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Electronic current transformer (ECT) is widely used in smart grid, especially intelligent substation. However, fault is unavoidable for ECT in long term operation. In this paper, the fault of an 110kV independent ECT based on low-power current transformer is an example to analyze the reasons for the fault via reasonable analyzing methods and proposed the corresponding treatments.
The structure and the results of measurements of a hybrid supplying system for the tests of an HTS tapes carrying the high amplitude AC current with DC offset is described in the paper. The system is dedicated to an examination of the second generation (2G) superconducting tapes operating under dynamic conditions (the transition between superconducting and resistive state). The tapes are bifilarly...
This paper presents a low cost methodology to measure common mode (CM) currents in and induction motor fed by a speed drive. These measurements were made with a Pearson current transformer and a Rogowski coil, which allow to find the highest resolution and sensitivity measuring CM currents in an induction motor. Finally, experimental results are shown, as well as a data comparative analysis.
Some of the most severe faults in electrical power networks are caused by faulty insulation or short-circuits. These events are accompanied by traces of partial discharges and traveling waves and recording such pulsed signals accurately is the key for providing effective on-line status monitoring of power lines. Capturing the high-frequency transients is very essential to protection means of local...
A new current transformer based on planar air core coil was presented in this article. The secondary coil of sensor was implemented on printed circuit boards and each PCB contains two coils in opposite directions to eliminate the impacts of outside magnetic field by the greatest degree. Moreover, multilayer boards were connected to improve mutual inductance. The PCBs were embedded in the primary coil...
The new generation of current sensors has performance characteristics that can improve design and operation of modern power systems. This paper presents novel solutions for protection of capacitor banks using Rogowski coils as currents sensors.
The electric current transducer plays a significant role in electric power system. In order to measure small current accurately, a newfashioned high precision electronic current transducer was designed. A novel high mutual inductance, high precision Rogowski coil was adopted as sensor head, and a novel analog signal process system, including magnifying, filtering, phase compensating was designed to...
Rogowski coils have been used for decades for non-invasive current measurement when other probe, such as current shunts, current transformers are impracticable. The measurement of diode beam current in pulse power system under vacuum and high voltage are challenging task which requires development of Rogowski coil for specific applications. They operate in large radiation fields, under intense electron...
In this paper, a new type of air core current transformer (Rogowski coil) for easily industrialized application is introduced. Based on the analysis of the working principle of air core current transformer with separate coils, a design method called error balance method (EBM) is proposed by considering the adjacent interference and sensitivity to the position variation of the conductor carrying primary...
A current transformer (CT) system centered on Rogowski coil is introduced to measure the low frequency heavy current of the linear induction motor (LIM) powered by the H-bridge sine pulse width modulation (SPWM) inverter. The frequency of the output current of the inverter ranges from 1 hertz to 200 hertz. The current test apparatus is made of the sensor head of Rogowski coil and the post-processing...
Calibrations of Rogowski coils at power frequencies are often performed at currents of only tens of amperes even though the coils are used at currents larger by two to three orders of magnitude, or even greater. The underlying assumption of an ideal linearity versus current amplitude is true for ideal coils. This paper addresses the question of practical significance as to what extent the linearity...
Starting from the basic requirements (including amplitude and frequency ranges), the design of a calibration fixture for AC and DC current sensors (with emphasis on Rogowski coils) is analyzed, focusing on its capabilities and accuracy budget. The design is reconsidered with usability and flexibility in mind, so that a wide range of physical dimensions, amplitude and frequency values are accounted...
This paper aims at analysis and comparison of the features of Rogowski-type and optical-type electronic current transformers(ECT). Referring the application results of digital substation in operation, it analyses engineering application, theory and reality combined, their advantages and disadvantages and summarizes experience in the application, providing reference for the application and research...
A high-accuracy system for calibration of Rogowski coils at frequencies up to 10 kHz, based on a reference current transformer, an I/V converter, and a digital sampling system, is described in the paper. The calibration system has been automated and its performance evaluated. At the frequency of 10 kHz, the calibration system is capable of generating currents up to 100 A. At power frequencies, it...
It is used to measure common-mode current (CMC) by Holl current transducer and traditional current transformer. In allusion to their limitation, a novel method of measuring CMC based on Rogowski coil is proposed in this paper. Take example for common-mode circuit of five-phase H-bridge three-level inverter, simulation indicates CMC belongs to a typical high frequency pulse current. The model of its...
The Steady current is different from pulse currents in frequency and magnitude. The interferences in the work environment of the currents transformer is greater than the lab. It is important to understand the Rogowski coil's character of measuring the 50 Hz currents and the measure error. This paper presents a model of Rogowski coil based on the control theory. Research based on the model about the...
The 50 Hz current is different from pulse currents in frequency and magnitude. The interferences in the work environment of the currents transformer is greater than the lab. It is important to understand the Rogowski coil's character of measuring the 50 Hz currents and the measure error. This paper presents a model of Rogowski coil based on the control theory. Research based on the model about the...
Accurate measurement of distorted, noisy and pulsed currents is still a challenge. Current transformers introduce unacceptable errors in magnitude and/or phase shift. Rogowski coils are useful for clamp-on field measurements, but can be cumbersome to use. This paper presents a transducer consisting of coreless transformer and a non-integrating electronic amplifier. Calibration of two prototype transducers,...
A digital optical fiber current transformer (OCT) based on Rogowski coil and optical fiber transmission for use in high voltage systems is described in this paper. The technologies of signal sampling, processing and communication for the optical current transformer are introduced. The paper analyzes the present supply power techniques on high voltage side, and puts forward a new closed-loop regulating...
Traditional transformers using iron cores were widely used for measuring voltage and current for several decades. But with the introduction of new digital technologies, novel measuring techniques were begun to apply to the transformers. Novel types of current and voltage transformers do not adopt iron core, so these types were called as Non-Conventional Instrument Transformers (NCIT). The common characteristics...
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