Passive(stand-by, the name “standby” can also be used, the official name of the type is VFD, Voltage and Frequency Dependent) - the most affordable type of UPS, so named because the battery and inverter (the circuit that converts direct voltage into alternating voltage) are in normal state when operating from the network, they are completely disconnected from the load at the output, and switching to them occurs only in the event of a loss of power at the input (or its voltage goes beyond acceptable limits), the switching time from operation from the network to operation from the battery is usually tenths of a second, and the output signal has the form of a square wave or the simplest approximation of a sinusoid.

UPS of this type, as a rule, do not protect the connected equipment from interference when operating from the network; it is also strictly forbidden to connect to them devices that have a significant component of inductive load, namely: transformer power supplies (except for low-power power supplies for modems, etc.) and AC electric motors, since supplying a non-sinusoidal signal to such devices is fraught with their failure, i.e. They work correctly only with switching power supplies, which are equipped with all modern PCs, monitors and a significant part of the peripherals and household equipment.

However, even in the case of switching power supplies, feeding a meander or trapezoid instead of a sine wave leads to an increased amount of noise at the internal outputs of the power supplies of devices operating from such UPSs. Therefore, it is not recommended to connect audio-video equipment to these UPSs, as well as expensive or sensitive PCs; their main use is home and office PCs.

Among APC products, this type includes the following series of UPSs that are optimal in terms of “capabilities/price” criteria:

At the beginning of 2010, APC released an updated model of the RS series - Back-UPS RS 550 (). This device has a new interesting energy saving feature. It is implemented in the form of “dependent” UPS output sockets, which are de-energized if you turn off the computer connected to the “main” sockets of the device. In this way, you can save energy by automatically turning off equipment such as hubs, modems, routers and other peripherals that are usually unnecessary when the computer is not working. Another important innovation that makes using UPS more convenient is the presence of a liquid crystal display that displays detailed information about the status of the UPS and the power grid.

Double conversion(double conversion, also called “online UPS”, the official name of the type is VFI, Voltage and Frequency Independent) - a UPS in which the battery is constantly charged from the mains and supplies current to the inverter, due to which the load connected to it is completely galvanically isolated from the electrical network for general use and is constantly powered by a pure sine wave.

These UPSs do not have any restrictions on the types of connected equipment if its maximum power consumption does not exceed the capabilities of the UPS. Their main application is control and measuring equipment, critical communications equipment, high-reliability servers and other applications where the highest quality and reliable power supply is required. APC offers the following series of UPS of this type:

(Sometimes referred to as Smart Online) is a series of UPS for the most critical applications, providing the most stable output voltage in any conditions.

The choice of uninterruptible power supply depends on what type of server equipment you plan to use it for. If it is necessary to ensure uninterrupted power supply for a single server, then you should choose models with a capacity from 0.5 to 1 kVA. For server groups, telecommunication racks with network and peripheral equipment, more powerful models will be needed from 1 to 5 kVA. UPS capacity from 6 to 10 kVA suitable for several medium-power server groups, small computer and server rooms, network storage. Models from 10 kVA and above should be considered when it comes to powering high-power server groups, server rooms and mini data centers.

You can find a suitable uninterruptible power supply option for a 19-inch rack in the assortment of manufacturers IMPULSE and Makelsan

What UPS configuration options are there?

Let's look at some options for setting up a UPS.

• Charge strategy

An option that allows the user to select an acceptable UPS operating scenario in the event of a power outage. This option allows you to choose one of three behavior options:

• turning off the computer immediately after a power outage in order to save battery power.
• switching the computer to operate from a UPS battery and continuing operation for as long as possible.
• switching the server to power from a UPS, with shutdown after a specified time.

• Automatic saving

An option that allows you to correctly shut down all running programs and operating systems when the power supply is turned off. Note that the default UPS settings have optimal values, but in some cases additional adjustment of the options for specific servers may be necessary, since the hibernation function does not work well on all servers and not on all OSes. Typically, this option prompts you to choose one of two options:

• end programs and turn off the computer.
• Quit programs and put the computer into hibernation mode.

• Energy saving

This option allows you to recognize the moment the server enters sleep mode and reduce the supplied power, as well as stop power supply to unused peripheral devices.

