Current injection Transformers
This type of transformer without secondary is for injecting a variable voltage into a current loop formed by the cable and accessories under test.
It can be designed with opening frame to facilitate the installation of the secondary cable.
The high current (several thousand amperes) is regulated by the control unit to make aging cycles or heating tests.
A strong reactive power consumed by the magnetic circuit and the test loop itself has a low power factor (cos phi often less than 0.3). Power capacitors can reduce consumption and avoid any penalties from the electricity supplier.