two or more electrical transformers connected in series to transform or use high voltage alternating current.

The principle of cascade excitation of transformers, particularly those connected in a circuit in which each transformer in turn is excited from a part of the step-up winding of the preceding transformer, is usually used. Cascade transformers for voltages up to 1.5 or 2 megavolts with a total of four to eight transformers in the cascade may be constructed according to this principle. The drawbacks of such a cascade transformer (the installed transformer capacity far exceeds the power of the cascade, there is considerable inductance, the distribution of the pulse voltages along the individual links of the cascade is nonuniform, and the design is cumbersome) are partially eliminated in the capacitor type of design. The windings are wound in a single layer on insulating cylinders; the number of cylinders and their length and diameter are chosen such that when the windings are connected in series the potential buildup on the turns corresponds to the potential distribution over the capacitance of the concentric layers of the winding. This design does not require large insulators, reduces the dimensions and weight of the transformer, and simplifies its installation and operation. Cascade connection of current- and voltage-measuring transformers is sometimes used for voltages of more than 110 kilovolts.