Ferranti Miniature Current Transformer – 1930-1950.

This current transformer was used to measure the current in an electrical cable, by connecting it to a meter and passing an electrical cable through the hole in the centre. The magnetic field of the cable induces a current inside the transformer, the level of which can be read on the meter.

It was produced around 1940 by the Manchester-based company Ferranti, part of a range of electrical meters designed for use by electricians. This particular example belonged to Percy Skipworth and his son Reg Skipworth, owners of the small electrical contractor S Charlesworth & Co in Oldham, Greater Manchester, much of whose business was for textile mills.