions of GOST 13109-97 (adopted by the Interstate Council for Standardization, Metrology and Certification, in return for GOST 13109-87). The standards of this document fully comply with international standards IEC 861, IEC 1000-3-2, IEC 1000-3-3, IEC 1000-4-1 and Publications of IEC 1000-2-1, IEC 1000-2-2 in terms of electromagnetic compatibility levels In power supply systems and methods for measuring electromagnetic interference.

Standard indicators for power grids in Russia, established by GOST, are the following characteristics:

  • power supply - 220 V ± 10%
  • frequency - 50 ± 1 Hz
  • the coefficient of non-linear distortion of the voltage form is less than 8% for a long time and 12% - briefly

Stipulated in the document and typical problems of power supply. Most often, we have to deal with the following of them:

  • Complete loss of voltage in the network (no voltage in the network for a while more than 40 seconds due to disorders in the power supply lines)
  • Sailing (short-term reduction in the network to a value of less than 80% of the nominal value for a time more than 1 period (1/50 seconds) are a consequence of the inclusion of powerful loads, externally manifests itself as flickering lighting lamps) and bursts (short-term increase in the voltage in the network by more 110% of nominal at a time more than 1 period (1/50 seconds); appear when the high load is turned off, externally appear as flickering lighting lamps) voltage of different duration (typical for large cities)
  • High-frequency noise - radio frequency interference of electromagnetic or other origin, the result of the operation of powerful high-frequency devices, communication devices
  • Frequency deviation beyond permissible values
  • High-voltage emissions - short-term voltage pulses of up to 6000V and duration up to 10 ms; appear during thunderstorms as the result of static electricity, due to the spark of switches, there are no external manifestations
  • The frequency elevation is the change in the frequency of 3 or more Hz from the nominal (50 Hz), appear when the source of electricity is unstable, can not appear.

All of these factors can lead to the failure of the "fine" electronics, and, as often happens, to data loss. However, people have long learned to defend themselves: the filters of the network voltage, "quenching" jumps, diesel-generators that supply electricity systems in the disappearance of voltage in the "global scale", finally, uninterrupted power sources - the main tool for protecting personal PCs, servers, mini-PBX And others. Just about the last category of devices and will be discussed.
Classification of UPS

You can "separate" the UPS by different signs, in particular, by power (or application) and by type of action (architecture / device). Both of these methods are closely connected with each other. By power, the UPS is divided into

  1. Sources of uninterrupted power low power(with full capacity 300, 450, 700, 1000, 1500 VA, up to 3000 VA - including on-line)
  2. Small and medium power (with total power 3-5 kVA)
  3. Middle power (with a total power of 5-10 kVA)
  4. Big power (with a full capacity of 10-1000 kVA)

Based on the principle of operation of devices, two types of uninterruptible power sources are currently used in the literature. According to the first type, the UPS is divided into two categories: ON-LINE and oFF-LINEwho, in turn, are divided into reserve and linear interactive.

According to the second type, the UPS is divided into three categories: reserve (OFF-LINE or STANDBY), linear interactive (Line-interactive) and UPS with dual voltage conversion (ON-LINE).

We will use the second classification type.

Consider to start the difference of the types of UPS. Sources of backup type Made according to a circuit with a switching device, which in normal operation provides a load connection directly to the external power supply network, and in emergency translates it to power from batteries. The advantage of the UPS of this type can be considered simplicity, disadvantage - non-zero time switching to nutrition from batteries (about 4 ms).

Linear interactive UPS Made according to a circuit with a switching device, complemented by an autotransformer-based input voltage stabilizer with switchable windings. The main advantage of such devices is to protect the load from an increased or low voltage without transition to alarm mode. The disadvantage of such devices is also nonzero (about 4 ms) switching time to batteries.

Double Conversion UPS Voltages are different in that it is first transformed into the input to the input to the rectifier in constant, and then with the help of the inverter - again into the variable. The battery is constantly connected to the output of the rectifier and the input of the inverter and nourishes it in an emergency mode. Thus, a sufficiently high stability of the output voltage is achieved, regardless of the voltage fluctuations at the input. In addition, interference and perturbations are effectively suppressed, which is replete with the supply network.

