Evaluation of different approaches to measure partial discharge characteristics within electric motor insulation

The demand to develop reliable electric motor design solutions stressed by resent development of semiconductor technologies and the need for higher voltage levels, become increasingly important. This paper compares different approaches of measuring and quantifying PD exposure in motor insulation material. In this context, both development and selection of suitable materials and test specimens employing diagnostics suitable for on- and off-line is of importance. To investigate this, electrical methods with a high-pass filter connection, the usage of current transformer as well as an antenna solution are compared for different rise times investigating two types of test objects. The different results are compared, the strength, disadvantages and limitations of each method are presented and implications of this discussed. The results presented constitute a base for development and selection of methods for on or off-line testing.