How does a UPS protect equipment? The main purpose of an uninterruptible power supply (UPS) is to protect computer equipment. Additional UPS functionality

To ensure that your uninterruptible power supply (UPS) lasts as long as possible and that its purchase brings tangible benefits, follow the tips below for care, connection and maintenance of the UPS.

Having decided on the question of which UPS is better and having unpacked your long-awaited purchase, do not rush to connect it right away. Before turning on the new uninterruptible power supply for the first time, you must fully charge the batteries. If the new source is immediately put under load, its batteries will not be able to provide the power required to power it.

Figure 1. APC Back-UPS CS-500 equipment

A self-test routine that runs automatically when turned on (except for Back-UPS models) checks whether the battery can handle the load applied. If the battery is not charged, the uninterruptible power supply may report that the battery is faulty and needs to be replaced. In this case, you just need to charge the batteries. To do this, connect the device to the network and leave it turned on for 24 hours.

Charging the batteries for the first time takes slightly longer than normal charging. When charging for the first time, the uninterruptible power supply may be disconnected. Some UPSs, for example, from the manufacturer APC, can be charged from the network, regardless of whether the source is turned on or not.

Only equipment that actually requires uninterruptible power should be connected to the power source.

If the device was brought in from the cold, you need to let it warm up for about two hours at room temperature.

The purchase of an uninterruptible power supply can only be justified if a power outage will lead to the loss of important data. Among the devices that require a UPS: servers, personal computers, routers, hubs, streamers, external modems, etc.

Figure 2. Connection diagram for communication devices

Scanners, printers and lighting equipment should be connected to an uninterruptible power supply at your discretion. If the printer turns off during printing, a piece of paper will simply be damaged, but a printer connected to an uninterruptible power supply, at the moment of switching to power from the battery, completely consumes their energy on itself, and thus deprives the computer of protection, which is in dire need of it. Therefore, connect peripheral equipment to the UPS only if you are sure that the battery energy is enough to power all devices.

Figure 3. Connection diagram of the UPS to the computer

If you need to protect equipment that does not carry important information from interference or discharge, it is enough to use a surge filter, such as Surge Arrest, or a network stabilizer, such as Line-R.

Never overload the uninterruptible power supply. Choose a UPS model whose power is not less than the total load power. Don't forget the difference between volt-amps and watts! Be sure to connect the device with a ground connection, as without it the noise suppression efficiency will be reduced. Turn off the UPS only using the button on the front panel. Unplug the cord only if you have to leave your home or office for an extended period of time. Many sources are capable of charging batteries even when turned off.

Most UPS systems decide on their own when to switch to battery power. However, if your source constantly switches to battery operation, it's worth checking its settings. Perhaps the sensitivity of the device or its response threshold is set too high. Don't forget to test your device periodically. The self-test procedure will allow you to be confident that the UPS is functioning correctly and is ready for use at any time.

By purchasing a UPS (Uninterruptible Power Supply) for a personal computer or other household appliances, you solve many problems at once. You will no longer have to constantly save it while working with a document, for fear of losing data due to a sudden power outage. Also, you now don’t have to worry at all that the power supply or, even worse, the hard drive will fail as a result of incorrect shutdown. If “trouble” happens, you can complete important work with the program within a few minutes and calmly turn off the computer. All this is due to the fact that the uninterruptible power supply almost instantly reacts to changes in indicators in the power grid and begins to work as a backup source of energy. The user's task is only to help the device perform its functions effectively. The service life of both the UPS itself and the consumers connected to it directly depends on responsible handling of equipment.

Commissioning

As a rule, when using new equipment, the preparatory stage is the most difficult. After all, you need to know as accurately as possible how to properly install and connect the device, what requirements must be met, and how to avoid mistakes. Before connecting your computer to an uninterruptible power supply, you must fulfill several very important conditions.

Under no circumstances should you turn on the device immediately after bringing it from outside. . It is especially important to follow this rule when the temperature outside is sub-zero. The “bespereboynik” must sit properly in the room, otherwise there is a possibility that condensation formed due to a sharp temperature change will cause a breakdown. Immediately before startup, the UPS must be dry. If it is severely frosty outside, the waiting time before turning on should be at least four hours.

Choose the most suitable location to install the device . The case of the uninterruptible power supply should not be located where it can be exposed to sunlight. Also, there should be no heating devices nearby, and the room itself should have a normal level of humidity. Install the device in such a way that nothing blocks the ventilation openings (they must have free access to air for effective cooling).

Carefully monitor the temperature regime . For most models of this type of equipment, the recommended operating temperature range is from 0 to +40 °C (ideally, for stable operation of the device, the temperature should always be between +20 and + 25 °C).

