Why do we need UPS? Uninterruptible power supply: purpose and types Using an uninterruptible power supply for a PC

Uninterruptible power supply systems are currently becoming very popular. It doesn't matter where he lives modern man, - in a city apartment, in country house, various household appliances, digital computer technology, life support systems.

Purpose and categories of UPS

The requirements for the quality of power supply for all these devices are increasing. The quality of power supply to external electrical networks does not always satisfy the population. Sharp voltage drops occur, both in the direction of decreasing and increasing its value. This has a very adverse effect on the operation of household equipment, and sometimes leads to its failure. Protect yourself from such troubles installation of uninterruptible power supplies helps, from which devices that are most sensitive to such sudden changes are powered.

Depending on the circuit solutions that determine the main characteristics of uninterruptible power supplies, they can be divided into several categories. Each of them ensures uninterrupted operation of a certain group of consumers.

Backup UPS

They can only protect simple home appliances and desktop computers.

If the mains voltage is normal, consumers are connected directly to it. When the voltage in the network fluctuates, the equipment switches to power from the battery, which is an integral part of the UPS. Noise and high-frequency impulses are partially suppressed, the voltage is maintained at a given level, and recharging is performed battery. Stabilization of the mains voltage supplying equipment connected to its output is not carried out for uninterruptible power supplies of this category.

The need to switch to battery operation in every model uninterruptible unit nutrition is determined in its own way. The limits of network operation are determined by the developer of this model. They are installed based on the conditions of normal functioning of the consumer equipment.

Battery operation will continue until the voltage in the network returns to normal. After this there is a switch to reverse side. The source battery must provide at least a five-minute reserve when operating from it. This is enough to save data on the computer and trouble-free shutdown of the consumer equipment.

The disadvantages of uninterruptible power supplies in this category include the following:

  1. Lack of mains voltage stabilizer.
  2. Long switching time (~20 ms).
  3. Step form of output voltage.
  4. Presence of high frequency interference.

Switch to offline mode power supply occurs at any slight deviation of the mains voltage parameters from the norm. This leads to rapid wear of the battery.

Linear interactive sources

Models in this category are equipped with network voltage stabilizers, which are made according to an autotransformer circuit. Switching of its windings, depending on the value of the input mains voltage, occurs stepwise according to the commands of the microprocessor built into the UPS circuit. Thus, it is possible to maintain a voltage at the output of the unit close to normal (220−230) V. Additionally, the circuit has a filter that protects the consumer from network interference.

Connecting the battery and disconnecting from the network occurs when the voltage parameters at the input of the unit go beyond the stabilization thresholds. The number of autotransformer terminals is not enough to maintain the rated voltage at the output. There are also tolerances on the shape of the input signal. For large distortions, a transition to battery mode power supply of consumer equipment.

The process of switching to battery power is fairly smooth for most consumers and takes no more than 4 ms.

Thus, Comparing sources of this category with backup UPSs, you can notice their advantages:

  1. Mains voltage stabilization has a stepwise nature.
  2. The output voltage shape is close to a sinusoid.
  3. Network interference filtering.
  4. Saving battery life due to fewer starts.

Ferroresonant power supplies

At their core, they are linear active sources. A ferroresonant transformer serves as a mains voltage stabilizer. It can store magnetic field energy, which maintains voltage in secondary winding transformer at switching moments. The transition process lasts no more than (8−16) ms. This is acceptable for most consumers. The voltage form at its output is sinusoidal, protected from network interference. The source performs its functions based on commands from its own network analysis and control unit.

Linear uninterruptible devices

Double conversion UPSs fall into this category. They contain a converter alternating current to DC (rectifier) ​​and DC to AC converter (inverter). The output voltage of the inverter is used to power the equipment connected as a load. The rectifier voltage is used to recharge the internal battery. It is included in the rectifier circuit and is constantly in active mode, which depends on the quality of the input AC voltage.

The positive qualities of a UPS in this category include:

  1. Output voltage stability.
  2. Possibility of replacing the battery without shutting down the UPS.

The disadvantages include:

  1. Low coefficient useful action(efficiency).
  2. Battery life is reduced due to constant operation.

Devices in this category are used to operate the equipment of large organizations whose servers store important data. They must be saved in case of any changes in the network and any disruptions in its operation.

