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 it in time rechargeable batteries.

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 it from back panel. 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 or the winding partially burns out. This can be facilitated by rather difficult conditions for using an uninterruptible power supply (electricity instability, constant voltage surges and powerful impulse noise, for example from laser printer or photocopier). 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 in any other electronic device, in the circuit of an uninterruptible power supply there are necessarily components that are subjected to serious 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 easy to verify this - look carefully at them 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.

For what faults should the UPS be written off?

UPS faults for write-off:

1. Serious mechanical damage, for example caused by a fall from a great height.
2. Fire damage to the device during a fire.
3. Water getting inside the unit during water supply accidents or other leaks and flooding.
4. When the device has a service life of more than 10–15 years. The service life is determined mainly by the survivability of the electrolytic capacitors of the device.
5. Any other irreparable damage or if the cost of repair exceeds the cost of purchasing a new similar uninterruptible power supply unit. In this case, it is advisable to buy a new UPS, for example, one of these: three-phase UPS. These models are efficient, economical and have proven themselves in operation.
6. The failed UPS has long been out of production and there is no supply of the required spare parts.

Important Note:

We consider batteries as consumables that must be replaced.

Name the most common UPS faults

Let's call it! Dust, contamination of the internal surfaces of the device when it is used indoors during construction work. During long-term operation: batteries reach the end of their service life, cooling fan grease dries out, electrolytic capacitors dry out.

The most common breakdown is failure of the inverter, caused by regular overloads of the device, long-term operation in heavy duty, including with faulty batteries, extremely poor quality of the input power supply, and high-voltage surges.

What to do if the UPS does not turn on?

For low-power UPS: check if there is voltage in the outlet, make sure the device is connected to the network, check the protective fuse.

When turning on the device, please strictly follow the startup procedure described in the user manual.

The test start should only be done with the load cable disconnected. Then you need to check that there is no overload or short circuit (short circuit) at the UPS output.

For low, medium and high power models: do not forget to press the inverter start button(s), check that the cable is connected correctly to the terminal block (phase-neutral-ground).

For three-phase units: check the phase rotation order, make sure the batteries are in good condition and that they are connected correctly. The most common mistakes are polarity reversal (mixed +/-), incorrect assembly of the battery kit, incorrect number of batteries in the kit, use of a different type of battery with a different rated voltage, for example, nickel-cadmium instead of lead-acid.

The last thing that can be recommended is: disconnect the load, check that its total power is less than the rated power of the UPS.

If nothing helps, contact the N-Power service center specialists.

What should I do if the UPS turns off during operation?

Possible reasons are:

1. Unaccounted overloads at the output.
2. If we are talking about premature shutdown when working in offline mode, then most likely the issue is the failure of the batteries and a decrease in autonomy time.
3. Very short voltage dips in the network due to faulty (expired) batteries.
4. Unfavorable environmental conditions. For example: overheating of the device, poplar fluff getting inside the body in the summer and blocking ventilation, etc.
5. It is possible that there is no malfunction. Distinguish between emergency and normal shutdowns. For example, if the input voltage is lost, the UPS can correctly work out the required autonomy time and turn off.

Important Notes:

• If you are using remote monitoring software, check the availability software settings with possible temporary and calendar shutdowns of the unit. This is one of its standard features. Make sure you are using the monitoring cable that came with your device. Otherwise, there may be problems, including shutdowns.
• If you are unable to detect the problem yourself, contact N-Power specialists.

What should I do if the UPS clicks during operation?

When operating a line-interactive UPS, slight clicking noises should be heard due to the operation of the automatic voltage regulator (AVR). This is a step stabilizer with a switchable winding. Switching is done via relays. For example, the UPS of the Smart-Vision S series has 5 stages of stabilization. Also device of this type has an input/output relay for switching from operating mode to battery mode. We should hear the operation of these switches, but the sound should not be too loud.

When using an On-Line UPS, there should be no relay clicks typical of line-interactive devices. However, an input bypass relay is installed internally. Blocks of this type can click during startup, diagnostics, shutdown, and also when entering abnormal modes (for example, Bypass). When the UPS is operating online in the main modes (mains and battery), there should be no clicks.

Sometimes users confuse clicking sounds with small sounds produced by high-frequency transducers. High-power three-phase UPSs may emit a constant sound while operating within the parameters specified in their technical specifications(see self-acoustic noise, dBA).

