Water pipes

Technical means and methods for measuring electrical quantities. Topic: Electrical measuring instruments and measurements of electrical quantities Technical measurement and control of electrical quantities

Basics of metrology

1. Metrology - the science of measurements

a. Subject and tasks of metrology

b. Metrological assurance and its structure

2. The concept of measurement, its role and place in metrology

a. The concept of measurement

b. Measurement classification

c. Measurement characteristics

d. Measurement methods and their classification

3. Units of physical quantities and their systems. Basic Measurement Equation

4. Measuring instruments

a. Classification of measuring instruments

b. Metrological characteristics of measuring instruments

c. Accuracy classes of measuring instruments and their normalization

d. Block diagrams of measuring instruments. Relationship between characteristics and structure of a measuring instrument

5. Transfer of the size of units from standards to exemplary and working measuring instruments. Verification of measuring instruments

a. Verification of measuring instruments. Main goals and objectives. The quality of verification and its frequency.

b. Standards and exemplary measuring instruments, their place in the system of reproduction and transmission of unit sizes

c. Verification schemes and methods for their construction.

d. Organization and verification of measuring instruments.

Measurement errors

General information about measurement uncertainty
Error classification
Systematic errors

a. The concept of systematic error

b. Causes of systematic errors

c. Detection and elimination of systematic errors

Random errors

a. The concept of random measurement error and the causes of their occurrence.

b. General population and its numerical characteristics

c. The most important distribution functions

d. Numerical characteristics of the general population

e. Sample and its characteristics

f. Building a confidence interval

g. Exclusion of gross errors

Processing and presentation of measurement results

1. Single direct measurements

2. Processing the results of direct measurements with multiple observations

3. Processing and presentation of the results of indirect measurements.

4. The choice of measuring instruments that provide the required quality of measurements.

5. Processing of measurement results in the presence of several sources of error.

6. Presentation of measurement results

Technical means and methods for measuring electrical quantities

1. Measures of electrical quantities, their structure and characteristics

a) EMF measure. Purpose, device, main characteristics.

b) Measures of resistance, capacitance and inductance. Purpose, device, main characteristics.

2. Analogue measuring instruments

a) The design and characteristics of the measuring transducers used in the means of measuring electric current and voltage

i. Passive converters without changing the type of current. Purpose, device, main characteristics.

ii. Passive converters with current type change

iii. Active transducers

b) Electromechanical measuring mechanisms and measuring instruments based on them

i. Magnetoelectric measuring mechanism. Purpose, device, main characteristics.

ii. Electromagnetic measuring mechanism. Purpose, device, main characteristics.

iii. Electrodynamic measuring mechanism. Purpose, device, main characteristics.

iv. Electrostatic measuring mechanism. Purpose, device, main characteristics.

c) Electronic analog measuring instruments

i. Electronic DC voltmeters. Purpose, device, main characteristics.

ii. Electronic AC voltmeters. Purpose, device, main characteristics.

d) Universal electronic oscilloscope. Purpose, device, main characteristics.

e) DC compensators and bridges. Purpose, device, main characteristics.

3. Digital measuring instruments

a) Principles of operation of the ADC. Discretization in time and level quantization.

b) Signal recovery from discrete samples. Kotelnikov's theorem (no proof)

c) Main characteristics and sources of ADC error.

d) Codes and number systems

i. Serial counting ADC. Principle of operation and main characteristics.

ii. bitwise balancing ADC. Principle of operation and main characteristics

f) DAC. The principle of operation of the comparison device.

g) Principle of operation, device and main characteristics of digital measuring instruments for sequential counting

i. Digital time interval meter. Purpose, device, main characteristics.

ii. Digital phase meters (without averaging and with averaging). Purpose, device, main characteristics.

iii. Digital frequency meters and periodometers. Purpose, device, main characteristics.

iv. Digital time-pulse voltmeter. Purpose, device, main characteristics.

"Not a single exact science,

no applied science

no measurements.

New measuring instruments

represent real progress."

/ acad. Yakabi B.S./

Lecture 1

1. Introduction and objectives of the course.

2. General information about measurements and measuring equipment:

a) basic concepts and definitions;

b) systems of units, basic units of the SI system;

c) types of means e-mail. measurements;

d) measures of electrical quantities;

e) classification of electrical measuring instruments;

f) the main characteristics and parameters of electrical measuring instruments.

Introduction

Cognition of the reality around us, the study of the patterns of natural phenomena, the development of science and technology is inextricably linked with measurements.

“Science begins ... as soon as they begin to measure; exact science is unthinkable without measure. - wrote D. I. Mendeleev.

Measurement, that is, the determination of the numerical value of a given quantity, plays an exceptional role in the national economy. There is no such area of science and technology, there is no such branch of industry or agriculture, where one of the decisive factors would not be measurement as such.

Scientific and technological progress is the central economic and important political task of our country. The core of scientific and technological progress is to increase labor productivity by automating production, automating management and accelerating scientific research in order to quickly introduce their production.

