• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2008-2010
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• 2000

The first objective of this study is to set up the switching surge analysis method in motor driving distribution system. The simplified model which can simulate the motor energization and circuit breaker re-ignitions. and each circuit element model is presented in this paper. The second objective is to calculate the quantity of surge over-voltage in real nuclear power station. And the surge suppressing measures are verified on the simulation basis. It is clarified that most cases are not satisfactory to meet the IEEE standard 522-1992 without using surge suppressing measures. In cases that the surge arrester are installed in distribution board at the load side of circuit breaker. The IEEE specification is fully met.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.381-389
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• 2003

Nowadays, Vacuum Circuit Breaker(VCB) is used in the most medium voltage level because vacuum has environment-friendly characteristics as well as excellent dielectric strength. In order to elevate the breaking performance, the improvement of vacuum interrupters and the driving mechanism should be proceeded. In this paper, the development of a Permanent Magnet Actuator could replace the mechanical spring mechanism which is the driving mechanism of existing VCB. The holding force and opening characteristics of magnetic actuator are analysed with FEM and the result is verified through experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.190-195
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• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1001-1003
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• 1993

Steep-fronted surges associated with motor witching cause relatively large turn-to-turn winding stress. In order to calculate the surge level at the motor terminals, equivalent circuits consist of three parts with power sources, load cable and motor constants. This paper presents switching surges phenomena occurred in a high voltgae induction motor witching by EMTP.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.10
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• pp.521-527
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• 2006

After various measuring methods and system were investigated, Rogowski colis for the measurement of parameters in current zero region were designed and manufactured. Using the Rogowski coils and a 38kV 40kA VCB (vacuum circuit breaker), at last the post-arc current has been successfully measured firstly. It was found that the Rogowski coils used in this study have good characteristics and propriety to measure the parameters of current zero. We realized that the data processing for evaluating the post-arc current from the experimental results needs much more careful attention than that for building the measuring technique and system. The magnitude of post-arc current and the falling time of it to zero are proportioned to the rate of current di/dt. The magnitude of post-arc currents were around $1{\sim}3A$ to the interruption current of $20{\sim}30kA$ in the model VCB.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1159-1164
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• 2018

Vacuum circuit breakers(VCB) are widely used for current interruption of high-voltage inductive loads such as induction motors. This VCB can be chopped off before the current zero due to its high arc-extinguishing capability. One of the outstanding features of VCB is that it can cut off high frequency re-ignition current more than other circuit breakers. If the transient recovery voltage generated in the arc extinguishing is higher than the dielectric strength of the circuit breaker, a re-ignition phenomenon occurs. The surge voltage of the re-ignition is very high in magnitude and the steepness of the waveform is so severe that it can act as a high electrical stress on the winding. If the high frequency current of one phase affects the other two phases when the re-ignition occurs, it may cause a high surge voltage due to the virtual current chopping. If the magnitude of the voltage allowed in the motor winding is high or the waveform level is too severe, it may lead to insulation breakdown. Therefore, it is necessary to reduce the voltage to within a certain range. In this study, we briefly explain the various phenomena at the time of interruption, analyzed the magnitude of the dielectric strength and the transient recovery voltage at the simultaneous three-phase interruption that can give the greatest influence to the inductive load, proposed a method to reduce the impact.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.5
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• pp.15-21
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• 1980

An engine control system in which the conventional mechanical ignition system is studied. The contact point of the breaker is replaced by the contactless magnetic pick up sensor from which the information of the speed and the position of the crankshaft is extracted , and further an electronic High Energy Ignitim System Is designed, implemented and tested . The High Energy Igniticwl System increases the secondary spark voltage of the ignition coil from the conventional 10000~15000 volts to the 30000~40000 volts resulting in improving the combustion efficiency. Also, instead of the conventional advimce mechanism forigniliontiming control, a microprocessorbased timinng mechanisn is installed to determine the ignition timing data in response to the engine rpm and the intake manifold vacuum.