Practically, the UPS of this class when connecting to the AC network behave like a linear load. The plus of this design can be considered the zero switching time to power from batteries, minus - decreased efficiency due to losses at twofold voltage conversion.


Physics

In all reference books, four types of power differ in electrical engineering: instant, active, reactive and full. Instant power It is calculated as a product of an instant voltage value and an instantaneous current value for an arbitrarily selected point of time, that is

Since in the chain with the resistance R u \u003d IR, then

Average Power period P of the circuit under consideration is equal to constant consideration instantaneous power.

The average for the period of the power of alternating current is called active . The unit of active power of the volt-amp is called Watt (W).

Accordingly, the resistance R is called active. As u \u003d ir, then


Typically, precisely active power is understood under the power consumed of the device.

Reactive power - The value that characterizes the loads created in electrical devices by the oscillations of the energy of the electromagnetic field. For sinusoidal current is equal to the product of the active current and voltage on the sine of the phase shift angle between them.

Full power - Total power consumed with a load (both active and reactive components are taken into account). It is calculated as a product of the standard input and voltage values. Unit of measurement - VA (Volt-Amperon). For sinusoidal current is equal

Almost on any electrical device is a label with an indication of either the full power of the device or active power.
Testing

The main purpose of testing - Demonstrate the behavior of the UPS tested in real conditions, give an idea of \u200b\u200badditional characteristics that are not reflected in the general documentation on the device, in practice, determine the influence of various factors for the work of the UPS and, possibly, help determine the choice of one or another uninterruptible power supply.

Despite the fact that the recommendations on the choice of UPS currently there are a great set, during testing we expect, firstly, consider a number of additional parameters that are worthwhile before buying equipment, secondly, the need to adjust the set of selected methods and parameters. Testing and develop a database for the future analysis of the entire path of power supply.

The general test plan looks like this:

  • Specifying device class
  • Specifying the characteristics stated by the manufacturer
  • Description of delivery package (availability of manuals, additional cords, software)
  • Short description of the appearance of the UPS (the functions made on the control panel and the list of connectors)
  • The type of batteries (indicating the battery capacity, served / maintained, name, possibly - interchangeability, the ability to connect additional battery blocks)
  • "Energy" component tests

In the testing process, it is planned to check the following parameters:

  • The input voltage range in which the UPS operates from the network without switching to batteries. A larger range of input voltage reduces the number of UPS transitions on the battery and increases its service life
  • Switching time to battery powered. The smaller the switching time, the smaller the risk of failure of the load (devices connected via UPS). The duration and nature of the switching process largely determine the possibility of normal continuation of the equipment. For computer load Admissible interrupt time 20-40 ms.
  • Oscillogram switching to battery
  • Switching time from the battery to external nutrition
  • Switching oscillogram from battery for external nutrition
  • Offline work time. This parameter is determined exclusively the battery capacity established in the UPS, which, in turn, increases with the increase in the maximum output power of the UPS. To provide autonomous power in two modern computers of SOHO typical configuration for 15-20 minutes, the maximum output power of the UPS should be about 600-700 VA.
  • Output voltage options when working from batteries
  • Impulse shape at the beginning of the battery discharge
  • Pulse shape at the end of the battery discharge
  • Range of output voltage UPS when the input voltage changes. Than this range is already, the less the effect of changing the input voltage on the feed load
  • Stabilization of output voltage
  • Output voltage filtering (if it is)
  • UPS behavior when overloading
  • UPS behavior when the load is disappeared
  • Calculation of the efficiency of the UPS. Determined as the ratio of the output power of the device to the power consumed from the power supply
  • The coefficient of nonlinear distortion that characterizes the degree of difference of the voltage or current form from the sinusoidal
    • 0% - sinusoid
    • 3% - distortions are not noticeable to the eye
    • 5% - distortion is noticeable to the eye
    • up to 21% - trapezoidal or step form
    • 43% - the signal has a rectangular shape
Equipment

When testing, we will use non-real work stations and servers, but by equivalent loads that have a stable nature of consumption and the power utilization factor close to 1. As the main equipment that will be used during testing, the following set is currently being considered:

