Transformers

Learn what JOHSUN Variac transformers do, how they differ from standard transformers, and how to select portable, 120V, 500VA, or rack formats.

A comprehensive variac transformer guide covering construction, brush mechanism, terminal wiring, comparison with dimmers and tap changers, selection criteria, maintenance, and safety rules.

A complete classification guide covering autotransformer types by voltage function, control method, number of phases, core design, and application — with comparison tables, an 8-type summary chart, and a 5-step selection process.

A practical wiring guide covering step-up, step-down, variable, and three-phase autotransformer circuit configurations with terminal identification charts, common mistakes, and testing procedures.

The auto transformer symbol uses a single continuous winding with tap points, distinguishing it from the conventional two-winding transformer symbol. This guide explains single-phase, three-phase, and variable variants, plus IEC and ANSI drawing standards.

A conventional transformer uses two separate windings with galvanic isolation. An autotransformer uses one shared winding without isolation. This comparison covers construction, efficiency, cost, safety, and application fit for both types.

An autotransformer is a single-winding transformer that shares part of its coil between primary and secondary circuits. Compact and efficient, it suits voltage conversion, motor starting, and power distribution where isolation isn't needed.

A practical, step-by-step guide to choosing the right step-up or step-down autotransformer. Covers voltage direction, kVA sizing, single vs. three-phase, application matching, safety considerations, and common selection mistakes.

A detailed comparison of autotransformers and control transformers covering construction, electrical isolation, efficiency, safety considerations, typical applications, and selection criteria.