• Sound notification

This option is included in almost all equipment models and is intended to notify about equipment transitions to another operating mode. Some models provide the ability to turn off notifications using buttons on the case or through proprietary software, while others do not.

• Response thresholds and sensitivity

This option allows you to change the response threshold of the power supply in order to reduce the number of operations and switches to battery power mode, if the server’s built-in power supply already copes well with voltage fluctuations in the network.

The choice of an uninterruptible power supply becomes relevant for every owner of expensive home appliances under conditions of unstable power supply.

The following failures and malfunctions in the electrical network may prompt you to the question “how to choose an uninterruptible power supply”:

• sudden complete power outage;
• a sharp “dip” in voltage – the signal disappears for a short time;
• increase in voltage - jump up;
• voltage reduction to nominal value;
• occurrence of radio frequency and electromagnetic interference;
• appearing high-voltage pulses;
• high frequency pulse signals;
• transient switching;
• various distortions in a sinusoidal voltage signal.

An uninterruptible power supply can eliminate the negative consequences of these phenomena. Due to the widespread problems with power supply, many are wondering which uninterruptible power supply to choose for a boiler, and how to choose a UPS for a computer. What requirements should an optimal UPS meet that is not a waste of money? We have provided 9 simple tips that you can rely on when deciding which UPS to choose.

Tip 1: Determine what power problems you are facing

When deciding which UPS to choose for a gas boiler or how to choose the right UPS for a server, the very first step that is required of you is to identify the most common problems in the power grid. Uninterruptible power supplies produced on the modern market have a significant variation in technical characteristics and cost. Therefore, the chance of making a mistake and overpaying for an overly powerful unit is the same as the chance of choosing an uninterruptible power supply that is not reliable enough.

Please note:

• Are the light bulbs in the apartment/house/office blinking?
• How often do complete unplanned power outages occur?
• whether the voltage jumps so much that electrical appliances turn off or restart.

Tip 2: Decide on the level of UPS reliability you need

There are 3 UPS production topologies, depending on which the output voltage varies, the time it takes for the device to switch to battery mode, and the voltage change when switching to battery operation. To ensure that the operation of equipment is not interrupted by sudden power failures, the choice of UPS for a computer or other devices should be an uninterruptible power supply with a switching time to battery mode of less than 10 ms.

1. Backup uninterruptible power supplies (Standby, Off-line, Back-UPS).
The answer to the question of which UPS to choose for your computer. If you do not have a gaming station or a complex office equipment unit, then the simplest type of UPS - a backup - will be an excellent economical option. It will provide equipment with 5-7 minutes after a power outage, and this time is enough to correctly terminate simple programs and processes and safely shut down the PC.

Before choosing a backup UPS, make sure that your network does not experience large voltage fluctuations (175-190 V). In this case, the UPS, without a stabilizer, will constantly switch to battery mode, which will shorten the life of its battery.

2. Line-interactive UPS equipped with an automatic voltage regulator. This is the choice of an uninterruptible power supply for a computer or even an entire server room in case of strong surges in voltage levels. The device corrects the output voltage shape and stabilizes it. Compared to backup UPSs, linear ones are more expensive, but also more reliable in protecting your equipment. By choosing this option, you can choose an uninterruptible power supply for a heating pump, as well as for oversized, but complex and sensitive equipment and critical applications.

3. UPS with double voltage conversion topology (On-line, double conversation)– devices with the highest degree of reliability and protection of your equipment. There is no better way to secure an uninterruptible power supply for a gas boiler than to choose an online device. It continuously converts the incoming energy into a stable (fluctuations of no more than 1%) DC voltage. The disadvantage of such devices is their high cost: it is advisable to use such devices in large data centers, medical institutions and enterprises.

Tip 3: The power of the UPS should be 20-30% greater than the power of the system

The best possible advice on how to choose an uninterruptible power supply is to take into account the power reserve. If the UPS is selected incorrectly based on power, and more powerful equipment is connected to the uninterruptible power supply, this will lead to the uninterruptible power supply shutting down due to overload of the equipment itself. How to choose an uninterruptible power supply for a computer: calculate the maximum power of the entire load (including peripheral devices) and select a UPS with a rated power that is 20-30% higher than the obtained value. Using the same principle, you can calculate how to choose a UPS for a gas boiler.

