Online Condition Monitoring Technique Research Articles

Condition monitoring and warning of a belt drive system based on a logical analysis of data regression-based residual control chart

The belt drive system is commonly used to transmit power in different industrial systems to maintain high performance and safety. Online condition monitoring techniques (CMTs) are used to monitor the operational conditions of such systems. Vibration-based monitoring techniques (VMT) are among the CMTs that are used in the analysis and diagnosis of the state of a belt drive system. Machine learning techniques are integrated with the VMT based on Industry 4.0 aspects for vibration analysis and fault diagnosis. Most of these techniques are based on the collection of vibration data from the belt drive system under known normal and different known faulty operations. This enables a fault to be diagnosed when it is detected during the operation of a system. In this paper, a new condition monitoring and warning mechanism is proposed to monitor the operational conditions of a belt drive system. The mechanism is based on an integration of a logical analysis of data regression (LADR) with a residual control chart (RCC). It uses vibration data from the belt drive system under normal operation only. This mechanism exhibits better performance in fault detection and also in interpreting the root cause of the faults in a belt drive system. Experimental investigations on a belt drive test rig have been carried out to collect vibration data based on a design of experiment for operational factors during normal operation. The LADR-RCC is implemented to monitor the operation of the belt drive system and detect faulty states. The accuracy of LADR is compared with multiple linear regression-based RCC, support vector regression-based RCC and random forest-based RCC. The LADR-RCC demonstrates significant enhancements in fault detection. The advantage of LADR-RCC over other model-based RCC is that it finds the root cause of a fault that is experienced in the system.

A review of aircraft environmental control system simulation and diagnostics

The aircraft Environmental Control System (ECS) enables the aircraft to maintain a comfortable and safe environment for its passengers throughout its operating envelope. The Pressurised Air Conditioner (PACK) is the heart of the ECS, and is composed of multiple sub-systems: heat exchangers, valves, compressor, turbine, and a water separator. The PACK’s principle function is to enable conditioning of the hot, high pressure bleed air from the engine or APU, for temperature, pressure and humidity against the cabin requirements. The operation of the PACK is governed by a control system which has the ability to mask degradation in its component during operation until severe degradation or failure results. The required maintenance is then both costly and disruptive. The PACK has been reported as major driver of unscheduled maintenance by the operators. The aviation industry is currently proactively exploring innovative health management solutions that aid the maintenance of aircraft key systems based on predictive based maintenance approaches using online condition monitoring techniques. This paper presents a comprehensive review of the simulation and diagnostic methodologies applicable to fault diagnostics of the ECS PACK. The existing literature suggests that model-based and data-driven methods are effective for conducting fault detection and isolation of the PACK system. The conceived findings indicate that the model-based diagnostic approach have been extensively employed to conduct PACK diagnostics at component level only. Their successful implementation requires robust experimental verification and validation against the actual data under healthy and faulty conditions. Although a substantial amount of work has been reported on developing first principles based simulation models and diagnostic strategies for the ECS, the acquired findings suggest that there is a compelling need for a verified and validated ECS simulation model to enable accurate PACK system-level diagnostics based on single and multiple component level degradation scenarios. It has also been identified that the existing literature lacks the evaluation of humidity regulation and the effect of the control system on the PACK performance characteristics. Finally, a taxonomy of diagnostic techniques and simulation models is compiled based on the available literature.

A Negative Sequence Current Phasor Compensation Technique for the Accurate Detection of Stator Shorted Turn Faults in Induction Motors

Stator faults are the most critical faults in induction motors as they develop quickly hence requiring fast online diagnostic methods. A number of online condition monitoring techniques are proposed in the literature to respond to such faults, including the signature analysis of the stator current, vibration monitoring, flux leakage monitoring, negative sequence components of voltage and current and sequence components monitoring based on the identification of asymmetrical behavior in a machine. Negative sequence components of voltage and current and sequence components monitoring are commonly considered for the identification of asymmetrical behavior of induction motors. Negative sequence current analysis is a sensitive technique for the detection of shorted turns as it directly measures the asymmetry produced by the fault. However, the technique is sensitive to other asymmetrical faults and disturbances, which can also produce negative sequence currents. These disturbances include sensor errors, inherent asymmetry and voltage unbalance. This paper provides a comprehensive investigation of the disturbances using a motor model along with experimental measurements under varying load conditions. Then, a new phasor compensation technique is explained to eliminate such disturbances effectively. This technique enables the accurate detection of even relatively small shorted turn faults, even at an early stage. The technique is tested experimentally, and a set of practical results are given to validate the methods developed.

