• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권6호
• /
• pp.279-285
• /
• 2005

The lightning causes the damage of power system equipments as well as large power failure. Therefore, the insulation design should be established not only to decrease the damage of the facilities itself but also to increase the reliability of electric power system. This paper describes the useful way applying underbuilt ground wire and guy wire in transmission tower that safely protect the substation equipments. One or more shield wires under the phase conductor will not intercept lightning stroke, but they may improve reduce lightning voltages almost as effectively as if they were above the phase conductors. And the guy wires will mitigate the tower surge response. These would not only reduce backflashover possibility but also minimize crest and duration of surges entering the substation. EMTP is used to analyze the efficiency of the proposed methods.

• 조명전기설비학회논문지
• /
• 제28권12호
• /
• pp.6-12
• /
• 2014

The safety and reliability of the power system short-circuit current, the short-circuit current depends on the failure to obtain the objective is to quickly eliminate the breaking capacity of the circuit-breaker selection of the cable, the insulation of electrical equipment and protective relay an important factor in determining the level correction and protective relay selection scheme to be meaningful. Standards used in the domestic circuit breaker is applied to the production of IEC standard, but the American National Standards (ANSI / IEEE) by NEMA specification of the fault current calculations and the application of the asymmetric coefficient Korea. Therefore, in this paper, the IEC 60909 standard IEC breaker fault current calculation method and the method for selection of system configurations reviewed and protection system for reviewing the configuration of various protective relays appropriate correction and the correction value is main protection, back-up protection the equipment so that the period of protection relay coordination to minimize accidents and accident protection to minimize interruptions proposed for cooperation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.403-405
• /
• 1999

Power transformers have a tendency of ultra-high voltage and huge capacity as power demand increases day after day. Therefore, the fault by insulation destruction gives rise to large area of power failure in huge capacity transformers. On-line predictive diagnostics is very important In power transformers because of economic loss and its spreading effect. Hence, this study presents experiments of partial discharge method using ultrasonic sensor in order to confirm the possibility of ultrasonic sensor in power transformers. It carries out the experiments of measuring delay time between ultrasonic sensor and transducer, sensitiities by temperature change of oil and by barriers inside transformers. It is also Included wave analysis by ultrasonic sensor for needle-plate electrode powered on through high-voltage equipments.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1903-1905
• /
• 2000

Power transformers have a tendency of ultra-high voltage capacity as power demand increases day after day KEPCO also will have plan to supply transmission power from 345KV to 765KV in the early of 2000. Therefore, the fault by insulation destruction gives rise to large area of power failure in huge capacity transformers. On-line predictive diagnostics is very important in power transformers because of economic loss and its spreading effect. This study presents the algorithm for transformer oil analysis used KEPCO code, IEC code, gas pattern method and Dornenburg & Roger Ratio method. We also describe the MMI display of expert system programmed by Element Expert Tool(Neuron Data Inc.).

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 추계 학술논문 발표대회
• /
• pp.165-166
• /
• 2017

The purpose of this study is to investigate the effect of tile adhesion failure due to weak adhesion with concrete admixture (FA, SP) on walls. The test specimens were divided into four types : (1) OPC 100% (2) OPC 80%+FA 20% (3) OPC 80%+SP 20% (4) OPC 60%+SP 40%, each adhered on a 650 × 650mm wall with 200mm thickness capable of attaching two insulation tiles (300 × 600mm). The tests were carried out on the four types of walls by mortar bedding application method, and after 4 weeks of curing period, adhesion strength test was carried out. The adhesion strength difference was investigated between the concrete wall with added admixture (FA, SP) and general concrete wall.

• 전기학회논문지
• /
• 제60권3호
• /
• pp.531-537
• /
• 2011

This paper proposes a finite element method (FEM)-based model of an interior permanent magnet (IPM) type BLDC motor having stator inter-turn faults. For more realistic simulation studies, the magnetic non-linearity is also considered in proposed model. And the simulation data are verified through experiment. By integrating the developed model with a current-controlled voltage source inverter (CCVSI) model, the characteristics of an inter-turn fault operated by six-switched inverter are investigated considering the speed control. And the circulating current, which is induced by magnetic linkage flux originated from PM, was analyzed from the view point of distortion of air-gap magnetic flux distribution caused deterioration of their torque.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2005년도 학술대회 논문집
• /
• pp.399-403
• /
• 2005

In this paper, we analyze on the effect of RC filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of switching surge appears more serious in high voltage induction motor than low voltage induction motor. Consequently, we demonstrated that the RC filter connected to the motor terminals greatly reduces the transient voltage stress md ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1997년도 추계학술발표회논문집
• /
• pp.70-73
• /
• 1997

This paper describes the technique for detecting failure symptom of mold transformer. This study uses the vibration signal analysis method and FEM as the technique. A loading back method is constructed for experiment, accelation sensors are adhered for measurement of vibration signal. Vibration signal measured by this method is analyzed into variation trend of measurement variables by control of control variables. Magnetic field distribution of molded winding is also acquired by FEM considering the design specfication and the characteristics of insulation material, in conclusion, he relation of results between vibration signal and FEM is studied by these methods.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
• /
• pp.2220-2222
• /
• 2005

Epoxy Insualtion spacers for supporting the conductors and partitioning the sections in $SF_6$ Gas insulated Switchgear(GIS), require higher electrical, Thermal and mechanical reliability with other principal components in GIS to be operated without any failure in use. In this paper, we describe the results of the performance evaluation of electrical and mechanical properties for extra high-voltage GIS according to KEPCO spec. and the requirements of the insulators for GIS specified by IEC 62271-203(2004).

• 조명전기설비학회논문지
• /
• 제12권4호
• /
• pp.47-54
• /
• 1998

발전설비에 있어 고신뢰성이 요구됨에 따라 진행되는 고장을 조기에 발견하는 예방 보전적 진단 시스템이 요구되고 있다. 본 논문에서는 발전설비 중에서 회전체의 절연진단과 진동진단에 대한 지식을 지식 베이스로 구성하고 이것을 다표정 언어를 이용하여 전문가 시스템을 구성하였다. 이 전문가 시스템은 진단 룰의 수정과 추가가 용이하며, 사용자와의 인터페이스도 양호한 구조를 취하고 있다.