Looking for an uninterruptible power supply? Which one should you choose to ensure that the protected equipment is not damaged due to power surges? If you are figuring out how to choose a UPS for your PC, then for a regular computer, 5-7 minutes is enough to save current documents and correctly close all applications and programs. This is the average time provided by any modern power source. But if we are talking about more complex and heavy-duty programs, then there is nothing else to do but choose a UPS with a longer battery life.

The backup time can be extended by installing additional batteries. If necessary, you can decide which UPS to buy: models with support for external batteries are equipped with special connectors.

Tip 5: Make sure you have the software

Before choosing a UPS for your computer, it is logical to make sure that this computer itself will run special software for installing, setting up, managing and monitoring the UPS. The software will allow you to save data when completing non-standard programs and complex applications. Even if you are not present in the room near the computer during a power failure, your data and equipment will be completely safe under the reliable protection of an uninterruptible power supply.

How to choose the right UPS? Make sure that it has sufficient capabilities to protect not only the computer, but also peripheral devices. If the UPS is equipped with connectors for telephone lines, then your fax and modem will also not be afraid of voltage surges. Destructive interference can occur even during a thunderstorm: if the modem is connected to an uninterruptible power supply, it will easily withstand this test.

Tip 7: Prefer UPS with clear controls

This nuance is especially relevant for home use of uninterruptible power supplies. In addition to the question of how to choose, you will also have to face the need to independently manage this unit later. Choose models with an intuitive interface and a convenient LCD display for displaying information. You can at least find the meaning of the symbols on the screen in the UPS operating instructions and understand what the device is trying to communicate.

When deciding which UPS to choose for a boiler, computer or other home appliances, choose a model with replaceable batteries. The UPS battery life is no more than 3-5 years, and the battery module accounts for almost 50% of the cost of the entire device. It is cheaper to buy a new battery than to replace the entire UPS!

Tip 9: Find a suitable location for the UPS in your apartment

Uninterruptible power supplies are very noisy during operation (40-45 decibels), so placing the device in the bedroom is not the best idea. Even with how to choose an uninterruptible power supply for a boiler and place it, difficulties may arise. It is important that the equipment (UPS and external) does not overheat, otherwise it will fail ahead of schedule. Try to place each piece of equipment at a distance of at least 1 meter from another building so that the operation of the batteries does not lead to overheating from the adjacent unit.

The requirements that an uninterruptible power supply meets for a personal computer and for a server are different. The conditions imposed on a server UPS are much higher than for a personal computer UPS. Still, not only peripheral devices are always connected to the server (servers), but also computers whose users can connect to this network remotely.

In addition to common tasks that are solved by any uninterruptible power supply, server UPSs have several more specific functions. These include: remote control using a local network, automatic UPS testing and automatic battery diagnostics.

Since the power that UPS supplies to a server is very large, the power system usually consists of units installed in one server rack. Such a UPS has another real advantage: it becomes possible to perform “hot repairs,” testing, and replacing a faulty system unit without disconnecting the uninterruptible power supply from the network. Actually, replacing the faulty unit with a backup (workable) one, and then making repairs without haste (or contacting the service department) is always more convenient and simpler.

Online or not Online?

An on-line class UPS, that is, a double conversion system, provides the highest degree of protection for electrical appliances connected to it.

The main disadvantage of backup (off-line), as well as line-interactive UPSs, remains the need to switch the supplied load from the mains voltage to a generator (inverter) powered by a battery. The time of such load switching, however, cannot be considered “zero”; the switching itself will cause a transient process, with the presence of unwanted “bursts”. All this leads to at least a malfunction, a short-term loss of power on each device connected to the UPS.

Double conversion power eliminates this problem. In such UPSs, the load from the inverter (alternating voltage generator) will be constantly powered. As you can understand, the inverter input is connected to the direct (not alternating) voltage of a charged battery or rectifier. The rectifier here converts alternating voltage 220 V into direct voltage (12 V or 24). When the "rectifier" voltage disappears, the inverter will continue to operate, powered only by the battery.

