Memo for managers selling electrical equipment.
Section: Reactive power compensation devices. Basic concepts.
1. What is reactive power?
This is conditionally part of the total power required to operate an inductive load in consumer networks: asynchronous electric motors, transformers, etc.
2. What is the indicator of reactive power consumption?
An indicator of reactive power consumption is the power factor - Cos φ.
Cos φ decreases when the load's reactive power consumption increases. Therefore, it is necessary to strive to increase Cos φ, because low Cos φ leads to overloading of transformers, heating of wires and cables and other problems in the operation of consumer electrical networks.
3. What is reactive power compensation?
This is compensation for reactive power deficiency (or simply compensation for reactive power) in the network, which is typical for low Cos φ.
4. What is a reactive power compensation device (RPC)?
A device that compensates for the consumer's reactive power deficiency.
5. What reactive power compensation devices (RPC) are used?
The most common compensation devices are devices using special (cosine) capacitors - capacitor units and capacitor banks.
6. What is a capacitor unit and a capacitor bank?
Capacitor installation - an installation consisting of capacitors and auxiliary equipment - switches, disconnectors, regulators, fuses, etc. (Fig.1).
A capacitor bank is a group of single capacitors electrically connected to each other (Fig. 2).
7. What is a filter - compensating unit (FKU)?
This is a capacitor installation in which the capacitors are protected from harmonic currents by special (filter) chokes (Fig. 3).
8. What are harmonics?
This is current and voltage having a frequency different from the mains frequency of 50 Hz.
9. What harmonics are capacitors protected from?
From odd harmonics relative to the frequency of 50 Hz (3,5,7,11, etc.). For example:
Harmonic No. 3: 3 x 50 Hz = 150 Hz.
Harmonic No. 5: 5 x 50 Hz = 250 Hz.
Harmonic No. 7: 7 x 50 Hz = 350 Hz...etc.
10. Why is it necessary to protect capacitors in PKU?
Conventional cosine capacitors used for compensation are heated by harmonic current to a temperature unacceptable for normal operation; At the same time, their service life is greatly reduced and they quickly fail.
11. What is a power harmonic filter?
This is an installation used to filter (reduce the level) of harmonics in the network (Fig. 4). It consists of capacitors and inductors (reactors) tuned to a specific harmonic (see above).
12. How does a PKU differ from a harmonic filter?
FKU is used to compensate reactive power; capacitors and inductances (chokes) are selected in such a way that harmonic currents do not pass through the capacitors. In harmonic filters, it is the other way around: capacitors and inductors (reactors) are selected so that harmonic currents pass (short circuit) through the capacitors, so the overall level of harmonics in the network is reduced and the quality of power is improved.
13. Does this mean that the capacitors in the harmonic filters heat up - because harmonic currents pass through them?
Yes, but harmonic filters use capacitors specifically designed for this purpose, designed for high currents, for example, oil-filled ones.
14. In what modes do capacitor units operate?
Automatic operating mode - when the capacitor unit is controlled using a regulator (other names: controller, PM regulator).
Manual mode – the condenser unit is controlled manually from the installation control panel.
Static mode - the installation is only turned on and off by a switch, external or built-in, without regulation.
15. What are the main installation parameters?
The main parameters of the UKRM are the power of the installation and the rated (operating) voltage.
16. How is the power and voltage of the UKRM measured?
The power of the UKRM is measured in kVAr - kilovolt ampere reactive.
Voltage is measured in kV - kilovolts.
17. What are these stages of regulation?
All power of automatic or manually controlled UKRM is divided into certain parts - control stages, which are connected by the regulator or manually to the network, depending on the required compensation for the reactive power deficit. For example:
Installation power: 100 kVAr.
Regulation levels: 25+25+25+25 - 4 steps in total.
Therefore, the power can vary in 25 kVAr steps: 25, 50(25+25), 75(25+25+25) and 100(25+25+25+25) kVAr.
18. Who determines how many and what steps are needed?
This is determined by the customer based on the results of a network survey.
