Mobile electrical laboratory

Electrotechnical laboratory of LLC "Judicial and non-state construction expertise" GARANT EXPERT "- professional assessment of the quality of acceptance and electrical installation works, establishing the compliance of installed electrical installations with regulatory documentation and a wide range of measurements and tests of electrical equipment.

The laboratory is certified by the territorial authority of Rostechnadzor in accordance with the General Requirements for the Certification of Electrical Laboratories and Thermal Measurement Laboratories and complies with GOST / IEC 17025-2019 General Requirements for the Competence of Testing and Calibration Laboratories.

Experts of the electrical laboratory of LLC "Judicial and non-state construction expertise" GARANT EXPERT "study the latest developments in the field of measuring and test equipment, methods of its application, monitor changes in the regulatory and technical base within their competence. Modern high-precision instruments of foreign and domestic production allow making measurements with the smallest error, including in industrial networks with an alternating current frequency of 400 Hz.

The devices used are in the State Register of Measuring Instruments of the Russian Federation and are supplied with licensed software. All equipment used undergoes regular operational checks, has valid certificates of metrological verification, and the software is updated in a timely manner.

We implement advanced solutions in the production process, for example, measuring the parameters of 0,4kV electrical installations using automatic sequences. Modern equipment and software allow us to pre-program the sequence of measurements, set the parameters and limits of individual single tests and issue the results in the form of Russian-standard protocols, which significantly reduces the time for production and execution of work.

Highly qualified certified specialists with experience in specialized work on complex industrial and civil objects, the presence of a mobile laboratory, a constantly improving park of modern devices, give us the opportunity to competently and promptly measure and test the parameters of electrical installations practically throughout the country.

The electrical laboratory of LLC "Judicial and non-state construction expertise" GARANT EXPERT "guarantees the impartiality, independence and reliability of the results of our work, the fulfillment of the tasks set with high quality and on time.

Electrotechnical laboratory services

Experts of the electrical laboratory of LLC "Judicial and non-state construction expertise" GARANT EXPERT "offer the following services in the diagnosis of electrical installations:

Visual inspection 

This type of work provides for the analysis of design documentation and verification of the installed electrical installation for compliance with design and regulatory documentation. Inspection of electrical control rooms, switchgears up to and above 1000V, main and secondary switchboards, secondary circuits, protection devices, electrical wiring and cable lines inside buildings, grounding device, potential equalization system elements, interior lighting, lighting fixtures and wiring accessories, marking of electrical installation elements ... Based on the results of a visual inspection, a protocol is drawn up on the compliance or non-compliance of the mounted electrical installation with the requirements of regulatory documents.

Measurement of resistance of grounding conductors and grounding devices. Measurement of soil resistivity using the Venus method

Measurements are carried out to establish the actual resistance of the grounding devices, which should not exceed the standardized values ​​at any time of the year. The resistance of the grounding device is variable and changes throughout the year depending on the specific resistance of the soil, which depends on the temperature and moisture content. Measurements are best done during the period of the most unfavorable conditions, these are periods with the greatest freezing and drying of the soil.

Measurement of soil resistivity is necessary before starting the design of grounding and lightning protection systems, or if the actual resistance of the grounding devices does not meet the standards, in this case, the permissible degree of non-compliance is checked with an increased specific soil resistance. 

Checking the presence of a circuit between a grounded electrical installation and elements of a grounded electrical installation

The presence of a circuit (metal connection) is checked by measuring the contact resistance of contact connections between a grounded electrical installation and elements of a grounded electrical installation, including collapsible contact connections in these conductors. All protective conductors, including grounding conductors, as well as conductors of equipotential bonding systems should not have breaks and broken contacts at the points of their connection to open and third-party conductive parts. The presence of the circuit and the continuity of the conductors is established by measuring the resistance of the contact connections, which should not exceed the specified values. The absence or disruption of the metal connection between the elements can lead to the occurrence of dangerous voltage on the conductive parts of the equipment, and, the possibility of electric shock to a person.

 Measuring voltage, frequency, checking phase sequence

The mains voltage test is carried out to establish whether the measured voltage corresponds to the range of the voltage used. Modern electrical equipment and household electrical appliances can operate with a wide range of applied voltages. This range should be between the lowest and highest operating voltage under normal operating conditions, excluding transient and abnormal conditions, at any time and at any point in the electrical system. Electrical equipment must be used in accordance with standard voltages, while the highest voltage of the electrical network for electrical equipment must be less than or equal to the highest voltage for electrical equipment. 

