We present a method for testing the operational stability of Low Voltage Power Supply modules of the ATLAS Tile Calorimeter, based on a self-consistent determination of the stability criteria. The recorded voltage, current, and temperature values of each module are retrieved from the Oracle database for a long and smooth running period and their mean and RMS values over that period are determined, as well as their average recording rates, by taking into account the â??smoothingâ?? procedure which is applied during data recording to reduce data storage. The average behavior of the ensemble of all modules is determined from those time-integrated quantities and the modules are then tested one-by-one by comparing with the ensemble averages. The proposed method is tested for all Long Barrel modules operated during April of 2007
