• 전기의세계
• /
• v.28 no.7
• /
• pp.49-55
• /
• 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.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.516-517
• /
• 2011

마이크로그리드는 분산전원 또는 계통의 Sag/Swell 및 단락사고, 지락사고 등으로 인한 정전 발생 시에 사고 지점을 제외한 독립운전이 가능해야 한다. 따라서 사고 발생지점을 신속하게 분리할 수 있는 기술이 필요하다. 이러한 배경으로 본 연구에서는 신속하게 사고지점을 차단하는 고속차단 시스템(TCB :Thyristor Circuit Breaker)을 제안한다. 도통손실이 작고 경제적인 Thyristor를 이용하여 25 [kVA]급 TCB 시스템을 제작하고 사고를 모의하여 사고 발생 시의 TCB 시스템 동작특성에 대해 연구한다.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.272-281
• /
• 2017

The DC circuit breaker is essential for supplying stable DC power with the advent of DC transmission/distribution and sensitive loads. Compared with mechanical circuit breakers, which must interrupt a very large fault current due to their slow breaking capability, a solid-state circuit breaker (SSCB) can quickly break a fault current almost within 1 [ms]. Thus, it can reduce the damage of an accident a lot more than mechanical circuit breakers. However, previous DC SSCBs cannot perform the operating duty, and are not economical because many SCR are required. Therefore, this paper proposes a new DC SSCB suitable for DC grids. It has a low semiconductor conduction loss, quick reclosing and rebreaking capabilities. As a result, it can perform the operating duties of reclosing and rebreaking. The proposed DC SSCB is designed and implemented so that it is suitable for home dc distribution at a rated power of 5 [kW] and a voltage of 380 [V]. The operating characteristics are confirmed by simulation and experimental results. In addition, this paper suggests design guidelines so that it can be applied to other DC grids. It is anticipated that the proposed DC SSCB may be utilized to design and realize many DC grid systems.

• Journal of the Korean Society of Safety
• /
• v.37 no.1
• /
• pp.12-19
• /
• 2022

Circuit breakers are a crucial factor in ensuring the safety of a Direct Current (DC) grid. One type of DC circuit breaker, the Z-source DC circuit breaker (ZCB), uses a thyristor, which is a type of semiconductor switch. In the event of a fault in the circuit, the ZCB isolates the fault by generating a zero crossing current in the thyristor. The thyristor quickly and actively isolates the fault while generating a zero crossing current, but thyristor switch cannot control turn-off and the allowable current is lower than the current of the mechanical switch. Therefore, it is best to use a mechanical switch with a high allowable current capacity that is capable of on/off control. Due to the slow reaction time of mechanical switches, they may not isolate the fault during the zero crossing current time interval created by the existing circuit. In this case, the zero crossing current time can be increased by using the property that hinders the rapid change in the current of the inductor. This paper will explore whether adding system inductance to increase the zero crossing current time interval is a solution to this problem. The simulation of changing inductor and capacitor (LC) of the circuit is repeated to find an optimal change in the zero crossing current time according to the LC change and provides an inductor and capacitor range optimized for a specific load. The inductor and capacitor range are expected to provide optimization information in the form LC values for future applications of ZCB's using a mechanical switch.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.4
• /
• pp.368-376
• /
• 2012

According to developed distributed generators, Solid State Circuit Breaker(SSCB) is essential for high power quality of DC Grid. In this paper, a simple and new structure of DC SSCB with a fast circuit breaker and fault current limiter is proposed. It can help to choice low specification of elements because of the limiting of fault current and achieve economic efficiency for minimizing auxiliary SCRs. Also all of SCRs have little switching loss because they operate under ZVS and ZCS. Through simulations and experiments of short-circuit fault, the performance characteristic of proposed circuit is verified and a guideline is so suggested that the DC SSCB is applied for a different DC grid using formulas.

• 전기의세계
• /
• v.28 no.12
• /
• pp.41-45
• /
• 1979

Improvement of power factor is achieved by reactive-current compensation, connecting power condenser to the circuit. This paper describes a method of reactive-current compensation, employing thyristor switching of capacitor banks without any breaker. This method reduces supply transients to the minimum by means of connecting condenser, because thyristor is triggered at zero point in condenser current. The reactive current detection and the experimental system to trigger thyristor at appropriate moment are given. IThe results show the fast reactive-current compensation on the condition of minimum transient.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.11
• /
• pp.1575-1583
• /
• 2017

With the development of DC distribution, DC circuit breaker is required to ensure the stability of the DC grid. Unlike a mechanical circuit breaker that blocks after several tens of milliseconds, a DC SSCB(Solid-State Circuit Breaker) can break the fault well within 1 [ms], so it can prevent the damage of accident. However, the previous DC SSCB requires a lot of switching elements for charging commutation capacitors, and the control is complicated. Therefore, this paper proposes a new DC SSCB suitable for DC grid. The proposed DC SSCB is simple to control for charging commutation capacitors, and it can perform the rapid breaking and operating duty of reclosing and rebreaking. The proposed DC SSCB was designed to 380 [V] and 5 [kW] class which is suitable for residential DC distribution, and the operating characteristics of the proposed DC SSCB were verified by simulations and experiments. It is anticipated that the proposed DC SSCB may be utilized to design and realize DC grid system.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.1303-1308
• /
• 2004

This paper proposes a reduction method for the mis-operation analysis of the DC High Speed Circuit Breaker(HSCB) in electric railway substation system. The analysis method is based on present condition of operation which is a method for accuracy level up. There is reason to operation of HSCB that it is mis-operation of fault detection relay(50F), operation of ground fault relay(64P), and trouble of electric car. A countermeasure is relay resetting through field test, induction of GTOCB(Gate Turn Off Thyristor Circuit Breaker), HSVCB(High Speed Vacuum Circuit Breaker), coordination with electric car. The results presented in the paper can be used as a reference for maintenance free in electric railway substation system.

• Journal of Power Electronics
• /
• v.15 no.4
• /
• pp.1074-1084
• /
• 2015

These days, the widespread use of sensitive loads and distributed generators makes the solid-state circuit breaker (SSCB) an essential component in power circuits to achieve a high power quality for AC Grids. In traditional AC SSCB using SCRs, some auxiliary mechanical devices are required to make the reclosing operation possible before fault recovery. However, the proposed AC SSCB can break quickly and then be reclosed without auxiliary mechanical devices even during the short-circuit fault. Moreover, its fault current breaking time is short and its SSCB reclosing operation is fast. This results in a reduction of the economic losses due to fault currents and power outages. Through simulations and experiments on short-circuit faults, the performance characteristics of the proposed AC SSCB are verified. A design guideline is also suggested to apply the proposed AC SSCB to various AC grids.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.7
• /
• pp.367-372
• /
• 2006

A novel coil gun type actuator has been proposed and tested for its possibility as an actuator for a high voltage circuit breaker by experimental method. The 20kJ capacitor bank with the electrolytic condensers was charged up to 500V and discharged to a couple of 100 turn coils connected with parallel through a thyristor switch. The repulsive force between coil and the actuator made by copper conductor of 20kg reached up to 23,000 N, and over 800J of energy was transferred to the kinetic energy of the conductor. The experimental results showed that the coil gun type actuator has a good possibility for the high voltage circuit breaker.