A variable isolation transformer, Variac, is mostly designed as a toroid transformer where a wiper on the secondary winding allows to tap off a variable voltage. The Philips in the above picture is rated for 0-240Vac and up to 3A. It utilizes a On-Off switch and a quite exact needle instrument.

Since my ebay-purchased trafo was not only quite dusty, but obviously tweaked by one of its previous owners, I took it apart first. Besides dirt and dust several rather dilettantish roasted soldering joints and a added PE-wire linked to the power outlet emerged!!!

The isolation transformer lost its safety functionality .... with associated danger for one´s life and measurement device.

This again proved, that:

a) only people with a certain basic intellect and basic training should handle with power line voltages ... and

b) don´t trust any ebay bargain without proper checking.

After replacing the whole cabling and the power switch with decent components the variac is almost as new and useable for many years to come.