On the frequency of testing electrical equipment. Testing of electrical equipment and automation equipment includes: acceptance, preventive, rejection, operational, control, standard (special) Testing of power equipment
After equipment repair or completion of installation work, inspections must be carried out, since the devices may be damaged during transportation or installation.
Types of testing of electrical equipment during commissioning
The study must first meet the technical specifications. It allows you to establish the overall serviceability of the system, identify the presence of defects and obtain initial data for preventive maintenance.
There are the following types of testing of electrical equipment:
- electrical installation type tests,
- acceptance tests of electrical installations,
- operational testing of electrical installations,
- control tests of electrical installations,
- special electrical installation tests.
Typical types of testing of electrical equipment during commissioning are carried out by the manufacturer in order to verify compliance with all established requirements that apply to units of this type.
Acceptance checks are carried out after the installation of equipment is completed in order to determine its readiness for operation. Each product undergoes a control test at a certain stage of production; it is carried out according to an abbreviated program.
Equipment that is located in the working system is subjected to operational testing. This check is carried out during major, unscheduled and routine repairs in order to accurately determine the serviceability of all devices and mechanisms.
Special tests are usually carried out for research purposes for specifically established programs.
MOSENERGOTEST LLC will perform any type of high-voltage testing of electrical equipment in the shortest possible time at attractive prices. Our employees will quickly calculate the cost of electrical laboratory work and go to the site to conduct research. We will also carry out any types of technical reports.
Licenses and certificates
Testing and measuring parameters of electrical equipment of electrical installations
Electrical equipment is a set of electrical devices designed to perform specific functions. It can provide safe and reliable operation if the design is suitable for the environmental conditions and operating conditions.
Tests- This is a type of control. The testing system includes the following main elements:
1) test object- product being tested. The main feature of a test object is that, based on the test results, a decision is made on this particular object: about its suitability or rejection, about the possibility of submitting it for subsequent tests, about the possibility of serial production, etc. The characteristics of the properties of an object during testing can be determined by measurements, analyzes or diagnostics;
2) test conditions- this is a set of influencing factors and (or) operating modes of an object during testing. Test conditions can be real or simulated, provide for determining the characteristics of an object when it is functioning and not functioning, in the presence of influences or after their application;
3) testing facilities- these are technical devices necessary for testing. This includes measuring instruments, test equipment and auxiliary technical devices;
4) test performers- these are the personnel involved in the testing process. He is subject to requirements for qualifications, education, work experience and other criteria;
5) normative and technical documentation (NTD) for testing, which consists of a set of standards regulating the organizational, methodological, regulatory and technical basis for testing; a set of standards for the system of development and production of products; regulatory, technical and technical documents regulating requirements for products and test methods; Regulatory and technical documents regulating the requirements for testing tools and the procedure for their use.
Measurements and tests in electrical installations are carried out in accordance with the requirements of the Rules for the Construction of Electrical Installations (PUE) and the Rules for the Technical Operation of Consumer Electrical Installations (PTEEP) by specialized electrical laboratories (ETL).
The purpose of measurements and tests is to verify the compliance of the measured quantities with regulatory requirements that ensure the safe operation of electrical installations.
Tests and measurements of parameters of electrical equipment of electrical installations are carried out during major repairs, during routine repairs and during between-repair tests and measurements, i.e. during preventive tests performed to assess the condition of electrical equipment and not related to the removal of electrical equipment for repair.
The following types of tests and measurements are most often carried out in electrical installations up to 1000 V:
- Ø Measurement of insulation resistance of electrical wires and cable lines;
- Ø Measurement of single-phase short circuit current in the “phase-zero” circuit;
- Ø Measurement of resistance of grounding devices;
- Ø Checking the circuit between grounding conductors and grounded elements;
- Ø Checking residual current devices (RCDs);
- Ø Checking circuit breakers with thermal and electromagnetic releases.
The specific timing of tests and measurements of electrical equipment parameters is determined by the Consumer's manager based on Appendix 3 of the PTEEP, taking into account the recommendations of factory instructions, the state of electrical installations and local conditions.
The required scope of testing and measuring parameters of electrical equipment can be determined together with ETL employees professionally involved in testing electrical installations. Although any energy engineer can do this on their own.
Timely and high-quality testing and measurements of electrical equipment parameters ensure its safe and trouble-free operation.
