Increased losses in a D-C motor when operated from grid-controlled rectifiers

The increase in copper losses and iron losses of a d-c shunt motor when operated from grid-controlled rectifiers is studied. Fourier components of the rectifier output voltage are calculated, and the superposition principle is applied to predict copper losses. Tests were run to determine copper loss and iron loss; increased copper loss is seen to closely approximate the predicted value, and discrepancies are interpreted as being due to nonlinearity of the iron. The increased iron losses follow a pattern, explained in the text. Results are graphed on normalized co-ordinates and are thought to be representative.