Power cable lines

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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

Power cable lines

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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
6.1. Determination of the integrity of the cores and phasing	K, T	All cores must be intact and in phase	It is carried out after the installation is completed, the couplings are remounted or the cable cores are disconnected.
6.2. Insulation resistance measurement	K, T, M	The insulation resistance of power cables with voltage up to 1000 V must be at least 0,5 MΩ. For power cables with voltages above 1000 V, the insulation resistance is not standardized	Produced by a megohmmeter for a voltage of 2500 V for 1 min.
6.3. Rectified voltage test	K, T, M	Test voltages are taken in accordance with Table. 10 (Appendix 3.1) taking into account local operating conditions of power cable lines Duration of test voltage application: for cables for voltage up to 35 kV with paper and plastic insulation during acceptance tests - 10 minutes, and during operation - 5 minutes. cables for voltage 3 - 10 kV with rubber insulation - 5 min. for cables for voltage 110 - 220 kV - 15 min. Permissible leakage currents and values of the asymmetry factor when measuring the leakage current are given in Table. 11 (Annex 3.1) Tests may not be carried out: two parallel cables up to 60 m long, which are the outputs of the line from the transformer substation and switchgear cables with a service life of more than 15 years, on which the specific number of breakdowns is more than 30 per 100 km per year cables to be decommissioned within the next 5 years Cables with rubber insulation for voltages up to 1000 V are not subjected to increased rectified voltage tests.	The frequency of testing cables for voltage up to 35 kV - 1 time per year during the first 5 years of operation, and in the future: 1 time in 2 years for cable lines that did not experience breakdowns during testing and operation during the first 5 years 1 time per year if insulation breakdowns were noted during this period 1 time in 3 years for cable lines in closed areas (substations, factories, etc.) during repairs of equipment for cables connected to the units, and cable jumpers with a voltage of 6 - 10 kV between busbars and transformers in switchgears Cables for voltage 110 - 220 kV are tested 3 years after commissioning and then 1 time in 5 years It is recommended to measure the insulation resistance of cables for voltages above 1000 V before and after the overvoltage test.
6.4. Control of the degree of drainage of vertical sections d	М	The difference in heating of individual points at currents close to the nominal ones should be no more than 3 °C. Dehumidification can also be controlled by taking curves tgδ = f (U) in vertical sections	Produced on cables 20 - 35 kV with paper insulation impregnated with a viscous composition by decision of the technical manager of the Consumer by measuring and comparing the heating temperatures of the sheath at different points of the vertical section
6.5. Ground control	К	Manufactured in accordance with Section 26 In operation, the integrity of the metal connection between the grounding conductors of cable lines for a voltage of 110 - 220 kV and the neutral of transformers is checked once every 1 years	Produced for metal terminations and terminations of cables with voltages above 1000 V, and for cables with voltages of 110 - 220 kV - also for metal structures of cable wells and make-up points
6.6. Measurement of current distribution on single-core cables	К	The uneven distribution of currents on the cables should be no more than 10% (especially if this leads to an overload of individual phases)	-
6.7. Checking anti-corrosion protection	М	During the test, the potentials and currents in the cable sheaths and electrical protection parameters (current and voltage of the cathode station, drainage current) are measured in accordance with the guidelines for the electrochemical protection of underground power structures from corrosion The assessment of the corrosivity of soils and natural waters should be carried out in accordance with the requirements of state standards The timing of measurements of stray currents in the ground is determined by the head of the Consumer, but at least 1 time in three years	The operation of anti-corrosion protection is checked for: cables with a metal sheath, laid in soils with medium and low corrosive activity (soil resistivity above 20 Ohm), with an average daily leakage current density in the ground above 0,15 mA/dm² cables with a metal sheath, laid in soils with high activity (ground resistivity less than 20 Ohm) at any average daily current density in the ground cables with an unprotected sheath and destroyed armor and protective covers steel pipeline of high-pressure cables, regardless of the aggressiveness of the soil and types of insulating coatings
6.8. Cable temperature measurement	М	The temperature of the cables must not exceed the permissible values	Produced according to local regulations on sections of the route where there is a danger of overheating of cables
6.9. Testing a plastic sheath (hose) with increased rectified voltage	K, T, M	A test voltage of 10 kV is applied between the metal sheath (screen) and the ground, the duration of the application of the test voltage is 1 min.	The test is carried out 1 year after commissioning and then 1 time in 3 years

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