• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.03b
• /
• pp.32-32
• /
• 2010

A epoxy/multilayered silicate nanocomposite was prepared by a new AC electric application method and micro silica particle was poured into the nanocomposite in order to prepare epoxy/micro-and-nano- mixed composites (EMNC). Electric insulation breakdown strength was measured in a sphere-sphere electrode system designed for the prevention of edge breakdown and the data were estimated by Weibull plot. As the exfoliated silicate nano-plates were homogeniously dispersed in the micro silica particles, the insulation property was higherd.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.124-124
• /
• 2010

Diagnostic tests were performed on six high voltage motors. These tests included ac current, dissipation factor(tan6) and partial discharge(PD) magnitude. The rewind of motor stator insulation at rated voltage is assessed by the results of these tests. After completing the diagnostic tests, the stator windings of motors were subjected to gradually increasing ac voltage, until the insulation punctured. No. 1 and No.2 motors(4.16 kV) failed near rated voltage of 12.3 kV and 14.2 kV, respectively. The breakdown voltage of No.3 and No.4 motors(6.6 kV) was 17.6 kV and 17.8 kV, respectively. These motors are higher that expected for good quality coils in 6.6 kV class motors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.266-267
• /
• 2008

The flashover of insulators in vacuum is the main factor to limit the performance of insulation in vacuum insulation system. It is believed that the pre-flashover phenomena would play a very important role in the procedure of the flashover in the interface between the insulators and vacuum. This paper is mainly concerned on the pre-flashover phenomena of Alumina insulators in vacuum. There are 24 different types of alumina insulators were tested with a 0.7/4 ${\mu}s$ pulsed voltage under a $1\times10^{-4}Pa$ vacuum. The observed pre-flashover phenomena were classified and the pre-flashover characteristics were concluded. It is useful to study further on the flashover mechanism in vacuum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.152-155
• /
• 2002

During normal operation, partial discharge(PD) tests were performed using turbine generator analyzer(TGA) in high voltage motor. Epoxy-mica couplers are installed at motor terminal and analyzed PD signal using TGA. #A motor stator insulation is good because small partial discharges are detected PD pattern show that PD occurs in insulation. PD of #B motor is larger than that of #A motor and PD pattern show that positive PD larger than negative PD. It means that PD occurs between insulation and slot. And A phase PD magnitude of #B motor is large and high compare with any other phase. Therefore wedge, core and slot of #B motor need to check and repair.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.199-202
• /
• 2002

During normal operation, partial discharge(PD) tests were performed using turbine generator analyzer(TGA) in high voltage motor. Epoxy-mica couplers are installed at motor terminal and analyzed PD signal using TGA. #A motor stator insulation is good because small partial discharges are detected. PD pattern show that PD occurs in insulation. PD of #B motor is larger than that of #A motor and PD pattern show that positive PD larger than negative PD. It means that PD occurs between insulation and slot. And A phase PD magnitude of #B motor is large and high compare with any other phase. Therefore wedge, core and slot of #B motor need to check and repair.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.274-277
• /
• 2001

This paper describes the simulation study. conducted on the propagation characteristics of AE signal. In the case of gas insulation, such as $SF_6$, the equipment is less affected by the environment condition than air insulation, because the component parts of equipment were placed in the enclosure, which is filled with compressed gas. But. when the breakdown in the electric insulation occurs. it takes much time and economical efforts to repair. Therefore it is very important to diagnose the equipment before the accident. And. in general. UHF and AE signal is the most common transducer to diagnose the state of the power equipment, so, in this investigation, we make a experimental apparatus with aluminum plate and transient analysis with ANSYS to observe the propagation characteristics of AE signal. Through the result of the analysis. we can make a further understanding on the propagation characteristics of AE signal, and get the fundamental skills for the GIS diagnosis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.12S
• /
• pp.1299-1304
• /
• 2003

Fault current limiters (FCL) are extensively needed to suppress fault currents, especially for trunk power systems heavily connected to high voltage/large current transmission lines. Due to its ideal electrical behavior, high-temperature superconductor fault current limiter (HTSFCL) becomes one of the most important developing trends of limiters in power system. This paper describes the result of an investigation of the dielectric characteristics of turn-to-turn insulation for pancake and solenoid type reactor coil in liquid nitrogen. The influence of thickness in a variety length, on AC, DC and impulse surface flashover has been investigated. Also, the relationships between the number of turn and breakdown characteristics were clarified. The information gathered in this test series should be helpful in the design of liquid nitrogen filled DC reactor type HTSFCL.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.225-228
• /
• 2001

Partial discharge(PD) testing for different capacitive couplers was performed on a 6.6kV, 448kW pulverizer motor. The motor has been in service for twenty years. PD tests were measured using digital partial discharge detector(DPDD) and partial discharge analyzer(PDA), respectively. PDA is used to in the motor stator insulation, which three 80pF or three 500pF epoxy-mica couplers were installed, one per phase. The 500pF couplers did detect more normalized quantity number(NQN) than the 80pF couplers. DPDD and PDA showed that PD and NQN magnitudes increased with increase of ac voltage. Internal discharge was discovered in the motor stator insulation. DPDD and PDA test results are in accordance with the pattern and magnitude of PD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.05b
• /
• pp.1-4
• /
• 2005

The electric power demand is steadily high. It becomes difficult to secure the land for overhead transmission lines year after year. Downsizing of overhead transmission lines can be most effectively achieved by applying polymer insulation arm. This paper describes the outline of compact overhead transmission lines and the result of mechanical evaluation of FRP for the compact transmission towers. Bending strength of FRP was evaluated according to the fiber orientation because the fiber orientation in FRP has a great effect on the strength of FRP.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.375-376
• /
• 2008

The flashover of insulators in vacuum is the main factor to limit the performance of insulation in vacuum insulation system. It is believed that the pre-flashover phenomena would play a very important role in the procedure of the flashover in the interface between the insulators and vacuum. This paper is mainly concerned on the pre-flashover phenomena of Alumina insulators in vacuum. There are 24 different types of alumina insulators were tested with a 0.7/4 ${\mu}s$ pulsed voltage under a $1\times10^{-4}$Pa vacuum. The observed pre-flashover phenomena were classified and the pre-flashover characteristics were concluded. It is useful to study further on the flashover mechanism in vacuum.