Assessment of the operability of a technical facility in real time is important for the stable and trouble-free operation of the facility during its operation. Previously, a classification model for the rate of parameter change was proposed based on specialized point cloud processing of a time series segment without trend extraction. However, some proposals, for example, related to the non-inclusion of some points of the series in the model construction procedure, were not sufficiently justified and are an unobvious attempt to get rid of abnormal values of the time series. Some stages of the model implementation, for example, building an ellipse on a transformed point cloud, require a detailed representation, which is important for further model training and classification. In the article, as part of the preliminary data preparation, a procedure is proposed for detecting and screening out abnormal values of the time series of a parameter based on a modification of the Irwin method. In addition, an updated scheme for evaluating the values of the criterion in the classification model for the condition of a technical facility parameter is presented. The ellipse compression ratio is used as the evaluation criterion, which is based on a cloud of scatter plot points cut out by a sliding time window from the time series of the parameter. An iterative ellipse construction procedure has been developed for this purpose. The new procedure provides a more informed and accurate assessment of the criterion. Thus, a modified model has been built that will allow real-time assessment of the occurrence of an emergency situation at an early stage of its development. The evaluation procedure can be implemented as part of the hardware and software of the monitoring system of a technical facility
