In message <FCA549BE3ECF9D4CB8CB8576837EA48920A1A4@ZEUS.cetest.local>, dated Sat, 7 Sep 2013, "ce-test, qualified testing bv - Gert Gremmen" <g.grem...@cetest.nl> writes:

Anyway, the primary circuit always need to be build for high surge currents,

and one should always insert induction to limit surge currents.

As the impedance of the spark gap is low, only a small amount of induction

will reduce the surge current substantially

Quite true, but the mains supply itself (unless it's from a very nearby private MV/LV transformer, has inductance of the order of a millihenry (0.3 ohms at 50 Hz), so there is not much point in adding only a few microhenrys.

IEC TR60725 gives 'reference impedances' for various types of mains supply. While these tend to be higher than the actual impedance at the 'point of common coupling', they are a guide to the impedance at a typical wall-socket. This impedance limits the prospective short-circuit current.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
If dictionaries were correct, we would only need one, because they would all
give the same information.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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