- Ø Measuring the insulation resistance of electrical wires and cable lines:
Monitoring the insulation resistance is necessary, since during the operation of electrical equipment for various reasons (natural aging, heating due to overloads, humidification, etc.) its decrease may occur and, as a result, insulation breakdown followed by a short circuit, equipment damage and fire.
To measure the insulation resistance of electrical equipment that is not energized, the Eurotest VE 2.5 kV MI 3102H CL megohmmeter is used.
Measuring the insulation resistance of electrical equipment should be preceded by a thorough inspection of visible elements of electrical installations. Equipment rejected during external inspection must be repaired or replaced.
The insulation resistance must be measured:
- between current-carrying conductors, taken in turn relative to each other;
- between each live conductor and the ground;
- between current-carrying conductors while excluding the influence of leakage currents (the shielding circuits are grounded).
Shielding is used in cases where it is necessary to exclude the influence of the surface of the insulating structure or to limit the area of controlled insulation.
The obtained measurement results must meet the requirements of the Electrical Installation Rules, ed. sixth, revised and additionally, with changes; ed. seventh, section 1 (chap. 1.1; 1.2; 1.7; 1.8; 1.9), section 6, section 7 (chap. 7.1; 7.2; 7.5; 7.6; 7.10) and the Rules for the technical operation of consumer electrical installations, otherwise the equipment is rejected.
- Ø Measuring the current of a single-phase short circuit in a “phase-zero” circuit:
Measuring the single-phase short circuit current is necessary in order to assess the possibility of the protection triggering when a short circuit occurs. That is, it is necessary to make sure that the amount of current generated during a single-phase short circuit is sufficient to trip the circuit breaker release or blow out the fuse link within the maximum permissible time.
To perform measurements, instruments are used that are included in the Gosstandart register, in good working order and timely verified (once every 12 months) by enterprises (organizations) accredited for this type of work.
Measurements are carried out after successful testing of the grounding device and insulation of live parts of the electrical installation.
When preparing to carry out measurements, it is necessary to determine the most powerful and remote electrical installations from the power source, the phase-zero circuits of which are checked.
Measurements should begin with a visual inspection of the phase-zero circuit, which is necessary to establish the presence of mechanical damage to the circuit breakers and fuses, the neutral wire circuit, as well as compliance of the cross-section of the neutral wire with the requirements of the PUE.
The impedance is measured between the phase and neutral working and protective conductors alternately.
The measurement results must be recorded in the appropriate measurement protocol, signed by persons entitled to do so.
The obtained measurement results must meet the requirements of the PUE and PTEEP.
- Ø Measuring the resistance of grounding devices:
Grounding is one of the most important functions in protecting people, animals and connected loads from the effects of electric current.
Periodic monitoring of the grounding resistance is necessary, since during operation the metal parts of grounding devices are destroyed by corrosion. If the open parts of the grounding device can be inspected visually, then its part hidden underground can be checked using special equipment. The work is carried out by enterprises (organizations) that have permission to carry out this type of work. To carry out measurements, instruments are used that are included in the Gosstandart register and are in good working order and timely attorneys.
Measuring the resistance of the grounding device is preceded by a thorough inspection of the visible elements and welded connections of the grounding device. A grounding device rejected during external inspection must be repaired.
Resistance measurements that have undergone visual inspection are carried out by our electrical laboratory using the “EurotestXE 2.5 kV Electrical Installation Parameter Meter MI 3102HCL”.
- Ø Checking the circuit between grounding conductors and grounded elements:
The above-mentioned conductors are an important part of the protective system that protects everything in the room from dangerous voltage damage (dangerous in the aspect of duration as well as in the sense of absolute value). These conductors can serve this purpose successfully only if they are properly sized and properly connected. This is why it is important to check their continuity and connection resistances. Conductors that are too long, with a cross-section that is too small, poor contacts, incorrect connections, etc. may cause unacceptably high resistance of protective conductors. Poor contacts are the most common cause of high resistance, especially in older installations, while the other causes listed may cause problems in new installations. Testing the circuit between the ground electrodes and the earthed elements is preceded by a thorough inspection. Chains rejected during external inspection must be repaired.
The resistance of a circuit that has passed a visual inspection is measured by our electrical laboratory using the “EurotestXE 2.5 kV Electrical Installation Parameter Meter MI 3102H CL”.