Route wires carefully . The power connection cable and wires connecting the UPS to the load must be located in such a way that there is no tension and the possibility of accidentally touching them is eliminated. The power cable must be connected to a grounded outlet as required by safety regulations.

Wait until the battery is well charged . Immediately after turning on the uninterruptible power supply for the first time, it will not be possible to work with the load fully; the diagnostic system will generate an error (in some cases, a message will pop up that the battery is faulty and requires replacement). This happens because new batteries are not charged, and therefore are not capable of supporting power to connected consumers. In order for the batteries to be fully charged, leave the UPS plugged in for a day, since the first charge takes longer than planned.

For some uninterruptible power supply models to work effectively, you need to install some software on your computer. The product package should include a disk, the installation of which can be easily handled by almost any ordinary PC user. Many modern UPSs have a self-diagnosis system, which must be activated before the first start-up (after which the correct connection will be checked, as well as the proper functioning of the internal operating elements). In the event of any malfunction, for example, when the “phase” and “neutral” inputs are reversed or there is no grounding, the device will sound a sound signal or display an error code on the display. To immediately determine what’s wrong, carefully read the instructions before use, then all the signals will be clear to you, and you can quickly eliminate the error.

Connecting and operating the UPS with a load

Upon completion of the preparatory stage, you can start using the UPS by connecting the load to it. Let's give an example of a standard connection diagram for the efficient operation of computer equipment in domestic conditions: a UPS and a printer (or scanner) are connected to the surge protector, and the computer system unit and monitor are connected to the UPS itself. In principle, if there is a connector for a printer on the UPS panel, you can connect one to it, but only on the condition that it is an inkjet printer and its power consumption was initially included in the total load power when purchasing an uninterruptible power supply. Never even try to connect a laser printer, as it is much more powerful than an inkjet printer, and at the time of peak loads it can overload the UPS. Also, you cannot connect lighting fixtures and other household appliances that are not in such dire need of protection during a power outage. The same can be said about the use of these devices. in offices: the load from all connected servers to one UPS should in no case exceed its capacity.

What are the consequences of large overloads? A large number of electricity consumers will certainly lead to an unjustified load on the uninterruptible power supply, and there may not be enough power to power the computer. It happens that the device simply “drops” the load, which causes an emergency shutdown of computer equipment and loss of data, and what’s even worse is that important working parts can break down (for a UPS it’s a battery, for a PC it’s a hard drive or power supply). Agree that additional repair costs will be an unpleasant surprise.

Proper compliance with permissible power loads guarantees that the uninterruptible power supply can effectively support the operation of computer equipment for the time declared by the manufacturer during power outages. You will have time to save important information to your hard drive or removable media and complete your work correctly.

It should be noted that it is not recommended to use the entire reserve time to continue working at the computer. If it is possible to save the data earlier and turn it off, do so. Thus, you can preserve the battery capacity and reduce the load on the uninterruptible power supply. In general, experienced specialists advise using an uninterruptible power supply in conjunction with a generator for long-term operation without a central power supply: when the power goes out, the equipment will operate on the UPS for a few seconds, and then the load can be transferred to the electric generator without interrupting operation.

How to extend the life of a UPS?

Since the uninterruptible power supply basically ensures the operation of the equipment connected to it for a period of time from 10 to 20 minutes, the battery is subject to the greatest wear. On average, the service life of rechargeable batteries reaches 3 years with proper use. Although for “ON-LINE” type devices this period can be increased to 5 or even 10 years, thanks to modern technologies that allow more careful charging/discharging of the battery. Do not try to artificially extend the “life” of the battery by disassembling it and adding distilled water, as some people do, based on their experience with car batteries. The UPS is equipped with special sealed or, as they are also called, maintenance-free batteries. When the resource of such a battery is exhausted, it is necessary to replace the old one with a new one. However, there are several rules that, if followed, will help extend the life of your batteries.

№ 1. Avoid cases where switching to battery power is not justified. For example, a small power surge occurs and the entire load switches to battery operation. This may be due to the fact that the upper and lower transition thresholds are incorrectly configured. By changing them to the correct ones, based on the power grid indicators, at which the equipment will function stably, you can avoid increased load on the batteries. The adjustment is carried out either on the control panel or through a program installed on the computer.

№ 2. Be sure to ensure that the uninterruptible power supply does not overheat under any circumstances. For normal battery operation, the ambient temperature, including inside the device body, should not exceed 30 °C. Regardless of whether natural or forced cooling occurs during operation of the device, it must be as efficient as possible.