The main task of the 10th Five-Year Plan is to consistently implement the course of the CPSU to raise the material and cultural standard of living of the people on the basis of the dynamic and proportional development of social production and increase its efficiency, accelerate scientific and technological progress, increase labor productivity, improve the quality of work worldwide at all levels. National economy.

To solve these problems, it is envisaged in the industry ...

To expand the output of progressive, economical types of machinery, equipment and examples for all branches of the national economy.

To increase the output of instruments and means of automation by 1.6-1.7 times, of means of computer technology by 1.8 times.

To develop the production ... of devices for recording and transmitting information for automated control systems of technological processes and optimal control in the branches of the national economy.

To expand the production of instruments for the needs of agriculture.

The study of natural phenomena, the search for the laws to which these phenomena are subject, and, in general, all scientific research is always connected with measurements, since such studies are ultimately reduced to the determination of quantitative relationships through which the qualitative aspects of the studied phenomena and objects are also revealed.

Improvement in measurement techniques, which manifests itself in an increase in the accuracy of measurements and in the creation of new methods and instruments, contributes to certain new achievements in science.

New discoveries in science, in turn, lead to the improvement of measurement techniques, as well as to the creation of new instruments.

Modern information and measuring equipment has a set of measuring instruments for about two hundred different physical quantities of electrical, magnetic, thermal, mechanical, light, acoustic, etc.

A huge number of different quantities in the measurement process is converted into electrical quantities as the most convenient for transmission, strengthening comparison, accurate measurement.

Therefore, in the development of modern information-measuring technology, the development of means for measuring electrical quantities acquires a predominant importance.

The level of development of electrical measuring equipment largely determines the state of technical progress in all sectors of the national economy. 04/29/1745 was presented by Academician Richmon to the general meeting of the St. Petersburg Academy "Indicator of electric spark" - the first electrical measuring device.

Currently, without high-quality e-mail. measurement technology, it is impossible to conduct scientific research at the modern level, and it is also impossible to realize the potential of a modern computer fleet, develop and implement automated control and management systems - the main means of technical progress and increase labor productivity.

Electrical measuring instruments and devices are widely used in industry for scientific research, in cosmonautics, in transport in communication and navigation systems, in geological exploration, in hydrometeorology, and in many other areas of human labor activity.

This is due to the advantages inherent in electrical measurements, the main of which are:

1. A wide range of measured values, characterized by 18 digits (for example, voltage from 10-14 to 106 V, current from 10-9 to 106 A, resistance from 10-6 to 10-14 Ohm);

2. High sensitivity (for example, current 1*1012 mm/A, voltage 1*106 mm/V).

3. High precision. The error of modern indicating instruments has been brought up to 0.05%, and of comparison instruments - up to 0.001%.

4. The ability to obtain the value of the measured value not only at the moment, but also to record its change over time.

5. Feasibility of measurements at a distance (telemetry).

6. Ability to measure non-electric quantities by electrical methods.

7. The feasibility of automating the acquisition and processing of measurement results.

8. Possibility to make measurements without disturbing the course of the technological process.

9. Ability to measure both slowly and rapidly changing quantities.

The fulfillment of the majestic plans for the development of the national economy in the 10th five-year plan, the implementation of grandiose construction projects, pose new tasks for all branches of Soviet industry. Such tasks are also facing electrical engineering - in particular, electrical measuring equipment.

The increase in the production of email. energy in the country by 1980 to 1340-1380 billion kWh, the implementation of the plan for comprehensive mechanization and automation of production will require the creation of qualitatively new electrical measuring instruments and devices, the replacement of obsolete instruments with modern ones based on new measurement principles.

Currently, electrical measuring equipment is intensively developing in the following areas:

a) improving accuracy and speed, expanding the partial range, improving the design of diverse email. measuring instruments;

b) expanding the range and improving the characteristics of various measuring transducers widely used in measuring electrical and non-electrical quantities, as well as in automatic control systems;

c) development and production of various specialized email. measuring installations designed to test email. measuring instruments, testing of ferromagnetic materials and other purposes;

d) release and improvement of IIS intended for automatic receipt, transmission, processing and presentation in one form or another and in the values of measured or controlled physical quantities (IIS - information and measurement system);

e) improvement and creation of new state standards of units of el. values, which provides an increase in the level of accuracy email. measurements.

e-mail should play a special role. measurements in the electrification of agriculture. Increasing every year, the automation of production processes in animal husbandry and field farming, the introduction of el. energy into biological processes on the basis of general electrification of agriculture are inextricably linked with the development of el. measuring technology.

In connection with the automation of management and regulation, which all measures will be implemented in agricultural production, the requirements for el. measuring technology. The ongoing gradual transition to in-line production technology in livestock and field farming puts forward new requirements for technological measurements that ensure high reliability of operation and product quality.

The solution of these problems today requires that an engineer of agricultural production be well versed in a wide range of issues and have serious technical erudition.

In particular, an electrical engineer requires a deep knowledge of the theory and practice of email. measurements.

2. General information about measurements and measuring equipment.

a) basic concepts and definitions.

A quantitative assessment of the properties of various objects of measurement (research) is carried out by measuring the physical quantities characterizing the specified properties.

