Grounding devices

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Annex 3. Standards for testing electrical equipment and apparatus for electrical installations of consumers

Grounding devices

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Encyclopedia of radio electronics and electrical engineering / Rules for the technical operation of consumer electrical installations (PTE)

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K, T, M - are produced within the time limits established by the PPR system.

Name of the test	Type of test	Test norms	Directions
26.1. Checking the connections of grounding conductors with grounded elements, including natural grounding conductors	K, M	The check is made to detect breaks and other defects by inspection, tapping with a hammer and measuring transient resistances. Checking the connection with natural grounding conductors is carried out after the repair of grounding conductors	In the case of measuring transient resistances, it should be taken into account that the resistance of a good connection does not exceed 0,05 Ohm For cranes, the presence of a chain must be checked at least once a year.
26.2. Checking the touch voltage on the territory of the electrical installation and the voltage on the grounding device	K, M	The maximum voltage must not exceed: 500 V at exposure time 0,1 s 400 V at exposure time 0,2 s 200 V at exposure time 0,5 s 130 V at exposure time 0,7 s 100 V at exposure time 1 s 65 V with duration of exposure from 1 s to 5 s	Produced in electrical installations, made according to the standards for touch voltage at control points, in which the values of the touch voltage are determined during design, after a major overhaul of ground electrodes The duration of exposure is taken as the total time of operation of the backup relay protection and the intrinsic time of switching off the switches
	М	Intermediate allowable stresses in the time interval from 0,1 s to 1 s should be determined by interpolation
26.3. Checking the condition of the elements of the grounding device located in the ground:		The corrosion condition is checked at least once every 1 years. The ground electrode element must be replaced if more than 12% of its section is destroyed
1) electrical installations, except for overhead lines		Checking of grounding switches in outdoor switchgear of power plants and substations is carried out selectively, in places most susceptible to corrosion, as well as near the grounding points of neutrals of power transformers, connections of arresters and surge arresters	In ZRU, inspection of grounding elements is carried out by decision of the technical manager of the Consumer
2) VL		On overhead lines, a random check with the opening of the soil is carried out for at least 2% of the poles of the total number of poles with ground electrodes	The check should be carried out in a populated area, in areas with the most aggressive, blown and poorly conductive soils.
26.4. Measurement of resistance of grounding devices:
1) supports of overhead power lines	K, T, M	The values of the resistance of the earthing of supports are given in Table 35 (Annex 3.1)	They are carried out after repairs, but at least once every 1 years for overhead lines with a voltage of up to 6 V and 1000 years for overhead lines above 12 V on poles with arresters and other electrical equipment and selectively at 1000% of metal and reinforced concrete poles in areas in populated areas. Measurements are also made after the reconstruction and repair of grounding devices, as well as when damage or traces of overlapping of insulators by an electric arc are detected.
2) electrical installations, except for overhead power lines	K, T, M	The resistance values of the grounding devices of electrical installations are given in Table. 36 (Annex 3.1)
26.5. Checking the condition of blow-out fuses in installations up to 1000 V	K, T	Fuses must be serviceable and correspond to the rated voltage of the network	Produced at least once every 1 years, as well as under the assumption of operation

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