№ 3. Completely eliminate the possibility of mechanical impact on the device (shocks, falls, etc.). You need to install the UPS in a place where it will be stable and nothing will accidentally fall on it.

Many buyers ask themselves the following question: is it necessary to have a spare battery? This will only be justified if the uninterruptible power supply is used intensively and may need a backup battery charge. But if there is no such need, storing the battery for several years “just in case of fire” will not be rational - since it will already lose its performance properties.

As for the efficiency of the UPS as a whole, it largely depends on you. If you have carried out all the preparatory work correctly, followed the recommendations for operating conditions and promptly responded to signals from the diagnostic system, then you can be sure that the likelihood of breakdowns will be minimal. If a problem does occur that cannot be resolved using the methods described in the instructions, do not try to disassemble the uninterruptible power supply yourself. It is better to contact the service center, where you will be provided with qualified assistance with warranty and post-warranty service.

UPS stands for "uninterruptible power supply". Abbreviation in English - UPS (Uninterruptible Power Supply) , therefore the names UPS, YUPS, and oopsnik are also common.

The main function of an uninterruptible power supply is to ensure the supply of electricity to the equipment connected to it during outages in the main network. But, depending on the type of equipment, the parameters of such autonomous power supply may be required to be radically different. Accordingly, the UPS market offers different types of devices, which differ in a lot of parameters:

• principle of operation: offline, linear-interactive, online;
• type of automatic voltage regulation;
• quality of filtering network interference;
• capacity (number of ampere-hours, or in other words - how long the battery life will last);
• time to switch to batteries during a power outage;
• possibility of connecting additional external batteries;
• various additional functions (filtering sockets, sockets for telephone and network cables, LCD display, synchronization with a PC), etc.

How to choose a UPS with such a variety of models ? How to understand how they differ? In this article we will look at the main types of uninterruptible power supplies, their differences, and what additional functions manufacturers equip UPS with. In the next one - how to choose a UPS depending on the features of your equipment, how to calculate its required power, etc.

Three main types of UPS

Off-line (Back-UPS, backup, Standby) uninterruptible power supply

Example of a backup UPS: model .

The operating principle of this type of uninterruptible power supply is very simple:

As long as there is electricity in the network within the set values, the UPS supplies the connected devices with voltage directly from the network, while simultaneously recharging the battery. The power passing through the UPS is not regulated; pulses and noise are filtered at the simplest level, using passive filters. The signal shape corresponds to the network signal, i.e., a sinusoid.

As soon as the mains power is lost, the UPS switches to battery power. The inverter that converts direct current from the battery into alternating current output is one of the simplest installed in this type of UPS, so the waveform does not correspond to the correct sine wave. The maximum that manufacturers do is to bring it somewhat closer to a sinusoid, making it stepwise.

The UPS also switches to off-line autonomous power supply if the voltage level in the network falls below or rises above the threshold values, they can be different depending on the brand of uninterruptible power supply.

The switching time to batteries in various models ranges from 5 to 20 ms. This is relatively long, and for some equipment models such a long delay may adversely affect operation . The long-term operation of the relay is due to the fact that the device needs the phases of the mains and battery voltages to coincide when the autonomous power is turned on, and since they are not synchronized, this takes some time.

Scheme of operation of a backup uninterruptible power supply.

Pros of Standby UPS:

• inexpensive price,
• high efficiency,
• silent operation.

Flaws:

• long switchover to battery operation (from 5 to 20 ms);
• the output signal shape is not a sinusoid;
• filtering interference, noise and impulsesquite rough on the line;
• There is no voltage and frequency regulation when operating from the network.

Line-interactive UPS

Example of a line-interactive UPS: model

Buyers choose this type of uninterruptible power supply most often, as it optimally combines functionality and price.

The principle diagram of the operation of line-interactive UPS includes AVR - a module for automatically adjusting the incoming network voltage. That is, unlike a backup UPS, it not only passes power through itself, but also stabilizes it, although not smoothly, but in steps.

When operating from the mains at a normal voltage level, the line-interactive uninterruptible power supply passes the incoming signal through passive interference and noise filters, while the battery is charged.

When the voltage in the network increases or decreases, the line-interactive UPS makes its stepwise adjustment. When the voltage reaches a certain threshold, the AVR lowers or lowers it by a fixed amount (or percentage). Several such threshold steps can be specified in the AVR operating scheme; also, for working with a lower and higher level, a different number of adjustment steps can be assigned (for example, 2 for an increase, and 1 for a decrease).