In fact, it is possible to create a UPS of serious power (up to 500 kVA) only using a double conversion scheme. Of course, such a UPS provides power not to one computer, but to a server room, office, or the entire building. When choosing, keep in mind that UPSs with a power of 10 kVA or more are intended for use in conjunction with a three-phase network.

Layout

UPSs of not too high power (up to 1000 VA) usually operate on batteries for 7-20 minutes. UPSs with high output power may not have batteries at all as standard. Based on operating conditions, they are additionally equipped with battery packs of different capacities. The number of batteries, that is, the total capacity, affects the emergency operation time. As a rule - proportionally.

What should it be like? A common option for using a UPS to power the load before starting the generator (diesel) motor will involve a choice depending on the characteristics of the diesel engine. For emergency termination (of programs and services) - now, in general, 10 or 15 minutes are enough, at the “modern” processor speed.

Additional functions related specifically to the electrical part of UPS systems include the ability to operate without using batteries when the network is at high or low voltage (SmartTrim and SmartBoost modes, respectively). The threshold value (at which the transition to “battery” will still occur) can be configured (for both modes – separately).

Control

Any APC Smart rack-mounted UPS has a scheduled shutdown or power-on function, for which a server (connected to the UPS via the COM port) or a Web/SNMP management network card is used.

As a rule, one function is needed: turning off the workstation within, say, 10 minutes after turning on the “battery” mode. That is, we give the OS a full 10 minutes to extinguish. And to turn it on when voltage appears in the 220V network, you can configure the BIOS of the motherboard - Power On when the PC is powered on (when turned on). Actually, is anything else needed?

This setting is typical. And the schedule is not used here: if there is light, the server is working, if there is no light, there is no work.

The APC UPS adapter is called Power Net SNMP (example: AP9617). Actually, the APC Power Net SNMP adapter plays the role of both an SNMP agent and an Ethernet card for all Smart-UPS of this company. The adapter board itself has only one RJ connector (LAN 10MBit), and the computers receiving the signal from the UPS are located in the same Base 100 (or 1000MBit) local network segment as the UPS itself.

A warning signal is sent to all workstations (the signal has a “common” IP), after which each one that receives this signal will automatically perform the following actions: stop all services; shutdown (using the operating system).

To control these functions (software shutdown - enable), you need to remember two “words”: When power fails (“when the electricity goes out”) - when exactly to start shutting down; When power returns (“when electricity appears”) – turn on the UPS immediately, or after the specified (“never” means turn on manually).

The When power fails parameter can be configured for the time until the batteries are completely discharged (for example, “start shutdown 7 minutes before discharge”), but you can select the immediate value (“immediately”) to give the maximum time for stopping and shutting down the servers using OS tools.

Note: the time to discharge is set based on the full (maximum) power consumption.

Setting using buttons (and, typical malfunctions)

Most of the necessary UPS parameters for the server can be configured “hardware” (using buttons on the device panel). For example, in the APC Smart series, there is a “Configuration Settings Button”.

In APC, with one button you can set the threshold at which the UPS will switch to batteries, that is, the upper and lower voltage limits (the LED indicator displays the value of the current setting with its brightness). Pressing the same button with the “On” key will allow you to change the When power fails parameter.

Connection faults (we are talking about a local network) are diagnosed by the SNMP card:

1. The green lamp is on – the SNMP agent is working normally;
2. The green lamp is blinking – the SNMP agent is not configured;
3. The red lamp is on - hardware failure;
4. The red lamp is flashing – the LAN cable is broken.

"Soft" management

As already mentioned, the APC Smart UPS network card is a web server, that is, a web interface is provided to manage (set parameters) the UPS. For APC, it is called Power Chute Net-work Shutdown.

By typing the desired name in the browser, we get to the Configuration Wizard:

The Configuration Wizard: Security page allows you to set a login and password. By clicking “Next”, we see the Electrical Configuration page:

The UPS software can also work with a server that has two internal power supplies (the program “sees” 2-3 UPS as one). In each case, a running server (or several) will receive messages correctly. So:

1. Single UPS. Everything is clear here, there is one UPS, one power line.
2. Redundant – a backup scheme using 2 or more UPSs connected to a machine with 2 or more power supplies (there can be several such “machines”);
3. An array of UPS, the output of which is “paralleled” (is it possible to do this? And, if so, then with which UPS companies?).

