Figure 7.1 shows a typical cascade arrangement of transformers used to obtain up to 300 kV from three units
each rated at 100 kV insulation. The low voltage winding is connected to the primary of the first transformer,
and this is connected to the transformer tank which is earthed. One end of the high voltage winding is also
earthed through the tank. The high voltage end and a tapping near this end is taken out at the top of the
transformer through a bushing, and forms the primary of the second transformer. One end of this winding is
connected to the tank of the second transformer to maintain the tank at high voltage. The secondary of this
transformer too has one end connected to the tank and at the other end the next cascaded transformer is fed.
This cascade arrangement can be continued further if a still higher voltage is required.