Unfortunately, these blackouts provide the practical proof of a wrong old engineering concept stated in the holy books of safety codes and other regulations: that ‘demand coefficient’ or however they call it, which is considered to be 0.7 – 0.9 of the installed power of the feeder. This de-rating of power transformers and circuit breakers is not compensated by a forecast in power consumption that the feeder might be forced to deliver not at the time of its design, but over a period of time that can be considered up to 3 decades. And what’s wrong with the designing data that cover 100% installed power of the feeder? I know, one will say that this de-rating concept saves money; but look, is it a real saving when you purchase two transformers (one that burnt, the other is the replacement) instead of installing from the beginning a transformer that is able to carry the whole load?
Maybe the code experts will rethink the whole dimensioning calculations and allow power system designers to provide data that will be more close to reality.