The default is one UPS. By clicking “Next”, we see the “details” of the IP connection (UPS-Details):

Click “Next”, “Next”, and ultimately we get to the device settings page:

We can configure the reaction to events (events) as we please. We configured the UPS to “shut down” when the battery charge is 15% and the case is overheated (the ap9631 board comes with an external temperature sensor).

We examined only one brand of UPS, however, others will not differ so much in function. When choosing a UPS, it becomes clear what to pay attention to: the presence of sensors; cost of the Ethernet control board.

UPS parallel connection

A “parallel” connection is a technical solution aimed at both increasing overall reliability (hardware redundancy of the UPS) and increasing the output power of a given system. Electrical parallel connection of several peer-to-peer UPSs is possible. At the same time, their inputs and outputs are combined.

Of course, it is impossible to parallel voltage sources “just like that.” The functionality of such systems is ensured by the presence of a phase synchronization circuit for the output voltage. APC has a technology called “Active Sync”.

We get: uniform load distribution between all sources; If one fails, the power will be redistributed among the serviceable ones. Typically, an N+1 redundancy scheme is used (you need 3000 VA - we take 4 UPSs of 1000 VA each).

Please note that not all UPSs (even server ones) support this feature.

Note: the maximum number of UPSs used in parallel is always limited. Usually 3 or 4 (for some UPS models it is 8).

Power calculation

On the website of each equipment manufacturer, they offer to calculate the power for UPS automatically (and select the UPS models you need). For APC, this site: www.apc.com/tools/ups_selector/index.cfm.

The battery capacity will also be calculated (depending on the operating time you specify).

As you can see, there are two options for automatic calculation. The first is to “substitute” your existing computer configuration (processor, number/type of hard drives, presence of a printer). In general, this calculation is quite accurate. But it is done in abundance.

Another method of calculation is when you yourself know how many Volt-Amps each workstation needs. Knowing their “number”, it is easy to calculate the total power.

About the influence of the power factor of the power supply on the calculated power

As you know, power consumption (in Volt-Amps) is equal to the maximum power in Watts multiplied by the correction factor (power factor):

The value of the power factor (Pf) is different for different types of computer power supplies. For a pulse power supply that does not have Pf correction (the input of which is a diode bridge and capacitors), it is equal to 0.6. The use of power factor correction systems in modern power supplies makes it possible to “bring closer” the value of the coefficient to 1. But with PFC systems (Pf correction), too, not everything is so simple.

First, passive correction (PPFC). The coefficient for calculations can be taken equal to 0.9 (0.85 for “powerful” power supplies). In principle, this works. But cheap UPSs (not online) do not tolerate such correction and can fail (which is caused by the presence of inductances at the input of the power supply).

With active correction, too, it’s not easy. It would seem that we can take Pf = 1 (so as not to bother). However, the subtleties are as follows.

Question: Is there a problem with the UPS and the APFC power supply working together? Does the shape of the UPS output signal (sine wave or approximation) affect the operation of such a power supply?

Answer: yes, there is a problem. It manifests itself to a greater extent only with APFC power supplies that have “autovoltage” (Full Range). UPS up to 1000VA (and perhaps a little higher) with such a power supply behave inadequately; if the computer is sufficiently “gluttonous” (over 300W), a short-term voltage drop occurs (the PC reboots).

Question: why is this problem possible?

Answer: due to short-term excessive current consumption by the APFC module, which has “autovoltage”.

For example, on the Hiper R HPU-580W power supply it is written:

110…120V (8A) and 200…240V (5A). 5A is a bit much (for 580 Watts), it’s good that it’s stated honestly.

There are power supplies with APFC without the “autovoltage” option (that is, with a switch). For example:

Hiper HPU 3S425 – probably other power supplies from this company (we have not encountered Hiper power supplies with autovoltage);
FSP Optima Pro 500W, 550W (230V) (and power supplies of this series 600W and higher, unfortunately, have auto-voltage).