19. How to decipher the designation of capacitor units?
The designation of ALL reactive power compensation devices follows almost the same rules:
1. Designation of installation type.
2. Rated voltage, kV.
3. Installation power, kvar.
4. Power of the smallest control stage, kVAr (for regulated UKRM).
5. Climatic design.
20. What is the climatic version and placement category?
Climatic modification - types of climatic modification of machines, instruments and other technical products in accordance with GOST 15150-69. The climatic design, as a rule, is indicated in the last group of symbols for all technical devices, including UKRM.
The letter part indicates the climate zone:
U - temperate climate;
CL - cold climate;
T - tropical climate;
M - maritime moderate-cold climate;
O - general climatic version (except for sea);
OM - general climatic marine version;
B - all-climate design.
The numeric part following the letter indicates the placement category:
1 - outdoors;
2 - under a canopy or indoors, where conditions are the same as outdoors, with the exception of solar radiation;
3 - indoors without artificial regulation of climatic conditions;
4 - indoors with artificial regulation of climatic conditions (ventilation, heating);
5 - in rooms with high humidity, without artificial regulation of climatic conditions.
Thus, U3, for example, means that the installation is intended to operate in a temperate climate, indoors, without artificial regulation of climatic conditions, that is, without heating and ventilation.
21. What are the most common designations for low voltage UKRM?
Examples of notation:
UKM58-0.4-100-25 U3
This is the old designation for UKRM:
UKM58 – Capacitor installation, with power control, automatic;
0.4 – rated voltage, kV;
100 – rated power, kvar;
25 – power of the smallest stage, kvar;
U3 is a product for moderate climates, for placement in a cold room without ventilation.
Another, modern, frequently encountered designation:
KRM-0.4-100-25 U3
RPC – installation of Reactive Power Compensation (or Reactive Power Compensator).
The rest is the same as in the previous example.
22. How are high-voltage installations designated?
The old (and more common) designation for high-voltage installations has its own characteristics.
UKL(or P)56(or 57)-6.3-1350 U3
UKL(P) – capacitor installation, cable entry on the left (L) or right (R);
56 – installation with a disconnector;
57 – installation without a disconnector;
6.3 – rated voltage, kV;
1350 – rated power, kvar.
23. How are capacitor banks designated?
The designation of capacitor banks is based on the same principle:
BSK-110-52000 (or 52) UHL1
BSK – Static Capacitor Battery (Static Capacitor Battery) – meaning that this is an unregulated (static) capacitor bank.
110 – rated voltage, kV;
52000 – rated power, kvar;
Or 52 – rated power, MVAr (megavolt amperes reactive) - 1 MVAr = 1000 kVAr.
UHL1 - work in moderately cold climates, outdoors - regions of the Far North, for example.
24. What does the letter “M” mean in the designation UKRM?
Sometimes in the designation UKRM the letter “M” is found at the end. Most often, it means that the installation is located in a container (module), less often - it is modernized.
25. What is a modular capacitor unit?
An installation consisting of capacitor modules - structurally and functionally complete blocks (Fig. 5).
26. Are there any fundamental differences in the design of the UKRM from different manufacturers?
There are no fundamental differences in the design of low voltage UKRM with electromechanical contactors (the most common).
The same can be said about high-voltage installations - controlled and static, as well as capacitor batteries.
27. Are there any fundamental differences in the configuration of the UKRM from different manufacturers?
Yes, I have. Different configurations, that is, the use of components from different manufacturers, greatly affects the reliability and final cost of installations. Therefore, in order to avoid misunderstandings, it is recommended to choose installations equipped with components from well-known manufacturers, with good MTBF statistics.
28. What is included in the UKRM delivery kit?
Standard UKRM delivery kit:
Capacitor unit in standard packaging;
Manual;
Passport;
Spare parts kit.
29. Conclusion
This section provides the most necessary information on reactive power compensation devices for sales managers. The next section will describe the components of UKRM.
Too high, or as it is also called, reactive energy and power, contribute to a significant deterioration in the operation of electrical networks and systems. We propose to consider in our article how automatic reactive power compensation (RPC) and overcompensation are carried out in networks in enterprises, in apartments and in everyday life.
Why do you need reactive power compensation?
The more energy required, the higher the level of fuel consumption becomes. And this is not always justified. Power compensation, i.e., its correct calculation, will help save up to 50% of consumed fuel in industrial power distribution networks in production, and in some cases even more.
