The mains power supply in Lweshal is dismal.
There are frequent outages, of course—the transformer in the village
blew up earlier this year, and we had no power for a week. Two or three
times in the summer (when forest fires were burning everywhere) a tree
fell on the line and cut off power for a few days. There's a big fuse
near Mauna which seems to keep melting down. But none of that is really
a surprise in a remote area.
The unpleasant surprise was how bad the supply could be when there's no
outage. For some reason, extreme voltages are quite common. I've seen
the mains voltage at a record low of 25V for several hours once, and
we've had whole days when it stayed around 60–90V—voltages so low that
the electricity meter stayed off, even though our 9W LEDs inside would
light up. Free power!
High voltages don't last nearly as long, but we've seen spikes of 300V
and more on occasion. It's difficult to decide which condition is more
destructive. High voltages fry appliances, but persistent low voltages
where some lights appear to work encourage people to draw more current
than their circuits can safely carry—and in a place where people use
1.0mm² wire even for 16A circuits, and nobody has any earthing, that
isn't something to be taken lightly.
Either way, voltage fluctuations blew up our UPS twice. The first time
we didn't have any sort of voltage regulator installed. After having to
pay for a new logic board, we installed a custom-made "constant voltage
transformer" (a big auto-transformer with a voltage meter). It clicked a
lot to indicate its displeasure, and we had to take it back to the shop
to make it cut off the output altogether if the voltage was too low (but
why didn't it do that to begin with?). Then the next fluctuation killed
the UPS again.
In such a dire situation, only a device with a genuine superhero name
could possibly save us, and the
certainly delivers on that front. I bought one from Amazon, and we
installed it upstream of the main distribution board. It doesn't do any
voltage regulation, just cuts off the output beyond the predefined low
and high voltage thresholds. Here is it in action.
It has worked correctly in various low-voltage conditions (we've had a
130V supply for most of the past two days). It has high- and low-voltage
bypass modes that I have never tried, and an optional output timer that
restores power to the house only if the power stays on for two minutes.
It's useful that it displays the input voltage (even when the output is
cut off), and the 32A circuit breaker is very handy when we're working
on the distribution board.
Other Amazon customers assured me that the device makes no noise during
operation, but of course it does. It clicks away merrily, but it's a
small price to pay for reliable voltage limits.
Update (2017-04-23): Our low- and high-voltage records for the
Accurex are 43V and 592V respectively (both voltages persisted for some
hours before returning to normal).