Bibliography
  1. GOST 721-77 Energy supply systems, networks, sources, transducers and electrical receivers. Rated voltages over 1000 V
  2. GOST 19431-84 Energy and electrification. Terms and Definitions
  3. GOST 21128-83 Power supply systems, networks, sources, converters and electrical energy receivers. Rated voltages up to 1000 V
  4. GOST 30372-95 Electromagnetic technical compatibility. Terms and Definitions
  5. Theoretical electrical engineering, ed. 9th, corrected, M.-L., Publisher "Energia", 1965
  6. Advertising materials companies
  7. Internet resource

Embossed power supply is one of the main problems of the failure of household, office or industrial equipment. Despite the fact that nozzles arising in the electrical network are periodic, they have a detrimental effect on the components of modern electronic devices connected to the outlet. To protect the critical equipment or storing data when the supply voltage disappears, uninterruptible power sources are most common.


The main schemes of work and scope of uninterruptible power sources

The assignment of the UPS is to ensure the correct operation of the load with sharp "failures" or "bursts" of voltage, as well as ensuring the short-term offline operation of the connected equipment with the full shutdown of the electricity. Modern uninterruptants are divided into three classes:

  1. Backup or offline
  2. Linear interactive
  3. Double energy conversion

Their design and functionality are somewhat different, but, how to use a smoothie, everyone can understand.

Why do you need a reserve UPS? The main scope of its application is the protection of household computer and multimedia equipment. The scheme of its work is extremely simple: the load is powered by the network, and when the voltage disappears in it, the device switches to battery mode. The switching time between the types of functioning is nonzero. It is relatively inexpensive and will allow protecting equipment from minor voltage drops and short-term stress disappearance.

The advantages of the Linear interactive type UPS are more smoothly stabilizing the signal and the possibility of working in a wide range of input voltages. Such devices do not allow to adjust the frequency of the signal from the power supply, in the same power mode from the battery cells, may produce "pure" or approximated sinusoid. How can I use Line-Interactive uninterruptible? It is great for protecting monitors, system units, LAN nodes, workstations, computer peripherals and other power supply devices, which makes it excellent.

The most perfect equipment protection - UPS with a double energy conversion. But what is valuable in uninterruptible designed according to the Online scheme? It is characterized by instant switching between operation modes and the independence of the signal parameters at the output from the parameters at the UPS input. Therefore, this type of UPS is designed to switch equipment, especially demanding power to the quality of the power supply. Among uninterruptants online topology, based on the scope of their application, you can select the following types:

Alternative protective equipment options

Many wonder: Does the uninterruptible need, if the voltage in the network does not disappear, but simply "jumps"? Does you need a uninterrupted computer in that case? The answer to these questions may be a look in the direction of voltage stabilizers. These devices allow you to adjust the signal in a very wide range, feeding the voltage of this level to the load input, which was set by the user. This is the main advantage of these instruments. The main disadvantage is that the stabilizer ceases to work simultaneously with the disappearance of the voltage in the power grid. The main problem of stabilization devices is the inability to ensure the autonomous workload. Therefore, it is important to clearly understand what the equipment must be protected: from fluctuations in the signal level or from frequent and short-term power outages. In the first case, the output from the situation will be the voltage stabilizer, in the second, the source of uninterrupted power supply, the purpose of which is somewhat extensive.

But what to do if the signal level in the power grid is relatively stable, but there are long-term power outages? Out of such a situation can be the acquisition of a diesel generator. They are produced with different power ranges and can be applied to maintain both domestic and industrial facilities. There are models on diesel fuel and on gasoline. The device starter can be both manual and electric. The advantage of using such an installation is that it can provide for a long time of autonomous operation of equipment with interruptions exclusively on service or refueling. This technique is compact, easy to maintain and easy to use.

The operation of DSU is not deprived of a number of shortcomings, they can be attributed to them:

  • The inability to independently transition to the power of the load when the voltage disappears in the power supply network;
  • Noise in the process of work;
  • The presence of exhaust gases;
  • A large number of consumables (candles, fuel, etc.)

Complex solutions for protecting electronic equipment

To ensure maximum protection of telecommunications, server or industrial equipment, the use of one type of devices may not be enough. Therefore, their combination can be the most optimal solution. For example, the UPS for emergency lighting will not provide a proper level of autonomy. This task is solved by the consistent connection of the uninterruptible power supply and DGU. Why do you need a uninterruptible in such a scheme? To filter the voltage and ensure the autonomy of the system, until the generator starts and does not enter the operating mode.

