The main purpose of an uninterruptible power supply (UPS) is to temporarily provide power to equipment during power outages. It is common practice to connect computers via a UPS everywhere. True, for many users this is a kind of “rule of good manners”, and the practical meaning of this ritual eludes them. “Well, a UPS protects your computer from power surges...” Let's try to figure it out: what, from what and how does the uninterruptible power supply protect?
According to the internal structure and operating logic, all UPSs are divided into three classes: passive, line-interactive and UPS with double conversion. Accordingly, they cope with incidents in the power grid to varying degrees and belong to different price categories.
Passive(stand-by, VFD, back-UPS, backup) sources are the simplest and cheapest. In them, the battery power circuit is usually turned off and starts only when there is a power failure. The switching time from mains operation to battery operation is tenths of a second, and the output signal when operating on battery power is noticeably different from the “correct” sine wave. As a rule, a simple noise filter and a high-speed fuse are installed at the input of such UPSs. The first partially smooths out impulse noise, and the second should operate when the voltage in the power network increases significantly. Passive UPSs are designed to power home and office PCs. A slight “dip” in the output voltage when switching to the battery computer units nutrition is not terrible.
Linear interactive(line-interactive, VI, Smart-UPS) UPSs differ in that the battery power circuit is constantly switched on. When the voltage at the input of the uninterruptible power supply disappears, its output sockets almost instantly switch to the internal converter - for the powered devices this transition is almost imperceptible. In addition, many line-interactive UPSs are capable of automatically maintaining an output voltage of 220 V. This is done in two ways.
As long as the mains voltage is between 175 and 275 V, the AVR (Automatic Voltage Regulation) mechanism is activated. When the input voltage deviates from 10 to 25% below the nominal value, the UPS increases the output voltage by 15%. When the input voltage deviates from 10 to 25% above the nominal value, the UPS reduces the voltage by 15%. If the mains voltage exceeds the limit values, the line-interactive UPS switches to battery power. In this mode, it continues to operate until either the mains voltage returns to normal or the battery is discharged. However, such UPSs should not be considered as voltage stabilizers. Their “stabilization” mode is forced and short-term!
IN Double conversion UPS(double conversion, VFI, Online-UPS) the output voltage is constantly supplied from the converter, the converter is constantly running on battery power, and the battery is continuously charged from the network. In fact, the input and output of the UPS are galvanically isolated from each other, and a stabilized voltage is supplied to the output. This is the most reliable, but at the same time uneconomical scheme. The UPS itself is expensive, large and heavy, the converter gets very hot and requires fan cooling, and energy losses during conversion amount to tens of percent.
Double conversion UPSs are used only to power servers and computers in critical applications. Such models rarely go on general sale - they are usually supplied to order. Most likely, to power your work computers you will purchase passive, maximum, line-interactive UPSs.
The power of uninterruptible power supplies is usually indicated in volt-amperes (VA, VA). To convert these values into more familiar watts (W), you need to multiply the power in volt-amps by a factor of 0.6. For example, a UPS with a power rating of 600 VA will provide power to equipment with a maximum consumption of 360 W. If you give a large load, the current protection will work and the uninterruptible power supply will turn off. In practice, it is desirable to provide about 30% power reserve. Thus, the most common 600 or 650 VA UPSs are suitable for powering a computer with a real consumption of 200-250 W and a monitor, which takes about another 30-60 W.
If the arrangement of computers in the room allows, it is more profitable to use one powerful UPS instead of several small ones. For two office computer you will need an uninterruptible power supply with a power of about 1000 VA. To power three computers standing next to each other, one source with a power of about 1400 VA is sufficient.
So what does a UPS protect against?
Filters in the power supply of the computer and monitor also do a good job of limiting impulse noise from the network. However, two filters are better than one! Surge protection is also important. If, for example, the neutral wire in the panel burns out, the voltage in the socket may be almost 380 V. In power supplies for computers and monitors, in this case, varistors and fuses usually burn out. Repairs are cheap, but take time. In theory, the UPS should respond to a voltage surge before the fuses in the equipment connected to it burn out.