Main characteristics

When purchasing a UPS, you must carefully understand the requirements for it. It is necessary to choose the model that best satisfies the “price - quality” criterion.

When choosing uninterruptible source power supply, much attention should be paid to comparing the characteristics of different models. These include the following:

  • UPS power.
  • time battery life.
  • switching time to battery operation and back.
  • range of input voltage changes.
  • limits for changing the network voltage frequency.

Power is calculated from the total load of the source. Its value should be at least one and a half times greater than the power of consumers. The optimal power of a unit installed in an apartment is considered to be 1000 VA (1000 volt-amperes).

The switching time directly depends on the size of the load connected to the this moment to the source output. The more current it consumes, the shorter the battery life. Capacity installed battery also determines the duration of the work.

Any UPS model has visual signaling elements. These can be light bulbs of different colors, LED indicators, which determine the state of the uninterruptible power supply at the current moment.

Constantly lit green indicators are a sign of normal operation of the unit. If the LED operates in pulse mode (its intermittent glow), then problems are possible or have already arisen. This is a warning signal that attracts attention.

A constant glow of the red indicator indicates the occurrence of emergency situation. Its occurrence is accompanied by warnings sound signals in the form of intermittent beeps.

Operating rules

Correct operation of the equipment is the key to its long and reliable operation. The basic rules that must be followed when operating an uninterruptible power supply include:

  • The need to constantly monitor the light indication and sound alarm of the unit.
  • Connecting consumers that really require uninterruptible power.
  • Grounding the UPS using a socket with three sockets for connecting the device plug.

If there is a power outage, you must turn off all equipment that is turned on at that moment. It is advisable to leave the UPS plugged in for possible battery recharging after the network fault is resolved. Operating the unit with a discharged battery leads to its rapid failure. The battery life is limited and is no more than 5 years.

Compliance with these simple but necessary rules will extend the life of all equipment that requires uninterrupted power supply, and most importantly, it will preserve important information on computer hard drives, which could be irretrievably lost in the event of sudden malfunctions in electrical networks.

Poor quality power supply is one of the main problems of failure of household, office or industrial equipment. Although the interference that occurs in electrical network, are periodic in nature, they have a detrimental effect on the components of modern electronic devices connected to an outlet. Critical for protection necessary equipment or saving data when the supply voltage disappears, uninterruptible power supplies are most often used.


Basic operation schemes and areas of application of uninterruptible power supplies

The purpose of the UPS is to provide correct operation loads during sudden “dips” or “spikes” of voltage, as well as ensuring short-term autonomous operation of connected equipment during a complete power outage. Modern uninterruptible power supplies are divided into three classes:

  1. Backup or Offline
  2. Linear interactive
  3. With double energy conversion

Their design and functionality are somewhat different, but everyone can figure out how to use an uninterruptible power supply.

Why do you need a backup UPS? Its main area of ​​application is the protection of household computer and multimedia equipment. The scheme of its operation is extremely simple: in normal mode, the load is powered from the network, and when the voltage in it disappears, the device switches to battery mode. The switching time between operating types is non-zero. It is relatively inexpensive and will protect equipment from minor voltage surges and short-term power failures.

The advantages of a line-interactive UPS are smoother signal stabilization and the ability to operate in a wide range of input voltages. Such devices do not allow you to adjust the signal frequency when powered from the mains; when powered by battery cells, they can produce a “pure” or approximate sinusoid. How can I use the Line-Interactive uninterruptible power supply? It is excellent for protecting monitors, system units, LAN nodes, workstations, computer peripherals and other devices with switching power supplies, which makes it excellent.