Why and how can you use a uninterruptible pair with a voltage stabilizer? For the correct operation of the equipment in the sections of the power grid, where private voltage differences are observed, which are not accompanied by its full disconnection. Due to this, a significant reduction in the construction can be achieved: an inexpensive stabilization device will ensure efficient signal adjustment, and the UPS of the average will allow achieving an acceptable level of autonomy.

Increasing the requirements for the quality of electricity at the present time is a completely natural process. The requirements of the mentioned standards are due to the two components. The first can be attributed to the desire of consumers to maximize themselves from the effects of emergency situations in the power system. The second component is associated with the workload conditions. This should include the requirements of the stable and continuous operation of intellectual and power electrical equipment, reduce losses in the supply network and so on. One of the effective options for technical solutions to the quality of the quality of electricity is uninterrupted power sources (UPS, English. UPS).

The main task of the UPS is to provide a consumer of electricity at the time of the output of the quality parameters from the regulated standards (drawdown, raising voltage, a significant distortion of the form ...). Performing this UPS task may be:

  • disconnect from the power supply and transmit the load capacity using your own source;
  • patient load with adjusted power supply voltage.

In more expensive UPS, the function of improving the quality of electricity consumed (integrated power factor corrector).

Types of "Uninterruptants"

There are three basic types of UPS.

  1. Reserve UPS (Standby, Offline, Back-UPS). The simplest and depletive technical solution (for example, a popular APC Back-UPS CS 500). With a significantly elevated or reduced voltage, the UPS is disconnected from the network 220V and goes to the operation of the battery. The main elements of the Offline UPS: Batteries (Battery), Charger, Inverter, Enhancement Transformer, Control System, Filter (Fig. 1).


    but)


    b)
    Fig. 1 Normal mode of operation (A) and battery mode (b) The advantage of offline UPS is low cost and high efficiency when working from the network. Disadvantages: High output voltage distortion (high harmonic coefficient, ≈30% in the case of a rectangular signal), no possibility of adjusting the input voltage parameters. In more detail, the output voltage characteristics will be discussed below.).
  2. Interactive UPS (eng. Line - Interactive). It is an intermediate type between the cheap and simple offline UPS and an expensive multifunctional Online UPS (for example, IPPON Back Office 600). Unlike offline UPS, an interactive source has an autotransformer that allows you to maintain the output voltage level in the range of 220V (+ -10%) when cutting / increasing the mains voltage (Fig. 2). As a rule, the number of voltage levels of the autotransformer varies within two to three.


    (but)


    (b)


    (in)


    (d)
    Fig. 2 The operation of an interactive UPS with normal network voltage (a), when the network stress drawdown (b), with an increased network voltage (B), with the disappearance of the network voltage or significant increase (g), the output voltage adjustment is implemented by switching to the appropriate transformer winding. With a deep drawdown or significant increase, or the full disappearance of the network voltage, this UPS class functions similarly to offline class: disconnects from the network and generates output voltage using battery power. Regarding the form of the output signal, it can be both sinus and rectangular (or trapezoidal).
    Advantages of Line - Interactive in comparison with the reserve UPS: Less switching time to battery life from batteries, stabilization of the output voltage level. Disadvantages: Lower efficiency when working from a network, a higher price (relatively with offline type), poor filtration of bursts (pulse overvoltage).
  3. Double Conversion UPS (Eng. Double-Conversion UPS, Online). The most functional and expensive type of UPS. Uninterruptible is always included in the network. The input sine current passes through the rectifier, filtered, then again inverted into variable. In DC link, a separate DC / DC converter can be installed. Since the inverter is always in operation, the delay in switching to the power of batteries is almost equal to zero. Stabilization of the outlet voltage with drawdown or dips of the network voltage is better, in contrast to the stabilization of the LINE - INTERACTIVE UPS. The efficiency may be within 85% ÷ 95%. The outlet voltage often has a sinus form (harmonic coefficient<5%).


