• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1567-1570
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• 2022

This paper, we presents a RF protection technique of antenna switch by improving the power handling capability in worst case environment mode for mobile phone applications without critical payment of circuit performances such as insertion loss, isolation and ACBV (AC breakdown voltage). By applying a additional capacitive path located in front of the antenna in cell-phone, it performs the effective reduction of input power in high voltage standing wave ratio (VSWR) condition. Under the all-path off condition which causes a high VSWR, it achieved 37.7dBm power handling level as high as 5.7dB compared to that of conventional one at 2GHz. In addition, insertion loss and isolation performances were 0.31dB and 42.72dB at 2 GHz, respectively which were almost similar to that of the conventional circuit. The proposed antenna switch was fabricated in 130nm CMOS SOI technology.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.68-75
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• 2014

Cascaded applications of surge protective devices(SPDs) are required in order to reduce the stress on the electrical and electronics equipment being protected, and the energy coordination between the cascaded SPDs is very important. This paper deals with the experimental results obtained from the installation conditions of full-scale SPDs. The energy coordination between the upstream Class I SPD and the downstream Class II SPD was measured using a $10/350{\mu}s$ impulse current due to direct lightning flashes. The distances between the cascaded SPDs were 3, 10, and 50m, and the maximum test current was 12.5kA. As a result, the energy sharing between cascaded SPDs was dependent on the voltage protection level of each SPD and the distance between two SPDs. An overview of how to select SPD ratings in applications of cascaded SPDs system was discussed based on the energy coordination between the two SPDs. The proposed test results for the energy coordination between two-stage cascaded SPDs can be used in effective applications of SPDs.

• Journal of IKEEE
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• v.28 no.2
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• pp.204-208
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• 2024

In this paper, we propose an ESD protection circuit that applies structural changes to LVTSCR, a general low-voltage ESD protection circuit, to improve the current driving capability (IEC-ESD) characteristics of the ESD protection circuit. Power consumption was minimized by separating the area where the electric field and ESD current path are formed in the LVTSCR structure, and the electrical characteristics were analyzed and current driving characteristics were improved. Structural problems resulting from deterioration of system level characteristics were analyzed through simulation, and the characteristics were verified by reflecting this. The electrical characteristics of the proposed ESD protection circuit were verified using a TCAD simulator and analyzed through HBM modeling and system level modeling. In addition, silicon production and HBM 10kV characteristics were verified through DB-Hitek 0.18um BCD process.

• Journal of the Korea Society for Simulation
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• v.30 no.2
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• pp.33-40
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• 2021

The situation of high-altitude electromagnetic pulses (HEMP) arises from high-altitude nuclear explosions. The HEMP situation can be simulated through the threat level investigation (TLI). In this paper, the induced voltage according to the antenna type of the tactical mobile radio communication system was measured and analyzed by TLI. Under the influence of HEMP, electronic equipment can be paralyzed or damaged. HEMP protection filters are commercially available for power lines and signal lines. However, commercialization of HEMP filters for antennas is insufficient, and even some of them exist for lightning protection. In order to make an appropriate HEMP protection filter according to the frequency and type of the antenna, the induced voltage was measured and the maximum induced voltage was analyzed through extrapolation. It was found that the measured induced voltage decreased as the frequency increased, such as in the HF, VHF and UHF bands of the measurement results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.10
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• pp.81-88
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• 2012

Surge protective devices(SPDs) are widely used as a most effective means protecting the electrical and electronic equipment against overvoltages such as lightning and switching surges. When installing SPDs, it is essential that the voltage protection level provided by SPDs should be lower than the withstand voltage of the equipment being protected. But even the proper selection of SPDs are achieved, the voltage at the equipment terminal may be higher than the residual voltage of SPD due to the reflection and oscillation phenomena. This paper was focused on the investigations of the conditions for which the equipment is protected by an SPD taking into account the influences of the protective distance and type of load. The protective effects of SPD with voltage-limiting component were analyzed as functions of types of load and protective distance between the SPD and load. As a result, in the cases of long protective distances, capacitive loads and loads with high resistance, the voltage at the load terminal was significantly higher than the residual voltage of SPD. It was found that the proper installation of SPDs should be carried out by taking into account the protective distance and type of load to achieve reliable protection of electronic equipments against surges.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.78-88
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• 2018

