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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Section 3. Electrical installations for special purposes Chapter 3.6. Guidelines for testing electrical equipment and apparatus for electrical installations of consumers
Encyclopedia of radio electronics and electrical engineering / Rules for the technical operation of consumer electrical installations (PTE) 3.6.1. The test standards for electrical equipment and devices of electrical installations of Consumers (hereinafter referred to as the standards) given in Appendix 3 of these Rules are mandatory for Consumers operating electrical installations with voltage up to 220 kV. When testing and measuring the parameters of electrical equipment of electrical installations with voltages above 220 kV, as well as generators and synchronous compensators, the relevant requirements should be followed. 3.6.2. Specific terms for testing and measuring the parameters of electrical equipment of electrical installations during major repairs (hereinafter - K), during current repairs (hereinafter - T) and during turnaround tests and measurements, i.e. during preventive tests performed to assess the condition of electrical equipment and not related to the withdrawal of electrical equipment for repair (hereinafter referred to as M), the head of the Consumer determines based on Appendix 3 of these Rules, taking into account the recommendations of factory instructions, the state of electrical installations and local conditions. The frequency of tests indicated for certain types of electrical equipment in sections 1 - 28 is recommended and can be changed by the decision of the technical manager of the Consumer. 3.6.3. For types of electrical equipment not included in these standards, specific standards and terms for testing and measuring parameters should be established by the technical manager of the Consumer, taking into account the instructions (recommendations) of manufacturers. 3.6.4. The test standards for electrical equipment of foreign companies should be established taking into account the instructions of the manufacturer. 3.6.5. Electrical equipment after repair is tested to the extent determined by the standards. Prior to the repair, tests and measurements are carried out to establish the scope and nature of the repair, as well as to obtain initial data with which the results of post-repair tests and measurements are compared. 3.6.6. The assessment of the state of insulation of electrical equipment that is in the stage of long-term storage (including emergency reserve) is carried out in accordance with the instructions of these standards, as well as being in operation. Separate parts and parts are checked according to the standards specified by the manufacturer in the accompanying documentation for the products. 3.6.7. The scope and frequency of tests and measurements of electrical equipment of electrical installations during the warranty period should be taken in accordance with the instructions of the manufacturers. 3.6.8. A conclusion on the suitability of electrical equipment for operation is issued not only on the basis of a comparison of test and measurement results with standards, but also on the basis of the totality of the results of all tests, measurements and inspections. The values of the parameters obtained during tests and measurements must be compared with the results of measurements of the same type of electrical equipment or electrical equipment of other phases, as well as with the results of previous measurements and tests, including their initial values. The initial values of the measured parameters should be understood as their values indicated in the certificates and protocols of factory tests and measurements. In the case of a major or refurbishment, the initial values are the measurement results obtained during these repairs. In the absence of such values, the values obtained during tests of newly introduced equipment of the same type can be taken as initial ones. 3.6.9. Electrical equipment and insulators with a rated voltage exceeding the rated voltage of the electrical installation in which they are operated can be tested with increased voltage in accordance with the standards established for the insulation class of this installation. 3.6.10. If the test with increased rectified voltage or power frequency voltage is performed without disconnecting the busbar from the electrical equipment, then the value of the test voltage is taken according to the standards for electrical equipment with the lowest test voltage. The high voltage test of insulators and current transformers connected to 6-10 kV power cables can be carried out together with the cables according to the standards adopted for power cables. 3.6.11. In the absence of the necessary test equipment for alternating current, it is allowed to test the electrical equipment of switchgears (with voltage up to 20 kV) with an increased rectified voltage equal to one and a half times the value of the test voltage of industrial frequency. 3.6.12. Tests and measurements must be carried out according to programs (methods) approved by the head of the Consumer and the relevant requirements of duly approved (recommended) documents, standard guidelines for testing and measurements. Programs should include measures to ensure the safe conduct of work. 3.6.13. The results of tests, measurements and testing must be documented in protocols or acts that are stored along with passports for electrical equipment. 3.6.14. Electrical tests of electrical equipment and sampling of transformer oil from the tanks of the apparatus for chemical analysis must be carried out at an insulation temperature of at least 5 °C. 3.6.15. The insulation characteristics of electrical equipment are recommended to be measured according to the same type of circuits and at the same temperature. Comparison of insulation characteristics should be carried out at the same insulation temperature or its close values (temperature difference is not more than 5 °C). If this is not possible, then temperature conversion should be carried out in accordance with the operating instructions for specific types of electrical equipment. 