You need to understand that the more resources spent on production, the higher the price of the final product will be. If it is possible to reduce the cost of manufacturing a product, a manufacturer or entrepreneur will be able to reduce its price, thereby attracting potential clients and consumers.
As a clear example, see a couple of diagrams below. E These vectors visually convey the full effect of the installation.
Diagram before installation operation
Diagram after installation In addition, we also get rid of losses in electrical networks, which has the following effect:
- the voltage is even, without drops;
- the durability of wires (abb - abb, aku) and induction windings in residential premises and factories increases;
- significant savings on the operation of home transformers and rectifiers;
- Compensation of power and reactive energy will significantly extend the operating time of powerful devices (three-phase and single-phase asynchronous motors).
- significant reduction in electrical costs.
General converter circuit Theory and practice
Most often, reactive energy and power are consumed when using a three-phase asynchronous motor, and this is where compensation is most needed. According to the latest data: 40% is consumed by motors (from 10 kW), 30 by transformers, 10 by converters and rectifiers, 8% by lighting consumption
In order to reduce this indicator, capacitor devices or installations are used. But there are a huge number of subtypes of these electrical appliances. What types of capacitor units are there and how do they work?
Video: What is reactive power compensation and why is it needed?
In order to compensate energy and reactive power with capacitor banks and synchronous motors, an energy saving installation will be required. Most often, such devices are used with a relay, although a contactor or thyristor can be installed instead. Arc compensation relay devices are used at home. But if compensation of reactive energy and power is carried out in factories, at transformers (where there is an asymmetrical load), then it is much more expedient to use thyristor devices.
In some cases, it is possible to use combined devices; these are devices that simultaneously operate through both a linear converter and a relay.
How using settings will help:
- the substation will reduce voltage surges;
- electrical networks will become safer for the operation of electrical appliances, problems with compensation of electricity and power in refrigeration units and welding machines will disappear;
- In addition, they are very easy to install and operate.
How to install capacitor devices
You will first need a diagram of the operation of the electrical network, and documents from the PUE, which will be used to make a decision on compensation of energy and reactive power of the EAF. Next, an economic calculation is required:
- the sum of energy consumption by all devices (these are furnaces, data centers, automatic machines, refrigeration units, etc.);
- the amount of current entering the network;
- calculation of losses in circuits before energy arrives to the devices, and after this arrival;
- frequency analysis.
Next, you need to generate part of the power immediately at the point where it enters the network using a generator. This is called centralized compensation. It can also be carried out using cos, electric, schneider, tg installations.
But there is also individual single-phase compensation of reactive energy and power (or transverse), its price is much lower. In this case, ordered control devices (capacitors) are installed directly at each power consumer. This is the optimal solution if a three-phase motor or electric drive is controlled. But this type of compensation has a significant drawback - it is not adjustable, and therefore is also called unregulated or nonlinear.
Static compensators or thyristors operate using mutual induction. In this case, switching is carried out using two or more thyristors. The simplest and safest method, but its significant drawback is that the harmonics are generated manually, which significantly complicates the installation process.
Longitudinal compensation
Longitudinal compensation is carried out using the varistor or arrester method.
Longitudinal reactive power compensation The process itself occurs due to the presence of resonance, which is formed due to the direction of inductive charges towards each other. This technology and theory of power compensation is used for jet and traction engines, steelmaking or machine tools Harmonics, for example, and is also called artificial.
Technical side of compensation
There are a huge number of manufacturers and types of condenser installations:
- thyristor;
- regulators on ferroalloy material (Czech Republic);
- resistor (manufactured in St. Petersburg);
- low voltage;
- detuning reactors (Germany);
- modular - the newest and most expensive devices at the moment;
- contactors (Ukraine).
Their cost varies depending on the organization; for more accurate and comprehensive information, visit the forum where reactive power compensation is discussed.
Intrusive advertising on the Internet and even on state television channels through a teleshop persistently offers the population a device for saving electricity in the form of “new products” from the electronics industry. Pensioners receive a 50% discount on the total cost.