Measurement is a cognitive process, which consists in comparing experimentally a measured value with some of its value, taken as a unit.

More broadly

Measurement is the process of receiving and converting information about the measured quantity in order to obtain a quantitative result of its comparison with a unit of measurement in the most convenient form for research.

Thus, measurement is a process of obtaining information: after measurement, we learn more about the numerical value of the measured quantity, its relationships and relationships with other quantities than we knew before the measurement.

This means that measurement is an experimental comparison of the measured quantity with another homogeneous quantity, accepted and legalized as a unit. Since the measurement is a physical experiment, it cannot be carried out speculatively, abstractly. It follows from this that for any measurement, a legalized system of units and technical means of its implementation are necessary.

The measurement result is always the numerical value of the measured quantity A, which is equal to the ratio of the measured quantity Aiz to the unit of measurement X. In other words, the numerical value shows how many times the measured value is greater or less than the unit of measurement.

The measurement process can therefore be written as follows:

A \u003d Aiz / X, from where Aiz \u003d A X, i.e. "the measured value Aiz is so many A units of X."

The last equation is called the main measurement equation.

b) system of units. Basic SI units.

A system of units is a set of basic and derived units of measurement, covering a certain area of measurement of physical quantities.

In the USSR, on January 1, 1963, GOST 9867-61 was put into effect, which recommends the use of SI as preferred in all areas of science and technology, as well as in teaching.

The International System of Units (SI) is built on seven basic units, two additional and 27 derivatives.

Basic SI units.

The size of the base units is set independently of the sizes of other units.

Derived units - are defined by communication equations expressing the mathematical dependence of a given unit on other units.

Value name	Unit	Abbreviation
Value name	Unit	Russian	latin

	kilogram

The strength of el. current
Thermodynam. temperature
The power of light
Quantity substances		mole

Additional units

1. Radian - the angle between two radii of a circle, cutting an arc on its circumference, the length of which is equal to the radius (linear angle units).

2. Steradian - a solid angle, the value of which is located in the center of the sphere and which cuts out on the surface of the sphere an area equal to the area of a square with a side equal to the radius of the sphere (solid angle units).

In measuring practice, multiples and submultiples are often used. They are formed by multiplying whole units by 10k, where To is an integer. At the same time, the appropriate prefixes are added to the names of the units.

Longitudinal or multiplicity	Prefix name	Abbreviations (Russian)	Longitudinal or multiplicity	Name prefixes	Abbreviation (Russian)

Types of electrical measuring instruments.

Means of electrical measurements call the technical means used in electrical measurements and having normalized metrological properties.

There are the following types of electrical measuring instruments:

2. Electrical measuring instruments.

3. Measuring transducers.

4. Electrical installations.

5. Measuring information systems (IIS).

Measures called measuring instruments designed to reproduce a physical quantity of a given size. (Really reproduced unit of measurement).

Distinguish single-valued, multi-valued measures and a set of measures.

Unambiguous measure reproduces a physical quantity of the same size.

Multivalued measure reproduces a number of quantities of the same name of various sizes (capacitor of variable capacity, inductance variometer, etc.).

Measure set is a specially selected set of measures used not only individually, but also in various combinations in order to reproduce a number of similar quantities of various sizes (resistance box).

Electrical measuring instruments called electrical measuring instruments designed to generate measurement information signals, i.e. signals functionally related to the measured physical quantities, in a form that can be directly perceived by the observer.

Measures of electrical quantities.

In the practice of electrical measurements, measurements are widely used measures e. ds, electrical resistance, inductance, mutual inductance and capacitance.

Measure E.D.S. exemplary measure e. d.s. serves as a normal element, which is a galvanic cell, characterized by a very stable value, developed by it e. d.s. E.D.S. n. e. differ from 1 V, but it is precisely known. This is achieved by selecting the component parts of the element from substances strictly defined in terms of chemical composition, their exact dosage and strictly uniform design. At a temperature of 20°C e. d.s. saturated n. e. is 1.0185 - 1.0187 V, i.e. the most acceptable discrepancy between e. d.s. exceeds 200 µV. N. E. are made of two types: saturated and unsaturated differing from each other in design, electrolyte and stability of the developed e. d.s. Unsaturated - have less internal resistance (~ 300 Ohm) and a small temperature coefficient. At temperatures from 10 to 40 ° C - does not exceed 15 μV per 1 ° C. For saturated ones, the temperature coefficient is 4 times greater than e. d.s.

NE changes little over time. According to GOST 1954 - 64, it is allowed to change e. d.s. saturated n. e. for a year no more than 50 - 100 μV.

Depending on the accuracy of e. d.s., its stability n. e. are divided into classes.

N. E. cannot be used as a source of electrical energy, it cannot be loaded with a current exceeding the allowable values.

Measures of electrical resistance are performed in the form of exemplary measuring resistance coils or measuring resistance magazines. Their resistance value is 10 ± n Ohm, where n is an integer.

Exemplary coils are supplied with two pairs of clamps, two of which are called current and are designed to include an exemplary coil in the current circuit, the other two are called potential. The resistance between the potential clamps is equal to the resistance of the reference coil. The wires leading to the measuring circuit are connected to the potential clamps.

