• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.37-40
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• 2007

Large critical current is one of the prerequisites for the design of superconducting electrical equipments with large power capacity. To enlarge the critical current. multiple parallel connection is inevitable. In multiple parallel superconducting coils. the difference in normal resistance of each shunt leads to unequal current distribution. which may yield burnout. Therefore. uniform current distribution is required for a stable operation of multiple parallel superconducting coils. In this paper, Rogowski coils were fabricated to measure each shunt current of a 4-parallel superconducting coil. Four Rogowski coils were installed at the copper bars, which are used as current leads in superconducting coils. As a result, linearity of the Rogowski coils was ascertained and coefficients of each coil, the ratio of voltage and current, were derived. The coefficients were compared with theoretically calculated values. Based on the coefficients, each shunt current was calculated in a 4-parallel superconducting coil, where uniform current. distribution was confirmed. This paper verified the feasibility of the fabricated Rogowski coils as well as operational stability of the 4-parallel superconducting coil in 77K.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.108-110
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• 2018

This paper proposes shortcircuit fault protection method in a synchronous buck converter using the PCB pattern Rogowski coil. The PCB pattern Rogowski coils are embedded in the gate driver to measure the device currents of the top and bottom side. When shortcircuit occurs in the system, the gate signal is blocked by the proposed fault protection method using the device current. The simulation and experimental results show that the proposed fault protection method is verified in the shortcircuit system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.10
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• pp.521-527
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• 2006

After various measuring methods and system were investigated, Rogowski colis for the measurement of parameters in current zero region were designed and manufactured. Using the Rogowski coils and a 38kV 40kA VCB (vacuum circuit breaker), at last the post-arc current has been successfully measured firstly. It was found that the Rogowski coils used in this study have good characteristics and propriety to measure the parameters of current zero. We realized that the data processing for evaluating the post-arc current from the experimental results needs much more careful attention than that for building the measuring technique and system. The magnitude of post-arc current and the falling time of it to zero are proportioned to the rate of current di/dt. The magnitude of post-arc currents were around $1{\sim}3A$ to the interruption current of $20{\sim}30kA$ in the model VCB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents. and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore. geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error was examined as well. In the results, the source of error was associated with coil designs. i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents, and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore, geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error wa examined as well. n the results, the source of error was associated with coil designs, i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1206-1213
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• 1994

This paper presents the operation principle and design rule of the Rogowski coil which can measure the transient current and describes the calibration and application experimental results for performance evaluation. It is obtained that the response curves of the Robowski coil with the turns of 300 and the passive integrator to sinusoidal input give a good linearity up to the frequency of 500 [kHz] and the current measurement system gaving the Rogowski coil is the frequency bandwidth of 40 [Hz]~700 [kHz]. As an application experiment for the fabricated modeling power transmission line, the impulse current, which limitates the direct lightning return stroke to overhead ground wire, is measured by the Rogowski coil and its fast Fourier transformation is carried out. The equivalent circuit of the Rogowski coil considering the stray capacitances is proposed, and the theoretical analysis is in good agreement with the measurement results. Also, it is found that for high frequency domain the stray capacitance such as a distributed capacitance to the shield and the capacitance between windings of coil should be considered in designing the Rogowski coils since the resonance originates from the stray capacitance and the self-inductance of the Rogowski coil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.583-584
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• 2005

In this work, a novel hybrid FL sensor consisting of two Rogowski coils has been designed for the installation on the ground wire of the transmission tower. The operation range of these coils is as follows: 30kA for the fault current comingfrom the ground fault or short-circuit and for the lightning current up to 150kA over 500kHz. Thus, two important functions could be provided: one is to detect the fault current and the other one is to find the fault location between towers or the location of induced lightning stroke. The on-site investigation at 800kV test yard has been under progress for its on-site application.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.787-789
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• 2000

This paper describes the theory and practical design of Rogowski coil and active integrator. The coils and integrators have the ratings as follows. 1) current ratings between 20kArms and 200kArms 2) current duration 3 seconds 3) time constant of primary circuit looms 4) inner diameter of coil is suitable for mounting at the busbar $200mm{\times}200mm$. The actual results in the short-circuit tests and compare with other sensors, such that shunt. are given also.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.57-60
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• 2008

Purpose: The radial speed of plasma current sheath was measured at the plasma focus apparatus. Methods: The measurement was used to time-resolved spectroscopic method and Rogowski coils. Results: Radial current sheath speed was measured with $10^5$ cm/s at Helium and Argon pressure between 5 to 100 torr and discharging voltage of 15 kV. When the gas pressure was increased, the current sheath speeds were decreased. Conclusions: At the optimum condition of plasma focus apparatus, the radial speed is guessed $10^7$ cm/s as a results of the measurement of current sheath speed.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.69-74
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• 2007

The axial speed of plasma current sheath was measured with Rogowski coils and compared with the theory of snowplow model. Current sheath speed is measured with $10^6cm/s$. The speed of light gas, $H_2$ and He were similar to the theory of model, but the heavy gas, Ar was not similar to the theory. The disagreement of the heavy gas was guessed as a results of the instability of the current sheath.