If the mains voltage drops or rises to values ​​that lie outside the available input range of the uninterruptible power supply, the device switches to battery operation, just as in the case of a complete power outage. These minimums and maximums may vary depending on the load on the UPS. For example, if the UPS is 70% loaded and the voltmeter shows 160V in the network, the uninterruptible power supply switches to the batteries. And at 30% load and a voltage of 150V, it still makes adjustments using an AVR transformer.

Some linear-interactive models are no different in the shape of the output signal from backup-type uninterruptible power supplies: they have a stepped sine wave. Some manufacturers, especially with the growing demand for UPS for boilers, equip their uninterruptible power supply systems with inverters that produce the correct sine wave.

The switchover time to battery operation in pure sine wave line-interactive UPSs is faster than that of its standby counterparts. The reason is that in UPSs of this type, the voltage waveforms coincide (both from the network and from the battery, this is a sinusoid), which speeds up phase synchronization and, accordingly, the start of autonomous power supply.

Pros of line-interactive UPS:

• reasonable price,
• silent operation,
• automatic regulation of incoming voltage,
• in some models - pure sine wave at the output,
• switching time is less than in backup ones (on average 4-8 ms, in some models 2-4 ms).

Flaws:

• no frequency adjustment,
• insufficiently complete filtering of interference, noise and network impulses,
• voltage regulation is not smooth, but stepwise,
• The efficiency is lower than in an off-line uninterruptible power supply.

Double conversion UPS (on-line)

Double conversion UPS example: model .

This is the most expensive, but also the best type of UPS. It is optimally suited for expensive, capricious equipment, for which not only constant voltage is important, but also frequency, as well as effective noise filtering, a signal in the form of a pure sine wave, and the absence of delays when switching to battery operation.

In fact, such an uninterruptible power supply operates constantly, stabilizing, filtering the incoming signal, equalizing the frequency and shape of the output signal.

In mains mode, the incoming AC voltage is stabilized and converted to DC by the rectifier and distributed between the battery (for recharging if necessary) and the inverter. The inverter converts direct current into alternating current, producing an output signal in the form of a pure sine wave, the correct frequency, the correct voltage. Interference and noise are completely absent - they simply do not remain after double conversion.

This constant “inclusion” of the uninterruptible power supply into the network provides one of its significant advantages: Instant switching to battery operation. Actually, it’s hard to even call it “switching”, since power passes through the rectifier, battery (during charging) and inverter constantly. When the network voltage drops below threshold values ​​or there is a complete power outage, the inverter simply begins to take part of the energy from the battery, and not from the rectifier. It happens instantly.

Double conversion UPSs usually have another operating mode: bypass. This is a backup line that goes directly from the input to the output of the UPS, bypassing the rectifier, battery and inverter. It allows in critical moments for the UPS: overload (for example, with starting currents), failure of the inverter and others - to supply electricity directly to the connected devices, avoiding failure of the device elements.

Constant operation of the UPS has a certain disadvantage: increased heat generation, which requires effective cooling. Therefore, UPS online are most often equipped with fans, which makes their operation in residential areas not as comfortable as other types of silent uninterruptible power supplies.

Pros of online UPS:

• constant voltage stabilization,
• constant frequency stabilization,
• pure sine wave at the output,
• effective filtering of noise, impulses and interference,
• Instant switching to batteries.

Flaws:

• high price,
• increased noise level,
• the lowest efficiency among all types of UPS.

When choosing an uninterruptible power supply, you need to take into account that there are exceptions. Some line-interactive UPSs may cost more than online models from another manufacturer, the switching time to battery operation in a backup UPS may be no more, or even less, than in some line-interactive UPS, etc. Therefore, In any case, it is necessary to read the characteristics of a specific model.

Additional UPS functionality

In addition to determining the type of uninterruptible power supply you need, when choosing a UPS you should also pay attention to what functionality is included in it. UPS can have various additional functions and design features:

Synchronization with PC. This feature is not present in the cheapest models, but it is very convenient. Using special software, the UPS transmits data in real mode to the computer about the state of the power line and battery charge level. In addition to the purely informational component, there are also features such as, for example, autonomous shutdown of the computer while saving data in all applications during a power outage.

Cold start. An uninterruptible power supply equipped with this function can be turned on when there is no power in the network. For example, the lights went out, you saved the documents, turned off the computer and UPS, but after some time there was an urgent need to copy the document to a flash drive. A UPS with cold start support can be turned on, even if there is still no power, and get the job done.

Previously, connectors for connecting devices in a UPS looked basically like this:

This IEC 320 standard connector is perfect for connecting various computer equipment. However, equipment with a regular power cord, such as a WiFi router, cannot be connected to it. For these purposes, you can use a surge protector with a similar connector, which is connected to the UPS, and then connect various equipment to it. But this is not always convenient.