The following requirements are imposed on the material from which the coils are made:

1) more specific resistance is possible;

2) the lowest temperature coefficient and thermal e. d.s. paired with other metals;

3) resistance of wire metal against oxidation.

These requirements are best met by manganin.

Depending on the error of exemplary resistances and other characteristics (resistance change over time, permissible power, etc.), exemplary resistances are divided into accuracy classes, for which errors and other characteristics are normalized by the corresponding GOST.

Measures of inductance and mutual inductance.

Measures L and M are performed in the form of individual coils or magazines. Model inductance and mutual inductance coils are usually made in the form of flat coils of insulated thin wire wound on a frame. The coils must have a constant inductance, low active resistance, independence of the inductance from the magnitude of the current, and perhaps a small dependence of the inductance on the purity of the current.

To obtain the independence of L of the coil from the current strength, the coil frame is made of a material whose M is equal to unity and does not depend on the magnetic induction in it (porcelain, marble, ceramics, plastics, less often - wood). For the windings, a stranded wire is chosen (to reduce the influence of frequency, they reduce the distributed capacitance).

Mutual inductance coils consist of two windings rigidly fixed on a common frame.

Measures with variable values of L and M are variometers.

Capacitance measures . They are air (no more than 11000 pF) or mica capacitors of constant and variable capacitance.

Exemplary measures of capacitance should have a constant capacitance and its low temperature coefficient, very small energy losses in the dielectric, independence of capacitance from frequency and shape of the current curve, and high resistance and insulation strength.

Classification of measures and measuring instruments.

Electrical measuring instruments are very diverse in principle of operation and design, due to the various requirements placed on them.

Measures and measuring instruments can be classified according to a number of criteria.

1. On a functional basis:

a) means of collecting, processing and presenting information;

b) means of certification and verification.

a) working measures and measuring instruments;

b) exemplary measures and measuring instruments;

c) standards.

Standard - this is a measure that reproduces a unit of measurement with the greatest accuracy for a given historical time.

2. According to the method of presenting the measurement results:

a) showing;

b) registering.

3. According to the measurement method:

a) direct reference;

b) comparisons.

4. According to the method of application and design:

a) portable;

b) stationary.

5. By measurement accuracy:

a) measuring;

b) indicators;

c) pointers.

6. According to the method of reproducing the measured value:

a) analog;

b) digital.

Analog- electrical measuring instruments, the readings of which are continuous functions of changes in the measured quantity.

Digital - electrical measuring instruments that automatically generate discrete signals for changing information, the readings of which are presented in digital form.

Measuring instrument - technical means intended for measurements, having normalized metrological characteristics, reproducing and (or) storing a unit of physical quantity, the size of which is assumed to be unchanged (within the established error) for a known time interval. This definition reveals the essence of the measuring instrument, which consists in the ability to store (or reproduce) a unit of physical quantity, as well as the invariance of the size of the stored unit. These factors determine the possibility of performing a measurement.

By appointment measuring instruments are divided into measures, measuring transducers, measuring devices, measuring installations and measuring systems.

Measure - a measuring instrument designed to reproduce and (or) store a physical quantity of one or more specified dimensions, the values of which are expressed in established units and are known with the required accuracy.

There are the following types of measures:

● unambiguous measure — the measure reproduces a physical quantity, of the same size;

● multivalued measure. the measure reproduces the physical quantity of different sizes;

● set of measures - a set of measures of different sizes of the same physical quantity;

● shop measures ~ a set of measures structurally combined into a single device, in which there are devices for their connection in various combinations. For example, an electrical resistance box provides a range of discrete resistance values.

Some measures simultaneously reproduce the values of two physical quantities. A measure is necessary in the comparison method to compare the measured value with it and obtain its value.

Measuring transducer - technical means with normalized metrological characteristics, which is used to convert the measured value into another value or measuring signal, convenient for processing, storage, further transformations, indication or transmission. The principle of its operation is based on various physical phenomena. The measuring transducer converts any physical quantities (electrical, non-electrical, magnetic) into an electrical signal.

By the nature of the transformation distinguish between analog, analog-to-digital converters (ADC) that convert a continuous value into a numerical equivalent, digital-to-analog converters (DAC) that perform the inverse conversion.

In place in the measuring converter circuits are divided into primary, which is directly affected by the measured physical quantity; intermediate, included in the measuring circuit after the primary; converters designed for scale conversion, i.e. to change the value of a quantity by a certain number of times; transmitting, reverse for inclusion in the feedback circuit, etc.

Measuring converters include AC-to-DC converters, voltage and current measuring transformers, current dividers, voltage dividers, amplifiers, comparators, thermocouple, etc. Measuring converters are part of any measuring device, measuring installation, measuring system or used together any means of measurement.

Measuring device(IP) - a measuring instrument designed to obtain the values of the measured physical quantity in the established range. Devices are showing and recording, digital and analog.

