• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.69-74
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• 2004

In general the surge pressure generated in hydraulic systems causes noise, vibration and odd effect to the system. To reduce the surge pressure, high frequency PWM control of 20KHz was attempted. To estimate the braking noise caused by surge, a vehicle equipped with on-board ABS hydraulic modulator has been experimented with respect to the various breaking condition. Thorough this experiments, it was found that breaking noise has been reduced using high frequency PWM control method compare with low frequency method. To evaluate high frequency control m practice, including verification of general functionality, EMI tests was experimented. Its was found that it is necessary to have the solution to electromagnetic interference(EMI) generated by switching elements.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.503-505
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• 1995

The surge arrester plays a vital role in the protection of substation against transient overvoltages resulting from lightning surges and system switching operations. The proper selection and application of the surge arrester is an integral part of the process of substation equipment insulation level selection. The paper outlines the basic consideration in modeling the lightning stroke, the surge arrester, and the system to be protected. The paper discusses the results of various cases simulated using the alternative transient computer program to evaluate the separation effects.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.47-53
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• 2015

The study concerning about the grid connection of the large-capacity energy storage system(ESS) is increasing. However, the transient study such as lightning or switching surge necessarily occurred at power system with ESS has been hardly performed. Therefore, this paper performs the analysis of lightning surge in distribution system with ESS using electromagnetic transient program(EMTP). The battery model in Matlab/Simulink is modeled by EMTP, which is the specialized software for power system transient study. Also, the bi-directional power electronics for interconnection of the battery and distribution system are modeled by EMTP. When the lightning is occurred at interconnection point of ESS, this paper simulates the existence of ESS and operation conditions of ESS and analyzes the surge in distribution system and ESS according to the various conditions.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1698-1699
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• 2007

This paper deals with the surge measurement system for low voltage power line of industrial plants. It consists of a capacitive divider, A/D conversion part, signal processing and control part. A FPGA and a DSP board were designed to fast signal processing and control. Also, in order to measure lightning surge and switching surge for a long time, data backup device was applied by using SD memory. A performance of the measurement system was verified through evaluation test using impulse calibration generator.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.21-26
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• 2018

In this paper, the switching characteristics of the active clamp type flyback converter, which is deemed suitable for the miniaturization of the external power supply for home appliance, were analyzed and the process of reducing the switching loss was explained. The active clamp type flyback converter operating in the DCM has confirmed that the surge voltage of the main switch does not occur and the turn-off / on loss of the switch do not occur in principle. Also, in the case of the switch for synchronous rectifier, it was showed that the switch current showed half-wave rectified sinusoidal characteristic, and the switching loss was reduced. The switching characteristics of the experimental results gathered from 120 W class prototype were compared with the theoretical waveform in the steady-state and it was confirmed that the power conversion efficiency of the active clamp type flyback converter was maintained high due to the reduction of the switching loss.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1675-1677
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• 1998

It is currently increasing to use surge protection devices in the protection of various electronic circuits from the transient overvoltages such as lightning strikes and switching surges. For this reason, the simulation methods, which can easily predict the protection performance of the devices, are strongly required in order to design the adequate surge protection circuits in lightning surge cut-off performance and economic aspects. This paper deals with ZnO varistor modeling method for designing a surge protection circuit and suggests the Pspice simulation model which takes the characteristic of varying clamping voltage into consideration during the time-to-crest, in range of $8{\sim}30{\mu}s$, of surge current applied to a ZnO varistor. The ZnO varistor Pspice simulation data introduced in this paper has produced almost same values as the measured results experimentally.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.111-117
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• 2008

Generally, speed control for Induction motor widely used in industrial field is accomplished by commercial inverter. Induction motor driven by commercial inverter causes the micro surge voltage because of high speed switching of inverter. Micro surge brings about not only the breakdown of motor but also noise in PLC control system. And they court the enormous interference in activity for production. In this paper, we suggest the suppressible countermeasure for the breakdown of motor after the consideration of productive mechanism about micro surge. Experiment is performed by inverter with LCR filler in its output terminal. As a result, we confirmed that micro surge voltage is reduced. And the suppressible countermeasure for the noise of PLC control system is suggested by theoretical consideration.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.1
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• pp.31-37
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• 2004

In this paper, the analysis result of the switching surge in substation including GIS(Gas Insulated Switchgear) has been described using the EMTP(Electro Magnetic Transient Program) program. After performing the modeling of the input data, we have reviewed the energization overvoltages of GCB(Gas Circuit Breaker) without closing resistor in 345kV network, according to the conditions of simultaneously operating switch and statistically operating switch. Firstly, it can be known that the energization overvoltage of single line is higher than that of parallel energized line. Secondly, the maximum energization overvoltage obtained in statistics switch is higher than one in simultaneous switch. From these results, it can be known that the phase-to-earth energization overvoltages of $\alpha$-$\beta$ section are less than 2.2 p.u when closing resistor is eliminated. Therefore, it is possible to consider the circuit breaker eliminated the closing resistor in $\alpha$-$\beta$ section.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.399-403
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• 2005

In this paper, we analyze on the effect of RC filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of switching surge appears more serious in high voltage induction motor than low voltage induction motor. Consequently, we demonstrated that the RC filter connected to the motor terminals greatly reduces the transient voltage stress md ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• 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.