EN IEC 60230:2018 pdf free download

EN IEC 60230:2018 pdf free download
EN IEC 60230:2018 pdf free download.Impulse tests on cables and their accessories
A.2.1 General sequence of lightning-impulse tests
With the temperature conditions as specified, lightning-impulses shall be applied in the following sequence:
1 ) 1 0 negative lightning-impulses at withstand voltage plus approximately 5 %;
2) 5 positive lightning-impulses, the first at 50 % of the value used for 1 ) and the remainder at progressively increasing values up to 85 % of the value used for 1 );
3) 1 0 positive lightning-impulses at withstand voltage plus approximately 5 %;
4) 1 0 positive lightning-impulses at withstand voltage plus approximately 1 0 %;
5) 5 negative lightning-impulses, the first at 50 % of the value used for 4) and the remainder at progressively increasing values up to 85 % of the value used for 4);
6) 1 0 negative lightning-impulses at withstand voltage plus approximately 1 0 %.
A.2.3 Re-calibration of the generator
In case an approved measuring system is used, A.2.3 is not applicable.
In case an approved measuring system is not used, then, in general, no recalibration of the generator is necessary throughout this series of tests and the voltage can be determined by extrapolation from the original calibration. When, however, the margin between the test voltage and the maximum voltage used for the original calibration is considered too large for accurate results, a fresh calibration as described in Annex B may be necessary.
Both ends of the test assembly shall be connected to the impulse generator. A measuring sphere-gap and an oscillograph, with its associated voltage divider, shall be connected in parallel and remain so connected throughout the test.
For every setting of the sphere-gap, the charging voltage of the generator shall be so adjusted as to give 50 % flashover of the gap (see IEC 60060-1 :201 0, Annex A) and an oscillogram of the impulse voltage shall be taken. This procedure shall be carried out for at least three different settings of the sphere-gap. The settings shall be so selected that their 50 % flashover voltages are approximately 50 %, 65% and 80 % of the test level specified.
A curve showing the charging voltage as a function of the sphere-gap flashover voltage shall be drawn for this positive polarity. This curve, which should be a straight line, shall be extrapolated to determine the charging voltage necessary to obtain the specified level with positive polarity.