“Saving Box” is the name of one of the proposed devices. They have already been written about in the article. It's time to continue the topic using the example of a specific model, explaining in more detail:
what is reactance;
how active and reactive power is created;
how reactive power compensation is carried out;
on what basis do reactive power compensators and energy saving devices work.
People who buy such a device receive a package in the mail with a beautiful box. Inside there is an elegant plastic case with two LEDs on the front side and a plug for installation in a socket on the back.
A miracle device for saving energy (click on the picture to enlarge):
The attached photograph shows the characteristics declared by the manufacturer: 15,000 W at a network voltage of 90 to 250 V. Let us evaluate them from the point of view of a practicing electrician using the formulas given under the pictures.
At the lowest specified voltage, such a device should pass a current of 166.67 A through itself, and at 250 V - 60 A. Let us compare the calculations obtained with the loads of alternating voltage welding machines.
The welding current for steel electrodes with a diameter of 5 mm is 150÷220 amperes, and for a thickness of 1.6 mm, 35÷60 A is sufficient. These recommendations can be found in any electric welder’s reference book.
Remember the weight and dimensions of a welding machine that welds with 5 mm electrodes. Compare them to a plastic box the size of a mobile phone charger. Think about why 5 mm steel electrodes melt from a current of 150 A, but the plug contacts of this “device” and all the wiring in the apartment remain intact?
To understand the reason for this discrepancy, I had to open the case, showing the “insides” of the electronics. In addition to the board for illuminating the LEDs and the fuse, there is another plastic box for props.
Attention! This scheme does not have a device for saving energy or compensating it.
Is it really a hoax? Let's try to figure it out using the basics of electrical engineering and existing industrial power compensators operating at energy enterprises.
Electrical supply principles
Let's consider a typical diagram for connecting electricity consumers to an alternating voltage generator, as a small analogue of an apartment's power supply network. For clarity, its characteristics of inductance, capacitance and active load are shown, and. We will assume that they operate in a steady state when a current of the same magnitude I passes through the entire circuit.
Electrical diagram (click on the picture to enlarge):
Here the energy of the generator with voltage U will be distributed by its components into:
inductor winding UL;
capacitor plates UC;
active resistance of heating element UR.
If we represent the quantities under consideration in vector form and perform their geometric addition in the polar coordinate system, we obtain an ordinary voltage triangle in which the magnitude of the active component UR coincides in direction with the current vector.
UX is formed by adding the voltage drops across the inductor winding UL and the capacitor plates UC. Moreover, this action takes into account their direction.
As a result, it turned out that the generator voltage vector U is deviated from the direction of current I by an angle φ.
Please note again that the current in circuit I does not change, it is the same in all sections. Therefore, we divide the components of the voltage triangle by the value I. Based on Ohm’s law, we obtain a resistance triangle.
The total resistance of inductance XL and capacitance XC is usually called the term “reactance” X. The total resistance of our circuit Z applied to the generator terminals consists of the sum of the active resistance of the heating element R and the reactive value X.
Let's perform another action - multiplying the vectors of the voltage triangle by I. As a result of the transformations, a power triangle is formed. Active and it creates the full applied value. The total energy supplied by the generator S is spent on active P and reactive Q components.
The active part is consumed by consumers, and the reactive part is released during magnetic and electrical transformations. Capacitive and inductive powers are not used by consumers, but they load the conductors with generators.
Attention! In all 3 right triangles, the proportions between the sides are maintained, and the angle φ does not change.
Now we will understand how reactive energy manifests itself and why household meters did not take it into account.
What is reactive power compensation in industry?
In the energy sector of the country, and more precisely, of the countries of the entire continent, a huge number of generators are engaged in the production of electricity. Among them there are both simple home-made designs of enthusiastic craftsmen and the most powerful industrial installations of hydroelectric power stations and nuclear power plants.
All their energy is summed up, transformed and distributed to the end consumer via sophisticated technologies and transport routes over vast distances. With this method of transmission, electric current passes through a large number of inductances in the form of windings of transformers/autotransformers, reactors, suppressors and other devices that create an inductive load.
Overhead wires, and especially cables, create a capacitive component in the circuit. Its value is added by various capacitor units. The metal of the wires through which current flows has active resistance.
