A system and method to evaluate characteristics of notches in sine wave type electrical signals. An example method includes measuring a voltage waveform. A reference waveform is derived from the measured voltage waveform. A series of threshold voltage values is determined based on corresponding voltages of the reference waveform. The voltages of the voltage waveform are compared with the corresponding threshold voltages. The presence of a notch is indicated when a voltage of the voltage waveform is lesser in magnitude than the corresponding threshold voltage.