Measuring setup- a set of functionally combined measures, measuring transducers, measuring instruments and other devices. Designed to measure one or more physical quantities and located in one place, for example, a device for measuring the characteristics of a transistor, a device for measuring power in three-phase circuits, etc.,

Measuring system - a set of functionally combined measures, measuring instruments, measuring transducers, computers and other technical means placed at different points of a controlled object in order to measure one or more physical quantities inherent in this object and generate signals for different purposes.

Depending on the purpose, measuring systems are divided into measuring information, control, technical diagnostics, etc. Microprocessor-based measuring systems are widely used - control computer systems with a microprocessor (MP) as an information processing unit. In the general case, the MP includes: an arithmetic-logical unit, a block of internal registers for temporary storage of data and commands, a control device, internal bus lines, input-output data buses for connecting external devices.

Modern technical devices are a collection of a large number of so-called "component products", combined by electrical, electronic, optoelectronic, mechanical connections into nodes, blocks, systems, complexes for solving certain problems. Electronic automated control systems and other devices may include thousands, tens and even hundreds of thousands of components. At the same time, changes in the parameters (properties) of one or more products affect the quality of functioning of other interacting, connected products. Any product has, unfortunately, not an unlimited resource and service life. Its parameters over time, sooner or later, begin to change gradually, and sometimes under the influence of external influences and transiently.

The presence of links between elements causes a corresponding change in some common parameter of the set of connected components. At a certain level of change in one or more parameters, the node (unit, system, complex) loses its performance. In order to prevent the loss of performance or restore the lost quality of a technical device, it is necessary to quantify its main parameters or the parameters of its blocks, assemblies, even individual components.

The parameters of any technical devices, their modes of operation are represented by sets of numerical values of a set of physical quantities (electrical, linear-angular, thermal, optical, acoustic, etc.). The values of physical quantities at the moment of operation of a technical device objectively exist, but are unknown if they are not measured. Therefore, the determination of unknown numerical values of physical quantities is the purpose of measurements.

The correctness of determining the value of the measured physical quantity depends on the quality of the measuring instruments used, which are also technical devices capable of measuring one or another physical quantity with a predetermined accuracy.

During the operation of radio-electronic complexes, automated control systems, in order to maintain operability, it is necessary to periodically sequentially or simultaneously measure a large number of physical quantities with significant limits of change in a wide frequency range. First of all, in almost every session of a complex technical device, it is necessary to control the compliance of the values of physical quantities with the established values or limits (tolerances). Such control of parameters and characteristics to determine the possibility of the normal functioning of technical devices, associated with finding the values of physical quantities, is called measuring. In some cases, there is no need to determine (with a given accuracy) the numerical values of physical quantities: it is often necessary to fix only the presence of a signal or the presence of a parameter in a wide tolerance field (no less, no more, etc.). In such cases, a qualitative assessment of the parameters of a technical device is made, and the assessment process is called quality control or simply control. When monitoring, color indication is often used (the color of the signal indicates to the operator that the parameter corresponds to a certain limit). In some cases, so-called indicators - measuring instruments with low accuracy characteristics.

The fundamental differences between measurement control and quality control are as follows: in the first case, the measured physical quantity is estimated with a given accuracy and in a wide range of its possible values (measurement range). Any of the values obtained during the measurement of a physical quantity is always quite definite and can be compared with a given value; in the second case, the estimated physical quantity can take on any value (in a wide range of its possible values), which is indefinite, with the exception of one (or two), when the value of the physical quantity becomes equal to the upper (lower) limit of the tolerance field (this moment is accompanied by light or another signal). If a measuring instrument is used as an indicator during control, then the corresponding values of the physical quantity are obtained quite definite, but without guaranteeing the accuracy of the control result, since the indicators are not subject to periodic verification.

Measurement of electrical quantities at industrial enterprises provides control of technological processes (TP), control over compliance with the established operating mode, control of equipment operation, control of insulation of electrical equipment and electrical networks, conditions that allow maintenance personnel to navigate in emergency conditions.

Instruments for measuring electrical quantities must meet the requirements for the accuracy class of measuring instruments (not lower than 2.5), the measurement limits of instruments. Measuring devices must be installed at the points from which control is carried out.

Measurement of current, voltage and power is carried out in circuits of all voltages, where it is necessary for the systematic control of TS or equipment. At substations, voltage measurement is allowed only on the low voltage side, if the installation of voltage transformers on the HV side is not required for other purposes. Voltage measurement should also be carried out in the circuits of power converters, storage batteries, charging and recharging devices, in the circuits of arc extinguishing reactors. Power is measured in the circuits of active and reactive power generators, in the circuits of synchronous compensators - reactive power, in step-down transformers, depending on the voltage - active and reactive power.

Accounting for active and reactive power and energy, as well as power quality control for settlements between an energy-saving organization and a consumer, is usually carried out at the border of the balance sheet ownership of the power grid. Electricity metering is carried out on the basis of measurements of electric energy using meters, as well as information-measuring systems. The use of automated electricity metering and control systems increases the metering efficiency. In electrical installations, various multifunctional meters are used. They can be used to record daily and monthly power consumption, record power consumption on the first day of the month, after a power outage, 30-minute power value, unauthorized memory access attempts, seasonal time changes, etc.