However, data protection comes first. If the computer's power is turned off, all unsaved information is lost. The UPS allows you to either save open documents and shut down correctly, or put the computer into sleep mode. Manually saving documents is the easiest way. When switching to battery power, the UPS begins to beep loudly. Once you hear such a warning, check if everything is saved. Next, look at the situation: either simply turn off the computer, or put it into sleep mode.
To activate the automation, you need to connect the control port (USB or RS-232, depending on the model) of the uninterruptible power supply to the computer with a signal cable and install the necessary software on the computer. Unfortunately, many users are not even aware of this possibility! The operation of the UPS is controlled by a built-in microcontroller. Its microprogram (firmware) constantly monitors voltages and currents in external circuits when turned on and periodically tests the electronics and battery during operation. It also provides information about the current operating mode and the state of the UPS components to the control port. This data is transmitted via cable to a computer, where it is processed by a monitoring program.
To work with the UPS, it is advisable to use the program offered by its manufacturer. For example, for APC (www.apc.com) this is the Power-Chute program, for Ippon (www.ippon.ru) - WinPower2009 and Ippon Monitor, etc. The program can be installed from the disk included in the kit, but it is better to download the most its latest version from the manufacturer’s website.
In the application settings you need to set the automatic shutdown parameters. As a rule, there are two options to choose from: either turn off the computer after a certain time after switching to backup power, or do it some time before the batteries are expected to be completely discharged.
How long can an uninterruptible power supply operate on battery power?
This depends on the battery capacity and power consumption. Most mass-produced models have one battery with a voltage of 12 V and a capacity of 7 Ah. Theoretically, a UPS with such a battery has an energy reserve of about 80 watt-hours. Simply put, it should power an 80 W load for about 1 hour, 160 W for half an hour, 300 W for about 15 minutes, etc. In reality, taking into account conversion losses, this time is approximately half that time.
Sources with a power of more than 800 VA usually have two of the same batteries or one, but with a larger capacity. Time tables or calculators battery life at different loads for various models are provided on the manufacturers' websites. However, “offhand” we can assume that any model will be able to power a load of its rated power for about 5-15 minutes. If you need to provide power to your computer from batteries for a sufficiently long time, it is better to take a high-power UPS with capacious batteries. It will operate at only a third or a quarter of the rated power. But he will be able to supply such a load, low for himself, with energy for half an hour or longer.
Network equipment (switches, routers, NAS) also benefit from uninterruptible power supply. Otherwise, when the power goes out, the network will immediately “fall”, and documents opened from network folders will not be able to be saved. You can power the switch from the UPS of the workstation closest to it, although it is more correct to install a separate “uninterruptible power supply” of low power for this.
Battery life is limited. As it operates, its capacity steadily decreases and after 3-5 years of operation it drops to almost zero. Even before the indicator on the UPS signals the need to replace the battery, it becomes noticeable that the battery is no longer “holding a charge.” Each time the battery life gets shorter. In principle, a couple of minutes are enough to save documents and correctly turn off the computer. When the UPS starts to shut down even earlier, it’s definitely time to change the battery.
Replacing the battery is easy. In popular APC brand UPSs and some others, the battery is located under a removable hatch or cover. To get to the battery in UPS brands Ippon, SVEN and similar in design, you need to unscrew the four screws on the bottom and separate the halves of the case. In the instructions and on the official website, you are unlikely to find a description of self-disassembly and replacement: like printer manufacturers, UPS manufacturers receive a significant share of their income from the sale of “original” batteries with their installation in authorized service centers.
However, almost all computer stores sell sealed lead-acid batteries in the most popular sizes. The brand and manufacturer do not matter: these are completely standard products. First open your UPS and find out what kind of battery is installed in it. For most “office class” UPSs (500-700 VA), batteries marked 12V 7Ah with dimensions of 151x94x65 mm are suitable. Installing new battery, try to fit the terminals tightly onto the contact tabs of the battery. If the terminals are loose, they can be carefully tightened with pliers.