The liberalization of electricity market and environmental concerns are the major driving forces for the development of Distributed Generation (DG). The mode of grid-connected wind power generation is becoming popular and has matured as a reliable DG technology. The voltage generated by the wind generator is stepped up to the higher voltage by the transformers before connecting to the grid. Operating algorithm of the differential relays for transformer protection used in the wind farms need to be modified to take care of the dynamic nature of fault current caused by the intermittent nature of the wind power. An algorithm for the differential relay is proposed in which dual slope characteristics are adjusted with varying fault level situation according to the wind generator in service as well as with the wind speed. A case study conducted for a typical wind farm shows that the proposed method avoids mal-operation of the differential relay in varying wind power conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.81-87
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• 2015

In order to effectively protect electrical and electronic circuits which are extremely susceptible to lightning surges, multi-stage surge protection circuits are required. This paper presents the operational characteristics of the two-stage hybrid surge protection circuit in extra-low voltage DC power lines. The hybrid surge protective device consists of the gas discharge tube, transient voltage suppressor, and series inductor. The response characteristics of the proposed hybrid surge protective device to combination waves were investigated. As a result, the proposed two-stage surge protective device to combination wave provides the tight clamping level of less than 50V. The firing of the gas discharge tube to lightning surges depends on the de-coupling inductance and the rate-of-change of the current flowing through the transient voltage suppressor. The coordination between the upstream and downstream components of the hybrid surge protective device was satisfactorily achieved. The inductance of a de-coupler in surge protective circuits for low-voltage DC power lines, relative to a resistance, is sufficiently effective. The voltage drop and power loss due to the proposed surge protective device are ignored during normal operation of the systems.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1773-1779
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• 2015

Insulation coordination is a key problem in UHVDC systems in terms of safety and cost. Although high-voltage ±1100kV UHVDC projects are being planned in China, the characteristics and key points of high-voltage systems have not yet been analyzed. This study aims to improve the safe, effective operation of these high-voltage power transmission systems. First, we analyzed two typical insulation coordination schemes used in ±800kV UHVDC systems in China. Next, we used the two typical ±800kV insulation coordination schemes as a reference to analyze the ±1100kV UHVDC system. Finally, we compared these schemes and proposed an effective insulation coordination solution, as well as developing principles for ±1100kV UHVDC systems. Our findings indicate that the points enduring the highest voltage in the system should be protected separately by special arresters. Our analysis of the insulation coordination of ±800kV and ±1100kV UHVDC systems concluded that, in ±1100kV UHVDC systems, the main goal of insulation coordination is to lower the insulation level of points enduring the highest voltage. However, in a ±800kV UHVDC system, the main goal is to reduce the cost of manufacture for arresters, as well as the space occupation in the valve hall, with an acceptable insulation level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1240-1248
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• 2013

This paper describes a switching-level operation analysis of BTB(Back-To-Back) converter for HVDC(high voltage DC) application based on MMC(modular multi-level converter). A switching-level operation analysis for BTB converter is very important to understand the converter operation in detail and check the voltage and current transients in each components. However, the development of switching-level simulation model for the actual size BTB Converter is very difficult because the MMC normally has more than 150 sub-modules for each arm. So, a switching level simulation model for the 11-level MMC-based BTB converter was developed with PSCAD/EMTDC software, which has 12 sub-modules for the positive arm and another 12 sub-modules for the negative arm. The DC-voltage balance algorithm, the circulating-current reduction algorithm, the harmonic reduction algorithm, and the redundancy operation algorithm were included in this simulation model. The developed simulation model can be utilized to analyze the MMC-based BTB converter for HVDC application in switching level and to develop the protection scheme for the MMC-based BTB converter for HVDC application.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.589-590
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• 2006

A novel Triple-Well P-type Triggered Silicon Controlled Rectifier (TWPTSCR) for on-chip ESD protection implemented with a triple-well CMOS technology is presented. Unlike conventional SCR devices, the proposed TWPTSCR offers a reduced triggering voltage level as well as the enhanced ESD performance of the SCR devices. From the experimental results, the TWPTSCR with a device width of 20um has the triggering voltage of 1.1V.