• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1422-1423
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• 2006

In our study, the PTFE nozzle ablation in the high-voltage self-blast type $SF_6$ gas circuit breaker was investigated. The test circuit breaker has the structure that the pin electrode is moving and the pressure reservoir volume and the dimension is almost same as commercial 145kv 40kA circuit breaker for similar result in real circuit breaker. The variation of current and arcing time was the range of $36kA_{rms}$(symmetry) - $40kA_{rms}$(asymmetry) and 10-16 ms. From the measured data the tendecy of the mass loss of the nozzle to current load and arc energy was estimated. In this process, the distance from the arc to nozzle(PTFE) surface, area which was exposed to arc and stroke contour was considered. These results will be used to enhance the accuracy of the computational fluid dynamics analysis in circuit breaker and estimate the residual life time of a circuit breaker.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.144-146
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• 2002

The latest development flow of MCCB(Molded Case Circuit Breaker) is largely separated from which are high capability of interrupting compact of size and multi-ability in functions. As follow of development of industrial system. MCCB which are including communication function and having a ultimate interrupting capability is required in electrical system. to attain an effective limitation of the peak let-through current and the let-through energy, the arc has to move rapidly off the contacts and has to increase the arc voltage which mainly effect to interrupt. In this paper. we made high performance circuit breaker which including current limiting unit which is attached to the main which is simulated by CAE tool that are repulsion force and mechanical dynamics after that we tested and finally selected optimized for circuit breaker.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.86-89
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• 1991

In recent years, Vacuum Circuit Breaker(VCB) has been widely used to enhance the confidence and at the same time to ease maintenance of waterworks requipment as the power supply breaker of high voltage motor. When making and breaking the sources as VCB the powerful surge voltage, repetitive reignition phenomenon resulted from exceeding inter-pole endurance voltage of CB, has occured. It has transmitted to the winding of motor stator through the cable, and this surge voltage is repeated over and over again before finishing making and breaking action of CB according to cumulation of repetitive reignition surge, motor has become burned in the end. This paper describes surge voltage occuring in making and breaking of VCB as circuit parameters by transient phenonenon and examines closely the variance of peak values, wavefront-length, wavetail-length, when changing inductance and capacitance of a cable. Finally we will expect to protect motor winding breakdown from surge voltage through parallel connection of suitable-size in the motor.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.6
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• pp.284-292
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• 2005

Because all of the short-circuit testing laboratories have the limitation of test facilities, the synthetic making test methods have been used to estimate the short-circuit making performance of the ultra high-voltage circuit breaker as the alternative to direct test methods. So, KERI(Korea Eelctrotechnology Research institute) has completed the construction of the synthetic making test facilities using the low capacity step-up transformer method which fulfill the requirements specified in newly revised IEC 62271-100 Edition 1.1(2003) and have the testing capability up to 550kV, 63kA full-pole circuit breaker. The test facilities using the low capacity step-up transformer method presented in this paper are made up of the unit equipments such as HCS(High-speed Closing Switch), ITMC(Initial Transient Making Current) circuit and UP TR(low capacity step-up transformer) and have the operating range of 17.6$^{\circ}$ $\~$ 145.1$^{\circ}$ for testing the circuit breaker rated on up to 50kA and 43.1$^{\circ}$ $\~$ 119.6$^{\circ}$ for more than 50kA.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.61-63
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• 2005

In this paper, a new type of permanent magnetic actuator (PMA) with multi-stage coils is proposed. Although the conventional type of PMA has many advantages, it cannot be applied in the high voltage circuit breakers due to its short stoke length. The new type of PMA has long stroke length by using multi-stage coils, so it can be applied as an actuator for the high voltage circuit breakers. Dynamic characteristics are calculated by the finite element method (FEM), equation of electric circuit and dynamic equation. The position of plunger and the current of coils in case of the actuator applied in 38kV, 40kA vacuum circuit breaker are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1321-1328
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• 2009

In this paper, an electromagnetic force driving actuator (EMFA) and three-link mechanism are proposed as a driving mechanism and connection device for low voltage air circuit breaker (ACB). As the result of dynamic characteristic analysis, the actuator and link mechanism are designed from the simulation and manufactured. The magneitc field of the EMFA is analyzed using the finite element method (FEM). The dynamic characteristic analysis with calculation of the circuit equation and kinetical equation is performed by the time difference method (TDM). Also, the result of the analysis is verified through the experiment of the fabrication model. In this paper, the EMFA size is smaller than the actuator for high voltage circuit breaker. Thus, the dynamic characteristic is analyzed with end-winding inductance that is calculated by the same method which is applied on the circle type end-winding of motors. The designed model for 1600 ampere-frame ACB and the three-link mechanism for connecting contact part with actuating part are manufactured. It is confirmed that the three-link mechanism is possible for improving the circuit breaker efficiency and reducing the size of the EMFA. It is proved that the improved 2-D analysis is more accurate than established method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.328-332
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• 2010

The SLF(Short Line Fault) breaking capability test for high voltage class $SF_6$ GCB(Gas Circuit Breaker) was conducted. Simplified LC resonant circuit test facility was used for SLF breaking test. During test, Test current was measured by Rogwski coil and arc voltage was measured by voltage divider. Arc conductance was calculated by using these test results before 200ns at current zero. Critical arc conductance value at rated voltage 145kV class is about 2.3mS regardless of breaking current magnitude and arc conductance value at rated voltage 170kV class is about 2.6mS.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.813-823
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• 2013

On-line monitoring system is important for high voltage vacuum circuit breakers (HVCBs) in operation condition assessment and fault diagnosis. A distributed multilayer system with client/server architecture is developed on rated voltage 10kV HVCB with spring operating mechanism. It can collect data when HVCB switches, calculate the necessary parameters, show the operation conditions and provide abundant information for fault diagnosis. Ensemble empirical mode decomposition (EEMD) is used to detect the singular point which is regarded as the contact moment. This method has been applied to on-line monitoring system successfully and its satisfactory effect has been proved through experiments. SVM and FCM are both effective methods for fault diagnosis. A combinative algorithm is designed to judge the faults of HVCB's operating mechanism. The system's precision and stability are confirmed by field tests.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.232-234
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• 2002

A Vacuum Circuit Breaker Model for simulation of transient overvoltages was developed by using the PSCAD/EMTDC. The Model includes the power frequency chopping current. Breaker withstand voltage, and quenching capability of High frequency currents. To verify the abilities of the breaker model, the simulation on the Lindmayer's single-phase circuit was carried out. The results show that using the proposed model, the transient overvoltages, current chopping, and multiple reignitions of vacuum breaker are properly reproduced as real phenomena. In further study, virtual chopping current will be incorporated into the model for 3 phase system.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.396-397
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• 2015

With the increasing utilization of high-voltage, direct current (HVDC) transmissions in modern power systems, the DC grid is becoming a hot topic in academic and practical systems. In the DC grid, one of the urgent problems is the fast clearance of the DC fault in the DC network. One preferred method is to isolate the faulty point from the DC network in a short time. The DC circuit breaker is to interrupt the overcurrent after DC faults occur. In this paper, a self-excited resonant DC circuit breaker is an easy and cheap equipment to interrupt the DC fault current. The Mayr's arc model is utilized to simulate the self-excited DC circuit breaker in a DC test system in PSCAD/EMTDC.