This page shows both AC and DC Power Conditioners
Typically all AC Line Conditioners have a front end section devoted to overload conditions using fuses or breakers.
The next section or several sections are for Spike removal using MOVs ( Metal Oxide Varistors ) that clip high voltage spikes off.
They also include a series of Torroid Inductors that limit surge currents and these also act as the high impedance section of the last section that has AC Capactitors which are used for high frequency filterin. Ttypically radio frequency interference that gets coupled into AC Power. This can come from welders, RTs and other devices.
There are three types of AC AVRs
Type 1 – Automatic voltage regulators (AVR) using tapped transformers,
Type 2 – AVRs using servo variacs
Type 3 – AVRs using IGBTs and Transformers.
Noye:- The Simple AVR units are basically a Line Interactive UPS front end with torroid inductance, MOV surge protection, high energy capacitors for filters and an automatic tapping transformer often driven by a microprocessor.
Passive units like the Euro 4 from TrippLite are a simple surge protection system with MOVs, torroids and caps for filters. (no AVR), either as Power Bars, DIN Rail mount or mountable boxes. Some have Parts redundancy and indicators for the condition of the protection system