Minami-rinkan, Japan
Minami-rinkan, Japan

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Nakamura H.,TOENEC Corporation | Chihara M.,Photonix Corporation | Inoki T.,Photonix Corporation | Higaki T.,Photonix Corporation | And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2010

Short circuit fault of a motor, due to breakdown of an insulating material of winding, is one of the most probable faults in motor drive systems. Establishment of an easy and effective fault diagnosis method has been strongly required to assure operation with high reliability. This paper proposes a novel diagnosis method for insulation failure of motor windings by a combination of impulse testing and pattern recognition based on Hidden Markov Model (HMM). A voltage waveform across two winding terminals is recorded under application of an impulse voltage. HMM is exploited to distinguish a small difference in voltage waveforms between healthy and faulty winding insulations. Usefulness of the proposed diagnostic method is verified through voltage waveforms experimentally obtained for motors with several kinds of turn-to-turn insulation failures. © 2010 IEEE.


Iritani E.,Nagoya University | Katagiri N.,Nagoya University | Takaishi Y.,Toenec Corporation | Kanetake S.,Nagoya University
Journal of Chemical Engineering of Japan | Year: 2011

The single constant pressure filtration test for dilute colloidal dispersions has been newly developed for easily determining the pressure dependence of the permeability characteristics such as the average specific cake resistance. The method made use of the gradual variation of the effective pressure drop across the filter cake with time generated by using the filter medium with a high medium resistance. The correlations between the average specific cake resistance and the effective pressure were obtained from the flux decline data. The data of the flux decline behavior obtained for the various values of the slurry concentration, applied pressure and medium resistance were largely merged by the normalized form of the reciprocal filtration rate vs. the filtrate volume. The validity of the method was confirmed not only for slurries of bentonite, Hara-Gairome clay, and polymethyl methacrylate (PMMA), but also for nanoparticle colloids of bovine serum albumin (BSA) and silica sol. Copyright © 2011 The Society of Chemical Engineers, Japan.


Inagaki S.,Nagoya University | Egami T.,Nagoya University | Suzuki T.,Nagoya University | Nakamura H.,Toenec Corporation | Ito K.,Toenec Corporation
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2011

This paper presents a new nonintrusive appliance load monitoring technique based on integer programming. Nonintrusive appliance load monitoring is the problem of identifying the operating conditions of electric appliances in a house by observing only the overall load current and voltage. Since the overall load current is expressed as a superposition of the currents of the operating appliances, the monitoring problem can be formulated as an integer quadratic programming problem by expressing the operating conditions as integer variables. This problem is solvable with a sufficiently small computational burden thanks to the recent development of commercial software. The proposed method does not require relearning even when a new appliance is installed in the house. Furthermore, the proposed formulation is applicable to cases in which some appliance has multiple modes, and cases in which some appliances of the same type are operating simultaneously. The usefulness of the proposed technique is verified by experimental results. © 2010 Wiley Periodicals, Inc.


Nakamura H.,TOENEC Corporation | Mizuno Y.,Nagoya Institute of Technology
IEEJ Transactions on Industry Applications | Year: 2012

Short-circuit faults of winding due to the deterioration in the insulation is one of the most probable faults in motor drive systems. An easy and effective fault diagnosis method has been strongly required to assure operation with high reliability. This paper proposes a novel method for diagnosing both short-circuit faults and insulation deterioration in windings. This method involves an impulse voltage test and probabilistic process for gauging the probability of fault occurrence by considering the distributions of features depending on the condition of the winding. In this paper, first, we discuss the results of several impulse tests on the winding. Second, two features that represent the characteristics corresponding to the condition of the winding are induced, and their feature distributions are determined. Third, we introduce the probability that can be used to diagnose the condition of the winding. The average and standard deviation of both features are calculated. By using the calculated values and features observed in a target winding to be examined, the fault probability is computed. Finally, the usefulness of the proposed diagnosis method is verified by performing experiments involving the use of faulty and deteriorated windings. © 2012 The Institute of Electrical Engineers of Japan.


Yagami Y.,Nagoya Institute of Technology | Araki C.,Nagoya Institute of Technology | Mizuno Y.,Nagoya Institute of Technology | Nakamura H.,TOENEC Corporation
2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014 | Year: 2014

Short-circuit fault of stator winding due to aging of electrical insulation is one of the most probable faults in motor drive systems. The authors have proposed a simple method for diagnosing the fault probabilistically by considering distributions of features, i.e. magnitude and phase of load current. Laboratory experiments proved that the method was promising. In order to enhance accuracy of diagnosis, especially in the case of a slight insulation failure such as one turn-to-turn short circuit, this paper proposes a method with the aid of Support Vector Machine using the features. Effectiveness of the new method is evaluated compared with the probabilistic one. © 2014 IEEE.