When checking the frequency of the power supply voltage, a value is measured that should not differ from the nominal value of the frequency of the power supply voltage, more than permissible. The main effect of changing the frequency is to change the speed of rotation of electrical machines. The power consumption of the motors increases or decreases. Any electrical and electronic equipment that uses the frequency of the current in the electrical system as a time indicator is also affected. 

Checking the phase sequence is necessary in three-phase networks to prevent incorrect operation of electrical equipment, prevent accidents and prevent personal injury. Depending on the sequence of connecting electrical equipment to the outlets of the electrical network, a direct and reverse phase sequence can be observed. With the direct phase sequence, the electrical network leads and electrical equipment are connected correctly, the operation of three-phase metering devices is correct, the rotation of the electric motor mechanisms occurs in the right direction, it is possible to parallel power transformers, generators and a number of other electrical machines into operation. When the phase sequence is reversed, the rotation of the electric motor mechanisms occurs in the opposite direction, which can lead to an emergency and personal injury, incorrect operation of metering devices is possible, parallel connection to the operation of electrical machines can lead to a short circuit.

Insulation resistance measurement

Insulation resistance is checked for electrical wiring, cable lines, electrical equipment and secondary circuits with a megohmmeter for voltages from 100 to 2500V. Measurement of insulation resistance is based on Ohm's law and allows you to determine the margin of safety and identify insulation defects. Based on the measurement results, the compliance of the insulation resistance with the standards is established in order to ensure human safety from electric shock and for fire safety purposes. By measuring the insulation resistance at appropriate time intervals, it is possible to determine the dielectric absorption coefficient DAR (the degree of moisture of the insulation dielectric) and the polarization factor PI (the degree of aging of the insulation). Measurements are made on completely disconnected electrical installations.

Checking circuit breakers up to 1000V

Tests of trip units of automatic switches (electromagnetic, thermal, semiconductor) are carried out in order to check the compliance of their operation limits. The parameters of the circuit breakers must comply with the manufacturer's data, provide protection against electric shock in case of short circuits and protect networks from overloads and fires caused by technological overloads or insulation damage. Ensuring the requirements of protection against electric shock in case of indirect contact by means of automatic power off must be ensured by the normalized disconnection time of the damaged section of the circuit.

Phase-to-zero loop measurement

Measurement of the "phase-zero" loop is carried out to establish whether the choice of the protection device corresponds to the expected short-circuit current of the line. The short-circuit current is determined taking into account the impedance of the phase-to-zero loop. If the wrong choice of the protective device and the occurrence of an overcurrent, the line will be disconnected untimely, which can lead to the danger of electric shock by indirect contact, damage to electrical equipment or even a fire. The obtained value of the expected short-circuit current of the line is compared with the time-current characteristic of the protection device. Based on the results of the comparison, the correct choice of the protection device is established for the timely disconnection of the line in case of a short circuit. If the single-phase current leads to the operation of the switching-protective devices during the normalized power-off time, then the continuity of the protective conductors is considered to be ensured.

Checking residual current devices

Checking of residual current devices is carried out to establish the possibility of quick disconnection of the protected line in the event of a leakage current. Residual current circuit breakers are controlled by differential current and are subdivided into residual current circuit breakers (RCCB) and residual current circuit breakers (RCBO). RCCBs provide protection against indirect contact. RCBOs provide protection against indirect contact and protection of lines against overloads and short-circuit currents. Residual current devices are also used to increase fire safety, in this case, when a leakage current occurs in the event of a fault, the protected line must be quickly disconnected to prevent ignition from heat release. When checking the RCD, the differential breaking current is measured, checked for operation of the RCD at half the value of the rated differential breaking current and its operation at the rated value of the differential breaking current during the specified time.  

Measurement of current and power in AC circuits

Measurements are made to check the compliance of the selection of conductor cross-sections for long-term permissible currents and the compliance of the power of consumers with the declared (design) loads. Measurements are made in the event of frequent shutdowns of the overload protection switching devices, when traces of damage to the cable insulation from possible overheating from overload are detected. 

Thermal imaging inspection of electrical equipment

Produced according to the instructions of the electrical equipment manufacturing plants, or in a complex manner. Thermal imaging survey allows you to determine the overheating zones or differences in operating temperatures, to establish possible overloads, broken contact connections of electrical equipment. A timely thermal imaging inspection of electrical equipment can prevent the development of accidents with the repair of electrical equipment and shutdown of technological processes, and avoid fire hazardous situations.

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