Induction machines either as motors or wind generators are the most commonly used in the industrial applications due to its prices, robust design and less maintenance. So, it is very important to keep this element running. In modern industry, the new trend is to focus on condition monitoring and fault detection systems. In this direction it is very important to have an efficient and reliable fault diagnosing system. The target of this book is to find a way to have on line reliable and efficient condition monitoring systems for turn-to-turn fault either in single phase and multi-phase faults. Stator current signals are used for the proposed condition monitoring systems due to their availability and sensitivity to electrical faults. Two on line artificial neural networks (ANN) fault diagnosing systems for turn-to turn faults are presented. First system is by using stator current values while the second is by using the ellipse trace parameters of two stator phase’s currents. Also a novel modeling of Induction machines under faulty conditions is introduced in this book; this model was verified by experimental works.