    Fig. 3 Functional diagram of one of the ONLINE options IBPN. 3 shows the block diagram of the ONLINE IPS version. Network voltage here is straightened by a semi-constable rectifier. The pulse voltage is filtered and then inverted. In the Online UPS schemes, one or more so-called bypass (bypass switches) may be present. The function of such a switch is similar to the relay function: switching load for power from the battery or directly from the network.
    Based on the Online structure, not only low-power single-phase, but also industrial three-phase UPSs. The continuity of the power supply of large file servers, medical equipment, telecommunications is carried out solely based on the Online structure of the UPS.
  4. Special types of UPS. Other specific types of UPS are used. For example, a ferroresonance uninterruptible power supply. In this UPS, the special transformer accumulates the energy charge, which should be enough for the power supply time from the network to batteries. Also as a source of energy, some UPSs use the mechanical energy of the supermanemy.

The main characteristics of the UPS.

  1. Power. Power Measurement Units: Volt-Ampere (BA), Watt (W), Volt-Ampere Jet (VAR). Recall that there is a complete S, active P and reactive Q power. Power binding equation
    S2 \u003d P2 + Q2
    Active power (W) is spent on useful work, reactive (VAR) - does not fulfill useful work. Accordingly, the complete power by definition is the maximum power to have a source to provide the load with the necessary energy. The ratio of active power to full shows the quality of the use of electricity and is called the power factor (English Power Factor, PF):
    (incandescent lamps, heaters) has PF \u003d 1, full power is active. PC, microwave ovens, air conditioners are making a calculation.
    Calculate the uninterruptible power supply for a computer (two PCs + two monitors). PC power is easy to estimate, knowing what power is the power supply unit. Let the PC are installed 450 W power supplies (active power). With an unknown PF for a PC with a power supply unit without PFC (English. Power Factor Corrector, power factor corrector) PF can be taken equal to 0.65. Similarly, the PF monitor is taken equal to 0.65. The active power of the monitor is 50 W. As a result, the overall active power of the consumer (two jobs)
    P \u003d 450 + 50 + 450 + 50 \u003d 1000 W
    Full power (from Formula 2):
    S \u003d P / PF \u003d 1000 / 0.65 \u003d 1538 (VA).
    If the power factor is installed in the power supply (PC) blocks (PF \u003d 1), then the total power S is active.
    S \u003d P \u003d 1000 (BA)
    For a load in the form of a PC, you can calculate the UPS without a stock in power, based on the following facts:
  • Computer power supplies have overload protection. In other words, PC will not be able to consume power, greater than the stated power of BP.
  • Power supply power - maximum power. In fact, in unloaded mode (immediately after starting), the PC consumes about 50% of its power.

Result.
So, the necessary minimum parameters of the UPS:

  • for PCs with power supplies without PFC - 1kW / 1540 VA.
  • for PCs with power supplies with PFC - 1kW / 1KVA.

For the first embodiment, the uninterruptible power supply of APC Smart-UPS C 2000VA (linear - interactive UPS 2QA / 1.3 kW) is suitable. For the second - IPP Ippon Smart Winner 1500 (1.35 kW) or Eaton 5SC 1500 VA (1.05 kW).
When calculating, it is important to take into account the short-term increase in power for such a load as electric motors. At the moments of starting the current of the IPAS five, seven times higher than the nominal IN:
Ipset \u003d (5 ÷ 7) * IN


Features of application.

Sources of uninterrupted power supply for boiler heating, as well as uninterruptible power supplies for gas boilers have a feature associated with the mode of operation of the zero conductor. Often, the automation of the boiler requires a network neutral connection. The fact is that the burner flame control chain is connected to grounding and in a four-wire network 220V zero conductor and grounding the boiler will ultimately closed through physical land. However, when leaving neutral or with a mechanical shutdown of the zero of the consumer from zero of the power supply (offline operation Offline UPS), the flame control circuit turns out to be broken. To eliminate this problem, the following solutions are possible:


conclusions

The initial definition of uninterruptible power source is the definition of the load nature (UPS for a computer for boilers heating ...). For responsible consumers and devices containing alternating currents, you should choose expensive and functional Online UPS. For PCs and office equipment, a cheaper line-interactive or back IPB is suitable. The next selection point is the calculation of the power and time of work from the batteries UPS. It should also be envisaged to use the "through" zero. When forming the final decision, the popularity of brands should be taken into account: the APC leader has about 50% of all sales, then with a significant margin follow IPPON, Eaton Powerware, Powercom.