Therefore, now many models have simply begun to be supplemented with Schuko-type sockets (in our country they are often called Euro sockets) so that the equipment can be turned on directly:

Sockets for filtering interference. A UPS may be equipped with an outlet or several for sensitive equipment that does not provide power support during a power outage but protects the connected equipment from utility power interference.

Sockets for telephone line, twisted pair. High-voltage pulses can be transmitted not only directly via an electric power cable, but also in the event of various accidents and breakdowns - both via a telephone cable and twisted pair cable. To protect telephone, network and computer equipment, some manufacturers provide special connectors (input/output) where you can connect a telephone or Internet line.

To be continued in the next article.

Before you buy a new UPS, you should familiarize yourself with some of the “internal” aspects of its operation. To ensure that your uninterruptible power supply serves you as long as possible and that your investment is as effective as possible, try to follow the tips below.

What batteries are used in the UPS

All UPS products manufactured by APC (and other well-known major UPS manufacturers) use lead acid batteries, much like the most common car batteries. The difference is that, if we are to make such a comparison, the batteries used by APC are made using the same technology as the most expensive car batteries available today: the electrolyte contained inside is in a gel-like state and does not spill if the case is damaged; The battery is sealed, as a result of which it does not require maintenance, does not emit harmful and explosive gases (hydrogen) during operation, it can be “turned over” in any way without fear of spilling the electrolyte.

How long do UPS batteries last?

Although different UPS systems appear to use the same battery technology, the lifespan of UPS batteries from different manufacturers varies widely. This is quite important for users, since replacing batteries is expensive (up to 30% of the original cost of the UPS). Battery failure reduces system efficiency, causing downtime and unnecessary headaches. Temperature has a significant impact on battery reliability. The fact is that the natural processes that cause battery aging largely depend on temperature. Detailed test data provided by battery manufacturers shows that battery life decreases by 10% for every 10°C increase in temperature. This means that the UPS must be designed to minimize battery heating. All UPSs with an online topology and hybrid online sources heat up more than standby or line-interactive ones (which is why the former require a fan). This is the most important reason why UPSs of standby and line-interactive types require battery replacement less often than UPSs with an online topology.

Should you pay attention to the design of the charger when choosing a UPS?

The charger is an important component of the UPS. The conditions under which batteries are recharged have a significant impact on their longevity. The UPS battery life is maximized if it is continuously charged from a constant or floating voltage charger. In fact, the service life of a rechargeable battery significantly exceeds the period of simple storage. This happens because some natural aging processes are halted by constant recharging. Therefore, it is necessary to recharge the battery even if the UPS is turned off. In many cases, the UPS is turned off regularly (if the load being protected is turned off, there is no need to keep the UPS on, since it may trip and cause unwanted wear and tear on the battery). Many commercially available UPSs do not provide the important feature of continuous charging.

Does voltage affect reliability?

Batteries are made up of individual cells of approximately 2V each. To create a higher voltage battery, individual cells are connected in series. A 12-volt battery has six cells, a 24-volt battery has 12 cells, etc. When the battery is on trickle charge, as in UPS systems, the individual cells are recharged simultaneously. Due to the inevitable spread of parameters, some elements take a larger share of the charging voltage than others. This causes premature aging of such elements. The reliability of a group of series-connected elements is determined by the reliability of the least reliable element. Therefore, when one of the cells fails, the battery as a whole fails. It has been proven that the rate of aging processes is directly related to the number of elements in the battery; therefore, the rate of aging increases with increasing battery voltage. The best types of UPS use fewer higher-power elements instead of more lower-power elements, thereby achieving increased reliability. Some manufacturers use high-voltage batteries, which, for a given power level, can reduce the number of wiring connections and semiconductors, thereby reducing the cost of the UPS. The battery voltage of most typical UPSs with a power of about 1 kVA is 24...96 V. At this power level, the batteries of APC UPSs, in particular the Smart-UPS family, do not exceed 24 V. Low voltage batteries in UPSs manufactured by APC, have a longer service life compared to competing devices. The average service life of APC batteries is 3-5 years (depending on temperature conditions, frequency of discharge/charge cycles), while some manufacturers indicate a service life of only 1 year. Over the 10-year lifespan of a UPS, some system users spend twice as much on batteries as they do on the unit itself! Although developing a UPS using high-voltage batteries is easier and less costly for the manufacturer, there is a hidden cost to the user in the form of a shorter UPS life.

