Diagnosing of Failures of Automotive Alternators Based on Amplitude of Fluctuations of Voltage

Abstract

— Automotive alternators problems constitute about 21 % of total automotive electrical faults. Fault in automotive alternator can cause different implications, ranging from fault in battery accumulator or electronics through road traffic accident. Fluctuation of output voltage is accepted as the main diagnostic parameter as being the most sensitive to faults in automotive alternators. Disadvantage of existing methods for determining the fluctuation of output voltage is a smoothing effect of battery accumulator and absence of methods for interpreting the obtained quantitative data. It is suggested to improve the diagnostic method using an oscilloscope through the exclusion of smoothing effect of battery accumulator. The developed diagnostic method makes it possible to assess the technical condition alternators without dismounting them from a car based on the parameters of output voltage through the comparison of the obtained value of output voltage fluctuation with the allowable value. It is found that fluctuation of output voltage of serviceable alternators increases monotonically with increasing time in service without reaching limit or allowable values. Voltage fluctuation in alternators with electrical problems significantly exceeds allowable values that makes it possible to use this parameter for the determination of technical condition. Fluctuation of output voltage used as a diagnostic parameter makes it possible to assess the residual operation time of automotive alternators. Determination of residual operation time of automotive alternators can improve the operational efficiency of cars by means of decrease in standby time during repair.