The most advanced in terms of equipment protection is a double-conversion UPS. But what is valuable in an uninterruptible power supply developed according to the Online scheme? It is characterized by instant switching between operating modes and independence of the output signal parameters from the parameters at the UPS input. Therefore, this particular type of UPS is designed for switching equipment that is especially demanding in terms of power supply quality. Among the UPS Online topologies, based on the scope of their application, the following types can be distinguished:

Alternative protective equipment options

Many people ask the question: is an uninterruptible power supply necessary if the voltage in the network does not disappear, but simply “jumps”? Do you need a UPS for your computer in this case? The answer to these questions may be a look towards voltage stabilizers. These devices allow you to correct the signal over a very wide range, applying a voltage to the load input at a level specified by the user. This is the main advantage of these devices. The main disadvantage is that the stabilizer stops working simultaneously with the disappearance of voltage in the electrical network. The main problem of stabilization devices is the inability to ensure autonomous operation of the load. Therefore, it is important to clearly understand what exactly the equipment needs to be protected from: from signal level fluctuations or from frequent and short-term power outages. In the first case, the way out of the situation will be a voltage stabilizer, in the second - an uninterruptible power supply, the purpose of which is somewhat broader.

But what to do if the signal level in the power grid is relatively stable, but there are long-term power outages? A way out of this situation may be to purchase a diesel generator. They are available in different power ranges and can be used to service both domestic and industrial facilities. There are diesel and gasoline models. The starter of the device can be either manual or electric. The advantage of using such an installation is that it can provide long battery life for the equipment with interruptions only for service maintenance or refueling. This equipment is compact, easy to maintain and easy to operate.

The operation of diesel generator sets is not without a number of disadvantages, these include:

  • Inability to independently switch to power supply to the load when the voltage in the power supply network disappears;
  • Noise during operation;
  • Presence of exhaust gases;
  • A large number of Supplies(candles, fuel, etc.)

Comprehensive solutions for protecting electronic equipment

To provide maximum protection telecommunications, server or industrial equipment, using one type of device may not be enough. Therefore, the most optimal solution may be to combine them. For example, a UPS for emergency lighting will not provide the required level of autonomy. This problem is solved by connecting an uninterruptible power supply unit and a diesel generator set in series. Why do you need an uninterruptible power supply in such a scheme? To filter the voltage and ensure autonomy of the system until the generator starts and enters operating mode.

Why and how can you use an uninterruptible power supply in combination with a voltage stabilizer? For the correct operation of equipment in areas of the power grid where there are frequent voltage drops that are not accompanied by a complete shutdown. Due to this, a significant reduction in the cost of the design can be achieved: an inexpensive stabilization device will provide effective signal correction, and a mid-level UPS will allow you to achieve an acceptable level of autonomy.

Requirements for the quality of electricity are legally prescribed by state standards and fairly stringent regulations. Electricity supply organizations make a lot of efforts to comply with them, but they are not always implemented.

In our apartments, and in production, the following periodically arise:

    complete power outages for an indefinite period of time;

    aperiodic short-term (10÷100 ms) high-voltage (up to 6 kV) voltage pulses;

    surges and drops in voltage with varying durations;

    high-frequency noise overlays;

    frequency drifts.

All these problems negatively affect the work of household and office electricity consumers. Microprocessor and computer devices are especially affected by the quality of power supply; they not only fail, but can also completely lose their functionality.

Purpose and types of uninterruptible power supplies

To reduce the risks of malfunctions in the power supply network, we use backup devices, which are commonly called uninterruptible power supplies (UPS) or UPS (derived from the abbreviation of the English phrase “Uninterruptible Power Supply”).

They are manufactured with different designs to solve specific consumer problems. For example, powerful UPSs with gel batteries can maintain power supply to an entire cottage for several hours.

Their batteries receive a charge from the power line, wind generator, or other carriers of electricity through the inverter rectifier device. They also feed the electrical consumers of the cottage.

When the external source is turned off, the batteries are discharged to the load connected to their network. The larger the battery capacity and the lower their discharge current, the longer they work.

Medium power uninterruptible power supplies can back up indoor climate control systems and similar equipment.

At the same time, the simplest UPS models are only capable of completing the computer emergency shutdown program. At the same time, the duration of the entire process of their work will not exceed 9÷15 minutes.

Computer uninterruptible power supplies are:

    built into the device body;

    external.

The first designs are common in laptops, netbooks, tablets and the like mobile devices, powered by a built-in battery, which is equipped with a power and load switching circuit.

