Different configurations of transient voltage quashing (TQ) transformers, harmonic current quashing (HQ) transformers, and transient voltage and harmonic current quashing (THQ) transformers include one or more of: a tertiary winding radially placed between the primary and secondary windings, with a surge suppressors coupled thereto, which quashes transient voltages in the transformer and any output device attached to output leads of the tertiary or secondary windings; and an arrangement of the secondary windings, separated by at least a second type intra-winding insulation, into one or a plurality of output winding groups, each used to provide power to N serially-connected output devices that exhibit known/expected output voltage characteristics. The second type intra-winding insulation has a dielectric strength to withstand the sum of the voltage output of the device being powered by the output winding and the adjacent serially-connected device, such that the output device experiences minimal harmonic currents.