In modern power system power electronics drives in which 6 pulse and 12 pulse uncontrolled converters are provided for high power application. The scheme concede the distortion of the current waveforms caused by 6 pulse and 12 pulse uncontrolled converter under balanced and unbalanced input line condition. This paper endeavors to present a new technique based on wavelet transform for detection of harmonics in 6 pulse and 12 pulse AC/DC uncontrolled converter under balance and unbalance input line condition. The modeling and simulation of 6 pulse and 12 pulse topologies using MATLAB software to collate their input harmonic current, voltage ripple and THD are presented. The key plan is to decompose a simulated signal into a smooth and close version of the first signal. The signal is decompose by using db4 as a wavelet function of DWT with multi resolution technique. Microcontroller is used for monitoring the voltage balance and unbalance.