At the reasonably sized datacentre that I ran we had a voltage conditioner that also had "sag protection". It was an HPC shop and we decided that it wasn't wort

At the reasonably sized datacentre that I ran we had a voltage conditioner that also had "sag protection". It was an HPC shop and we decided that it wasn't worth the money to put the compute on UPS (just storage and core servers but the Top 500 machines ran off mains) but we still had 10s of millions of dollars worth of hardware that a lightning strike etc could fry. The conditioner provided a constant voltage to the servers and could correct "sags" where the voltage would drop, and it could keep things going for a few seconds if the power went off completely. As you say this took our total outages down from probably 10 a year to maybe 1 or 2 - most outages are quite short. Although looking at the graphs on this thing, there were pretty frequent surges and sags coming from the street, like when you see light bulbs flicker in your house. One other thing we noticed was that if there was a short interruption, all of the HP servers could survive for a second but the Dells turned off right away. Different power supplies store up some amount of power locally. https://new.abb.com/ups/power-and-voltage-conditioners/voltage-conditioners/pcs100-avc-40 https://new.abb.com/ups/power-and-voltage-conditioners/volta...