An uninterruptible power supply (Fig. 1.13) is perhaps one of the most necessary devices. Not only the stability of the computer depends on it, but also the frequency of occurrence of hardware faults.

Rice. 1.13. Uninterruptable power source

Uninterruptible power supplies, of course, can also fail. Although, as practice shows, the only thing you need to do to prevent damage to this device is to change the batteries on time.

As for repairing an uninterruptible power supply at home, having a little understanding of the basics of electrical engineering and having a multimeter, you can independently determine and remove the causes of many malfunctions.

Load connection sockets

If the indication of the uninterruptible power supply does not show any deviations in its operation, and there is no voltage at the outputs, then first of all you need to check the output sockets on the rear wall of the device.

Disassemble the uninterruptible power supply and remove the back panel from it. Pay attention to the wires coming from the AC input connector and stabilizers. To one output (usually marked white) the wires should go directly from the input, and to the outputs connected in parallel using plates, two wires from the stabilizers should go - red and yellow (Fig. 1.14).

Rice. 1.14. Outputs on the rear wall of the unit

If you see some kind of problem, such as a soldered wire or plate, arm yourself with a soldering iron and solder and fix the problem. If all the wires are in their places, then the cause of the malfunction should be looked for elsewhere.

Circuit breakers

Like any other AC-powered device, an uninterruptible power supply is equipped with fuses. Fuses allow you to quickly shut down the entire electronic control circuit if a short circuit or other serious fault occurs.

Typically, an uninterruptible power supply is equipped with a pair of fuses enclosed in a plastic shell, that is, made in the form of a key that closes the circuit. They have different powers, and, as a rule, the fuse with weaker characteristics blows.

After pulling out each of them, make sure that the connecting thread between the fuse contacts is not destroyed. Otherwise, they need to be replaced. To easily locate a blown fuse, you can use a multimeter to check for resistance. If the fuse is good, the multimeter will show a resistance of several ohms, otherwise there will be no reading.

Transformer

The uninterruptible power supply contains a power transformer, which is designed to step down or step up the voltage by using the magnetic properties of the transformer. The use of a power transformer allows you to achieve higher output power than switching power supplies.

Be that as it may, quite often a short circuit occurs in the transformer winding or the winding partially burns out. This can be facilitated by rather difficult conditions for using an uninterruptible power supply (electricity instability, constant power surges and powerful impulse noise, for example from a laser printer or copier). In this case, the transformer becomes very hot, and its further use is possible only after the short circuit has been eliminated.

If the transformer gets very hot, test all windings in pairs with a multimeter. If damage is detected, the transformer must be replaced, since at home it is quite difficult to make a new winding with the required characteristics.

High voltage transistors

As with any other electronic device, the circuit of an uninterruptible power supply unit necessarily contains components that are subjected to severe loads, passing through a large current. At the same time, heat generation increases, and if the cooling system does not cope with its functions, then these components simply burn out.

It’s quite simple to verify this - look carefully at their appearance. As a rule, such components have cracks, and sometimes are so destroyed that only their leads remain instead.

As a rule, such elements are powerful transistors or microcircuits installed on aluminum radiators (Fig. 1.15). The minimum number of transistors is two. High-quality uninterruptible power supplies usually contain more than four transistors.

Rice. 1.15. Powerful field effect transistors

To check transistors, use a multimeter, having previously specified the location of the semiconductor junctions of the transistors in a special reference book or on the Internet. As a rule, transistors fail in pairs, so if you find one faulty element, continue further testing.

Accumulator battery

The battery (Fig. 1.16) is one of the main components of an uninterruptible power supply. Depending on the power, the uninterruptible power supply may contain several batteries. The power of the unit and the battery life of devices connected to it depend on the state of the battery.

UPS failures are of a wide variety of nature, but this technology is characterized by a certain set of problems that most owners of uninterruptible power supply systems face. Compliance with the basic recommendations for operating UPS will allow you to avoid common problems that arise when using them. The best recommendations for proper operation of the UPS are provided by the manufacturer.