Why "pulsating" current reduces battery life

Ideally, to increase usage time, the UPS battery should be kept on a “float” or constant charge. In this situation, a fully charged battery draws a small amount of current from the charger, called float or self-charging current. Despite battery manufacturers' recommendations, some UPS systems additionally expose batteries to ripple current. Ripple currents occur because the inverter that produces AC current for the load consumes DC current at its input. The rectifier, located at the input of the UPS, always produces a pulsating current. The coefficient remains non-zero even when using the most modern rectification and ripple suppression circuits. Therefore, a battery connected in parallel with the output of the rectifier has to supply some current at those moments in time when the current at the rectifier output decreases, and vice versa - to be recharged when the current at the rectifier output drops. This causes mini-discharge/charge cycles at a frequency typically equal to twice the operating frequency of the UPS (50 or 60 Hz). These cycles wear out the battery, heat it up and cause it to age prematurely.

In a UPS with a battery in reserve, such as a classic backup, a ferroresonant backup, or a line-interactive UPS, the battery is not exposed to ripple currents. The online UPS battery varies to varying degrees (depending on the design features), but is nevertheless always exposed to them. To determine whether ripple currents are occurring, it is necessary to analyze the UPS topology. In an online UPS, the battery is placed between the charger and the inverter, and there will always be pulsating currents. This is the classic, “historically” earliest type of “online double conversion” UPS. If in an on-line UPS the battery is separated from the inverter input by a blocking diode, converter or switch of one type or another, then there should be no pulsating current. Naturally, in these designs the battery is not always connected to the circuit, and therefore UPS with a similar topology are usually classified as hybrid.

What you can't rely on in a UPS

The battery is the least reliable element of most well-designed UPS systems. However, the UPS architecture can affect the longevity of this critical component. If you keep the battery under continuous charging even when the UPS is turned off (as is done in all UPS manufactured by APC), its service life increases. When selecting a UPS, topologies with high battery voltage should be avoided. Beware of UPSs that expose the battery to ripple currents or overheating. Most UPS systems use the same batteries. However, design differences between UPS systems in different systems cause significant differences in battery life and, consequently, in operating costs.

Before turning on your new UPS for the first time, be sure to charge the batteries.

The batteries of the new UPS naturally lost most of their “factory” charge during transportation and storage in the warehouse. Therefore, if you immediately put the UPS under load, the batteries will not be able to provide adequate power support. Moreover, a self-test routine that automatically runs each time the UPS (except Back-UPS) is turned on, among other diagnostic operations, checks whether the battery is able to handle the load. And since an uncharged battery cannot cope with the load, the system may report that the battery is faulty and requires replacement. All you need to do in such a situation is to let the batteries charge. Leave the UPS connected to the network for 24 hours. This is the first charging of the batteries, so it takes more time than the usual standard charging, regulated in the technical description. The UPS itself may be turned off. If you brought the UPS in from the cold, allow it to warm up at room temperature for a few hours.

Connect only those loads to the UPS that truly require uninterruptible power.

The use of a UPS is justified only where a loss of power can lead to data loss - in personal computers, servers, hubs, routers, external modems, streamers, disk drives, etc. Printers, scanners, and especially lighting lamps do not require a UPS. What happens if the printer loses power while printing? A sheet of paper gets damaged - its value is not comparable to the cost of a UPS. In addition, a printer connected to an uninterruptible power supply device, when switching to battery power, consumes their energy, taking it away from the computer that really needs it. In order to protect equipment from discharges and interference that does not carry information that can be lost as a result of a power failure, it is sufficient to use a network filter (for example, APC Surge Arrest) or, in case of significant fluctuations in the network voltage, a network stabilizer.

If your source frequently switches to battery mode, check that it is configured correctly. It may happen that the response threshold or sensitivity is set too demanding.

Test the UPS. By periodically running a self-test, you will always be sure that your UPS is fully operational.

Do not unplug the UPS. Turn off the UPS using the button on the front panel, but do not unplug the UPS unless you are leaving it for an extended period of time. Even when turned off, the APC UPS charges the batteries.

ComputerPress 12"1999

As civilization develops, it begins to consume more and more energy, in particular electrical energy - machines, factories, electric pumps, street lights, lamps in apartments... The advent of radios, televisions, telephones, computers gave humanity the opportunity to speed up the exchange of information, however, it tied them even more it to sources of electricity, since now, in many cases, a loss of electricity is tantamount to the loss of a channel for delivering information flow. This situation is most critical for a number of the most modern industries, in particular, where the main production tool is computer networks.

It has long been calculated that after a couple of months of operation, the cost of information stored on a computer exceeds the cost of the PC itself. Information has long become a type of commodity: it is created, evaluated, sold, bought, accumulated, transformed... and sometimes lost for a variety of reasons. Of course, up to half of the problems associated with information loss arise from software or hardware failures in computers. In all other cases, as a rule, problems are associated with poor-quality power supply to the computer.

