Uninterruptible power systems: types, characteristics, installation. Uninterruptible power supplies
Domestic electricity supply is characterized bylow reliability and unsatisfactory quality of electricity. This is due to outdated electrical networks, equipment wear, low characteristics of energy converters, transients in sources and users of electricity, natural and climatic factors. In such conditions, uninterruptible power systems are extremely necessary to ensure the work of consumers of both the first and other categories.
For owners of apartments and houses stable workmains is also important. The cessation of the work of household appliances is not the greatest of ills. Much more important is the failure-free operation of life support systems, in particular a heating system, if it directly depends on electricity supply. Uninterruptible power supply UPS (UPS) - a device that protects electric receivers from power outage in the accumulation of electricity in storage batteries (ACB) and guarantees the required energy quality (CE) in the autonomous and network modes of operation - comes to the rescue.
Before outlining the approach to creating power loads without failures, it is necessary to find out what failures can be expected from domestic power grids.
Low voltage is a frequent phenomenon inpower supply. But it does not particularly prevail over the elevated, which is also often found. At night, the voltage is stable, in the daytime it decreases, and in the evening, when most of the loads turn off, it increases.
An unstable frequency is also a failure, althoughquite rare. With a high network load, it can drop to 45 Hz, which leads to significant signal distortion, which negatively affects the operation of the UPS. Some devices perceive a reduction in frequency as an accident, and the battery can quickly be discharged.
Complete power outage is not so muchrare case. Electricians do not really take into account the work of electronics and can suddenly turn off the building. Instantaneous power outage is sufficient to lose information on the computer. If the networks are overloaded, there may be power outages. Therefore, it is important how the UPS system reliably delivers uninterrupted power.
They are grouped into three groups:
- Low-power UPS for connection via electrical outlets. The performance is desktop or outdoor, and the power is from 0.25 to 3 kW.
- Devices of medium power - from 3 to 30 kW -contain a block of outlets, built-in, or are also included through groups of outlets in the supply network of consumers from the control panel. Devices are made for placement both in offices and in separate equipped rooms.
- UPS of high power - from 10 to 800 kW. Are located in the electric room. They are assembled into groups and create high-power energy systems - up to several thousand kW.
Types of UPS
Now 4 types of UPS (UPS) are common. Common for all properties are:
- filtering from pulses and noise;
- elimination of waveform distortion;
- voltage stabilization (not for all models);
- maintaining the battery charged;
- When the UPS battery is discharged, it will first give a signal, and then turn off the consumer.
The operating principle of the devices of this modificationconsists in powering the consumer from the active network and instant switching to stand-alone backup power in emergency situations (4-12 msec). They are simpler and cheaper than other types.
The UPS normally switches to work from the built-in battery.
When operating from a network, the device suppresses noise frompulses and maintains the voltage at a given level. Part of the energy is spent on recharging the battery. In the case of network operation in non-standard mode, the user switches to battery operation. Each UPS model in its own way determines the need for switching to this mode. The operating time through the battery depends on its characteristics and the power consumed by the load. In the event of the discharge of the backup power source, the command to switch off the consumer is given. If the mains voltage reaches the normal level, the UPS goes into normal network mode, the battery charging begins.
Models Line interactive ups are equipped with stabilizers, which work constantly and provide a rare connection of batteries.
The device interacts with the network, controlling the amplitude and shape of the mains voltage.
When the voltage is reduced or increased, the unitcorrects its value by switching the autotransformer taps. In this way, its nominal value is maintained. If the parameter is out of tolerance and the switching range is no longer sufficient, the UPS switches to battery backup. The unit can be disconnected from the main power supply when a distorted waveform is input. There are models that adjust the shape of the voltage without switching to battery operation.
FERR Resonance UPS
The device contains a ferroresonancetransformer that works as a voltage regulator. Its advantage is the accumulation of energy in a magnetic field, which is released when switching during 8-16 ms. This period of time is sufficient for the UPS to exit to a new operating mode.
The transformer performs an additional noise filter function. The distortion of the input voltage does not affect the output shape, which remains sinusoidal.
Double Conversion UPS
Dual Energy Conversion Deviceworks on the principle of rectifying the voltage of the network, and then again turns it into an alternating stabilized one. A more powerful rectifier is used here, which not only recharges the battery, but also supplies the inverter with a stabilized DC voltage.
From the output of the device, the variable stabilized voltage is applied to the load.
When the double conversion is not enough to correct the mains voltage, an additional charge is applied to the inverter from the battery. Switching does not happen, but the mode is different.