It should also be noted that for UPSs of different brands, the same problem can be caused by different faults. Most often, the causes of malfunctions in uninterruptible power supply systems are long-term operation and difficult working conditions. Failure of the device can be caused by ordinary dust, and construction dust has a particularly negative impact. This is why it is so important to maintain the cleanliness of the room in which the IPS is located. If you do not follow the simple rules of proper operation, you may soon find that the device cannot withstand the load. In any case, you can contact the Bestcom service center, where they will give you a free diagnosis, and then agree on it.

UPS does not turn on

The control board of small UPSs is usually powered by a built-in battery. That is why, if the battery is completely discharged or its capacity is lost, it may be difficult to turn on the UPS. You can try to turn on the uninterruptible power supply by using the same battery and inserting it into the UPS (if available). If a spare battery is not available, the existing battery must be charged. To do this, you can plug the UPS into the network and leave it for a day - some uninterruptible power supply systems allow you to charge your batteries in this way.

If this method does not help, you will still have to find a working and charged battery. When it is connected, the device may not work - this may have various reasons:

• The connection cable is broken connecting the display and other boards;
• Fuse burned out;
• The start buttons are faulty after a long service life of the UPS (from 2 to 5 years);
• Onboardthere are any defects. To find out if there are defects on the board, you need to diagnose it by taking the program from a working device.
• Available software malfunctions UPS. The software is checked using special diagnostic software.
• The voltage sensor has failed. It is necessary to check the serviceability of this element.

UPS beeps

• In most cases, a beeping sound from the UPS indicates that the battery is insufficiently charged.

To solve this problem, just charge the battery. For this action, if there is power from the network, you do not need to do anything. After a few hours, the battery will charge automatically and you will be able to continue working from the UPS. If there is a constant lack of power from the network, then you need to disconnect the battery (battery) and recharge it with a third-party device in places where there is electric power. If such manipulations do not help solve the problem, then you need to replace the battery.

• It beeps due to insufficient power of the equipment.

When equipment is connected to the UPS that exceeds the power permissible for the load of the corresponding UPS. In this case, you need to reduce the load on the UPS or purchase equipment with higher performance. It is possible to reduce the load by disconnecting devices one by one from the UPS, or by comparing the permissible loads displayed on the back of the uninterruptible power supply with the power of the connected equipment.

• Sometimes you can see an error code on the UPS screen.

In this case, after studying the instructions for the equipment in detail, we will find out the cause of the defect and a method for eliminating it.

The UPS does not want to hold the load

• When the UPS turns off after a fairly short period of battery operation, the battery is clearly to blame.

It is quite easy to verify that the battery is working. On a fully charged battery, connect a 100 W incandescent lamp to the UPS output. A battery with a performance of at least 7 Ah should last about 20 minutes. When the values ​​are significantly below 20 minutes, the battery has outlived its usefulness.

• The UPS turns off immediately after the mains is disconnected.

In this case, the cause of the problem may be a faulty battery or a broken UPS. You will need to check the battery separately from the UPS. It is best to do this using a tester, which can be purchased at any household store for pennies. In another scenario, the UPS itself needs repair.

The UPS does not shut down randomly

• In most cases, the cause of the shutdown is a UPS reboot.

This can be found out by manipulating the disconnection of equipment from the UPS. If, when minimizing the UPS load, the operation stabilizes (no shutdowns occur), you will need to study the equipment that causes the overload. In some household equipment, the starting load significantly exceeds the operating load, so when choosing a UPS, you need to focus on the startup load.

If even without load the equipment turns off or reboots, you need to entrust the repair to professionals.

• Sometimes the cause of a shutdown may be a faulty UPS plug.

In this case, the equipment will not turn on at all, or it will turn on when the cord of the plug plugged into the socket is moved. You can also replace the UPS plug at home by first disconnecting the UPS from the power supply.