Thus, the most complex energy system can be simplified to the circuit we considered from a generator, inductance, active load and capacitance. Only it still needs to be combined into three phases.
The task of the energy sector is to provide consumers with high-quality electricity. In relation to the final object, this means supplying electricity to the input panel with a voltage of 220/380 V, a frequency of 50 Hz with the absence of interference and reactive components. All deviations of these values are limited by GOST requirements.
In this case, the consumer is not interested in the reactive component Q, which creates additional losses, but in receiving active power P, which performs useful work. To characterize the quality of electricity, the dimensionless ratio P to the applied energy S is used, for which the cosine of the angle φ is used. Active power P is taken into account by all household electric meters.
Electric power compensation devices normalize electricity for distribution between consumers and reduce reactive components to normal. At the same time, “alignment” of phase sinusoids is also carried out, in which frequency interference is removed, the consequences of transient processes when switching circuits are smoothed out, and the frequency is normalized.
Industrial reactive power compensators are installed after the inputs of transformer substations in front of distribution devices: the full power of the electrical installation is passed through them. As an example, see a fragment of a single-line electrical diagram of a substation in a 10 kV network, where the compensator receives currents from the AT and only after processing it does the electricity flow further, and the load on energy sources and connecting wires is reduced.
Let's return for a moment to the Saving Box device and ask the question: how can it compensate for power when located in the final outlet, and not at the entrance to the apartment in front of the meter?
Look at the photo how impressive industrial expansion joints look. They can be created and operate on different element bases. Their functions:
smooth regulation of the reactive component with high-speed unloading of equipment from power flows and reducing energy losses;
voltage stabilization;
increasing the dynamic and statistical stability of the circuit.
Fulfilling these tasks ensures reliable power supply and reduces costs for the design of current conductors by normalizing temperature conditions.
What is reactive power compensation in an apartment?
Electrical appliances in the home electrical network also have inductive, capacitive and active resistance. For them, all the relationships of the triangles discussed above, in which reactive components are present, are valid.
You just need to understand that they are created when a current (counted by the meter, by the way) passes through a load already connected to the network. The generated inductive and capacitive voltages create corresponding reactive components of power in the same apartment and additionally load the electrical wiring.
Their value is not taken into account by the old induction counter. But individual static accounting models are capable of recording it. This allows you to more accurately analyze the situation with current loads and thermal effects on insulation when operating a large number of electric motors. The capacitive voltage created by household appliances is very small, as is its reactive energy, and meters often do not show it.
Compensation for the reactive component in this case consists of connecting capacitor units that “dampen” the inductive power. They must be connected only at the right moment for a certain period of time and have their own switching contacts.
Such reactive power compensators have significant dimensions and are more suitable for production purposes; they often work with an automation kit. They do not reduce active power consumption in any way and cannot reduce electricity bills.
Conclusion
The capabilities and technical characteristics of “Saving Box” declared by the manufacturer do not correspond to reality and are used for advertising based on deception.
It is high time for the Consumer Rights Protection Society and law enforcement agencies to take measures to stop sales of low-quality products in the country, at least through government information channels.
Saving energy resources is one of the main tasks of modern civilization. More and more articles are appearing on the Internet about saving electricity using the compensation method. Indeed, this process is relevant for industrial enterprises, as it saves money. Quite a lot of people are starting to think, if industrial enterprises save on the reactive component, is it possible to save on this in everyday life, by compensating for the reactive component in the workshop, at the dacha or in the apartment.
I will probably disappoint you - this cannot be done for several reasons:
- , which are installed for private consumers, keep track of only active power;
- Accounting for the reactive component is carried out only at large industrial enterprises; this accounting is not carried out for private consumers;
- Such energy does absolutely no useful work, but only heats wires and other devices;
Yes, in domestic conditions it is possible to install filters; this will reduce the total current in the circuit and reduce the voltage drop. When starting high-power devices (vacuum cleaners, refrigerators), household reactive power compensators reduce the starting current. It’s quite easy to assemble a reactive power compensator with your own hands at home. To do this, you need to calculate the reactive power for a single-phase device:
To do this, you need to measure the voltage and current of the circuit. How to find cosφ? Very simple:
P – active power of the device (indicated on the device itself)
f is the network frequency.