The measurement results are recorded in the appropriate measurement protocol, signed by persons entitled to do so.
The obtained measurement results must meet the requirements of the PUE and PTEEP, otherwise the equipment is rejected.
- Ø Checking residual current devices (RCDs):
Damage in the electrical network is the most common cause of fires, but approximately 20% of all fires can be prevented with the proper use of a residual current device (RCD), which is designed to protect people from electric shock due to electrical equipment malfunctions or contact with live parts of an electrical installation. The purpose of measurements and tests is to check the compliance of technical parameters and installation of residual current devices with current standards and regulations (PUE, GOST, PTEEP).
When testing an RCD, the following functions can be performed:
- Touch voltage measurement;
- Measurement of response time;
- Trigger current measurement;
- Automatic RCD test.
When testing an RCD, the following parameters and limit values can be set:
- Maximum permissible touch voltage;
- Rated differential current of RCD operation;
- Multiplier of the rated differential current of the RCD;
- RCD type;
- Initial polarity of the measuring current;
- Maximum permissible touch voltage.
The safe touch voltage for standard residential installations is limited to 50 VAC. Under special operating conditions (hospitals, rooms with high humidity, etc.), the touch voltage limit is limited to 25 V AC.
Rated differential current of RCD operation.
The rated differential operating current of the RCD is set in accordance with the specified differential operating current of the RCD being tested.
Our electrical laboratory checks the RCD using the “EurotestXE 2.5 kV Electrical Installation Parameter Meter MI 3102H CL”.
The measurement results are recorded in the appropriate measurement protocol, signed by persons entitled to do so.
The obtained measurement results must meet the requirements of the PUE and PTEEP, otherwise the equipment is rejected.
- Ø Checking circuit breakers with thermal electromagnetic releases:
Tests of circuit breaker releases are carried out to verify compliance of the time and temperature limits of their operation with the manufacturer’s data, PUE, GPEEP, GOST R-50669-94, RD 34.35.613-89, GOST R 50571.3-94.
The work is carried out by enterprises (organizations) that have permission to carry out this type of work. To perform measurements, instruments are used that are included in the Gosstandart register, are in good working order and have been verified in a timely manner.
Measuring the resistance of the grounding device is preceded by a thorough inspection. Circuit breakers rejected during external inspection must be replaced.
Circuit breakers that have passed visual inspection are checked using the Saturn M1 complete testing device.
The measurement results are recorded in the appropriate measurement protocol, signed by persons entitled to do so.
The obtained measurement results must meet the requirements of the PUE and PTEEP, otherwise the equipment is rejected.
Purpose of testing electrical equipment- checking compliance with the required
technical features, establishing the absence of defects, obtaining
initial data for the next prevention trials, also a study
equipment operation. The following types of tests are distinguished: 1) standard; 2)
control; 3) acceptance; 4) operational; 5) special.
Typical tests of new equipment, different from the existing one
design, materials or technological process adopted in its
manufacturing are carried out by the manufacturer to verify compliance
all requirements imposed on equipment of this type by standards or
technical criteria.
Control tests Each product (machine, apparatus, device and
etc.) upon release from the manufacturer to check the conformity of the product
products to the main technical requirements. Control tests are carried out according to
abbreviated (compared to standard tests) program.
Acceptance tests everything is subjected again upon completion of installation
equipment being put into operation to assess its suitability for operation.
Equipment in operation, including those beyond repair,
exposed operational tests, the purpose of which is to check it
serviceability Operational tests are for serious and ongoing
repairs and preventive tests not related to the removal of equipment
repair.
Special tests are carried out for research and other purposes for
special programs.
Programs (also norms and methods) for standard and control tests
established by GOSTs for the corresponding equipment. Volume and norms
acceptance tests are determined by the “Rules for the Construction of Electrical Installations”.
Operational tests are carried out in accordance with the “Test Standards”
electrical equipment" and "Rules for technical operation of electrical installations
consumers." During acceptance and operational tests
it is necessary to additionally take into account the requirements of industrial and departmental
instructions.
A certain part of the test work is common when setting up different
parts of electrical installations. Such work includes checking circuits
electronic connections, insulation checking and testing, etc.