Also, “problem sounds”, including clicks, crackling, rattling, etc., can be produced by faulty fans. In this case, they need to be replaced.

Uninterruptible power supply failures can be of a very different nature, but there is a set of typical problems that any UPS owner may encounter. In most cases, following certain recommendations can avoid any problems when working with uninterruptible power supplies. Manufacturers are required to indicate recommended operating conditions. Next, we’ll look at why the uninterruptible power supply doesn’t work and what can be done about it.

It is also necessary to pay attention that UPS from different manufacturers may have the same symptom indicating different faults. Problems with uninterruptible power supply usually arise after prolonged use or due to difficult working conditions. Ordinary dust can damage the uninterruptible power supply. Construction dust is especially destructive, so you must ensure the cleanliness of the room. If you don't comply simple rules, then you will very soon wonder why the uninterruptible power supply does not support the load.

Other common faults include battery wear, which is the most common cause of uninterruptible power supply failure for a computer. The electrolyte in the capacitors may dry out. The grease on the air circulation fans may also dry out. Very often, the reason that the uninterruptible power supply has stopped working is a breakdown of the inverter, which does not tolerate frequent overloads. The inverter can be adversely affected by voltage surges, extremely poor quality of power supply in the network and faulty batteries.

Some users notice interference from the UPS, which is caused by the operation of the uninterruptible power supply itself. They can be eliminated by installing special filters against electromagnetic and radio frequency interference.

UPS does not turn on

Why doesn't the uninterruptible power supply turn on? The situation when the uninterruptible power supply does not turn on can be perplexing, but the problem may lie in simple things. If your UPS has low power, then first of all you should make sure that the UPS is connected to the network. Next you need to check the voltage. If the voltage level is low enough for a long time, the UPS will not be able to operate under such conditions. In such conditions, the battery will be discharged, and the network parameters will not allow starting. If the uninterruptible power supply stops turning on with a known good battery, then diagnosing the problem will require special skills.

The launch must be carried out in the strict order specified in the instructions. You can try a test run, which is carried out without a connected load.

Next, you need to make sure that there is no short circuit or overload at the output of the uninterruptible power supply. Overload occurs when the load power exceeds the power of the UPS, which should not be allowed. IN modern devices UPS protection against short circuits and overloads is built-in. If such protection is not provided, a sign of a malfunction is that the uninterruptible power supply regularly breaks down under load.

If the connection is made using a terminal block, you must ensure that correct connection neutral, ground and phase. Very often, in three-phase uninterruptible power supplies, an error occurs in connecting the cables. Including polarity reversal, when the plus and minus are in the wrong place. Also, the UPS may not turn on if the battery pack is assembled incorrectly or the number of batteries is incorrect. It is important to note that if the rated voltage of the battery does not meet the requirement, the UPS may not turn on. In all these cases, it is necessary to double-check everything before concluding that the uninterruptible power supply cannot support the load.

The use of third-party batteries may not have the best effect on the condition of the UPS. In uninterruptible power supplies Car batteries cannot be used. They are completely unsuitable for UPS, as they have a different structure and parameters.

If the above tips do not help, then you need to contact, where the uninterruptible power supply will be diagnosed using professional equipment.

UPS shuts down during operation

Why does the UPS turn off during operation? This problem It is very common when in the middle of work after a short time the uninterruptible power supply simply turns off the load. A number of reasons may contribute to this. In this case, first you should check whether there are any unaccounted overloads at the output.

It is worth paying attention to the mode in which the uninterruptible power supply turns off: when operating from backbone network or offline. If a shutdown occurs when operating on battery power, then most likely the battery itself is faulty or simply worn out, which does not allow it to provide the required operating time.

If you notice that uninterruptible power supply turns off the computer Even if electricity is available, do not rush to conclusions. Voltage dips can be so short that a person may not notice them. However, in this case, the UPS transfers power to the load to the battery, and if it is still faulty, then the load is disconnected.

Another possible case is when the UPS turns off the computer when operating in offline mode. This may be caused by a special . Standard features include the ability to turn off the computer according to specified settings. Such settings can be installed automatically along with software. In this case, how to make sure that the uninterruptible power supply does not turn off is immediately clear. It is worth noting that such shutdowns can be made in certain time or dates.

The exact same problem can arise with remote monitoring. If you are using a non-original cable for remote monitoring, which comes with an uninterruptible power supply. The answer to the question why the uninterruptible power supply turns off may lie in it. The use of non-branded accessories can not only cause the UPS to turn off, but also a number of other problems.

