• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.2
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• pp.66-70
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• 2005

Linearity of ratio error of instrument transformer comparator has been tested using wide ratio error voltage transformer(VT) with the ratio errors in the range of -3 ％ to 3 ％. The technique is the method for evaluation of the linearity for instrument transformer comparator by comparing both the theoretical and experimental values in wide ratio error VT. The developed method has been successfully applied for calibration and correction in instrument transformer comparator belonging to industry.

• Journal of the Korean Society of Safety
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• v.22 no.4
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• pp.20-25
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• 2007

Instrument transformers are a safe measurement device designed to measure high voltage and large current. A current transformer(CT) is a type of instrument transformer designed to provide a current in its secondary winding proportional to the current flowing in its primary. It is commonly used in metering and protective relaying in the electrical power industry where it facilitates the safe measurement of large current. But, care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as this will produce a dangerously high voltage across the open secondary, and may permanently affect the accuracy of the transformer. Especially, industrial disaster such as an electric shock and/or a burn accident occurs occasionally by disregard of warning or attention. In this paper, we developed the detector for open of current transformer secondary terminal, and which was tested by the Korea Electrotechnology Research Institute. Test results show that Current Transformer secondary Open Detector(CTOD) interrupted within one second electronically when the 2nd terminal of current transformer opened.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.456-459
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• 2004

Generally, instrument transformer of the core type have been used for measuring current. Because instrument transformer has defects, electronic instrument was appeared. Electronic instrument has many merit-linearity, small size, low cost, etc. Rogowski coil is typical electronic CT and R-divider is typical electronic VT. This paper is introduced a basic concept and theory of electronic current transformer, electronic voltage transformer.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.760-761
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• 2007

Instrument transformers provide the reproduction of the primary current or voltage to the measuring and protecting devices. The errors of an iron-cored transformer are caused by the difference between the primary and secondary currents due to the hysteresis characteristics of the iron-core. An error compensating algorithm for instrument transformer can improve the accuracy of conventional current and voltage transformers. This paper describes the performances of the electronic current and voltage transformers mounted an error compensating algorithm. The test results of the electronic transformers in Korea Electrotechnology Research Institute(KERI) are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.589-595
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• 2014

The error of instrument transformers is measured by connecting the external burden with the secondary terminal of the instrument transformers. Because the error of transformer is affected by the apparent power and power factor of the external burden, an accurate measurement of burden is important for transformer evaluation. We have developed the burden evaluation equipment for both potential transformer and current transformer by employing the series resistor in the range of $20m{\Omega}{\sim}5{\Omega}$ and the parallel resistor in the range of $1M{\Omega}{\sim}500{\Omega}$, respectively, together with visual basic program. We could reduce testing time more than 5 times by employing method developed in this study, compared with that developed in past. This method shows more better reliability by analyzing the evaluation results and fitting graphs of burden measurements. The test results of the developed system is compared with those obtained in the power meter analyzer to verify the validity.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.415-418
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• 1991

This paper described an instrument for the detection and geometric location of partial discharge(PD) sources in oil transformer. This instrument measures electric current pulse and ultrasonic pulse simultaneously in order to determine the geometric location of PD in transformer. Laboratory experiment systems are made for detection and location of PD in oil transformer. It was observed that there are effects of the barrier, such as insulation papers, silicon steel plate and actual transformer with location and detection of PD in model transformer. Through the laboratory actual test, it was clarified that this measurement device could be used satisfactorily for location of pd in oil transformer.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.291-294
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• 2007

Countries in the world are setting up policies to implement anti-global warning measures to actively cope with the Agreement on Climate Change. Rising problems related to energy and environment prompted research and development efforts to highly efficient electric instrument and environmentally friendly products to secure resources and save energy Korea's high dependency on imported energy and its lack in natural resources make it urgently necessary to develop energy efficient instrument and equipment that can save energy. Every household now uses a transformer, which is very important instrument among others. A variety of technologies to manufacture transformers are currently used along with efforts to develop new materials. Development nit of high efficient transformers is called for by the time and has direct economic impact on suppliers and consumers. In addition, it is desirable to install a transformer that is trustworthy, secure, low on loss, anti-incident capable, small, anti-flammable, environmentally friendly, cost-efficient high-frequency resistant and easy for maintenance. To do this, it is necessary to look deeper into a highly efficient transformer that can save energy. This paper will discuss the types and characteristics of various transformers and propose ways to save energy and raise efficiency tv analyzing a environmentally friendly amorphous transformer.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.140-141
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• 2008

Generally, an iron-cored instrument transformer has differences between the primary current and the secondary current transformer due to the hysteresis characteristics of the core. The errors of the instrument transformer can be removed by using a compensating algorithm. This paper describes the iron-cored electronic zero-phase current transformer(EZCT) having a compensating algorithm that removes the effects of the hysteresis characteristics of the iron-core. This product composes an iron-cored ZCT and an intelligent electronic device(IED) ported the compensating algorithm. The test results shows that the innovative new product can improve the performance of the conventional ZCT.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.951-953
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• 2005

The current transformer is used for the insulation of measuring instrument, enlargement of measurement scope, standardization of measuring instrument, control of protective device. It's required various performance as the intention of service, site of establishment, insulation. especailly, current transformer has small ratio errors. if current transformer has large ratio error, it's caused a electricity failure. so in this paper, we examine the theory of current transformer, major factor of errors, output performance on over-current.

• Proceedings of the KIEE Conference
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• summer
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• pp.310-312
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• 2004

Generally, instrument transformer of the core type have been used for measuring current. Because instrument transformer has defects, electronic instrument was appeasred. This paper is introduced a basic concept and thoery of electronic instrument and described the the simulation of core type CT and no saturation CT. The evaluation of CT models implemented using EMTP(Electro Magnetic Transients Program) was carried out. The result of comparison both core type CT and no saturation CT are presented.