Not too much, except that a CPT(Control Power Transformer), as its name might suggest, is designed to provide single-phase control power(typically 120V) from a higher voltage supply.
A transformer consisting of one or more primary winding(s) and one or more secondary winding(s). It may be designed for direct connection to an alternating current source for purposes of changing the secondary volts and amperes or designed to eliminate metallic interconnection between circuits in an overall one to one voltage ratio, with or without additional output windings, or items designed to automatically maintain a constant output voltage within specified limits under varying input or load conditions. Also includes items having a provision for mechanically changing the turns ratio or inductive coupling in progressive increments by means of voltage taps, ratio adjuster, or devices or similar design.
