Hot Plug and How to Defeat It
Finally I found the URL of a device I’ve been hearing rumours about. The HotPlug is a device to allow you to move a computer without turning it off [1]. It is described as being created for “Government/Forensic customers” but is also being advertised for moving servers without powering them down.
The primary way that it works is by slightly unplugging the power plug and connecting wires to the active and neutral terminals, then when mains power is no longer connected it supplies power from a UPS. When mains power is re-connected the UPS is cut off.