Ensuring high-quality power supply to PC components is the key to stable operation of any computer system. The fate of entire months of work sometimes depends on the shape and quality characteristics of the mains power supply, and on the successful choice of power components. Based on these considerations, the research methodology outlined below was developed, which is intended to later become the basis for testing the quality characteristics of uninterruptible power supplies.

1. GOST provisions
2. UPS classification (description, diagram)
   • Offline
   • Linear interactive
   • Online
   • Main types by power
3. Physics
   • a. Types of power, calculation formulas:
     • Instant
     • Active
     • Reactive
     • Full
4. Testing:
   • Purpose of testing
   • General plan
   • Parameters to check
5. Equipment used in testing
6. Bibliography

Everything related to electrical networks in Russia is regulated by the provisions of GOST 13109-97 (adopted by the Interstate Council for Standardization, Metrology and Certification to replace GOST 13109-87). The standards of this document are fully consistent with international standards IEC 861, IEC 1000-3-2, IEC 1000-3-3, IEC 1000-4-1 and publications IEC 1000-2-1, IEC 1000-2-2 regarding electromagnetic compatibility levels in power supply systems and methods for measuring electromagnetic interference.

Standard indicators for electrical networks in Russia, established by GOST, are the following characteristics:

• supply voltage 220 V±10%
• frequency 50±1 Hz
• THD of the voltage waveform less than 8% for a long time and 12% short-term

Typical power supply problems are also discussed in the document. Most often we encounter the following:

• Complete loss of voltage in the network (no voltage in the network for more than 40 seconds due to disturbances in the power supply lines)
• Sags (short-term decrease in network voltage to less than 80% of the nominal value for more than 1 period (1/50 of a second) are a consequence of the inclusion of powerful loads, externally manifested as flickering of lighting lamps) and surges (short-term increases in network voltage by more than 110% of the nominal voltage for more than 1 period (1/50 of a second); appears when a large load is turned off, externally manifested as flickering of lighting lamps) voltage of different durations (typical for large cities)
• High-frequency noise radio frequency interference of electromagnetic or other origin, the result of high-power high-frequency devices, communications devices
• Frequency deviation outside acceptable values
• High-voltage surges short-term voltage pulses up to 6000V and lasting up to 10 ms; appear during thunderstorms, as a result of static electricity, due to sparking switches, have no external manifestations
• Frequency run-out change in frequency by 3 or more Hz from the nominal (50 Hz), appears when the power source is unstable, but may not appear externally.

All these factors can lead to failure of fairly “thin” electronics and, as often happens, to loss of data. However, people have long learned to protect themselves: line voltage filters that “dampen” surges, diesel generators that supply power to systems in the event of a power outage on a “global scale”, and finally, uninterruptible power supplies the main tool for protecting personal PCs, servers, mini-PBXs etc. It is the last category of devices that will be discussed.
UPS classification

UPS can be “divided” according to various criteria, in particular, by power (or scope of application) and by type of operation (architecture/device). Both of these methods are closely related to each other. Based on power, UPSs are divided into

1. Uninterruptible power supplies low power(with total power 300, 450, 700, 1000, 1500 VA, up to 3000 VA including on-line)
2. Low and medium power(with total power 3–5 kVA)
3. Medium power(with total power 5–10 kVA)
4. High power(with total power 10–1000 kVA)

Based on the principle of operation of the devices, two types of classification of uninterruptible power supplies are currently used in the literature. According to the first type, UPSs are divided into two categories: on-line And off-line, which in turn are divided into reserve And linear-interactive.

According to the second type, UPSs are divided into three categories: reserve (off-line or standby), linear-interactive (line-interactive) and Double conversion UPS (on-line).

We will use the second type of classification.

Let's first consider the difference between UPS types. Reserve type sources are made according to a circuit with a switching device, which in normal operation ensures that the load is connected directly to the external power supply network, and in emergency mode it switches it to power from batteries. The advantage of a UPS of this type can be considered its simplicity, the disadvantage is the non-zero switching time to battery power (about 4 ms).

Line-interactive UPS made according to a circuit with a switching device, supplemented by an input voltage stabilizer based on an autotransformer with switchable windings. The main advantage of such devices is protecting the load from overvoltage or undervoltage without going into emergency mode. The disadvantage of such devices is also the non-zero (about 4 ms) switching time to batteries.

