These types of events can be highly damaging to electronics these days, especially microprocessor circuits. These sort of events are not prevented by surge protectors and power conditioners.
I have said this many times, that to properly protect modern electronics, a smart UPS with response times to narrow over voltage AND under voltage coupled with response times in the range of 1 to 3 msec is a mandatory expenditure. Everybody worries about the surges, but the sags are, if not more, as damaging.