Sudden shutdown may occur due to UPS is heating up. High temperatures do not have the best effect on the battery. Heat generation is characteristic of. But even their heating must be at a certain level. If you notice that the uninterruptible power supply is heating up, you need to make sure that the cooling fans are working properly. They should not be covered or clogged with dust, lint or anything else that might interfere with air circulation.

In case uninterruptible power supply turns on and off, the problem may be low mains voltage. This can be a problem for backup UPSs. This can be eliminated by purchasing a more advanced UPS or using voltage stabilizer.

It is possible that a shutdown occurs when switching to the battery. If the UPS does not switch to battery, but the battery is known to be good, then the problem is likely in a faulty relay that makes this switch.

When connecting a low-power load, you may encounter that the uninterruptible power supply turns off after 5 minutes. In some models, the minimum load power is perceived by the UPS as a signal to shut down. The essence of the idea is that the UPS perceives this as if, for example, the computer is turned off, and the UPS itself turns off to save power.

Red indication

The uninterruptible power supply is lit red, what does this mean? The most accurate answer about the meaning of the indicators can be found in the device instructions. Uninterruptible power supplies may have significant differences, including indicators. When the red light on the uninterruptible power supply is on, this may indicate that an overload has occurred, the battery is not connected or needs to be replaced.

Recovery

How to restore uninterruptible power? Without special skills, you can restore an uninterruptible power supply yourself only when the problem lies in the battery. Replacing it is extremely simple. In remaining cases, repairs can only be made by a specialist.

How can you understand that the UPS has burned out and why did this happen? You can tell that something irreparable has happened by the characteristic burning smell. This may be caused by a large power surge in the network. In this case, the fuse included in the UPS design should burn out. Also, the reason that the uninterruptible power supply has burned out may be a short circuit. In such cases, the possibility of recovery depends on the nature of the damage and its volume.

There are a number of cases when repairing uninterruptible power supplies becomes impossible. First of all, this concerns mechanical damage. If the UPS has fallen from a great height and is seriously damaged, then you can safely start looking for a replacement. Fires can cause irreparable heat and fire damage. Floods or other situations when water gets inside the UPS can also put an end to the life of uninterruptible power supplies. If used for a very long time, the electrolyte in the capacitors may dry out.

If your UPS is old, then it will probably be impossible to find spare parts for such a model. In this case, it is better to think about purchasing a more modern and reliable model. Don’t forget about the cost of repairs, which in some situations may exceed the cost of the UPS itself. In all of the above cases, it is pointless to look for the reason that the UPS turns off every time it starts.

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In this article, I will share with you a method for diagnosing and troubleshooting an uninterruptible power supply (UPS). So why might the uninterruptible power supply not turn on or not work from the network? one of the first reasons, a fuse has blown, perhaps the transformer or control board has failed, but in our case it’s a slightly different, but at the same time very basic problem...
Let's take a closer look...

We repair an uninterruptible power supply with our own hands

At the very beginning, before disassembling, we need to check whether the fuse is working, usually it is located on the back side of the UPS

We remove it and check it with a multimeter in dial mode.
In this case the fuse is good.

Let's move on to disassembling the uninterruptible power supply (UPS) itself.
I would like to note that the disassembly method may be distinguishable from your UPS model, but should not cause you any particular difficulties in disassembling.
Unscrew 4 screws and remove bottom part IPB housings.

After disassembly, carefully inspect the board for external damage to components. In our case, no damage was found.

The first step is to check the battery. Let's measure its voltage with a multimeter.
In our case, the battery is discharged to 2 volts, which is naturally not good and is a fairly deep discharge.

Let's check the battery for charge and discharge by connecting it to a laboratory power supply for recharging to eliminate the possibility of its breakdown.
As it turned out, the battery refused to accept the charge from the laboratory power supply, which means that there is a break somewhere and, accordingly, our battery is not working properly.

Let's take another battery to check. In my case it has a slightly larger capacity. Accordingly, the uninterruptible power supply should hold its charge longer and fits perfectly into the UPS case!

We connect the terminals - let's run it for a test without assembling the case. Started up.

We measure its voltage: - 12.4 volts.

To make sure that the battery is charging, measure the voltage at the battery terminals for a few seconds with the UPS connected to the network. The voltage should gradually rise.
12.9 volts tells us that the battery is charging, the uninterruptible power supply is working, it can be assembled and put into operation.

