• Title/Summary/Keyword: over-current protector

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A Study on Development of Open-Phase Protector Having Leakage Current Generation and Incapable Operation Prevention at Open-Phase Accident (결상 시 누전전류 발생과 오동작 방지 기능을 갖는 결상보호기 개발에 관한 연구)

  • Kwak, Dong-Kurl
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.1
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    • pp.182-187
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    • 2015
  • In the three-phase power system, when any one-phase or two-phases is open-phase, the unbalanced current flows and the single-phase power supplies to three-phase loads. Specially, motor coil and transformer coil receive over-current. As a result, great damage as well as electrical fire can occur to the power system. In order to improve these problems, this paper proposes that an open-phase detection device is designed by a new algorithm using electric potential difference between the resultant voltage of neutral point and ground, and a control circuit topology of open-phase protector is composed of highly efficient semiconductor devices. It improves response speed and reliability. The control algorithm circuit also operates the cut-off of a conventional residual current protective device (RCD) which flows an enforced leakage current to ground wire at open-phase accident. Furthermore, time delay circuit is added to prevent the incapable operation of open-phase protector about instantaneous open-phase not open-phase fault. The time delay circuit improves more reliability.

Characteristics of Short-Circuit Protector in Pad-Mounted Transformer (지상변압기의 단락보호장치 특성연구)

  • Kim, K.H.;Lee, W.Y.;Sun, C.H.;Kim, D.M.;Kim, S.J.
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1350-1352
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    • 1995
  • This paper discribed the characteristic of I-t cross-over-point between current limited-fuse and explusion fuse(Bay-O-Net Fuse) and fuse protection in pad-mounted transformer that was generated internal faults and the short circuit of secondary side(load side). In the I-t cross-over-point, current limited fuse was melted when transient recovery voltage was raised rapidly.

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A study on AC over-current breaker using thyristor (Thyristor를 이용한 교류과전류 차단에 관한 연구)

  • 박민호;심재명
    • 전기의세계
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    • v.28 no.7
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    • pp.49-55
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    • 1979
  • This paper describes the mechanisms which breaks A.C. over-current protection in low voltage load. For the high speed over-current protection, it consists of thyristor switching circuit by forced commutation, IC logic gate controlled circuit and over-current detector with reed switch. Under various duty conditions, breacker was carried out several experiments and discussions. The results are as follows; (1) over-current cut off is possible within a quarter cycle (4ms at 60Hz) and clear is at least ten times faster than its electromechanical equivalent. (2) as the forced commutation thyristor circuit breaker has capability of high speed break, equivalent surgy current capacity of switching thyristor is increased more than twenty times of its rated current. (3) breaker using solid state dose not produce any harmful arc during switching period. Therefore the breaker above described may be considered an effective over-current protector for soli state power devices in industrial applications.

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The Coupled Electro-Thermal Field Analysis for Predicting Over-Current Protector Behavior

  • Bae, Jae-Nam;Lee, Sung-Gu;Han, Jung-Ho;Chung, Hae-Yang;Lee, Ju
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.7
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    • pp.43-48
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    • 2008
  • The characteristics of heat transfer of the bimetal disc for over-current protection device is specified. Bimetal consists of two metals which have a different thermal expansion coefficient. To analyze the thermal characteristics, temperature distribution when bimetal acts as a switch is calculated. As usual, heat source is applied to the bimetal and electric current is heat source in the over-current protection switch. In this paper, thermal distribution are obtained by solving a coupled electro-thermal field with 3D finite element method.

Preparation and Properties of Polymer PTC Composites for Process Safety (공정안전용 Polymer PTC 소재의 제조 및 특성)

  • 강영구;조명호
    • Journal of the Korean Society of Safety
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    • v.18 no.3
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    • pp.101-108
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    • 2003
  • Polymeric positive temperature coefficient(PTC) composites have been prepared by incorporating carbon black(CB) into high density polyethylene(HDPE), polyphenylene sulfide(PPS) and polybutylene terephthalate(PBT) matrices. A PTC effect was observed in the composite, caused by the large thermal expansion due to He consecutive melting of HDPE, PPS and PBT crystallites. This theory is based upon the premise that the PTC phenomenon is due to a critical separation distance between carbon particles in the polymer matrix at the higher temperature. The influence of PTC characteristics of the PPS/CB composite can be explained by DSC result. HDPE, one of prepared composition, exhibit the higher performance PTC behavior that decreaseing of negative temperature coefficient(NTC) effect and improved reproducibility by chemically crosslinking. Also, PBT/CB and PPS/CB composites exhibit the higher PTC peack temperature than HDPE/CB PTC composite, individually $200^{\circ}C$ and $230^{\circ}C$. These PTC composite put to good use in a number of safety application, such as self$.$controlled heater, over-current protectors, auto resettable switch, high temperature proctection sensor, etc.

