Control Chart X-Rm and Area-Threshold for the Remaining Useful Life at Thermoelectric Power Plant

Abstract

The statistical process control charts are an important diagnostic technique indicative of operational deviations to enhance the quality of automated systems and products. The purpose of this work was to design the control chart (X-Rm) for monitoring the superheating steam temperatures in a thermoelectric power plant. The automatic control chart patterns recognition was performed using decision rules and test zones, from which the stability index and the areathreshold for the remaining useful life were calculated. The chart consisted of 2163 normal data, center line 521,73 °C, lower control limit 519,31 °C, and upper control limit 523,76 °C. Shift-trend presented the highest relative frequency due to the possible general causes: poor standardization, changes in work procedures, and failures in the industrial network. The area-threshold was 581-1193 u2 for WECO rules. This work is expected to contribute to implement condition-based maintenance strategy