• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.193-198
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• 2021

In this study, a nano-convergence material technology that can satisfy the superior impact resistance and electrical properties of the semiconducting flame retardant compound used in the Oversheath layer of Extra-high voltage cables was studied. When some of the carbon black used in the semiconducting flame-retardant compound was replaced with CNT (carbon nano tube), the change in physical properties was analyzed. Through the application of carbon nanotubes with remarkably excellent electrical properties, even a small amount of conductive filler formulations can provide superior electrical properties. In addition, as the total filler amount is reduced based on the compound, the workability is improved, and in particular, flexibility and impact resistance are improved, which is expected to contribute to the improvement of the durability of the cable.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.525-526
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• 2008

This paper proposes a new high-speed level shifter using a special high voltage device with low threshold voltage. Also, novel low voltage swing method is proposed. The high voltage device is a standard LDMOS(Laterally Diffused MOS) device in a $0.18{\mu}m$ CMOS process without adding extra mask or process step to realize it. A level shifter uses 5V LDMOSs as voltage clamps to protect 1.8V NMOS switches from high voltage stress the gate oxide. Also, level-up transition from 1.8V to 5V takes only 1.5ns in time. These circuits do not consume static DC power, therefore they are very suitable for low-power and high-speed interfaces in the deep sub-quarter-micron CMOS technologies.

• Journal of Power Electronics
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• v.19 no.3
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• pp.665-675
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• 2019

Renewable energy based on photovoltaic systems is beginning to play an important role to supply power to remote areas all over the world. Owing to the lower output voltage of photovoltaic arrays, high gain DC-DC converters with a high efficiency are required in practice. This paper presents a novel interleaved DC-DC boost converter with a high voltage gain, where the input terminal is interlaced in parallel and the output terminal is staggered in series (IPOSB). The IPOSB configuration can reduce input current ripples because two inductors are interlaced in parallel. The double output capacitors are charged in staggered parallel and discharged in series for the load. Therefore, IPOSB can attain a high step-up conversion and a lower output voltage ripple. In addtion, the output voltage can be automatically divided by two capacitors, without the need for extra sharing control methods. At the same time, the voltage stress of the power devices is lowered. The inrush current problem of capacitors is restrained by the inductor when compared with high gain converters with a switching-capacitor structure. The working principle and steady-state characteristics of the converter are analyzed in detail. The correctness of the theoretical analysis is verified by experimental results.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.270-273
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• 2001

In this paper, some of optical current transformers and optical potential transformers for extra high voltage system are introduced. The optical current transformer and optical potential transformer will be adopted in the near future, because of increasing demands of high accuracy and good reliability of current transformer and potential transformer. The application cases of optical current transformers and optical potential transformers are also introduced.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.215-218
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• 2002

In this paper some of optical current transformers and optical potential transformers for extra high voltage system are introduced. The optical current transformer and optical potential transformer will be adopted in the near future, because of increasing demands of high accuracy and good reliability of current transformer and potential transformer. The application cases of optical current transformers and optical potential transformers are also introduced.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.266-267
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• 2006

A coupling capacitor voltage transformer (CCVT) is used in extra high voltage and ultra high voltage transmission systems to obtain the standard low voltage signal for protection and measurement. To obtain the high accuracy at the power system frequency, a tuning reactor is connected between a capacitor and a voltage transformer (VT). Thus, no distortion of the secondary voltage is generated when no fault occurs. However, when a fault occurs, the secondary voltage of the CCVT has some errors due to the transient components resulting from the fault. This paper proposes an algorithm for compensating the secondary voltage of the CCVT in the time domain. With the values of the secondary voltage of the CCVT, the secondary and the primary currents are obtained; then the voltage across the capacitor and the tuning reactoris calculated and then added to the measured secondary voltage. The proposed algorithm includes the effect of the non-linear characteristic of the VT and the influence of the ferro-resonance suppression circuit. Test results indicate that the algorithm can successfully compensate the distorted secondary voltage of the CCVT irrespective of the fault distance, the fault inception angle and the fault impedance.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.3
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• pp.186-195
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• 2000

In this paper, partial discharge (PD) measurement was performed to evaluate the quality of the cable joint and termination constructions. The resistive coupling technique for PD detection using resistivity of semiconducting layer of the cable in the accessories, such as joints and terminations. With high frequency PD (HEPD) measurement, an excellent sensitivity below 20pC could be achieved under unshielded condition. The localization of the defects in the accessories could be identified. During heating cycle, PDs were monitored and analyzed. At that time, the PDs were dependent on the temperature of the heating cycle and showed cyclic behaviors, which were attributed to local delamination of the interfaces, between epoxy unit and stress relief cone(SRC) and between SRC and cable, due to the difference of thermal expansion. As a conclusion, HFPD measurement technique was proven to be an effective diagnostic method for qualification of extra high voltage (EHV) cable accessories. With this technique, the optimal design of the components of the accessories could be verified not only in an early stage but also under operating condition. This technique would result in the improvement of the reliability of the EHV cable accessories.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.86-89
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• 2004

To estimate a electrical performance of the extra high voltage XLPE cable the discharge properties due to shift of void position were investigated. The ${\phi}-q-n$ properties have been measured at room temperature by rising voltage ratio of 0.5[kV]. An obtained data was stored to personal computer through A/D converter. The period of applied wave form and discharge values were divided into 64 parts and discharge values generated during 10 seconds were accumulated by phases. As a result, it was confirmed that the charge, phase angle and counts of discharge changed due to void position.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.256-257
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• 2005

To estimate a electrical performance of the extra high voltage XLPE cable the discharge properties due to shift of void position were investigated. The $\Phi-q-n$ properties have been measured at room temperature by rising voltage ratio of 0.5[kV]. An obtained data was stored to personal computer through A/D converter. The period of applied wave form and discharge values were divided into 64 parts and discharge values generated during 10 seconds were accumulated by phases. As a result, it was confirmed that the charge, phase angle and counts of discharge changed due to void position.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.395-398
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• 2004

High-linearity voltage-controlled current sources (VCCSs) circuits for wide voltage-controlled oscillator and automatic gun control were proposed. The VCCS consists of emitter follower for voltage input, two common-base amplifier which their emitter connected for current output, and current mirror which connected the two amplifier for large output current. The VCCS used only five transistors and a resistor without an extra bias circuit. Simulation results show that the VCCS has current output range from 0mA to 300mA over the control voltage range from 1V to 4.8V at supply voltage 5V. The linearity error of output current has less than $1.4\%$ over the current range from 0A to 300mA.