Checking electronic connection diagrams
Checking electronic connection diagrams includes:
1) familiarization with design switching diagrams as fundamental ones
(full), and installation, also a cable magazine;
2) checking the compliance of the installed equipment and equipment with the project;
3) inspection and verification of compliance of installed wires and cables (brand,
material, section, etc.) to the project and current rules;
4) checking the presence and correctness of markings on the ends of wires and cores
cables, terminal blocks, device terminals;
5) checking the installation properties (reliability of contact connections, installation
wires on panels, cable routing, etc.);
6) checking the correct installation of circuits (continuity);
7) checking circuits of electronic circuits under voltage.
Primary and secondary switching circuits are inspected in full when
acceptance tests after completion of installation of the electrical installation. At
In preventive tests, the scope of switching checks is significantly reduced.
Installation errors or other deviations from the
the project is taken care of by adjusters or installers (depending on the volume and nature of
work). Fundamental configurations and deviations from the design are only permissible
after agreeing with the design organization. All configurations must be
shown in the drawings.
Inspection, testing and adjustment of electrical equipment.
General information. Before carrying out measurements related to setting up or testing devices, a set of preparatory measures must be carried out:
thorough inspection of the tested object in order to identify and eliminate defects;
studying the electrical circuit and establishing standards for test voltages and currents
drawing up a measurement diagram indicating the necessary devices, their class, measurement limit, permissible insulation resistance, etc.;
ensuring the necessary conditions for measurement (temperature, humidity, surface cleanliness, lighting, etc.) and safe performance of work;
preparation of the workplace and necessary equipment in accordance with the measurement scheme.
When making high voltage measurements, special attention must be paid to the quality of the equipment connection to the ground loop, checking it visually or using an ohmmeter.
All work should be carried out strictly observing safety regulations.
Selection of devices. Measuring instruments, depending on their purpose, area of application and operating conditions, should be selected according to the following basic principles:
it must be possible to measure the physical quantity under study;
The measurement limits of the device must cover all possible values of the measured quantity. With a large range of changes in the latter, it is advisable to use multi-limit devices;
the device must provide the required measurement accuracy. Therefore, you should pay attention not only to the class of the selected device, but also to the factors influencing the additional measurement error (non-sinusoidal currents and voltages, deviation of the position of the device when installing it in a position other than normal, influence knowledge of external magnetic and electric fields, etc.);
when carrying out some measurements, an important role is played by the efficiency (consumption) of the measuring device, its weight, dimensions, location of controls, scale uniformity, the ability to read readings directly from the scale, speed, etc.;
connecting the device should not significantly affect the operation of the device under study, therefore, when choosing devices, their internal resistance should be taken into account. When connecting the measuring device to matched circuits, the input or output resistances must be of the required nominal value;
the device must satisfy the general technical safety requirements when making measurements, established (GOST 22261-76), as well as technical specifications or private standards;
It is not allowed to use devices: with obvious defects in the measuring system, housing, etc.; with expired verification period; non-standard or not certified by the departmental metrological service; the insulation class does not correspond to the voltages to which the device is connected.
Determination of measurement error. The deviation of the measurement result from the true value of the measured value is called measurement error.
The error inherent in the measuring instrument under normal conditions of use (GOST 22261-76) is the main one. If one of the influencing quantities deviates beyond the limits established for the normal value or the region of normal values, additional errors appear. The limits of permissible main and additional errors of measuring instruments are established in the form of absolute, reduced, relative errors or in the form of a certain number of divisions.
The absolute measurement error Δ is expressed in units of the measured value and is defined as the difference between the measured Hizm. and the true values of the measured quantity X, i.e. Δ = Khiz. — X.
Due to the fact that the true value of the measured quantity is unknown, in practice they use the actual value of the quantity, found experimentally and closest to the true value.
The quality of measurement is most fully characterized by the relative measurement error δ, equal to the ratio of the absolute measurement error to the true (actual) value of the measured quantity, X:
For a comparative assessment of the accuracy of pointer instruments, we use the concept of the reduced instrument error γ, % - the ratio of the absolute error to the limit value of the scale:
The value of Xk is assumed to be equal to: the final value of the scale - for instruments with a one-sided scale; the sum of the final values of the instrument scale - for instruments with a double-sided scale; the difference between the final and initial values of the range - for devices with a zero-left scale; the length of the scale, if the scale has sharply tapering divisions.