Failure of the battery or loss of its energy capacity is one of the most common failures among all types of UPS. So don’t rush to throw them away right away.

There are several typical faults that are typical for uninterruptible power supplies different manufacturers. Let's look at what problems UPSs encounter, how to diagnose and fix them.

How to find out about UPS problems

Most UPS failures are caused by battery failure. A small portion of problems - about 2% - are related to electronics, incorrect configuration or improper operation of equipment. Typical problems and methods for resolving them are described in the instructions that the manufacturer comes with the devices. More complex breakdowns can be diagnosed and repaired by service center employees or technicians with the appropriate qualifications and tools.

Any problem can be eliminated only when the operation scheme is completely clear and transparent specific model UPS. In a critical situation, system messages become the main sources of information about faults. Conventionally, they can be divided into two categories.

• Information. The UPS, using indicator lights, notifies you that there are deviations in its operation or that the mode has changed. At the same time, the uninterruptible power supply continues to function normally. Information messages are often caused by heat environment, switching to battery operation, completing a battery test, and other relatively innocuous situations.
• Emergency. UPS with indicators and sound signals notifies the user of serious malfunctions. In this case, the red Fault indicator on the case lights up and a short squeak sounds at certain intervals - once every few seconds. After an emergency, the UPS can continue to power the load, switch to bypass mode, or shut down. The exact action depends on the equipment model.

A system message is only an indication of a malfunction and is not a direct guide to action. You need to understand the structure of the UPS in order to fix the problem yourself. Serious interference with its operation can damage the device. The exception will be those emergency situations, which are described in the official instructions for the UPS. In other cases, when you learned the probable cause of the malfunction and how to eliminate it from other sources (for example, the Internet), you need to seek advice from the service center specialists.

How to troubleshoot common UPS problems

Depending on the application, uninterruptible power supplies can be divided into two large groups. The first ones are from decentralized management, or local. Typically these are low-power UPSs - from 1 to 10 kVA - to protect one device located next to the UPS. They are used in offices to ensure smooth operation personal computers and peripheral equipment, in data centers for powering servers, at large facilities for powering surveillance systems. In such UPSs, to determine the cause of the malfunction, it is better to eliminate it by referring to the instructions - with a high probability, the solution to the problem will be described there. Typical problems of this type are shown in the table below.

Malfunction	Probable Cause	How to troubleshoot
UPS does not turn on	Battery disconnected	Connect the battery
	The battery is faulty or has insufficient capacity
	The flexible display connection cable is broken	Replace the cable that connects the display to the main UPS board
The UPS has shut down and there is a smell of burnt insulation.	The surge protector is faulty	Check the components surge protector
	It worked circuit breaker at the UPS input from overload	Reduce the load on the UPS, turn on the circuit breaker
	Batteries are not connected correctly	Check that the batteries are connected correctly
The UPS can only operate on battery power	The mains fuse has blown	Replace the fuse
The UPS is not connected to the line	The network cable connection is broken	Connect the network cable
The UPS is running on batteries, but there is mains voltage	The voltage in the network is too high, too low or distorted by interference	Wait for stabilization mains voltage
The UPS is rebooting	The power of the equipment connected to the UPS exceeds the rated power	Reduce the load on the UPS
Battery won't charge	The battery has failed	Replace the battery
UPS does not provide expected battery life	The battery is faulty or its capacity has decreased	Replace the battery
UPS does not turn on after installing new batteries	The batteries were not connected correctly when replacing	Connect the batteries correctly

Let's move on to the second group of UPS - centralized(are common) UPS capacity 10 kVA or more, which are installed in a separate room, powering a large number of pieces of equipment from them. Entire offices, server racks, workplaces of enterprise employees, and industrial equipment are connected to such UPSs. Malfunctions that are typical for them are described in the user manuals. In some cases, they can be fixed on site. But with this type of UPS, another scenario is possible - when diagnostics and restoration of functionality will require contacting an authorized service center or an official distributor.

Almost all modern high-power UPSs have a display that displays messages indicating a malfunction. Based on the messages, you can understand the essence of the problem and find a way to fix the problem. But in most cases, if an alarm message is displayed, diagnosis by a qualified technician will be required.

A UPS to which critical equipment is connected. For example, medical equipment or server racks in a bank must be submitted for diagnostics to authorized service centers or to an official distributor. This also applies to all alarm messages in any UPS.