The effect of coil parameters on the distribution of steep-fronted surges in machine windings

The authors identify the coil parameters that are of importance, when assessing interturn voltages produced by steep-fronted transients. The studies are based on a multiconductor transmission line computer model of a machine winding energized by a simple ramp function. Variations in interturn voltages produced by changes in insulation thickness, insulation permittivity, turn geometry, coil length and number of turns are examined and certain guidelines for avoiding high interturn voltages are evaluated. An application study is included to show how interturn voltages can be significantly reduced by applying these guidelines