If the inverter fails,switching to operation from mains through bypass. The choice of a double conversion UPS for private use is not rational due to large energy losses. This type of protection is used by organizations where high reliability of equipment is required.
Types of systems
Uninterruptible power systems can be centralized or distributed. In the first case, a single UPS works on the whole building or a separate floor, which copes with all the loads.
Distributed uninterruptible power systems include several protection devices, each of which operates on one computer or another unit of equipment. They are quite effective.
The advantages of a distributed system are as follows:
- The UPS is selected specifically for a particular device, which is the most important or operating under severe conditions.
- The system can be gradually expanded, starting with the protection of the server and switching to workstations.
- The failed UPS can be replaced with other, from less important elements of the system.
- A low-power UPS does not need to be installed and serviced by dedicated personnel.
- The possibility of connecting to a regular electrical network through outlets.
- UPSs are used independently of each other.
Centralized uninterruptible power systemshigh-level UPSs that better protect equipment. Despite their high cost, overall savings are achieved, since one device is cheaper than several. But for simple computers, the system will cost more, since it requires high-skilled personnel or services of specialized firms that install uninterruptible power systems and maintain them.
It is necessary in the following cases:
- computers are the main load of the network;
- some organizations need very reliable systems, such as banks;
- consumers significantly differ in power: computer system, emergency lighting, communications, security system.
What should I look for when choosing a UPS?
When choosing an uninterruptible power system, several important factors need to be considered. Let's list the main ones.
What does the equipment protect?
First of all, it is necessary to take measurementsvoltage in the electrical network. The minimum cycle of duration will be a day. It most reflects the operation of the electrical network. If you have to work on weekends, you need to get information on the weekly cycle, during the day and night.
It is important to determine the maximum and minimum voltage, as well as the power and frequency of pulses in the network. The device can be a digital oscilloscope or a recorder.
The simplest way for a user is to measure the voltage, during which, in his opinion, the voltage reaches a maximum and a minimum. It is not necessary to ignore the days off.
If the owner of the apartment has powerful equipment,It is necessary to measure the voltage in the home network when it is turned on and off. It is necessary to find out how often the voltage in the mains electricity is turned off and for what reasons. It is important to have an earth wire in the apartment. In this case, it is necessary to find out how reliably it is connected to the tire of the storey board.
Type of protected equipment
A list of equipment for whichthe use of the UPS is necessary. In this case it is necessary to know the power consumed by each device. It is enough to determine its nominal value, which is in the technical specifications. Some equipment sometimes consumes maximum energy, several times higher than the nominal value. For him, you need to set a power margin.
It is important to determine for which period it is possible to safely store data or complete the necessary technological operations (transfer of information, saving files, receiving a message).
Depending on the complexity of the system,a certain staff of specialists for its operation. It is necessary to find out in order to correctly calculate all costs. The price of the protection system should not exceed 10% of the cost of the main equipment.
UPS for home
For an average cottage, a convenient systemUninterruptible power supply UPS (UPS) with a capacity of about 15 kW. To provide autonomous work for 2-3 hours, we need 4 accumulators with a total capacity of 2000 Ah. They allow you to accumulate electricity around 7 kWh.
In the house the most important are the systemheating and household appliances with a computer. The cost of the UPS depends on the capacity, the number of batteries and the manufacturer. For the boiler, you can purchase a 360 watt power source at a price of 7,000. The entire house will need a UPS capacity of up to 15 kW, the price of which is more than 70 thousand rubles.
In addition to converters, you need batteries that need to be changed periodically. UPS for the house costs a round sum. Especially costly are battery systems of uninterrupted power supply.
Despite this, you can save on repairsthe rest of the technique. In addition, there are alternative alternatives using generators. Sometimes you can do with the installation of voltage regulators, which cope with many tasks, including the correct shutdown of equipment.
Modern UPSs are equipped with a clear interface.The display can monitor the operation of the system, where the main parameters are the voltage at the input and output, power consumption, operation scheme, battery power.
Which UPS to choose depends on the needsthe user. For a home computer, there may be enough energy for the time it is turned off. For trouble-free operation of the boiler within 8-9 hours, a protective device per 1 kW with three batteries of 65 A / h is required.
Uninterruptible power systems are designed forensuring the autonomous operation of electrical appliances and electronic equipment for a short time. The main indicator is the power of the UPS and the capacity of the battery. It is advisable to choose equipment containing a voltage regulator.
The running time through the battery depends on itscharacteristics and power consumption. In the event of the discharge of the backup power supply, the command to switch off the consumer is given. If the mains voltage reaches the normal level, the UPS goes into normal network mode and starts charging the battery.