Measuring instruments whose permissible error limits are expressed in the form of relative or reduced errors (according to GOST 13600-68) are assigned accuracy classes selected from a number of numbers (1; 1.5; 2; 2.5; 3 ; 4; 5; 6).
For pointer instruments, the accuracy class determines the maximum permissible value of the basic reduced measurement error. Knowing the accuracy class of the device, you can determine the limit of the relative measurement error:
Often the value of the desired quantity A is determined indirectly based on the results of several measurements related to the desired quantity by known dependencies. In this case, the relative error is determined as follows:
δ l=(| A δа| + | B δв| + | С δс |+..-)/Л, where δ а, δв, δс - relative errors of measurement of values В, С, В;
TYPES OF TESTS OF ELECTRICAL EQUIPMENT.
During the installation process and after its completion, as well as under operating conditions, the electrical equipment of electrical installations undergoes inspection, testing and adjustment.
Electrical equipment may be damaged during transportation and installation. During operation, it may be damaged due to natural wear and tear, as well as design defects.
The adjustment of electrical equipment is subject to regulated requirements, to comply with which the following tests are carried out:
typical in accordance with current GOSTs;
acceptance in accordance with the PUE, and in some cases with the instructions of the Ministry of Energy;
preventative and others in accordance with the Rules for the technical operation of electrical stations and networks (PTE), the scope and standards of testing electrical equipment and instructions for individual elements of electrical equipment.
Typical tests are carried out at manufacturing plants according to the programs and with the volumes specified in the standards and technical specifications, but some of them can be carried out at the installation site of electrical installations. During type tests, the compliance of electrical equipment with the requirements imposed on it by standards is checked.
Acceptance tests are carried out in newly constructed and reconstructed installations up to 500 kV. During testing, the compliance of the installed equipment with the design is determined, the necessary characteristics are taken and a certain amount of measurements are performed. After reviewing the test results, a conclusion is made on the suitability of the equipment for operation.
Preventive tests are carried out during the operation of the equipment, which allows expanding the possibilities of detecting defects for the purpose of timely repair or replacement of equipment.
Electrical equipment is regularly tested, which pursue the goals of checking compliance with established technical characteristics, obtaining data for carrying out the following preventive tests, establishing the absence of defects, as well as studying the operation of electrical equipment. The following types of tests are distinguished: operational, acceptance, control, standard, special.
Type tests are used for new equipment, which differs from old models in its updated design and device. This type of testing is carried out by the manufacturer in order to verify compliance with all requirements and standards that apply to this type of equipment or technical conditions.
To check the compliance of the manufactured product with all the main technical requirements, each product is subjected to control tests (apparatus, machine, instrument, etc.). To carry out control tests, as a rule, a reduced work program is used (compared to standard ones).
Acceptance tests used after completion of installation of newly commissioned equipment in order to assess its suitability for operation.
Performance tests are carried out for equipment in operation, including those that have undergone repair. This type of test is used to determine the serviceability of the equipment. Operational tests include tests during current and major repairs, as well as preventive tests that are not related to the removal of equipment for repair.
For research purposes or other special programs, special tests may be carried out.
Some of the testing work is carried out similarly for almost all elements of electrical equipment. These types of work include: testing and monitoring of electrical connection diagrams.
When checking electrical connection diagrams, the following actions are carried out:
1) familiarization with technical information on the facility - installation and fundamental (complete) switching diagrams, cable log are studied;
2) checking for compliance with the design of real equipment and equipment;
3) checking and inspecting the compliance of cables and wires (section, material, brand, etc.) with the current rules and design;
4) control of the correctness and presence of markings on cable cores and wires, device terminals, terminal blocks;
5) quality control of installation (cable laying, cable laying on panels, reliability of contact connections, etc.);
6) continuity testing (monitoring the correct installation of circuits);
7) testing the reliability of electrical circuits when voltage is applied.
The most complete tests in the primary and secondary switching circuits are carried out during acceptance tests after completion of installation. During maintenance tests, the number of switching control operations is significantly reduced. Installers or adjusters must eliminate deviations from the design or installation errors discovered during the inspection. In order to change or deviate from the project, it is necessary to first obtain the consent of the design organization. Any such changes must be provided in the form of drawings.
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