Double conversion UPS voltage differs in that in it the alternating voltage arriving at the input is first converted by a rectifier into constant, and then, using an inverter, again into alternating. The battery is constantly connected to the output of the rectifier and the input of the inverter and powers it in emergency mode. Thus, a fairly high stability of the output voltage is achieved regardless of input voltage fluctuations. In addition, interference and disturbances that abound in the power supply network are effectively suppressed.

In practice, UPSs of this class, when connected to an AC network, behave like a linear load. The advantage of this design can be considered zero switching time to battery power, the disadvantage is a decrease in efficiency due to losses during double voltage conversion.

All reference books on electrical engineering distinguish four types of power: instant, active, reactive And full. Instantaneous power is calculated as the product of the instantaneous voltage value and the instantaneous current value for an arbitrarily selected point in time, that is

Since in a circuit with resistance r u=ir, then

The period-average power P of the circuit under consideration is equal to the constant component of the instantaneous power

The average AC power over a period is called active . The unit of active power volt-ampere is called watt (W).

Accordingly, resistance r is called active. Since U=Ir, then

Reactive power a value characterizing the loads created in electrical devices by fluctuations in the energy of the electromagnetic field. For a sinusoidal current, it is equal to the product of the effective current and voltage and the sine of the phase shift angle between them.

Full power total power consumed by the load (both active and reactive components are taken into account). Calculated as the product of the rms values ​​of the input current and voltage. Unit of measurement is VA (volt-ampere). For sinusoidal current it is equal to

Almost every electrical device has a label indicating either the total power of the device or the active power.
Testing

Main purpose of testing demonstrate the behavior of the tested UPS in real conditions, give an idea of ​​additional characteristics that are not reflected in the general documentation for the devices, determine in practice the influence of various factors on the operation of the UPS and, possibly, help determine the choice of a particular uninterruptible power supply.

Despite the fact that there are currently a great many recommendations for choosing a UPS, during testing we expect, firstly, to consider a number of additional parameters that are worth asking before purchasing equipment, and secondly, if necessary, adjust the set of selected methods and parameters testing and develop a basis for future analysis of the entire power path of systems.

The general testing plan is as follows:

• Specifying the device class
• Indication of characteristics declared by the manufacturer
• Description of delivery contents (presence of manual, additional cords, software)
• Brief description of the appearance of the UPS (functions located on the control panel and list of connectors)
• Battery type (indicating battery capacity, serviceable/non-serviceable, name, possible interchangeability, possibility of connecting additional battery packs)
• “Energy” component of tests

During testing, it is planned to check the following parameters:

• The range of input voltage at which the UPS operates from the mains without switching to batteries. Larger input voltage range reduces the number of UPS transfers to battery and increases battery life
• Time to switch to battery power. The shorter the switching time, the lower the risk of failure of the load (device connected via the UPS). The duration and nature of the switching process largely determine the possibility of normal continued operation of the equipment. For a computer load, the permissible power interruption time is 20-40 ms.
• Oscillogram of switching to battery
• Switching time from battery to external power
• Oscillogram of switching from battery to external power
• Offline operating time. This parameter is determined solely by the capacity of the batteries installed in the UPS, which, in turn, increases as the maximum output power of the UPS increases. To provide autonomous power to two modern SOHO computers of a typical configuration for 15-20 minutes, the maximum output power of the UPS should be about 600-700 VA.
• Output voltage parameters when operating on batteries
• Pulse shape at the beginning of battery discharge
• Pulse shape at the end of battery discharge
• The UPS output voltage range when the input voltage changes. The narrower this range, the less the impact of changes in input voltage on the powered load.
• Output voltage stabilization
• Output voltage filtering (if available)
• Behavior of the UPS during output overload
• Behavior of the UPS during load loss
• Calculation of UPS efficiency. Defined as the ratio of the device's output power to the power input from the power source
• Nonlinear distortion coefficient, characterizing the degree to which the voltage or current waveform differs from the sinusoidal one
  • 0% sine wave
  • 3% distortion is not noticeable to the eye
  • 5% distortion visible to the eye
  • up to 21% trapezoidal or step waveform
  • 43% signal is rectangular

When testing, we will not use real workstations and servers, but equivalent loads that have a stable consumption pattern and a power utilization factor close to 1. The following set is currently being considered as the main equipment that will be used during testing:

1. GOST 721-77 Power supply systems, networks, sources, converters and receivers of electrical energy. 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 receivers of electrical energy. Rated voltages up to 1000 V
4. GOST 30372-95 Electromagnetic compatibility of technical equipment. Terms and definitions
5. Theoretical Electrical Engineering, ed. 9th, corrected, M.-L., publishing house "Energia", 1965
6. Company promotional materials
7. Internet resource