This is a transformer that can convert 200 VAC to 250 or 350 kVAC. The transformer is designed so that two can be connected in series. This doubles the generated voltage. The device was used to test the behaviour of components for high voltage lines.
It consists of two columns, each consisting of concentric cylinders that become longer toward the middle. A coil is wrapped around each cylinder. Each column contains a primary winding of the transformer; these windings are connected in parallel. The outer coils are coupling coils. These are intended for connecting the transformer in cascade (parallel) with another one. The other coils are connected in series.
In front of the two wide columns there are three narrower columns fitted with conductive rings, pins, and copper wire brushes. In front of those is another support column. The three columns, together with a special type of synchronous motor, form a mechanical rectifier. The column rotates in synch with the voltage across the coils, such that continuous connections are only established between the coils at the left and right when the alternating current across the coils is at its maximum positive value.