3.6.16. Before testing and measuring electrical equipment (with the exception of rotating machines in operation), the outer surface of its insulation must be cleaned of dust and dirt, except when measurements are carried out by a method that does not require shutting down the equipment. 3.6.17. When testing the insulation of windings of rotating machines, transformers and reactors with an increased voltage of industrial frequency, each electrically independent circuit or parallel branch must be tested in turn (in the latter case, if there is complete insulation between the branches). In this case, one pole of the test device is connected to the output of the winding under test, the other - to the grounded case of the electrical equipment under test, with which all other windings are electrically connected for the entire time of testing this winding. Windings that are tightly connected to each other and do not have the output of the ends of each phase or branch, must be tested relative to the body without disconnection. 3.6.18. When testing electrical equipment with increased voltage of industrial frequency, as well as when measuring current and no-load losses of power and instrument transformers, it is recommended to use the linear voltage of the supply network. The rate of voltage rise to 1/3 of the test value can be arbitrary. Further, the test voltage should rise smoothly, at a speed that allows visual reading on measuring instruments, and upon reaching the set value, be maintained unchanged during the test. After the required exposure, the voltage gradually decreases to a value of at least 1/3 of the test value and turns off. The duration of the test means the time of application of the full test voltage established by the standards. 3.6.19. Before and after testing the insulation with increased power frequency voltage or rectified voltage, it is recommended to measure the insulation resistance with a megohmmeter. The one-minute value of the measured resistance R60 is taken as the insulation resistance. If, in accordance with the norms, the determination of the absorption coefficient (R60 / R15) is required, the reading is made twice: 15 and 60 s after the start of the measurement. 3.6.20. When measuring the insulation parameters of electrical equipment, random and systematic errors should be taken into account due to errors in measuring instruments and apparatus, additional capacitances and inductive couplings between the elements of the measuring circuit, the effect of temperature, the influence of external electromagnetic and electrostatic fields on the measuring device, method errors, etc. When measuring the leakage current (conduction current), if necessary, ripples of the rectified voltage are taken into account. 3.6.21. The values of the tangent of the dielectric loss angle of the insulation of electrical equipment and the conduction current of the arresters in these standards are given at an equipment temperature of 20 °C. When measuring the tangent of the dielectric loss angle of the insulation of electrical equipment, its capacitance should be simultaneously determined. 3.6.22. A test with a voltage of 1000 V of industrial frequency can be replaced by measuring a one-minute value of insulation resistance with a megohmmeter for a voltage of 2500 V. This replacement is not allowed when testing critical rotating machines and circuits of relay protection and automation, as well as in cases specified in the standards. 3.6.23. When testing the external insulation of electrical equipment with increased voltage of industrial frequency, produced under environmental factors that differ from normal (air temperature 20 ° C, absolute humidity 11 g / m3, atmospheric pressure 101,3 kPa, if other limits are not accepted in the standards for electrical equipment) , the value of the test voltage must be determined taking into account the correction factor for the test conditions, regulated by the relevant state standards. 3.6.24. Carrying out several types of insulation tests for electrical equipment, testing with increased voltage should be preceded by a thorough inspection and assessment of the state of the insulation by other methods. Electrical equipment rejected during external inspection, regardless of the results of tests and measurements, must be replaced or repaired. 3.6.25. The results of the increased voltage test are considered satisfactory if, when applying the full test voltage, no sliding discharges, leakage current shocks or a smooth increase in leakage current, breakdowns or insulation flashovers were observed, and if the insulation resistance measured by a megohmmeter remained the same after the test. If the characteristics of the insulation have deteriorated sharply or are close to the rejection rate, then the cause of the deterioration of the insulation must be clarified and measures taken to eliminate it. If the insulation defect is not detected or not eliminated, then the timing of subsequent measurements and tests is established by the Consumer responsible for the electrical equipment, taking into account the state and mode of operation of the insulation. 3.6.26. After a complete oil change in oil-filled electrical equipment (except oil switches), its insulation must be re-tested in accordance with these standards. 3.6.27. The experience of idling of power transformers is carried out at the beginning of all tests and measurements before supplying the DC transformer windings, i.e. before measuring insulation resistance and winding resistance to direct current, heating the transformer with direct current, etc. 3.6.28. The insulation temperature of electrical equipment is determined as follows: type="disc">3.6.29. The values indicated in the norms with the indication "not less than" are the smallest. All numerical values "from" and "to" given in the standards should be understood inclusive. 3.6.30. Thermal imaging control of the state of electrical equipment should, if possible, be carried out for the electrical installation as a whole.
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