In this YouTube video, PS Audio talks about the differences between a toroidal isolation transformer and a power regenerator. Both take electricity and move it from the source to a building.
A toroidal transformer is a round donut shape with ingoing cords and outgoing cords.
In the center of the donut shape is epoxy, in which screws or other attachments can be placed. Inside the donut-shaped chamber are wrapped copper wires overlaid with wrapped iron. The banded iron creates a magnetic field. Typically, toroidal transformers are inside power plants as one of the active components. Still, they can also be used by themselves to isolate AC power and only send the AC power into the building.
Some studios and audio recording institutions invest a lot in buying an isolation transformer to clean the power coming into the building to remove the humming noise from the electricity. The humming noise interferes with audio recording. According to PS audio, this is unnecessary as it provides a one-to-one relationship; whatever goes in comes out, including the noise.
A power plant has several isolation transformers inside of them, along with electrical storage in batteries. It takes the AC power, converts it to DC power, and then regenerates new AC power at clean levels, providing the institution with pure energy, regardless of the noise or fluctuations in power from the power pole.