In message <45256ed0.8010...@itesafety.com>, dated Thu, 5 Oct 2006, 
Robert Johnson <john...@itesafety.com> writes

>Since this shutdown method might be considered normal operation, have 
>you considered the consequences
>of rating your wiring, switches, thermal contactor etc. for the short 
>circuit current capacity?

These issues have to be taken into account anyway, because a mains 
short-circuit is a foreseeable single-fault condition. The short-circuit 
current SHOULD flow only until the primary protection device opens, of 
course. This is normally of the order of tens of milliseconds.

The prospective short-circuit current may be estimated from the supply 
impedance data in IEC 60725.

-- 
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
Swine wave - a waveform whose spectrum is exceptionally difficult to calculate.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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