TC 1 controls the IEC IEV. There you find in the fundamental definitions

Area Electrical and magnetic devices / Operating conditions and testing
IEV ref     151-16-33
    thermal equilibrium
state reached when the temperature of the parts of a component or equipment operating in a given environment no longer varies faster than a specified limit

I remember when thermally testing CRT colour TVs that it took about 3 hours before the temperature stabilised. In this case, a fair bit of the power loss was power switching, which increased with the microclimate temperature. In part, it was more like a test for thermal runaway, with some of the TO-3 packaged transistors stabilising at about 130 degree C case temperature in a 40 degree C room ambient (Athens Valley in the summer I was told).

I was involved with a variant of the TC 1 data base. You had to enter the data as HTML expressions in an Excel spreadsheet - a frustrating exercise if you were not proficient in HTML.

Mick


On 12/01/2012 11:24, John Woodgate wrote:
In message <[email protected]>, dated Thu, 12 Jan 2012, Mick Maytum <[email protected]> writes:

Nice to see a harmonised approach from the various IEC TCs

The 60034 definition might be taken as more 'horizontal' (i.e. a reference definition that other committees should adopt) than the others.

May years ago, someone I know proposed to IEC that standard definitions and other widely-used wording should be held in a database from which product committees should select what they want. It wasn't progressed - it was probably a bit before its time, but it is quite practicable now.

Might take 100 years to agree on all the definitions, though. Can't be left to TC1 in isolation.

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