We select capacitors for a household reactive power compensator based on capacity, voltage, and type of current. Capacitors are hung parallel to the load.
Reducing the total current will reduce heating and allow maximum use of circuit power. But, in industrial enterprises, cosφ is strictly regulated, and in most cases is controlled automatically, that is, when a device is taken out of operation, cosφ is still maintained within a given range. Imagine that you calculated in your apartment, made a compensator and connected it to the circuit. But after some time, a consumer (for example, a refrigerator) turned off and the balance of the network was disrupted. Now you are not compensating, but generating reactive energy back into the network, thereby negatively affecting the operation of other consumers. In order to maintain balance, it is necessary to constantly monitor the operation of various devices. In everyday life, automating this process is too expensive and makes no sense, since this will not allow you to return the money even for a compensator.
We can conclude that reactive power compensation in everyday life is pointless, since it will not save money, and installing an unregulated compensator can lead to overcompensation and, as a result, only worsen the network power factor cosφ.
If you want to save energy, you should use old reliable methods:
- Buy household appliances of class A or B;
- Turn off lights and household appliances (except for the refrigerator) when leaving home;
- Replace incandescent lamps with energy-saving ones. They last longer and consume less;
- If you use an electric kettle, boil as much water as required, this will significantly reduce the energy it consumes;
- Clean the vacuum cleaner filter to improve traction and reduce energy consumption;
- Insulate rooms to minimize the use of electric heaters.
The video shows a DIY household reactive power compensator
The video uses a household compensator in the form of a block of capacitor batteries
In the modern global world, saving energy resources takes first place in its relevance. Energy saving, in some countries, is actively supported by the state not only for large consumers, but also for ordinary people. Which in turn makes the reactive power compensator relevant for home use.
Reactive power compensation:
Many consumers, having read on the Internet about reactive power compensation by large plants and factories, are also thinking about reactive power compensation at home. Moreover, now there is a large selection of compensating devices that can be used in everyday life. You can read about whether it is really possible to save some money on this at home in this article. And we will consider the possibility of making such a compensator with our own hands.
I’ll answer right away – yes, it’s possible. Moreover, this is not only a cheap, but also a fairly simple device, however, to understand the principle of its operation you need to know what reactive power is.
From the school physics course and the basics of electrical engineering, many of you already know general information about reactive power, so you should go straight to the practical part, but it is impossible to do this without skipping mathematics, which everyone dislikes.
So, to start selecting compensator elements, it is necessary to calculate the reactive power of the load:
Since we can measure components such as voltage and current, we can only measure the phase shift using an oscilloscope, and not everyone has one, so we’ll have to go a different route:
Since we are using the most primitive device of the capacitors themselves, we need to calculate their capacitance:
Where f is the network frequency, and X C is the reactance of the capacitor, it is equal to:
Capacitors are selected according to current, voltage, capacity, power, respectively, based on your needs. It is desirable that the number of capacitors be greater than one, so that it is possible to experimentally select the most suitable capacitance for the desired consumer.
For safety reasons, the compensating device must be connected via a fuse or circuit breaker (in case of too high charging current or short circuit).
Therefore, we calculate the current of the fuse (fuse link):
Where i in is the current of the fuse (fuse), A; n – number of capacitors in the device, pieces; Q k – rated power of a single-phase capacitor, kvar; U l – linear voltage, kV (in our case, phase without).
If we use an automatic machine:
After disconnecting the compensator from the network, there will be voltage at its terminals, so to quickly discharge the capacitors, you can use a resistor (preferably an incandescent light bulb or neon) by connecting it in parallel with the device. The block diagram and circuit diagram are given below:
Block diagram of switching on the reactive power compensator 
I'll demonstrate it more clearly The consumer is connected to hole number one, and the compensator is connected to hole number two.
Schematic diagram of the reactive power compensator 
Switching on via automatic fuse The compensating device is always switched on parallel to the load. This trick reduces the resulting circuit current, which reduces cable heating; accordingly, a large number of consumers can be connected to one outlet or their power can be increased.
