BS IEC 63075:2019 pdf free download – Superconducting AC power cables and their accessories for rated voltages from 6 kV to 500 kV – Test methods and requirements
9.1.1 Tests on cable core samples
The tests specified in 9.2 to 9.3 shall be carried out on cable samples cut from the finished cable core lengths at the factory. For each test, a separate sample might be used.
a) AC voltage test for cable followed by partial discharge test (see 9.2);
b) critical current measurement (see 9.3). The order in which these tests are carried out is at the discretion of the manufacturer.
NOTE At the current time, there is no accepted methodology to allow factory testing of full cable lengths after manufacturing. Sample testing is performed at various stages during the manufacturing processes and after completion. However, it is impractical to perform AC voltage tests and critical current measurements on full cable lengths. The need to cool the cable to cryogenic temperature and impregnate the dielectric tapes with cryogen makes tests on full reels of finished cable impractical. Further, in some cases, the cable reel at the factory does not include the cryostat. In all cases, the thermal contraction of the cable while on the reel would present extreme difficulties. Practical methodologies to enable factory testing of full cable lengths, similar to conventional cables, are likely to be developed in the future. For quality control purposes， it is recommended to implement continuous thickness monitoring, or at least periodical thickness measurements, during manufacturing of full cable lengths. This monitoring should ensure that the declared minimum insulation thickness is achieved along the complete cable lengths.
9.2.1 General
The test shall be performed on cable core samples with a minimum active length of 1 m using alternating voltage at power frequency. The test cable core shall be immersed in the cryogen in accordance with Clause 6. The maximum temperature of the cryogen shall be greater than or equal to the maximum operating temperature and its minimum pressure shall be less than or equal to the minimum operating pressure. One sample from each shipping reel shall be taken and subjected to the voltage test. If the length of the cable core on the shipping reels exceeds 1 000 m, one sample from each end of the reel shall be tested. Each dielectric in the cable shall be subjected to the electric tests.
9.2.3 Requirement
No breakdown of the insulation at test voltage shall occur and no detectable partial discharge shall occur. If the sample from any length selected for the tests fails, an investigation of the cause for failure shall be undertaken. If agreed between the customer and manufacturer to proceed with routine testing, two further samples shall be taken from either side of the same reel and the test shall be repeated. If both additional samples pass the tests, the reel from which they were taken shall be regarded as having complied with the requirements of this document. If either fails, this reel shall be regarded as having failed to comply.