Before you buy a new UPS, you should familiarize yourself with some "internal" aspects of its functioning. And in order for the uninterruptible power supply to serve you as long as possible and investing your funds turned out to be as efficient as possible, try to follow the advice below.

What batteries are used in the UPS

In all the UPSs produced by ARС (and other well-known major manufacturers of UPS), lead acid accumulatory batteries are used, very similar to the most common car batteries. The difference is that, if you already give a similar comparison, then the batteries used by ARS are manufactured by one technology with the most expensive car batteries available today: the electrolyte contained inside is in the gel condition and does not differ during the damage to the case; The battery is sealed, as a result of which it does not require care, does not highlight during the operation of harmful and explosive gases (hydrogen), it can be "conntive" anything, without fear of shed electrolyte.

How durable battery UPS

Despite the fact that in various UPSs it would seem to be the same battery technology, there are vibrations of the operation of the batteries of the UPS of different manufacturers widely. It is very important for users, since the replacement of the batteries is expensive (up to 30% of the initial cost of the UPS). The output of batteries reduces the efficiency of the system, is a source of downtime and excess headaches. The temperature is significantly influenced by the temperature of the battery. The fact is that natural processes that cause aging of the battery are largely dependent on temperature. Detailed test data provided by battery manufacturers show that the battery life of the temperature at a temperature of each 10 ° C is reduced by 10%. This means that the UPS design should provide for the minimum heating of the battery. All UPSs with online topology and hybrid online sources are stronger than the backup or linear interactive (which is why the first fan is required). This is the most important reason why the UPS of the backup and linear interactive types less often need to replace batteries than the UPS with the Online topology.

Is it worth paying attention to the design of the charger when choosing a UPS?

The charger is an important component of the UPS. Conditions for recharging batteries have a significant impact on their durability. The battery life of the UPS battery is maximum in the event that it is continuously recharged from a charger with a constant or "floating" type of voltage. In fact, the life of the rechargeable battery significantly exceeds the period of simple storage. This is because some natural aging processes are suspended by constant recharging. Therefore, you need to recharge the battery, even if the UPS is disabled. In many cases, the UPS is disconnected regularly (if the protected load is disabled, then there is no need to keep both the UPS, since it can work and cause unwanted battery wear). Many of the services offered on sale do not provide an important function of constant recharging.

Does the voltage affect the reliability?

Batteries consist of separate cells, approximately 2 to each. To create a higher voltage battery, individual elements are connected sequentially. In a 12-volt battery - six elements, in 24 volt - 12 elements, etc. When the battery is under continuous recharging, as in the UPS systems, individual elements are recharged simultaneously. By virtue of the inevitable variation of parameters, some elements are selected greater compared to other stakes of the charging voltage. This causes premature aging of such elements. The reliability of the group from sequentially connected elements is determined by the reliability of the least reliable element. Therefore, when one of the elements fails, fails and the battery as a whole. It has been proven that the speed of aging processes is directly related to the number of elements in the battery, in connection with this, the speed of aging increases with increasing the battery voltage. In the best types of UPS, a smaller number of more powerful elements is used instead of more elements of less power, thereby achieved increased reliability. Some manufacturers are used by high voltage batteries, which at a given power level makes it possible to reduce the number of wired connections and semiconductors, thus reduced the cost of the UPS. The battery voltage of most typical UPSs with the power of the order of 1QA is 24 ... 96 V. With this level of power in the PCP batteries, the ARS firms, in particular the SMART-UPS family, the voltage does not exceed 24 V. low voltage batteries in the UPS produced by ARS, Have a higher service life compared to competing devices. The average life in the ACS batteries is 3-5 years (depending on the temperature regime, the frequency of the discharge / charge cycles), while some manufacturers indicate the service life of only 1 year. During the 10-year term of using the UPS, users of some systems spend on batteries twice as much as the device itself! Although the development of UPS with the use of high-voltage batteries is simpler and costs the manufacturer and cheaper, in this case, hidden expenses are lowered in the form of a shortened service life of the UPS.

