Improving sensitivity of residual current transformers to high frequency earth fault currents

Czapp, Stanisław; Dobrzyński, Krzysztof; Klucznik, Jacek; Lubośny, Zbigniew; Kowalak, Robert

doi:10.1515/aee-2017-0036

Cited by 10 publications

(5 citation statements)

References 13 publications

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“…Step 2: Use the algorithm for a tuned harmonic filter designed in Section 3.1 and Equations ( 1) to (6).…”

Section: Conflicts Of Interestmentioning

confidence: 99%

“…The growing use of electronic systems in power receivers decreases energy consumption in numerous production processes [1][2][3][4], but also creates new risks. The associated dangers include higher harmonic components that lead to the unnecessary activation of protective devices, such as residual-current protection devices [5][6][7], harmonic components that disrupt the operation of automatic synchronizers [8], as well as harmonic components that occur in non-stationary signals in various interdisciplinary applications, for example related to acoustics [9], electric vehicles [10], or even seemingly distant biomedical engineering [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces

Lange

Redlarski

2020

Energies

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This article presents a method for selecting the elements of a C-type filter working with a conventional LC-type filter for compensating reactive power and filtering out higher harmonics generated by arc furnaces and ladle furnaces. The study was conducted in a steel mill supplied by a 110 kV transmission system, where higher harmonic currents and nonlinear loads were measured. A series of computer simulations were performed under various operating conditions, and an algorithm for selecting the parameters of a third-order C-type filter (for suppressing the second harmonic) and two second-order LC-type filters (for suppressing the third harmonic) was proposed. The filtering system was tested in an arc furnace with the highest rated power, and harmonics in the current spectrum were evaluated. The results of the measurements were used to analyze the effectiveness of the compensation system comprising two passive C-type and LC-type filters at different system configurations. C-type filters significantly influenced current harmonics. The influence of the changes in the number of arc furnace transformers on the true Root Mean Square (RMS) of the currents injected into the 110 kV transmission system and on the voltages of the 110 kV busbars was discussed.

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“…Step 2: Use the algorithm for a tuned harmonic filter designed in Section 3.1 and Equations ( 1) to (6).…”

Section: Conflicts Of Interestmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces

Lange

Redlarski

2020

Energies

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“…Analyses and tests presented in these papers were conducted within the relatively low frequency range-up to 1 kHz. A remedy for negative impact of the frequency up to 1 kHz is presented in [15]. The modification of the RCD's structure, giving stable tripping current within the range 1 kHz.…”

Section: Introductionmentioning

confidence: 99%

“…The modification of the RCD's structure, giving stable tripping current within the range 1 kHz. A remedy for negative impact of the frequency up to 1 kHz is presented in [15]. The modification of the RCD's structure, giving stable tripping current within the range 50 Hz-1 kHz, is described.…”

Section: Introductionmentioning

confidence: 99%

Behavior of Residual Current Devices at Frequencies up to 50 kHz

Czapp

Tariq

2021

Energies

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The use of residual current devices (RCDs) is obligatory in many types of low-voltage circuits. They are devices that ensure protection against electric shock in the case of indirect contact and may ensure additional protection in the case of direct contact. For the latter purpose of protection, only RCDs of a rated residual operating current not exceeding 30 mA are suitable. Unfortunately, modem current-using equipment supplied via electronic converters with a pulse width modulation produces earth fault currents composed of high-frequency components. Frequency of these components may have even several dozen kHz. Such components negatively influence the RCDs’ tripping level and, hence, protection against electric shock may be ineffective. This paper presents the results of the RCDs’ tripping test for frequencies up to 50 kHz. The results of the test have shown that many RCDs offered on the market are not able to trip for such frequencies. Such behavior was also noted for F-type and B-type RCDs which are recommended for the circuits of high-frequency components. Results of the test have been related to the requirements of the standards concerning RCDs operation. The conclusion is that these requirements are not sufficient nowadays and should be modified. Proposals for their modification are presented.

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“…The type of protective device and its operational algorithm depends on the type of power network (grounded, ungrounded, overhead line, cable line) [4,5], the necessity of detection of an arc fault [6,7], distorted voltages [8], special signals [9], DC currents [10,11], and the necessity of detection of non-sinusoidal alternating earth fault currents. Special attention should be given to the currents comprising very-low-frequency components [12] or high-order harmonics [13][14][15][16][17][18][19], as in circuits with power electronics converters [20]. If residual current devices are used (they are even obligatory in some circuits), their sensitivity to the non-sinusoidal earth fault (residual) currents has to be verified.…”

Section: Introductionmentioning

confidence: 99%

Testing Sensitivity of A-Type Residual Current Devices to Earth Fault Currents with Harmonics

Czapp

2020

Sensors

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In many applications, modern current-using equipment utilizes power electronic converters to control the consumed power and to adjust the motor speed. Such equipment is used both in industrial and domestic installations. A characteristic feature of the converters is producing distorted earth fault currents, which contain a wide spectrum of harmonics, including high-order harmonics. Nowadays, protection against electric shock in low-voltage power systems is commonly performed with the use of residual current devices (RCDs). In the presence of harmonics, the RCDs may have a tripping current significantly different from that provided for the nominal sinusoidal waveform. Thus, in some cases, protection against electric shock may not be effective. The aim of this paper is to present the result of a wide-range laboratory test of the sensitivity of A-type RCDs in the presence of harmonics. This test has shown that the behavior of RCDs in the presence of harmonics can be varied, including the cases in which the RCD does not react to the distorted earth fault current, as well as cases in which the sensitivity of the RCD is increased. The properties of the main elements of RCDs, including the current sensor, for high-frequency current components are discussed as well.2 of 20 may prevent a person from fatal electric shock, provided that the RCD's rated residual operating current does not exceed 30 mA, which is assumed as the threshold of ventricular fibrillation [3].

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Improving sensitivity of residual current transformers to high frequency earth fault currents

Cited by 10 publications

References 13 publications

Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces

Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces

Behavior of Residual Current Devices at Frequencies up to 50 kHz

Testing Sensitivity of A-Type Residual Current Devices to Earth Fault Currents with Harmonics

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