Laptop battery with a built-in controller is an uninterruptible power supply. His diagram in automatic mode protects operating equipment from electrical faults.

External UPS Designs, intended for the normal completion of desktop computer programs, are manufactured as a separate unit.

They are connected via network adapter power to an electrical outlet. They power only those devices that are responsible for running programs:

    system unit with a connected keyboard;

    a monitor displaying ongoing processes.

Rest peripherals: scanners, printers, acoustic speakers and other equipment is not powered by UPS. Otherwise, in case of emergency termination of programs, they will take over part of the energy accumulated in the batteries.

Options for constructing UPS operating diagrams

Computer and industrial UPS are manufactured in three main options:

    power backup;

    interactive diagram;

    double conversion of electricity.

With the first method backup scheme, denoted by the English terms “Standby” or “Off-Line”, the voltage is supplied from the network to the computer through a UPS, in which electromagnetic interference is eliminated by built-in filters. It is also installed here, the capacity of which is maintained by the charge current regulated by the controller.

When the external power supply disappears or goes beyond the established standards, the controller directs the battery energy to power consumers. A simple inverter is connected to convert direct current into alternating current.

Benefits of UPS Standby

Off-Line uninterruptible power supplies have high efficiency when the voltage is applied to them, operate quietly, emit little heat and are relatively cheap.

Flaws

UPS Standby stand out:

    long transition to battery power 4÷13 ms;

    distorted shape of the output signal produced by the inverter in the form of a meander rather than a harmonic sinusoid;

    lack of voltage and frequency adjustment.

Such devices are most common on personal computers.

Interactive circuit UPS

They are designated by the English term “Line-Interactive”. They are carried out according to the previous, but more complicated scheme by including a voltage stabilizer using an autotransformer with step regulation.

This provides adjustments to the output voltage, but they are not able to control the signal frequency.

Filtering of interference in normal mode and switching to inverter power supply in case of emergency occurs according to UPS Standby algorithms.

The addition of a voltage stabilizer of various models with control techniques made it possible to create inverters with a signal shape not only of a square wave, but also of a sinusoid. However, a small number of control stages based on relay switching does not allow the implementation of full stabilization functions.

This is especially true for cheap models, which, when switching to battery power, not only increase the frequency above the nominal one, but also distort the shape of the sine wave. Interference is introduced by a built-in transformer, in the core of which hysteresis processes occur.

Expensive models use inverters based on semiconductor switches. UPS Line-Interactive have faster performance when switching to battery power than Off-Line UPS. It is ensured by the operation of synchronization algorithms between the incoming voltage and the output signals. But at the same time there is some underestimation of efficiency.

The Line-Interactive UPS cannot be used to power asynchronous motors, which are widely installed on all household appliances, including heating systems. They are used to operate devices where the power is filtered and rectified at the same time: computers and consumer electronics.

Double conversion UPS

This UPS scheme is named after the English phrase “On-line” and works on equipment that requires high-quality power. It produces double conversion of electricity, when the sinusoidal harmonics of the alternating current are constantly converted by the rectifier into a constant value, passed through the inverter to create a repeated sinusoid at the output.

Here the battery is permanently connected to the circuit, which eliminates the need for its switching. This method practically eliminates the period of preparation of the uninterruptible power supply for switching.

The operation of an On-line UPS based on the battery condition can be divided into three stages:

    charge stage;

    waiting state;

    discharge for computer operation.

Charge period

The sine wave input and output circuits are interrupted by the internal UPS switch.

The battery connected to the rectifier receives charge energy until its capacity is restored to optimal values.

Readiness period

After the battery is charged, the automatic uninterruptible power supply closes the internal switch.

The battery maintains a state of readiness for operation in buffer mode.

Discharge period

The battery is automatically transferred to power the computer station.

Uninterruptible power supplies operating using the double conversion method have lower efficiency in line power mode than other models due to energy consumption for heat and noise. But in complex structures, techniques are used to increase efficiency.

UPS On-line is capable of correcting not only the voltage value, but also its oscillation frequency. This sets them apart from previous models and allows them to be used to power various complex devices with asynchronous motors. However, the cost of such devices is significantly higher than previous models.