Development of the Water Treatment System with High Performance Electromagnetic Field (고성능 전자장을 갖는 수처리 시스템의 개발)

  • Lee, Yong-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.54 no.3
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    • pp.155-159
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    • 2005
  • This paper presents the water treatment system with high performance electromagnetic field for a good quality of water. The electromagnetic field water treater consists of a solion, a solion body, and a high voltage converter. The high voltage converter is controlled by PWM current controller. The high voltage converter of 13W is designed for an isolation operation amp, an isolation current detector, and an over current protector. Using the high voltage PWM converter, the system with the proposed electromagnetic field water treater can be controlled easily. Simulation and experimental results show the effectiveness of the system strategy proposed for the scale rejection.

Development of the Electromagnetic Field Water Treater System (전자장 수처리 시스템 개발)

  • Kim, Sang-Uk;Kim, Jin-Hwan;Kim, Bo-Youl;Kim, Young-Bong
    • Proceedings of the KIEE Conference
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    • 2002.06a
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    • pp.142-145
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    • 2002
  • This paper presents the electromagnetic field water treater system with the high performance for a good quality of water. The electromagnetic field water treater consists of a solion, a solion body. and a high voltage converter. The high voltage converter is controlled by PWM current controller. The high voltage converter of 13W is designed for an isolation operation ramp. an isolation current detector, and an over current protector. Using the high voltage PWM converter, the system with the proposed electromagnetic field water treater can be controlled easily. Simulation and experimental results show the effectiveness of the system strategy proposed for the scale rejection.

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Design of Fuse Elements of Current Sensing Type Protection Device for Portable Secondary Battery Protection System (휴대용 이차전지 보호 시스템용 전류 감지 동작형 보호소자의 퓨즈 가용체 설계)

  • Kang, Chang-Yong;Kim, Eun-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.12
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    • pp.1619-1625
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    • 2018
  • Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.

A Study on Development of New 3-Phase Open-Phase Protector used in Distribution Panel (새로운 분전반용 3상 결상보호기 개발에 관한 연구)

  • Kwak, D.K.;Kim, J.H.;Park, Y.J.;Jung, D.Y.;Kim, D.K.;Kim, P.R.
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.546-547
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    • 2012
  • In the three-phase power system using the three-phase load, when any one-phase is open-phase, the unbalanced current flows and the single-phase power supplied by power supply produces over-current. As a result, the enormous damage and electrical fire can be given to the power system. In order to improve these problems, this paper is proposed a new control circuit topology for open-phase protection using semiconductor devices. Therefore, the proposed open-phase protection device (OPPD) enhances the sensing speed and precision, and has the advantage of simple fitting in the three-phase distribution panel in the field, as it manufactures into small size and light weight. As a result, the proposed OPPD minimizes the electrical fire from open-phase, and contributes for the stable driving of the power system.

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A study on Cause Analyses of Fatal injuries by the Mobile Cranes (이동식 크레인 사고사망재해 심층분석 연구)

  • Shin, Woon-chul;Yeo, Hyun-Wook;Kwon, Jun-hyuck;Yi, Kwan-Hyung
    • Journal of the Korea Safety Management & Science
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    • v.18 no.1
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    • pp.9-15
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    • 2016
  • In this study, the current regulations to be adequate in industrial site have to be renew in order to prevent the fatal injuries by mobile cranes. Fatal injury analyses were conducted with several accident cases by the mobile cranes. For each accident, the causes of the injuries were examined and proper safety measures were proposed. This study proposed a revision of the standard guideline as an accident prevention measures through in-depth analysis of fatal accidents. First, fatality rate per 10,000 persons by the mobiles cranes was 0.57 in 2011. Second, the in-depth analysis of the mobile crane accidents showed that the main factors of the accidents were the overturn of mobile crane, the fracture of connection part between mobile crane boom and rope, the breaking of rope and the misunderstanding over the signal between a mobile crane driver and workers around a mobile crane. Third, the order of high defection of connecting parts was bucket bolt, bracket and extension parts. Fourth, since there were several cases of overturn of mobile crane by itself in the in-depth analysis of the mobile crane, the over slop-proof device was proposed as the main alternative in this study. Fifth, the revision of standards of safety factor that shall be more than 10, of connecting parts of mobile crane was proposed.