This article deals with a new motor-operated valves (MOVs) condition monitoring method. MOVs mainly consist of an induction machine driving a valve through a mechanical actuator. Such systems need important maintenance policies since they are critical concerning the operational readiness of the safety related systems of nuclear power plants. Unfortunately, today's policies present a major drawback. Indeed, these monitoring techniques rely on the measurement of an internal mechanical quantity and require the presence of human operators in dangerous power plants areas. The aim of this research work is to develop a monitoring method relying exclusively on remote electrical measurements (MOV supply voltages and currents), without the need of any internal MOV quantity. In this article, the instantaneous active power absorbed by the induction machine is first shown to be an interesting electrical quantity to elaborate mechanical failure indicators. An efficient real-time algorithm developed to estimate this physical quantity is then detailed and mechanical failure indicators based on the estimated electrical power are proposed. Finally, their performance is illustrated through experimental data.
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