Dave Liquorice wrote:

Andy Burns wrote:

Quite annoyingly it runs it for the daily spikes of a couple of
seconds around midnight when "something" at the substation adjusts
for over-voltage.

Complain to your DNO. Ours (Electricity North West) takes complaints
about the supply quite seriously, especially if you have data to back
up the complaint. A regulator shouldn't spike

OK, it's not a spike, rather the times of day that the UPS goes into and
out of buck mode, due to over voltage.

"around midnight" (*) strikes me as a bit odd as well. I wouldn't
expect load variation to be that consistent, weekday/weekend being
different at the very least.
I plotted a chart in a spreadsheet of the time of day the overvoltage
starts and ends over the last year, the main periods are roughly 6am to
9am and 9am to midnight. I didn't look at weekday/weekend variations.