A method for detecting and characterizing an occurrence of at least one event during operation of a valve actuator as one of a deviation, malfunction or failure, the method comprising the steps of: detecting a series of signals received from a plurality of sensors, where each signal represents a condition of a different operational variable associated with the actuator; determining from the signals one or more of the operational variables that caused the occurrence of the at least one event; the method being characterized: determining at least one relationship between the one or more operational variables and the at least one event, determining a time-related succession of intermediate states of operation associated with the valve actuator, wherein each state of operation is a group of one or more of the operational variables being in a normal operation zone, a deviation zone, a malfunction zone or a failure zone, and wherein the states are interconnected by transition paths which are automatically quantified by cause-and-effect relationships and temporal and likelihood factors; characterizing each at least one event by the one of the operational related variables being in one of the normal mode of operation zone, the deviation zone, the malfunction zone or the failure zone; and communicating the at least one relationship through an output device. detecting a series of signals received from a plurality of sensors, where each signal represents a condition of a different operational variable associated with the actuator; determining from the signals one or more of the operational variables that caused the occurrence of the at least one event; the method being characterized: determining at least one relationship between the one or more operational variables and the at least one event, determining a time-related succession of intermediate states of operation associated with the valve actuator, wherein each state of operation is a group of one or more of the operational variables being in a normal operation zone, a deviation zone, a malfunction zone or a failure zone, and wherein the states are interconnected by transition paths which are automatically quantified by cause-and-effect relationships and temporal and likelihood factors; characterizing each at least one event by the one of the operational related variables being in one of the normal mode of operation zone, the deviation zone, the malfunction zone or the failure zone; and communicating the at least one relationship through an output device. determining at least one relationship between the one or more operational variables and the at least one event, determining a time-related succession of intermediate states of operation associated with the valve actuator, wherein each state of operation is a group of one or more of the operational variables being in a normal operation zone, a deviation zone, a malfunction zone or a failure zone, and wherein the states are interconnected by transition paths which are automatically quantified by cause-and-effect relationships and temporal and likelihood factors; characterizing each at least one event by the one of the operational related variables being in one of the normal mode of operation zone, the deviation zone, the malfunction zone or the failure zone; and communicating the at least one relationship through an output device.