Kishino M.,Nagoya Institute of Technology | Mizuno Y.,Nagoya Institute of Technology | Nakamura H.,TOENEC Corporation
Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP | Year: 2011

Insulation failure of motor windings is one of faults that are likely to occur during the lifetime of motors. The authors have proposed a novel and simple method to diagnose insulation failure in a stator winding in terms of "fault probability", which is calculated on the basis of feature distributions of magnitude and phase of current flowing into windings. Validity of the method was confirmed under no load condition in the previous report. In this paper, it will be shown that the proposed method is also quite effective under loaded conditions based on the results of a series of laboratory experiments using motors with an artificially introduced insulation failure in a stator winding. © 2011 IEEE.


Kishino K.,Nagoya Institute of Technology | Mizuno Y.,Nagoya Institute of Technology | Nakamura H.,TOENEC Corporation
Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP | Year: 2012

This paper proposes a novel and simple method for diagnosing insulation failure (short-circuit) in stator windings of motors under load conditions. The method involves probabilistic process for gauging the probability of failure occurrence by considering distributions of features, i.e. magnitude and phase of current flowing into stator windings, depending on the condition of the insulation failure of windings. A series of laboratory experiments and analyses of the results for motors with artificially introduced insulation failure prove that the proposed method is promising. © 2012 IEEE.


Yagami Y.,Nagoya Institute of Technology | Araki C.,Nagoya Institute of Technology | Mizuno Y.,Nagoya Institute of Technology | Nakamura H.,TOENEC Corporation
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2015

Turn-to-turn short-circuit of stator winding due to deterioration of electrical insulation is one of the most probable faults in motor drive systems. This paper proposes two diagnostic methods to detect the fault based on Support Vector Machine. In the first method, magnitude and phase of load currents at fixed rotating speeds are considered as features reflecting winding condition. It is found that the method is effective particularly in slight insulation failure like one turn-to-turn short-circuit. Classification of winding condition, i.e. specification of number of short-circuit turns, is also achieved by this method. In the second method, only magnitude of load currents is treated as feature aiming at diagnosis available when load current varies. The method also has the advantage of low cost and short data processing time. It is found that two turn-to-turn short-circuit can be diagnosed with practically acceptable accuracy. An appropriate choice of the two methods should be recommended depending on the goal as well as circumstance of diagnosis. © 2015 IEEE.


Nakamura H.,TOENEC Corporation | Ohno T.,Nagoya Institute of Technology | Abe T.,Nagoya Institute of Technology | Mizuno Y.,Nagoya Institute of Technology
IEEJ Transactions on Industry Applications | Year: 2010

This paper proposes a new method for the diagnosis of short circuit faults in the stator winding of a motor; the method involves gauging the probability of fault occurrence by considering feature distributions of a healthy motor. When a fault occurs, the current flowing into the motor increases, and the phase of the current leads that of the current in a healthy one. These characteristics of the current are valuable for fault diagnosis of motors. In this paper, first, we introduce the probability that can be used to detect a fault. Second, the average and standard deviation of both magnitudes and phases of the currents in several healthy motors are calculated. By using the calculated values and features observed in a target motor that is to be examined, the probability is computed. Finally, the usefulness of the proposed diagnosis method is verified through experiments involving the use of faulty motors. © 2010 The Institute of Electrical Engineers of Japan.


Nakamura H.,TOENEC Corporation
IEEJ Transactions on Industry Applications | Year: 2012

Short-circuit faults in windings due to the deterioration of insulation is one of the most common faults in motor drive systems. An easy and effective fault diagnosis method is urgently required to ensure a highly reliable operation. This paper proposes a novel method for the diagnosis of short-circuit faults in stator winding inside a low-voltage induction motor without removing the rotor, by performing an impulse voltage test. As the rotor does not need to be removed from the motor in the novel diagnosis method, the method can be applied for practical use. In this study, first, several impulse voltage tests are carried out on the stator windings of motors. Second, the values of two features that represent the characteristics corresponding to the condition of the motor are calculated, and it is found that the shape of the feature distribution does not depend on the rotor position but on the condition of the winding. Third, the distance between the feature distribution for the healthy motor and features obtained from a target motor is calculated. On the basis of this distance, the quality of stator winding inside the induction motor is determined. The effectiveness of the proposed diagnosis method is verified by performing experiments that involve several motors with healthy and faulty windings. © 2012 The Institute of Electrical Engineers of Japan.

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