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李殷雄,金宗謙 忠南大學校 産業技術硏究所 1991 산업기술연구논문집 Vol.6 No.2
In recent year, vacuum circuit breakers (VCB) have been widely used as the power supply breaker of high voltage motors, to enhance the efficiency and to make the maintenance of waterworks equipments easy. Poweful surge voltage, a repetitive phenomenon of reignition, occured when the VCB is switching between on and off, and is transmitted to the stator winding of motor through the cable. This surge voltage is repeated several times, though the action of the circuit breaker (CB) is not completed, and if the suge voltage is culmulated, the motor becomes burned by owing to breakdown of winding at the end. In this study, the surge voltage occuring at the opening and closing of the VCB was analyzed as the transient phenomenon by circuit parameters. By examining the variances of peak value, duration of wave-front, and duration of wave-tail under the variances of length and capacity of the cable, we could expect to protect the breakdown of winding with parallel connection of suitable capacitance in the motor.
구속 회전자 전류의 배수가 다른 이중 농형 유도발전기의 적용 시 동작 특성
김종겸 대한전기학회 2024 전기학회논문지 Vol.73 No.7
The induction machine can be operated as an induction motor or induction generator by adjusting the rotor speed before and after the synchronous speed. Induction machines are widely used in industrial sites because they are more advantageous than other rotating machines in terms of convenience of maintenance, robust and economical price. The biggest disadvantage of this induction machine is that the voltage drop is high due to the flow of large current when starting or connecting to the grid. Since the induction generator starts and then connects to the grid near synchronous speed, there is no need to set the value of the locked rotor current high to generate a large torque when starting like an induction motor. When an induction generator generates power and sends it to the grid, it must pass through a motor operating area lower than synchronous speed. This is because the reactive power required for magnetization must be supplied from the grid. At this time, a large voltage drop may occur, mainly in the distribution system. In this study, we analyzed how the voltage drop, change in power, and power factor vary depending on the size of the current depending on the magnification of rotor locked current when developing a three-phase double squirrel cage induction generator and connecting it to the grid.
김종겸,박영진,Kim, Jong-Gyeoum,Park, Young-Jeen 한국조명전기설비학회 2004 조명·전기설비학회논문지 Vol.18 No.6
대부분의 저압 수용가는 단상 및 3상 부하를 동시에 공급할 수 있는 장점을 지닌 3상 4선식 배전시스템을 적용하고 있다. 이 시스템은 구조적인 간단함 때문에 종래의 단상 및 3상 부하를 분리하는 방식보다 편리하다. 그러나 고르지 못한 부하 불평형이나 낮은 전기품질은 출력저하나 손실과 같은 문제를 발생하고 있다. 본 논문에서는 실제현장에서 전압 및 전류 파형을 측정하여 국제적으로 허용되고 있는 전압불평형 기준과 비교 분석을 실시하였다. Most of LV customer have applied the 3-phase four wire system distribution system because it has advantage of supplying both of 1-phase at 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But once in a while uneven load unbalance or unclean power quality lead some problems such as do-rating or power losses. In this paper, voltage and current waveform in the actual fields have been measured and analyzed in relation with intermationally allowable voltage unbalance limits.
김종겸 대한전기학회 2020 전기학회논문지 P Vol.69 No.2
Pumped-storage power generation is a method of generating by pumping the water at the upper reservoir by using surplus power at the late night and then discharging the water when power use is increased suddenly. Most of the generators used for pumped generation have used synchronous generators. Synchronous generators are more advantageous than induction generators, but they are disadvantageous in terms of maintenance and price. Up to now, pumped storage power generation has been mainly in large capacity, but recently, as requirements for renewable energy have increased, the class of small and medium capacity is required. If the output of the generator is not large, it may be more economical to apply the induction generator than the synchronous generator. In this research, various phenomena that may occur when induction generator is applied to fish farm pumped-storage power generation where output is not large are analyzed.