Why "pulsing" current reduces battery life

In the perfect embodiment, to increase the time of use, the UPS battery must be kept constantly on "floating" or constant recharging. In such a situation, a completely charged battery selects a small amount of current from a charger, called floating current, or a self-reading current. Despite the recommendations of battery manufacturers, in some battery UPS systems are additionally exposed to a pulsating current. The pulsating currents occur because the inverter generating an alternating current for the load consumes the input constant current. The rectifier located at the UPS entrance always issues a pulsating current. The coefficient remains non-zero even when using the most modern straightening and pulsation suppression schemes. Therefore, the battery included in parallel to the rectifier output has to give some current in those moments when the current at the output of the rectifier decreases, and vice versa, to recharge when the current at the outlet of the rectifier falls. This causes mini-cycles of discharge / charging with a frequency equal to the doubtable operating frequency of the UPS (50 or 60 Hz). These cycles wear the battery, heat it and cause its premature aging.

In the UPS with a battery located in reserve, such as a classic reserve, reserve ferroresonance type, linear interactive, the battery is not exposed to pulsating currents. Battery UPS type Online in varying degrees (depending on constructive features), but nevertheless is always exposed to their effect. To find out if there are pulsating currents, it is necessary to analyze the topology of the UPS. In the UPS type Online battery is placed between the charger and the inverter, and the pulsating currents will always be. This is a classic, "historically" the earliest type of UPS "Online with a double transformation". If, in the UPS type on-line, the battery is separated from the inverter inverter with a locking diode, a converter or a switch of one or another type, then the pulsating current should not be. Naturally, in these structures, the battery is not always connected to the contour, and therefore the UPS with a similar topology is usually attributed to hybrid.

What in the UPS cannot be reed

Battery - the least reliable element of most well-designed UPS systems. Nevertheless, the UPS architecture can influence the durability of this critical component. If you keep the battery under continuous recharge even when the UPS is turned off (as is done in all UPSs produced by ARS), its operation is increasing. When choosing the UPS, avoid topologies with high battery voltage. UPSs should be watched, in which the battery is exposed to pulsating currents or overheating. Most UPS systems use the same batteries. Nevertheless, constructive differences between the UPS of various systems determine significant differences on the service life of the batteries, and therefore, in the size of operating costs.

Before the first inclusion of the new UPS should be charged batteries

The batteries of the new UPS during transportation and storage in the warehouse, of course, lost most of the "factory" charge. Therefore, if you immediately put the UPS under load, the batteries will not be able to ensure the proper level of power maintenance. Moreover, the self-test procedure automatically launched each time the UPS is turned on (except back-UPS), among other diagnostic operations, checks whether the battery is able to cope with the load. And since the uncharged battery can not cope with the load, the system may not be reporting that the battery is faulty and requires replacement. All you need to do in such a situation - give batteries to charge. Leave the UPS connected to the network for 24 hours. This is the first charging of the batteries, so it requires more time than the usual standard charging, regulated in the technical description. UPS itself can be turned off. If you brought the UPS from the cold, let it be warm at room temperature for a few hours.

Connect only the load to UPS, which really requires uninterrupted power supply.

Using the UPS is justified only where the power loss is capable of leading data loss - in personal computers, servers, concentrators, routers, external modems, stripes, drives, etc. Printers, scanners and certainly lighting lamps do not need UPS. What happens if the printer loses food while printing? A sheet of paper will deteriorate - its value is not comparable to the cost of the UPS. In addition, the printer connected to the uninterruptible nutrition device, when switching to batteries, consumes their energy, taking it from a computer that really needs it. In order to protect the equipment from discharges and interference, the equipment that can be lost as a result of a power failure is enough to use a network filter (for example, APC Surge Arrest) or, with significant voltage fluctuations in the network, a network stabilizer.

If your source often goes to battery power mode, check whether it is configured correctly. It may be that the trigger threshold or sensitivity is too demanding.

Test UPS. Periodically launched a self-test procedure, you will always be sure that your UPS is fully ready for work.

Do not turn off the UPS from the outlet.Turn off the UPS using the button on the front panel, but do not pull it out of the cord from the outlet, unless you leave it for a long time. Even in the off state, the UPS produced by ARS carries out batteries.

ComputerPress 12 "1999