The above power supplies (but not only them) do not cause problems when working together with an Online UPS.

What happens when the UPS power is “low”?

If the output power of the uninterruptible power supply is insufficient, the following are possible:

1. A short-term shutdown of the computer (which immediately entails a “reboot” with loss of data).
2. Exceeding the current by 1.5-2 times will switch the UPS to protection mode. Even if the “excess” lasted 20-30 ms.

Of course, a computer, server, workstation does not always operate at full capacity. However, when choosing a UPS uninterruptible power supply (or UPS array), you should proceed from the maximum possible values.

The time required to correctly shut down the server

The workstation stops under the control of the operating system, which receives the appropriate command “from the outside.” In each specific case, the value of the time interval required to completely stop all applications and services is strictly individual.

In order to calculate it, you do not need to buy a UPS. You can calculate everything yourself. For this purpose, you can artificially load the server, simulating the worst of the situations (the highest computing load), in order to then detect how many minutes pass before shutting down.

By adding 20-30% to this interval, feel free to choose a UPS system with these parameters.

Sometimes the operating time “on batteries” is deliberately chosen to be slightly longer, so as not to “turn off” the machines every time the voltage drops (decreases) for a minute. The choice here depends more on the measured parameters of the electrical network.

Backing up a small MS SQL database takes a couple of seconds. Copying and saving (uploading) 1C Enterprise infobases may take 10 minutes (or more), depending on the size and configuration of the server.

We can say: it’s still worth focusing on the fact that over time, the resources of all “bases” on the server increase, and the backup time never depends linearly on the “volume”...

Therefore, when choosing a UPS, they focus on models that provide scaling of battery life (installation of additional batteries).

Briefly about companies

LIEBERT (ISO 9001 certification, Russian and CIS certificates)

Since 1975, Liebert GmbH has been supplying powerful professional solutions to our military-industrial complex. Liebert gained wider popularity 7 years ago, as it entered the UPS market of medium and low power. Using Liebert products, power supply systems for both servers, workstations, and centralized power supplies for buildings are created.

This company produces only online class sources. It was Liebert that first used microprocessor control. Now the company offers a wide range of products, power supplies designed for the entire range of power consumption (from 700 VA).

EATON-POWERWARE (supply of complete turnkey solutions)

Eaton uninterruptible power supplies are specially designed to work with servers and computer loads, and are highly efficient (efficiency from 0.9). On the market, the company's products are represented by various models designed for different power. The company has more than 40 years of experience in working with corporate clients.

APC (Computer Power Systems)

Since 2007, the American concern APC has been part of Schneider Electric, and together with the company MGE UPS, it forms a division of the global company Critical Power. Sometimes you will see the following emblem: “APC in collaboration with Schneider Electric.”

The history of APC begins in 1981. It was founded by three MIT graduates. Initially, the company's goal was research into the use of solar energy. However, APC soon shifted its interests, and since 1984 it has been engaged only in power protection. The company's first UPS was the 450AT+ model, released in the same year (84).

Widespread computerization gradually leads to the fact that in 1988 the APC budget was already one and a half million dollars. The first international plant in Ireland began operations in 1994. Now the company's budget is several orders of magnitude larger. But the main segment of products sold is “server” solutions, designed for power from 1000VA.

IPPON (product of the Taiwanese company Centralion Industrial)

Uninterruptible power supplies for home and office use and other power protection devices form the core of IPPON's market segment. The range includes UPSs designed specifically for Russian conditions.

The brand appeared on the Russian market in 2002, today IPPON is one of the three leading companies in the retail supply of UPS.

Today, the buyer is offered seven lines of models, of all classes (Off-Line, Interactive, On-Line). Under the IPPON brand, 25 different models are now produced, the power range of which is from 400 to several thousand VA. The most “expensive” line is Smart Power Pro. At the beginning of 2012, the company entered the online market with a powerful model designed for industrial equipment (server racks): Innova RT.

The reliability of IPPON UPS is confirmed by a two-year warranty and quality certificates.