The best method to determine what is wrong with your uninterruptible power supply is to read the instructions. It most likely describes all the little problems that arise with this particular UPS, and tells in more or less detail how to deal with it.

There are a number of different reasons for uninterruptible power failure. The cause of the breakdown may be a malfunction of any of the parts. It may be due to a failure of the entire software, or there may be, for example, a malfunction of the power board.

UPS does not turn on

The control board of small UPSs is traditionally powered by the built-in battery. Therefore, if the battery is completely discharged or has lost capacity, then turning on the uninterruptible power supply may not be an easy task.
If you have the same battery, you can insert it into the UPS and try to turn it on. If there is no charged battery, the batteries must be charged. Try connecting the UPS to the network and leaving it for a day - some UPSs can charge their batteries under these conditions.

If nothing is achieved in this way, you need to connect the device to a known-good and charged battery. If even after this the uninterruptible power supply does not start, there may be several reasons:

• a break in the connection cable that connects the display or other boards.
• fuse may blow
• The start buttons may not work when pressed after some operating time has passed (an average of two to five years).
• various board defects. To make sure, you need to diagnose the boards and take the program from a working UPS
• The uninterruptible power supply software may not work correctly. To check, you need to use a special diagnostic program.
• Voltage sensor failure. You need to check the condition of the elements.

Squeaks

Traditionally, the UPS beeps when the load is powered by the battery, the UPS is overloaded, or one of the UPS systems (for example, the battery) has failed the test. The front panel of the UPS has LED indicators or an LCD screen with small messages. Using them, it is possible to determine the cause of the squeak.

If the cause of the squeak is the UPS switching to power from the battery, everything is fine, it is an uninterruptible power supply and is made to protect valuable equipment from power outages. If the UPS beeps frequently, it means that interruptions occur frequently. In this case, you need to deal with the electrical network, and not with the UPS.

But if the equipment not connected to the uninterruptible power supply works well, but the UPS beeps, it makes sense to look at the instructions - perhaps it will be possible to minimize the sensitivity of the uninterruptible power supply to interruptions in the electrical network.

In case of overload, you can try to find the equipment whose inclusion will cause a squeak. To do this, you can connect different combinations of devices to the UPS to figure out what it is connected to. The solution to the problem will most likely be to switch to a higher power uninterruptible power supply or turn off part of the equipment.

Doesn't hold the load

If after a power outage the uninterruptible power supply suddenly turns off, there may be two reasons: either the electronics or the battery failed...

But if the UPS operates without a network even a little (at least without a load), the battery is most likely to blame.

It is very easy to verify that the battery is at fault. You need to connect a known load to the UPS output - for example, a 100 W incandescent lamp, and measure the time that it will work after disconnecting the UPS from electricity. For fully charged batteries, the time should be approximately 20 minutes if

The UPS is installed with a lead battery with a capacity of 7 A/h (the most common option). If the UPS battery consists of 2 such batteries, then the time will increase to approximately 60 minutes, and already with 4 batteries with a capacity of 7 A/h it will reach an hour and a half. If the battery operating time is less than 70% of the normal time, then it is better to replace the entire battery, otherwise it will fail in the near future and fail at the most inopportune moment.

If the uninterruptible power supply does not work on battery power at all, you will need to check the batteries separately from the UPS. Professionals do this with battery testers, but for the DIYer, a more conventional battery test is also suitable. After checking, we replace the battery if it was faulty. If events develop differently, we take the entire uninterruptible power supply unit for repair.

UPS shuts down

The most likely cause is that the UPS is overloaded. To find out, disconnect everything that was connected to it and check its operation. If the uninterruptible power supply is working normally, look for the equipment causing the overload by connecting one load after another to the UPS. Leave only equipment connected that does not cause overload.

If the uninterruptible power supply switches off even without load, take it in for repair - the professionals will sort it out.

An uninterruptible power supply serves the purpose of ensuring a uniform supply of power to the electrical consumer. For various reasons, network power may fluctuate. It could be:

• drop in solar panel generation (due to changes in illumination);
• change in output from wind power plants (due to calm weather, for example);
• power fluctuations in a network with a limited number of generators and a large number of consumers (so-called unstable networks).