UPS composition

Depending on the type of operating circuit, the uninterruptible power supply kit includes:

    batteries for storing electricity;

    Ensuring maintenance of battery performance;

    inverter for generating a sine wave,

    process control diagram;

    software.

For remote access A local network can be used for the device, and the reliability of the circuit can be increased by using redundancy.

Some uninterruptible power supplies use the “Bypass” mode, when the load is powered by filtered mains voltage without operating the main circuit of the device.

The UPS part has a step voltage regulator “Booster”, controlled automatically.

Depending on the need to perform complex technical solutions Uninterruptible power supplies can be equipped with additional special functions.

Greetings, my dear readers! In the current Russian realities, the owners desktop computers forced to solve problems of uninterrupted power supply. Decide this problem possible using uninterruptible power supplies. Their diversity on the computer market allows you to choose a UPS to suit your specific needs. We will talk about what a UPS is and what uninterruptible power supplies there are in this article.

A UPS, or uninterruptible power supply, is a device that acts as an energy “battery”. In the event of a power outage, the UPS automatically switches the computer's power supply to power from the built-in batteries, which allows you to shut down the work correctly and save all the necessary documents.

Variety of uninterruptible power supplies

Uninterruptible power supply is your guarantee of the safety of documents and computer components as a whole. After all, if the computer is turned off incorrectly, the HDD, And motherboard, and RAM.

We figured out what an uninterruptible power supply is. Let's move on to the next question.

What types of UPS are there?

Uninterruptible power supplies are divided into three types:

  1. Offline UPS;
  2. Line-interactive UPS;
  3. Online UPS (double conversion UPS).

Let's look at each type of uninterruptible power supply separately. This information will help you when choosing a UPS for your own needs.

Offline UPS

Principle of operation of this type power supply is to automatically switch the computer or other connected device to power from the built-in batteries when disconnected from the external power supply.

Often a mechanical relay acts as a switch, so you may hear a clicking sound when the UPS switches from external source power to batteries and vice versa.

This type has become widespread among ordinary users and in offices.

TO pros Such UPSs include simplicity, compactness and low cost. The main minus is the impossibility of stabilizing the input voltage, and therefore your computer will not be protected from sudden voltage changes. This species also exhibits increased wear and tear on batteries.

Line-interactive UPS

This type of uninterruptible power supply is in most cases used to protect network and other telecommunications equipment, as well as groups of computers.

The main feature of these sources is the ability to adjust the output voltage without connecting to batteries, regardless of the voltage (high or low) at the input.

Pros of this type of UPS are small sizes, low cost, automatic adjustment voltage, efficiency.

But he also has minuses– this is a relatively long switching to batteries, the impossibility of adjusting the shape of the output voltage when operating from an external power supply, the change in output voltage occurs in steps.

Double conversion UPS

This type of UPS performs voltage conversion twice: input AC voltage is converted to DC, and then the DC is converted to a reference AC voltage and supplied to the devices.

Applicable this type where a reference voltage is required and the powered devices are demanding on power quality. Connected devices can be very different: regular workstations, file servers, network devices and other power-hungry equipment.

pros Online UPS has significant features: full control of input and output voltage, zero waiting time for switching to batteries, connected equipment does not in any way affect the external power grid.

Minuses There are also: high cost, complex design, self-consumption of electricity in double conversion mode.

The first type of UPS is quite sufficient for home and office use. But if you have the financial opportunity, I would recommend the latter type to you. This is the most reliable type of protection for your computer equipment from poor quality voltage.

Main characteristics of the UPS

A UPS has several main characteristics that you should pay attention to when purchasing. Let's look at them below.

  1. Power. This characteristic directly determines what equipment can be connected to this UPS. Always choose a source with power reserves. This will avoid possible problems with a lack of power.

Usually this characteristic indicated by the value VA or W. If the value is indicated in VA (VA), then multiply it by 0.6 to get the value in Watts that are more understandable to us.

