A test transformer, often called a step-up transformer, is a basic testing tool for power stations, power supply and distribution systems, research units and other users. It’s applied to carry out insulation strength tests on all kinds of electrical products, equipment and insulating materials at set voltages. The tests are used to check the insulation level of products, find insulation defects in tested objects and judge their capacity to bear overvoltage.

AC test transformers and light AC/DC high-voltage test transformers are constructed with high-quality cold-rolled silicon steel sheets stacked together. Their coils are designed as concentric pagoda-shaped multi-layer cylinders, with low-voltage coils placed inside and high-voltage coils outside. The transformers have a portable shell, which makes them small, light, good-looking and easy to move.

Connect a 220V power frequency power source (380V for 10KVA and above) to the dedicated control box (console) — a supporting part for the test transformer (detailed info is in the control box (console) user manual). An autotransformer adjusts the voltage to 0-220V/380V and sends it to the primary winding of the test transformer. Following the electromagnetic induction principle, the secondary (high-voltage) winding produces power frequency high voltage, with its amplitude matching the turn ratio of the primary and secondary windings. This AC high voltage can be turned into DC high voltage through a high-voltage silicon stack for rectification and a capacitor for filtering, and the DC amplitude is a multiple of the effective value of the AC high voltage.

This product series has three main types: AC type, AC/DC dual-purpose type. Moreover, transformers with 200V taps can be connected to make a series-excited test transformer.