Mikkel L. Ellertson wrote:
I don't know about where you live, but in the US, they are also
required to keep the voltage within a specific range. If the voltage
is normally at one end of the range, and goes outside the range,
they can change the taps on the transformer to keep it in range. I
have also had the power company upgrade to a larger transformer
because the one they had was not large enough to meet peak loads.
Having records of the actual voltages helps.
When I was in Fort Worth, my UPS would cut in and out like a flip-flop
so bad was the supply during hot spells.
(Every time the whole streets air-cons cut in at the same or similar
time it would cause a major drop in line voltage. I gave my UPS logs to
a TX Employee who lived in our street and they had engineers out the
next day to change a faulty transformer in the neighbourhood. Everyone
had noticed the lights dip but didn't realise the power was dropping
that much. A few had noticed computers rebooting for no reason but
didn't make the connection).