Accounting for active electricity should provide the ability to draw up electricity balances for consumers, control over consumer compliance with specified consumption modes and electricity balances, consumers' payments for electricity at current tariffs (including multi-rate and differentiated), the ability to manage electricity consumption. Accounting for reactive electricity should provide the ability to determine the amount of reactive electricity received by the consumer from the power supply organization or transferred to it, if these data are used to calculate or monitor compliance with the specified operating mode of compensating devices.

When determining the amount of electricity, only the transformation ratios of measuring transformers are taken into account. The measured electricity is equal to the difference in the readings of the meter counting mechanism, multiplied by the transformation ratio, the introduction of other correction factors is not allowed.

According to the connection scheme to the electrical circuit, the meters are divided into direct switching devices and transformer ones. In addition, counters are analog and electronic. So far, analog induction meters such as SAZU-670M, SR4U-I673 and others are widely used for measuring active and reactive energy. At the same time, electronic meters became widespread. Energy measurement by electronic meters is based on the conversion of analog AC and voltage input signals into a counting pulse or code. The block diagram of an electronic counter based on amplitude and pulse-width modulation is shown in fig. 9.17.

Electronic multi-tariff meters of the SEA32 type of various designs are designed to measure active energy in three-phase AC networks with a frequency of 50 Hz and are used as an energy increment sensor in the ACS for control and accounting of electric energy (ASKUE) and power telemetry.

SE3000 meters are used to measure active and reactive energy and power in three phases in three-phase three- and four-wire AC circuits and to organize multi-tariff metering (number of tariffs - 4) of electricity at industrial enterprises and facilities.

Rice. 9.17. Structural diagram of an electronic meter

Schemes for direct connection of three-phase meters in electrical installations with a voltage of 380/220 V in four-wire networks, designed for rated currents of 5; 10; 20; 50 A are presented in fig. 9.18, turning on the meter through measuring transformers in fig. 9.19. The switching circuit is made ten-wire.

Rice. 9.18. Scheme of switching on the direct-flow meter SET4-1

Rice. 9.19. Scheme for connecting a three-element counter of the SA4U-I672M type to a four-wire network with separate current and voltage circuits

The connection of each of the three measuring elements of the meter requires obligatory observance of the polarity of the connection of the current circuits and their correspondence to their voltage. The reverse polarity of switching on the primary winding of the TA or its secondary winding causes a negative torque acting on the meter disk. The circuit provides a normalized measurement error. The connection of the neutral wire is mandatory.

The switching schemes for the reactive energy meter type SR4U-I673 and the active energy meter do not differ (Fig. 9.20). The current circuits of these meters are connected in series, the voltage circuits are connected in parallel. The schemes of internal connections of reactive and active energy meters are different. Due to the scheme of internal connections of the coils, designed for a voltage of 380 V, an additional 90 ° phase shift is performed between the magnetic fluxes.

Three-phase transformer universal meters SETA and SET4 are designed to measure active and reactive energy in three-phase three- and four-wire circuits of alternating current 380/220 V, 50 (60) Hz and are used for power needs for a voltage of 100/57.7 V, and ST1 meters , SET3, "TRIO", "SOLO" - to account for the consumption of active and reactive energy in everyday life and at work.

Rice. 9.20. Scheme of switching on counters for measuring active

and reactive energy in the 380/220 V network

TsE6807 meters are designed to measure active energy in single-phase two-wire AC networks 220 V, 40 (60) Hz, can be used as energy consumption increment sensors for remote information-measuring systems for accounting and distribution of ASUKUE, ESch TM201 meters have also found application there. Single-phase single-tariff meters TsE6807P, CE101, CE200, as well as multi-tariff meters CE102, CE201 are designed for electricity metering in the domestic and small-engine power consumption sectors, have protection against under-metering and theft of electricity.

Three-phase single-tariff meters TsE6803V, TsE6804, CE300, CE302 are designed to account for electricity in three-phase AC circuits in the domestic, small-engine and industrial power consumption sectors, and multi-tariff meters TsE6822, CE301, TsE6850M, CE303, CE304 - in the industrial sectors of power consumption.

Electricity meters multifunctional microprocessor types TsE6850, TsE6822, and other similar modifications are designed to measure active and reactive electricity and power, depending on the functional purpose. The functional set of parameters can be as follows:

· commercial accounting of intersystem flows, generation and consumption of electricity in power systems, at grid and industrial enterprises;

· capacity metering in regional, territorial grid and industrial enterprises, at small and medium-sized businesses, in the housing and communal environment;

metering of electricity in the industrial and domestic sectors (residential and public buildings, cottages, cottages, garages) when supplying consumers from a three-phase network, in industrial premises when supplying consumers from a single-phase network;

· technical and commercial accounting of generation and consumption of active and reactive energy;

registration of a daily schedule of half-hour capacities (loads) with a storage depth of up to 45 days;

measurement of instantaneous values of primary network parameters ();

· measurement of reactive power as a part of ASKUE.

Measuring transducers are used to convert the measured electrical quantity (current, voltage, power, frequency) into a unified DC or voltage output signal or frequency. Measuring transducers are used in systems for automatic regulation and control of electric power facilities in various industries, as well as for monitoring the current value of measured quantities.

