• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.12 no.1
• /
• pp.11-17
• /
• 1999

Aging characteristics of the crosslinked polyethylene have been measured after applying electrical, thermal and combined stresses. ICP and FT-IR measurements confirmed diffusion of low molecular weight components such as antioxidant and presence of carbonyl group. Carbonyl group of aged crosslinked polyethylene under combined stress was detected by FT-IR. As deterioration of the crosslinked polyethylene progresses, crystallinity degree and density decrease. Also, dielectric properties have been measured by tan $\delta$ and $\varepsilon$$_{r}$ measurements. The three-parameter Weibull distribution was found to be the best suited among other probabilistic distribution representing the dielectric breakdown strength of aged crosslinked polyethylene. The scale parameter and location parameter decreases as the applied stress increases. The shape parameter increases as the stress increases.s.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.6
• /
• pp.1007-1016
• /
• 2007

In power system, substation facilities have become too complex and larger according to an extended power system. Also, customers require the high quality of electrical power system. However, some facilities become old and often break down unexpectedly. The unexpected failure may cause a break in power system and loss of profits. Therefore it is important to prevent abrupt faults by monitoring the condition of power systems. Among the various power facilities, power transformers play an important role in the transmission and distribution systems. In this research, we develop intelligent diagnosis technique for predicting faults of power transformer by FCM(Fuzzy c-means) and Euclidean based distance measure. The proposed technique make it possible to measures the possibility and degree of aging as well as the faults occurred in transformer. To demonstrate the validity of proposed method, various experiments are performed and their results are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.481-484
• /
• 2001

High voltage induction motors are widely used in industrial factory because have many benefits. But the insulated materials of induction motor are aged by using time, electrical, thermal, circumstantial stresses and so on. Motor failures are occurred by these deterioration phenomena and give rise economic problems to user. In many motor failures, insulated material problems of stator winding happen frequently and occupy high percentages in the failure source. In this paper, the testing specimen(motorette) is manufactured by modeling of stator winding of high voltage induction motor and accelerating test is carried out. Partial discharge signals detected by RF sensor are used to analyze deterioration condition of stator windings. According to aging time, the 3D ( ${\Phi}$-Q-N) distribution and skewness of partial discharge signals are changed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.2
• /
• pp.145-152
• /
• 2013

Electrolytic capacitors used for smoothing DC link voltage is one of the major root causes of fault in power electronic system. The aging of aluminum electrolytic capacitors is expressed by the increase of their equivalent series resistance (ESR) and the reduction of their capacitance. Thus, the proposed technique in this paper is to measure capacitance, by comparing energy loss of DC link capacitors with stator resistor in electric machine. Condition of DC link capacitors can be estimated from the capacitance decrease rate between initial and aged capacitors. The results show that the proposed technique provides an easy, widely applicable and simple low cost solution for detecting dc link capacitor degradation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.459-462
• /
• 2002

The conventional thermal insulator and power transformer testing is widely used in surface aging measurement of outside insulator because those testing can carry out very short time in Lab testing. Also thermal testing is able to offer the standard judgement of relative degradation level of outside HV machine. There it is very useful method compare to previous conventional thermal testing method and effective Lab testing method. But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IRR-camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis. In this study, thermal testing of Power transformer is measured with partial temperature distribution in real time.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.127.2-127
• /
• 2001

A transformer is one of the most important elements in the power network. Transformer faults could cause costly repairs and be dangerous to personnel. To avoid this, its reliable operation has great significance and, therefore, the diagnosis system of the transformer is necessitated. The dissolved gas-in-oil analysis (DGA) is the worldwide popular method of detecting faults such as a hot spot or partial discharges inside the transformer. DGA, however, is not a reliable technique to identify aging phenomena and mechanical faults including insulation failure, inter-turn short, etc. To overcome the drawbacks of DGA, the transfer function method is used to identify effectively these kinds of the mechanical faults. The transformer has a unique transfer function independent of the shape of the input waveform, which can be evaluated through sweep test. This transfer function changes by winding ...

• Journal of Industrial Technology
• /
• v.34
• /
• pp.67-70
• /
• 2014

In this paper, we propose a diagnosis algorithm for 25.8kV $N_2$ insulated Pad-mounted Switchgear in oder to improve reliability by preventing of fault in advance. The proposed algorithm can diagnose the problems of Pad-mounted Switchgear such as gas leakage and VI(Vacuum Interrupter) trouble (contact abrasion, coil aging etc.) by using pressure sensor, stroke sensor and coil current sensor.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1801-1803
• /
• 1996

This paper describes a diagnosis of cable splices by analysis of ultrasonic signals which is generated by partial discharge. Peak-peak amplitude of ultrasonic signals was used to diagnose cable splices. It is proposed that aging discrimination is possible by analysis of ultrasonic signals in cable splices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.444-447
• /
• 2003

All objects with some temperature above absolute zero radiate in the infrared. The intensity of the infrared radiated from a object defends on the condition and temperature on the surface of the one. The present, these techniques are frequently adopted into diagnosis for electricity equipments. Simply, however, the applied techniques are passive thermal testing for the detection of loosened terminals and overcurrent. In this paper, a infrared thermal imager was applied to high voltage windings of cast resin transformers, and the accumulated value of the result temperatures was used for evaluating remained lifetime of them. At each aging level, dielectric loss tangent test was carried out. The results offered capabilities for deciding the condition of the transformers suffering difficulties to diagnose.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.16 no.1
• /
• pp.21-26
• /
• 2016

Canine cataract is developed with aging and can cause the blindness or surgical treatment if not treated timely. The first observation must be made by pet owners but they do not have proper equipment and knowledge to see the abnormalities. In this paper, we propose an intelligent image processing method to extract canine cataract suspicious object from non-professional equipment such as ordinary digital camera and cellular phone photographs so that even casual owners of pet dog can make a pre-diagnosis of such a surgery-needed disease as soon as possible. The experiment shows that the proposed method is successful in most cases except the dog has similar colored hair to the color of cataract.