The UPS is not designed to maintain the level of energy consumption for a long time. Its main task is to cover dips and surges in power so that “thin” electronics do not suffer from fluctuations. If there is no voltage for a long time (and if, for example, we are talking about computer equipment), then it is necessary that there is a possibility of correct shutdown of programs. UPS malfunctions can render entire expensive electrical equipment useless, despite the structural integrity of all its other components. It turns out that if the uninterruptible power supply fails, it is simply not possible to use such a device. Therefore, it is so important to pay attention to its correct operation.

We propose to consider in more detail the possible malfunctions of this electrical appliance, and also list ways to eliminate them. However, it is worth remembering that at the moment the UPS is a high-tech device, unprofessional intervention in the operation of which is fraught with more serious damage. Repair of an uninterruptible power supply should be trusted exclusively to specialists.

Diagnostics

Repair of an uninterruptible power supply is logically divided into diagnostics and subsequent correction of defects. Sometimes it is possible to diagnose visually (for example, a cable break), but often fault detection is carried out using specialized equipment.

Diagnostics includes the following activities:

1. Examination of key elements for dustiness and the presence of oxidations that can lead to short circuits and breaks in the power electrical circuit.
2. Regular inspection of rotating parts is required. In particular, cooling fans (coolers).
3. Rechargeable batteries, first of all, need to be inspected for reliability of contacts on the terminals, absence of signs of oxidation, or presence of damage to the case.
4. It is required to measure the parameters of various operating modes of the rectifier and inverter.
5. Using monitoring equipment, you need to check the capacity of each battery and its wear.

Standard repair measures

An uninterruptible power supply, as a rule, is always repairable. It is extremely difficult to imagine a situation where it would be hopeless (unless it was a fire emergency). And the entire set of repair actions after diagnosing a faulty UPS usually comes down to the following:

• Maintenance within the framework of warranty service repairs (this is carried out by certified centers).
• Carrying out qualified repairs of UPS control unit boards.
• Restoring the parameters of working uninterruptible power supply batteries using specialized charging and discharging equipment.
• The most extensive repair (in terms of cost) is the complete or partial replacement of UPS batteries.

Typical, common UPS problems and how to fix them

It is worth listing them with separate comments:

Uninterruptible power supply cannot be turned on

This is a fairly frequently reported fault. The cause is usually a lack of contact with the UPS storage batteries.

The device runs only on its own batteries

We are talking about a lack of power from the network. Most likely the fuses have failed. They just need to be replaced.

The battery change indicator light is on

If testing reveals that the battery is working properly, it means that the device is not able to complete the program cycle. To solve this problem, you should calibrate the incoming as well as the outgoing voltage of the batteries.

Being connected to the network, the UPS is not traced there - no energy is consumed from the circuit

A typical case of lack of contact. The device's network cable is damaged or broken.

After turning on the device and using its battery reserves, the power drops

Most likely the voltage sensor is broken. It needs to be replaced, and then calibrated to the parameters of the elements that depend on it.

Display indication suffers from flickering

Here the capacitors “flow” (i.e., an emergency intense loss of charge occurs). It is necessary to find out the defective capacitor (“ring” them) and replace them.

The indicator shows the activity of the charging procedure, but in reality the batteries do not accept a new charge

The range of reasons can be very diverse:

• violation of the program code of the uninterruptible power supply control unit;
• defective battery charging circuit;
• malfunction of the electrical circuit: internal loops, cables;
• failure of the battery(s).

It is necessary to find out in more detail the source of the malfunction. It is possible that you will have to change the battery.

The appearance of external signs of a fire emergency, such as smell and smoke

An urgent replacement of the entire device is required. Most likely, at this stage, partial repair of the UPS is no longer possible.

