]When the grid collapsed, the frequency was 50.2 hertz, he said, which is normal. Had states been overdrawing, the frequency would have dropped well below that level, he added.
I'm scratching my head on that statement.
IIRC, 50.x Hz is normal for a 220/240 grid system. Unlike us in North America, where 60Hz and 110/120 is the standard.
So I guess it just hums a few notes lower.