In the field of electrical measuring equipment of the highest class of complexity, measuring and computing complexes (MCC), information measuring systems (IMS) are used, designed to receive, convert, store and present measurement information.

The measuring and computing complex measures direct voltages and performs the conversion of analog signals into a digital code and digital-to-analog conversion of the signals coming through the input channels.

Multifunctional IMS type K734 are designed to collect, convert, measure, present, register and store information of various parameters of electrical signals.

Modern multifunctional converters include PTS 6806 converters designed to measure active and reactive energy in forward and reverse directions (consumed and returned), frequency, current, voltage, active and reactive power for each phase of the network. They are used for commercial and technical metering of electricity as part of ASKUE. Depending on the purpose, they perform the functions of telecontrol, telesignaling, indication of measured and calculated parameters on the built-in digital indicator, fixing the maximum power in each tariff zone, archiving parameters and events with real-time marks, etc.

Questions for self-control

1. What types of errors do measuring current transformers have and what do they depend on?

2. What are the main design features of the current transformers used.

3. Explain the principle of operation of a DC measuring transformer.

4. What types of voltage transformers exist and what are their features when used in measuring circuits?

5. Name the accuracy classes of voltage and current transformers.

6. Name the types of meters used to account for active and reactive energy.

7. What types of meters are used in ASKUE systems?

8. Name the types of multifunctional converters.

9. Draw vector diagrams of the voltage transformer.

10. Draw vector diagrams of the current transformer.

11. What types of errors do voltage transformers have?

1. Handbook of power supply and electrical equipment of industrial enterprises and public buildings / ed. ed. S.I. Gamazina, B.I. Kudrina, S.A. Tsyruk. M.: Publishing house. House MPEI, 2010. 745 p.: ill.

2. Opoleva G.N. Schemes and substations of power supply: a reference book / G.N. Opoleva: M.: FORUM: INFRA-M, 2006. 480 p.

3. Kuzhekov S.L. A practical guide to electrical networks and electrical equipment / S.L. Kuzhekov, S.V. Goncharov. 4th ed., add. and reworked. Rostov n/D.: Feniks, 2010. 492 p.: ill.

4. Gerasimenko A.A. Transmission and distribution of electrical energy / A.A. Gerasimenko, V.T. Fedin 2nd ed. Rostov n/a. 2008. 715 p.

5. Gerasimenko A.A. Transmission and distribution of electrical energy: textbook. allowance / A.A. Gerasimenko, V.T. Fedin. 3rd ed., revised. M.: KNORUS, 2012. 648 p.

6. Mironov Yu.M. Electrical equipment and power supply of electrothermal, plasma and beam installations: textbook. allowance for universities. Yu.M. Mironov, A.N. Mironov. Moscow: Energoatomizdat, 1991. 376 p.: ill.

7. Handbook of power supply design / ed. SOUTH. Barybina and others. Moscow: Energoatomizdat, 1990. 576 p.

8. Reference book on the design of electrical networks and electrical equipment / ed. SOUTH. Barybina and others. Moscow: Energoatomizdat, 1991. 464 p.: ill.

9. Vasiliev A.A.. Electrical part of stations and substations: a textbook for universities / A.A. Vasiliev, I.P. Kryuchkov, E.F. Nayashkova and others; ed. A.A. Vasiliev. 2nd ed., revised. and additional Moscow: Energoatomizdat, 1990. 576 p.: ill.

10. Electrical equipment e and power supply of electrothermal installations: method. directions to the lab. work / comp. A.N. Mironova, E.L. Lvov; Chuvash. un-t. Cheboksary, 2011. 48 p.

11. Baptidanov L.N. Basic electrical equipment, diagrams and designs of switchgears: a textbook for energy technical schools / L.N. Baptidanov, V.I. Tarasov. T.1. M.: State. Energy publishing house, 1947. 399 p.

12. Electrical equipment of electric welding installations: method. directions to the lab. work / comp. Yu.P. Ananin, Yu.M. Petrosov. Cheboksary: Chuvash Publishing House. un-ta, 2013. 48 p.

13. Orlov L.L. Optimization of the structure and technical and economic characteristics of digital substations / Relay protection automation, 02.06.2012. S. 66.

14. Daryan L.A. Digital measuring transformers. New approaches to the development of measuring equipment / L.A. Darian, A.P. Petrov, N.N. Dorofeev, A.V. Kozlov. Relay protection of automation, 04.12.2012. P.44.

15.Andreev V.A.. Relay protection and automation of power supply systems / V.A. Andreev. M.: Higher. school, 2008. 640 s

16.Vasilyeva V.Ya. Operation of electrical equipment of power stations and substations: textbook. allowance / V.Ya. Vasilyeva, G.A. Drobikov, V.A. Lagutin. Cheboksary: Chuvash Publishing House. un-ta, 2000. 864 p.

17. Mironova A.N. Rational operation of electrotechnological installations: textbook. allowance / A.N. Mironova, I.A. Lavigne. Cheboksary: Chuvash Publishing House. un-ta, 2008. 210 p.

