IEC 60230:2018 pdf free download

IEC 60230:2018 pdf free download Impulse tests on cables and their accessories
8 Superimposed impulse voltage test
8.1 General
The superimposed impulse voltage test shall be carried out on HVDC cable systems. The peak voltage level of the switching impulse is specified in the relevant product standard.
When a superimposed impulse voltage test is required, Clause 8 shall be applied in addition to the other clauses of this document.
8.2 Test setup
Some possibilities are given to apply an impulse voltage to a test object which is at the same time energized by a DC voltage; Annex C illustrates the possible superimposed impulse test circuit arrangements.
8.3Time parameters
The time parameters shall meet the requirements of Clause 6 or Clause 7 and shall bedetermined with the DC voltage source set to zero output or disconnected， i.e. withoutenergizing the test object by a DC voltage and with the spark gap (as applicable)short-circuited.Once the time parameters have been determined, there shall be no changesto the test setup other than connecting the DC voltage source and removing the short-circuitacross the spark gap.
The time parameters are to be determined in this way because a base level around 0 kV isrequired by lEC 60060-1.
8.4Application of the Dc voltage
Before the impulses are applied to the test object，if required，the test object shall beenergized by a DC voltage with a level and duration and polarity as specified in the productstandard.
The application of the impulses is given in Clause 10.
9Measuring system
The preferred method to measure the impulse voltage is by using an approved measuringsystem according to lEC 6o060-2.
Alternatively，the method described in Annex B may be used at the discretion of themanufacturer.
10 Application of the impulses
Both ends of the test object shall be connected to the impulse generator (via the spark gap orblocking capacitor in the case of a superimposed impulse test).
For an impulse test, the test object shall be subjected to a series of 10 positive impulses and10 negative impulses at the voltage and shape as specified.For a superimposed impulse testthe polarity, method of application of impulses and rest periods between DC polarity changesshall be as given in the relevant product standard.
As a means of conditioning the test object when using an approved measuring system, eachseries of 10 impulses may be preceded by one or more impulses of the same polarity at alevel of approximately 50 %,65 % and 80 % of the voltage and shape specified.
At least the first and tenth impulses at the voltage and shape specified shall be recorded, ineach series.
The impulses at the lower level may be recorded.
The ambient temperature，the cable temperature and,where applicable，the gas or oilpressure shall be recorded.
When, for research purposes,lightning-impulse tests to levels above the withstand level aremade, the procedure according to Annex A is recommended.