3.3 Unified specific creepage distanceThe unified specific creepage distances (USCD) for the equipment must be at least 43.3 mm/kV.3.4 Type of Service3.4.1 Sections 1 and 2The power cables identified as “Section 1” and “Section 2” in Figure 1 shall carry the high currents needed for the performance of high current / high power (or other kinds of) tests in HPL.These cables will be mostly exploited in the severe conditions imposed by the short-circuit test sequence, therefore they will be subjected to very high thermal, dielectric and mechanical stresses.A typical short circuit test sequence foresees:1) the application of no load nominal voltage to ground, up to 1 minute;2) the closure of the circuit in short-circuit condition;3) the circulation of the test current for some hundreds of milliseconds up to 3 s;4) the circuit opening;5) the appearance of a transient recovery voltage (TRV) superimposed to the power frequency voltage with frequency up to some kHz and peak factor up to 2 times the peak of the power frequency voltage.Points 2) to 5) here above can be repeated several times within few minutes, according to the nominal duty cycles described here under:a) No. 5 totally asymmetrical short circuits (either two-phase or three-phase) at rated current IR (see Table 2), each one lasting 0.15 s, in a period of 30 min. The interval between two consecutive short-circuits can be 0.3 s or 3 min.1At the end of this test cycle, a pause of 30 min is foreseen.b) No. 1 totally asymmetrical short-circuit (either two-phase or three-phase) at rated current IR (see Table 2) lasting up to 4 s, repeatable every 30 minutes.The basic duty cycles above described shall be repeated during 8 hours of laboratory operation.NOTE: Any other duty cycle, different from the ones listed above and with currents not exceeding the rated ones shall be allowed, provided that the let-through specific energy does not exceed the I2t given by the duty cycles here above described. 1 The time interval of 0.3 s may occur at most one-time per each duty cycle.