• 조명전기설비학회논문지
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• 제27권5호
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• pp.81-88
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• 2013

A low voltage circuit breaker protects electrical equipments from over current and short faults of system by cutting the power supply. The breaker use a thermal magnetic type trip device from the past. In recent years, electronic type relays are applied due to useful functions and services. The purpose of this development is full digitalizing of relay functions of a low voltage breaker. It includes separation of current sensor from current transformer, digital signal processing, high speed relaying, and voltage measuring for power meter. The suggestions are tested and implemented by making prototype and testing its all relay functions.

• 제어로봇시스템학회논문지
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• 제6권3호
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• pp.284-290
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• 2000

The measurement of electric current using optical techniques provides a number of important practical advantages including effective isolation from high line potentials and freedom from the saturation effects observed in conventional current transformers. In this work the optical current sensor which uses thin YIG(Yittrium Ion Garnet) film as a Faraday element has been developed. We have characterized this optical current sensor and implemented it to the OOCR(Opto-electronic OverCurrent Realy) Performance of the OOCR shows the possibility of replacing the present overcurrent relays with OOCR.

• 한국기계가공학회지
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• 제21권2호
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• pp.46-53
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• 2022

This paper presents the design and manufacture of a Solid State Relay (SSR) life prediction device that can predict the lifetime of an SSR, which is a key component of a glass forming machine. The lifetime of an SSR is over when the current supplied to the relay is overcurrent (20 A or higher), and the operating time is 100,000 h or longer. Therefore, the life prediction device for the SSR was designed using DSP to accurately read the current and temperature values from the current and temperature sensors, respectively. The characteristic test of the manufactured non-contact relay life prediction device confirmed that the current and temperature were safely measured. Thus, the SSR lifetime prediction device developed in this study can be used to predict the lifetime of an SSR attached to a glass forming machine.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.741-742
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• 2011

In this paper, an over-current relay algorithm module for a network-based protective relay simulator is proposed. The proposed protective simulator is based on the client-sever paradigm. The module composed of a server and user interface provides a network-based simulation environment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.451-465
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• 2008

지하철에서는 직류보호계전시스템으로 정한시과전류계전기(76i)와 저전압계전기(Mid-point Relay, 80A)를 사용하여 직류급전계통을 보호하고 있었으나, 최근에는 보호방식으로 고장선택계전기(50F)를 주로 적용하고 있다. 본 연구에서는 현재 서울메트로 3 4호선에 적용하여 사용하고 있는 76i/80A와 50F 각각의 직류급전계통 보호방식을 비교하기 위해 단락고장계산식을 이용하여 분석하였으며 PSCAD/EMTDC 과도프로그램을 통한 시뮬레이션으로 연구하였다. 분석한 결과 80A는 고장저항의 크기에 따라 동작여부가 달라지고, 50F의 경우 고장저항의 크기나 선로의 길이가 변하더라도 일정시간이 지나면 설정값에 따라 동작함을 확인하였다. 이에 향후 직류보호계전시스템의 운영에 있어 합리적인 적용을 제시하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.195-196
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• 2008

Output of wind generators are changed by windy level. The change of the output also affects the amplitude of fault current. And this fault current causes OCR's mal-operation. To solve the problem, this paper adopts that Over Current Relay adapted for Decentralized generator algorithm.

• 항공우주기술
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• 제10권2호
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• pp.56-64
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• 2011

최근 위성 시스템의 전력분배는 기존의 퓨즈와 릴레이로 구성된 것과는 달리 LCL(Latching Current Limiter) 회로로 구현되어, 각각의 부하전원을 단속한다. LCL은 부하에서 생기는 과전류를 제한함으로서 고장 의심이 있는 부하를 물리적으로 차단하는 기존 방법에 비하여 고장의 원인을 분석하고, 일시적인 고장인 경우 부하를 재사용할 수 있는 장점이 있다. 그러나 LCL 회로는 전자소자로 구현되는 만큼 주변회로(부하회로)와의 연동성과 회로 자체의 특성을 이해해야 하며, 무엇보다 과전류를 차단하기 위하여 설정하는 LCL 동작 파라미터의 정의를 위한 기술적인 접근이 요구된다. 따라서 본 논문에서는 전력분배 모듈의 LCL 동작 파라미터를 정의하기 위한 분석을 수행했고, 회로구현 및 특성 시험결과를 나타냈다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.173-175
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• 2005

Malfunction of Klippon relay in Cheju-Haenam HVDC system has been caused by the inflow of high voltage arc. In this paper, we have studied on the theoretical examination and data analysis of Klippon relay, and the countermeasures against the problems were suggested according to their causes. Grounding problem in Klippon relay is removed by one-point earth connection and by modification of grounding circuit. The effects of over current surge was removed by attaching blocking diodes by series In Klippon relay to remove surge input in Klippon relay's mercury contact. The problem of Induced overvoltage by 86re1ay excitation coil, was removed by attaching Free-wheeling diode in parallel with the excitation coil of Lock-out relay.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1000-1002
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• 1997

In this paper we proposes a scheme which can improve the detecting capability of the high impedance fault of the conventional distance relaying. It utilizes the directional ground overcurrent relay called HIFR together with the distance relay in order to secure the security and selectivity.

• 전기학회논문지
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• 제56권11호
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• pp.1873-1878
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• 2007

Current differential relays may maloperate during magnetic inrush and over-excitation because a significant differential current is produced. To prevent maloperation, the relays adopt some harmonic components included in the differential current. The harmonic restraints may increase the security of a relay but cause the operating time delay of a relay when an internal fault occurs. Moreover, the operating time delay is more increased if a current transformer (CT) is saturated. This paper describes a current differential relaying algorithm for power transformer protection with a compensating algorithm for the secondary current of a CT. The comparative study was conducted with and without the compensating algorithm. The performance of the proposed algorithm was investigated when the measurement CT (C400) and the protection CT (C400) are used. The proposed algorithm can compensate the distorted current of a CT and thus reduce the operating time delay of the relay significantly for an internal fault with CT saturation.