After installing the battery, it is advisable to calibrate the UPS so that its firmware evaluates and remembers the parameters of the new battery. Fully charge the battery within 24 hours. After this, remove the plug from the socket so that the UPS switches to autonomous power supply. Allow the battery to completely discharge until the uninterruptible power supply switches itself off. It is better to use not a computer as a load (although in extreme cases this is acceptable), but several light bulbs with a total power of about 300 W. Then reconnect to the network and turn on the UPS - let the battery charge and the device continue to operate as normal. In addition to calibrating the device as a whole, this procedure also “trains” the battery. After a complete discharge-charge cycle, the battery begins to use its capacity to its maximum.
Why do many UPSs have telephone (RJ-11) and network (RJ-45) sockets?
Neither phone nor the local network“uninterruptible systems” are not needed by definition. Just as a “bonus”, pass-through impulse noise filters for the telephone line and network are installed in the same housing with the device. Connect one socket to telephone socket on the wall, and turn on the telephone in the other. If high-voltage interference occurs in the telephone line, for example, during a thunderstorm, the filter will smooth out the voltage surge and protect the phone.
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 the 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 a new uninterruptible power supply for the first time, you must fully charge the batteries. If new source will be immediately placed under load, its batteries will not be able to provide the power necessary for power supply.
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 pack 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 long term. 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.
Poor quality power supply is one of the main problems of failure of household, office or industrial equipment. Despite the fact that interference occurring in the electrical network is periodic, it has a detrimental effect on the components of modern electronic devices plugged into an outlet. To protect critical equipment or preserve data during a power failure, uninterruptible power supplies are most commonly used.
Basic operation schemes and areas of application of uninterruptible power supplies
The purpose of the UPS is to provide correct operation load during sudden “dips” or “spikes” of voltage, as well as ensuring short-term autonomous operation of connected equipment during complete shutdown electricity. Modern uninterruptible power supplies are divided into three classes:
- Backup or Offline
- Linear interactive
- 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 ensure maximum protection for 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.
By purchasing a UPS (Uninterruptible Power Supply) for personal computer or other household appliances, you solve many problems at once “in one fell swoop”. 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 have absolutely no need to worry that the power supply will fail as a result of incorrect shutdown or, even worse, the power supply will fail. HDD. 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 . Most models of this type 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 UPS 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 efficient work Some models of uninterruptible power supplies require you to install some software. The product should include a disc that can be easily installed by almost anyone. regular user PC. Many modern UPSs have a self-diagnosis system that 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 beep or display an error code. 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. Here is an example of a standard connection diagram for efficient operation computer equipment in domestic conditions: a UPS and a printer (or scanner) are connected to the surge protector, and system unit The computer 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 laser printer, since it is much more powerful than inkjet, and at the time of peak loads it can overload the UPS. Also you can't connect lighting and another household appliances, which is 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 may 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.
Correct 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 shut down 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 experience. 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 on 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. Better contact service center, where you will receive qualified assistance with warranty and post-warranty service.
Uninterruptible power supply systems are currently becoming very popular. It doesn’t matter where a modern person lives - in a city apartment, in a 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. External power quality 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 each uninterruptible power supply model is determined differently. 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:
- Lack of mains voltage stabilizer.
- Long switching time (~20 ms).
- Step form of output voltage.
- Presence of high frequency interference.
Switching to autonomous power mode occurs at any slight deviation of the mains voltage parameters from the norm. This leads to rapid battery wear.
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:
- Mains voltage stabilization has a stepwise nature.
- The output voltage shape is close to a sinusoid.
- Network interference filtering.
- 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 converter direct current to AC (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:
- Output voltage stability.
- Possibility of replacing the battery without shutting down the UPS.
The disadvantages include:
- Low coefficient useful action(efficiency).
- 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 an uninterruptible power supply, great attention should be paid to comparing the characteristics different models. These include the following:
- UPS power.
- 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 operating time. The capacity of the installed battery also determines the operating time.
Any UPS model has visual signaling elements. These can be light bulbs of various colors, LED indicators that 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 an 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 to operate, and most importantly, it will allow you to save important information on computer hard drives, which could be irretrievably lost in the event of sudden malfunctions in electrical networks.