  1. UPS type. I talked about the types of uninterruptible power supply systems above. We came to the conclusion that the most optimal would be a double conversion UPS, but for home needs an offline or line-interactive source would be sufficient.
  2. Battery life. This value is very important, since it determines how long the computer will work without external power. Typically, battery life is set in the range of 5-30 minutes. Please note that when maximum load With a UPS, the operating time without electricity is significantly reduced.

These three characteristics are the most important. In addition to them, the UPS has many more characteristics. For example, when choosing a UPS in a store, pay attention to what power connectors are installed in the source, whether there is a display and additional interfaces(RJ-11, USB), how many batteries are installed and others.

Frequently encountered problems

  1. The most the main problem The most common problem that occurs with a UPS is battery failure. A dead battery can be determined by the fact that the uninterruptible power supply stops supporting the load - when the power goes out, the computer immediately turns off. Also, a damaged battery can manifest itself in a different way: the uninterruptible power supply does not turn on at all, or it turns on and beeps continuously. I wrote about how to change the battery in a UPS. It says about a specific UPS, but the replacement principle is practically the same in all sources.
  2. The UPS may not turn on at all due to a blown fuse.
  3. If the uninterruptible power supply starts normally, but the computer does not turn on, then check the wires; they may come out of the sockets.

I hope my article was useful to you and you learned something new. If you still have questions, you can ask them in the comments.

All types of uninterruptible power supplies are designed to perform a set of the following basic functions

  • Protection against small and short-term failures in the main power supply network.
  • Filtering of emerging impulse disturbances and noise reduction.
  • Backup power supply to the load during the set automation period.
  • Defence from short circuit and overloads.

More complex models have a set additional functions:

  • Automatic deactivation of protected equipment during longer critical power outages, as well as restart when the required parameters are restored.
  • Monitoring the main parameters of the source’s functioning, tracking its performance level.
  • Displays basic information about the operating UPS, as well as the parameters of the input voltage of the supply network.
  • Automatic alarm when abnormal calls occur.
  • Availability of an installed timer for configurable shutdown or switching on of the consumer at a set time.

Scope of application depending on UPS type

Backup uninterruptible power supply- the most common in this market segment. It is widely used in combination with home or office computers or low-power workstations local networks. It is also effective in terms of protection household appliances, which does not require special quality of power supply, allows power outages for a certain time and the occurrence of deviations from the input voltage parameters on average + -5%.

Interactive uninterruptible power supply can also act as a backup. However, its main tasks are broader: it also performs stepwise voltage stabilization, which allows it to be used in combination with electrical devices with high inrush currents. This is any device or other equipment that uses an electric motor, the starting of which requires increased power for a short time. In particular, the operation of a refrigerator under conditions of deviation from normal voltage parameters can lead to its overload and failure. However, the efficiency of these protective devices is slightly lower than the same parameter for backup ones.

Online or double conversion uninterruptible power supply provides maximum effective protection for file servers and more complex workstations. It is used in combination with equipment from financial institutions, medical clinics and research centers. That is, almost everywhere where absolutely high-quality energy supply is needed with the absence of even short-term voltage dips. But in everyday life, such devices are, firstly, ineffective (high cost at low loads), and they are also characterized by increased noise and impressive heat generation.

Application by current type

Online or double conversion uninterruptible power supply

Such uninterruptible power supplies are necessary to ensure the protection of electrical devices that are connected to a 24 V, 48 V and 60 V network.

AC UPS

Uninterruptible power supplies of this type are used in combination with critical consumers that require a voltage of 220 or 380V.

Application by power

UPSs are divided into three groups based on power:

  • - low-power;
  • - medium power devices;
  • - modular high power systems.

Low-power UPSs are widely used for domestic purposes, as well as to protect individual consumers from possible critical situations in offices or small industries.

Medium power devices are responsible for high-quality and uninterrupted power supply of local networks, data centers and various telecommunications equipment, as well as remote communication facilities.

A high-power uninterruptible power supply has several advantages in use. It is capable of providing protection for both a separate residential cottage and a large production process. In addition, such a UPS is a kind of modular system that allows you to synchronize several sources into one 19" rack to obtain higher power values ​​when solving specific technological problems.