18 . Rules for the installation of electrical installations. 7th ed. St. Petersburg: DEAN, 2004.

19. GOST 7746-2001. Current transformers. General specifications. M.: Publishing house of standards, 2003.

20. GOST 1983-2001. Voltage transformers. General specifications. M.: Publishing house of standards, 2003.

21. GOST R-52373-2005. Self-supporting insulated and protected wires for overhead power lines.

22. TU 16. K10-017-2003. Wires with protective insulation for overhead transmission lines of voltage 35 kV / JSC "Sevkabel". 2003.

23. Kudrin B.I. Power supply of industrial enterprises: a textbook for students of higher education. textbook institutions / B.I. Kudrin. 2nd ed. M.: Intermet Engineering, 2006. 672 p. ill.

24. Knorring G.M. Reference book for the design of electrical lighting / G.M. Knorring, I.M. Fadin, V.N. Si-dorov. St. Petersburg: Energoatomizdat, 1992. 288 p.

25. Svenchansky A.D. Electrotechnological industrial installations: a textbook for universities / I.P. Evtyukova, L.S. Katsevich, N.M. Nekrasov, A.D. Svenchansky; ed. HELL. Svenchansky. M.: Energoatomizdat, 1982. 399 p. ill.

26. Milyutin V.S. Power sources for welding: textbook. allowance / V.S. Milyutin, V.A. Korotkov. Chelyabinsk: Metallurgy of the Urals, 1999. 368 p.

27. Vereshchago E.N. Circuitry of inverted power sources for arc welding: textbook. allowance / E.N. Vereshchago, V.F. Kvasnitsky, L.I. Miroshnichenko, I.V. Pentegov. Nikolaev: UGMTU, 2000. 283 p.

28. Makarova I.V. Welding transformer or inverter, which is more expensive? // I.V. Makarov. Rhythm. 2009. No. 8 (46). Oct. S. 27.

29. Specialized catalogs of the group of companies "Weber Comechanics". 2007. No. 2.

30. Lvova E.L. Estimation of probabilistic characteristics of higher current harmonics of a group of electric arc furnaces / E.L. Lvov. Automated electrotechnological installations and systems. Cheboksary: Chuvash Publishing House. un-ta, 1989. S. 29-34.

31. Lvova E.L. Analysis of the harmonic composition of the melting process of the EAF group / E.L. Lvov. Inter-republican scientific and technical. foundry workshop "Modern technological processes for obtaining high-quality castings, increasing the durability of foundry equipment and cutting tools." Cheboksary, 1987, p. 72.

32. Lvova E.L. Determination of reactive power of arc steel furnaces / E.L. Lvova, N.B. Yosha, G.A. Germans. Industrial energy. 1991. No. 5. pp. 39-42.

33. Lvova E.L. Substantiation and development of a method for calculating the power of compensating devices with a sharply variable load / E.L. Lvova, G.A. Nemtsev, V.P. Shutsky // International Symposium "Mining Technology on the Threshold of the 21st Century". M., 1996. S. 469-480.

34. Lvova E.L. Issues of reactive power compensation in networks with arc furnaces. / E.L. Lvova, A.N. Mironova // 8th Intern. conf. on mining, construction and energy issues. Tula: TulGU, 2012, pp. 503 – 508.

35. Fishler Ya.L. Converter transformers / Ya.L. Fischler, R.N. Urmanov. M.: Energy, 1974. 224 p.: ill.

36. Chunikhin A.A.. High voltage devices / A.A. Chunikhin, M.A. Zhavoronkov. Moscow: Energoatomizdat, 1985.

37. Svenchansky A.D. Power sources and high-voltage switches for electrothermal installations / A.D. Svenchansky, M.D. Bershitsky // VIII All-Union. conference on electrothermy and electrothermal equipment (Cheboksary, July 3-5, 1985): proc. reports: M.: Informelectro, 1985. S.147-148.

38. Electrical equipment of electrotechnological installations: method. instructions for course design / comp. A.N. Mironova, E.Yu. Smirnova; Chuvash. un-t. Cheboksary, 2003. 64 p.

39. Vagin G.Ya. Electromagnetic compatibility of arc furnaces and power supply systems / G.Ya. Vagin, A.A. Sevastyanov, S.N. Yurtaev // Tr. Nizhny Novgorod. state tech. un-ta im. R.E. Alekseev. 2010. No. 2 (81). pp. 202 - 210.

40. Ignatov I.I. Mathematical modeling of electric regimes of an arc steel-smelting furnace / I.I. Ignatov, A.V. Hainson // Electricity. 1985. No. 8.

41. Dragunov V.K. Modern development of ELS / V.K. Dragunov, A.L. Goncharov// Specialized magazine. 2009. No. 8 (46). pp. 28-30.

42. Lvova E.L. Effective use of compensating devices in the conditions of industrial enterprises / E.L. Lvova, A.N. Mironova // Socio-economic development of Russia: experience, prospects and innovations: Sat. scientific tr. / ed. professor O.G. Maksimova. Cheboksary: CHIEM SPb GPU, 2009. S. 286-290, 305.