In conclusion, we can say that the “trends” of the market for budget solutions (inexpensive UPS for home and office) and professional power supply systems are different. One might even say that in some ways these two markets are opposite. Experienced, time-tested companies may move into the more expensive segment of server solutions, while “low-cost” UPS is now offered by an increasing number of “new” companies.

A brief overview of power supplies

In many enterprises, in order to organize efficient and productive work simultaneously, modern IT solutions are installed at all workplaces, working directly with one or several servers.

The stability and functionality of the entire enterprise depends on the reliability and continuity of the server, so this type of equipment requires flawless operation and the absence of accidents in the main power grid.

While progress around the world reaches new heights and brings full automation into our lives, data centers, storage systems and server rooms have become the real electronic “heart” of any company.

All reports compiled by your employees, all databases, strategic information and other information stored electronically are stored there - in the “heart” of any company, i.e. servers, storage systems and data centers.

In order for your computer system to operate efficiently and reliably, you must install an uninterruptible power supply (UPS) in the server room. Therefore, a UPS is a vital necessity in conditions of unstable operation of our electrical networks.

Even a short-term network outage can destroy expensive equipment or lead to the loss of critical data that cannot be recovered.

UPS types for servers

There are three types of UPS:

First - off-line (stand-by) comes into operation only in the event of a power outage in the network. In the event of power failures or in the event of its complete absence, a switch is activated in the UPS, which in turn connects a circuit with a battery and an inverter for power from the battery. The disadvantage of this type of UPS is that it takes a certain time to switch power from the mains to the battery, which causes a small voltage gap in the circuit to the consumer. Voltage surges are also possible, while most consumer power supplies do not have voltage stabilizers, and therefore pulse voltages may occur, which will subsequently lead to malfunctions of electronic equipment or even to its breakdown. The lack of output voltage regulation is also a significant disadvantage of this type of UPS.

The advantages of this type of UPS include a fairly high efficiency, since during normal operation of the electrical network, the UPS consumes energy only to power its circuit and recharge the battery if the battery is discharged.

The second type of UPS used for installation on a server

-On-Line. The device supplies the server with electricity continuously, charging its batteries, and the electricity is passed through a rectifier, resulting in almost zero switching time. Next, the inverter is switched on, which in turn converts direct current into alternating current, while providing the required alternating voltage at the output. In the case of a stable voltage in the electrical network, the output current of the rectifier is sufficient to operate the inverter and recharge the battery. If there is no voltage, the inverter is powered by the battery and continues to supply alternating voltage to the end consumer. Depending on the power of the consumer, the battery can provide the inverter with electric current from five minutes to several hours.

Thus, On-Line UPS provide an ideal output voltage in case of any problems in the electrical network and are characterized by zero switching time from normal to autonomous mode and back without transients in voltage.

The disadvantages of the On-Line UPS include low efficiency, since part of the power is spent on powering the rectifier and inverter.

Third - Line Interactive is an intermediate version of Off-line and On-line UPS. Its switching time is 3-15 milliseconds. Line Interactive UPSs are also used to protect servers and PCs, but unlike On-Line solutions, there is incomplete filtering of the network voltage from interference and surges, i.e. interference generated by the load is passed back into the network, which negatively affects the consumer’s power supply. Also, as disadvantages, one can note an abrupt change in the frequency, shape and magnitude of the output voltage when the battery is switched. Line-interactive UPSs occupy an intermediate position between simple and relatively cheap backup sources (Off-Line) and highly efficient double-conversion UPSs (On-Line).

Protection of devices such as file servers, storage systems, data centers and telecommunications equipment is currently carried out using UPS with On-Line or Line Interactive scheme, since these solutions provide:

Maximum filtering of mains voltage from interference

Minimum switching time to batteries

Stabilization of the shape and magnitude of electrical voltage

The StoreServ company offers its customers reasonable and cost-effective offers for UPS solutions for server rooms, data centers and storage systems. Our company's product range includes global brands whose quality speaks for itself: APC, EneltPro, Tripp Pite, Eaton Powerware, POWERCOM and many others. The company's portfolio includes a large selection of UPS of various capacities, designs, purposes and pricing policies.

Our company’s specialists will be happy to help you make the right choice and selection of equipment for your current tasks!