Condition Monitoring of Circuit Switchers for Shunt Capacitor Banks Through Power Quality Data

Aging of power system assets challenges utilities to maintain reliable service while minimizing their maintenance costs. Although malfunction of devices in the transmission or distribution networks can have catastrophic consequences, their failure is seldom unforeseen. Typically, the device aging occurs gradually over time until its health condition reaches a point of complete breakdown. The overall objective of this paper is to devise a non-invasive, online condition monitoring technique of circuit switchers for shunt capacitor banks. It aims to detect abnormal operation of these devices based on features derived from raw voltage and current waveforms, such that a predictive maintenance strategy may be employed before a complete failure occurs. The data analyzed in this paper are collected at a transmission capacitor bus, where the banks are equipped with pre-insertion impedance. Through a baseline range of values for selected parameters, the proposed technique is able to detect missing pre-insertion impedance during the capacitor energizing and failure of pre-insertion impedance switch out a few cycles after the energizing operation.

Design and Development of a Test Setup for Online Wear Monitoring of Mechanical Face Seals Using a Torque Sensor

Online condition monitoring technique helps to detect the root cause of failure of any machine. The present article describes a design of the online failure monitoring facility for mechanical face seals. The experimental test facility is to operate the seal (i.e., carbon-graphite) in real conditions of fluid pressure, temperature, and misalignment, which occur in an industrial environment. The developed test setup consists of two proximity displacement sensors (accuracy 2 μm), one fiber-optic sensor (accuracy 10 μm), one accelerometer (3.97 mV/ms-2), and one non-contact torque sensor (accuracy 0.05 N.m). To validate the test facility, a typical conical carbon graphite (C = 59.195%, O = 4.625%, and Sb = 36.18%.) mechanical face seal (outer dia = 82 mm and inner dia = 63 mm) for a rotary joint used in steam/hot water was selected. The root cause of failure of such seals has been identified. Finally, recommendations have been made that provide some assistance to design the mechanical face seal.

Fatigue damage monitoring in polymeric composites using multiple fiber bragg gratings

Cyclic loading during service may induce sub-surface defects in polymeric composite materials. These insidious defects may grow and eventually lead to catastrophic failures. The current work aims at exploring the possibility of using embedded fiber Bragg grating to monitor damage evolution. Fatigue damage evolution in Graphite/Epoxy coupons having a [−45/90/+45/0] 2s lay-up sequence with a central circular hole subjected to cyclic loading is evaluated. This study suggested that the embedded fiber bragg gratings have good potentials to detect the appearance of damage. It is hoped that this methodology can be further developed as an online condition monitoring technique for safety-critical structures, thereby improving the safety and reliability of composite structures.

An overview of the condition monitoring of overhead lines

Abstract Overhead lines are the most cost effective and frequently used carriers for electric energy. Exposure to environment accelerates deterioration; if this not detected and repaired quickly, some of it will degenerate into serious problems with time. Electrical Utilities, under pressure to reduce maintenance costs, increase line loading and increase quality of power supply, run inspection programs to locate and repair any significant failure at the earliest possible stage. However, present inspection techniques are often expensive and time consuming. Research and development into on-line condition monitoring techniques is thus timely and is as yet at an embryonic stage. This paper reviews the investigation into overhead line deterioration, briefly outlines the inspection methods available at present, and finally introduces a current project being undertaken in the Power and Energy Systems Research Group at the University of Bath in collaboration with two major utilities in the UK, into on-line condition monitoring of overhead lines.