Uninterruptible power supplies, like any other equipment, require timely maintenance, the absence of which may result in the UPS not starting. This is possible for a variety of reasons. There is a set of typical faults that can lead to the UPS not turning on, however, it is worth remembering that the design of each uninterruptible power supply may have its own characteristics, which can make adjustments to the process of diagnosing and repairing the UPS.

Since the UPS is the most important part of the power system, its failure exposes the equipment to certain risks. The easiest way to troubleshoot a problem is to study the instructions. There is a high probability that you will find a description of problems that may arise when operating a specific model of uninterruptible power supply. Most instructions contain at least some information on how to fix a minor problem.

To avoid problems, it is advisable to use the software that comes with the UPS. With its help, you can monitor the state of the system and take the necessary measures in a timely manner.

Functionality check

How to check the UPS for functionality? To do this, you need to turn off the electricity and monitor the operating time of the load. If the operating time is short, then the malfunction is most likely caused by high battery wear. In this case, repairing a UPS for a computer will consist of a banal replacement. It is important to remember that old batteries should not be thrown away due to their high environmental impact - old batteries must be recycled.

If the UPS beeps when starting up, this may be a signal that something has happened overload. This may also indicate that battery failed test, which is provided by the system. You can understand the cause of an unpleasant squeak using indicators on the front panel or using software.

Eaton 9PX UPS control panel

Why doesn't the UPS run on battery? This problem may be caused by charger malfunction, as a result of which the battery is not able to provide the declared battery life. You can check charging by measuring the voltage at the terminals without disconnecting from the network. It should be 13-14 V for a UPS with one battery and 26-28 V with batteries connected in series.

If the uninterruptible power supply for your computer does not work, then first you need to check the condition of the battery. In general, their service life is a maximum of 4-5 years. If your UPS is more than 5 years old, then the problem is probably in the battery. The condition of the battery can be determined by the voltage level. If it is above 12.4 V, then everything is in order, but if it is less than 12 V, then it’s time to say goodbye to it.

You can also check the battery using an ordinary light bulb with a power of 100 W. To do this, you need to connect the light bulb to the battery and see how long the battery charge will last. Typical batteries used in uninterruptible power supplies are lead-acid with a capacity of 7 Ah. A new battery of this type provides about 20 minutes of operation for a 100 W light bulb. As a result, if the battery shows a time that is less than 70% of normal, then it needs to be replaced.

If the battery is working properly, then the causes of the problem may lie in incorrect battery connection. Also the reason may be incorrect execution of the UPS program, this indicates that the device needs calibration. Otherwise, the reasons may lie in UPS component failures, which you cannot install yourself.

UPS does not turn on

There are often situations when the uninterruptible power supply simply does not turn on. What to do in this case? In low-power uninterruptible power supplies, as a rule, the control board is powered from the battery; therefore, the uninterruptible power supply does not turn on due to low battery. In such a situation, you need to try to charge the battery. Some devices can charge under these conditions, so simply plug the UPS into the mains and wait a while. You can also remove the battery and charge it using a suitable charger.

If you have just purchased a device, but it does not turn on, then you need to check whether the batteries are connected. According to transportation regulations, such devices must be transported with the battery disconnected. Another reason that the UPS does not start may be etcpressed power button. Possible cable breaks caused by short circuit.

Also, the reason that the uninterruptible power supply does not work may be overload. Checking this is quite simple - you need to turn off the entire load. If the UPS still works, then it is necessary to identify the equipment that is causing the overload. This can be done by connecting the load in series to the UPS. After this, such a load must be eliminated. If the UPS does not turn on even without a load, then you need to submit the device for diagnostics. Replacing the battery yourself may not solve the problem, so there is no point in buying a second battery just like that.

Servicing high-power UPSs can be dangerous. It is caused by the presence of high currents and voltages, which, if shorted, can damage equipment and cause burns. For this reason, it is worth following all precautions, and even better, contact a specialized center.

Our specialists will help you quickly identify and eliminate faults on any type of equipment. We provide both emergency repairs and preventative maintenance.

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