Presently, induction motor adjustable speed drives are being popular in the industrial applications and replacing existing techniques such as Direct Current (DC) motors and Silicon Controlled Rectifiers (SCR) bridges. In this paper, the induction motor's stator inter-turn fault has been diagnosed by advanced Digital Signal Processing (DSP) technique. The Wavelet Transform (WT) algorithm is applied for stator winding fault diagnosis purpose in the transitory period. The wavelet transform's approximation signal is chosen for stator inter-turn fault diagnosis purpose for variable load effectively. The obtained results by WT technique demonstrated that the early fault detection is possible and prevented the machine before reach in the disastrous conditions. Therefore, millions of dollars may be saved for industries and unexpected shutdown.