Frequency behavior of the residual current devices

Erdei, Zoltan; Horgos, Mircea; Lung, Claudiu; Pop-Vădean, A; Mureșan, Raul C.

doi:10.1088/1757-899x/163/1/012053

Cited by 4 publications

(4 citation statements)

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“…Since the alternating current exceeds 30 mA levels, an operational safety issue is emerged and some measures should be taken. For this purpose, the residual current relays, which are manufactured to compare phase current and neutral current for detecting possible leakage currents are used [29]. In a DC system need for residual current relays is decreased in which DC system is said to be much more economical.…”

Section: Feasibility and Efficiency Of Voltage Level On Lvdc Distribution Systemmentioning

confidence: 99%

A comparative study on AC/DC analysis of an operational low voltage distribution system

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Uzunoğlu

2021

IJAPE

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In the near future, the digitalizing world will continue to improve and the need for DC based devices will be increased beyond doubt. Today’s electrical grid is strictly dependent on AC-DC rectifiers. Each conversion process means additional power losses and signal quality deteriorations for the network. In addition, networks which are fed by batteries and renewable sources such as solar panels, and wind turbines are suffering from conversion-based power losses. In this respect, the idea of switching to DC on the low voltage side of the networks has become an intriguing subject. In this study, the applicability and efficiency of the low voltage direct current (LVDC) concept for low voltage distribution systems is discussed and a sample LVDC distribution system is analyzed. In this operational residential application electrical transient analyzer program (ETAP) is employed for comparison of different voltage levels such as 110 VDC, 250 VDC, 320 VDC and conventional 220/380 VAC. As a novel approach different DC voltage levels are compared with typical AC system in detail. Comparative analysis is conducted for safety regulations, voltage drops, current carrying capacities, power consumption and harmonic calculation of the proposed system. In this respect applicability, possible drawbacks and future aspects of LVDC systems are interpreted.

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Section: Feasibility and Efficiency Of Voltage Level On Lvdc Distribution Systemmentioning

confidence: 99%

A comparative study on AC/DC analysis of an operational low voltage distribution system

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Uzunoğlu

2021

IJAPE

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“…While the negative influence of the DC component of the residual current on the operation of RCDs has been recognized a long time ago [2,3] and the solutions are widely known [4][5][6][7], the influence of high frequencies is still being investigated. Papers [8][9][10][11][12][13][14] are focused on the tripping of RCDs for higher frequencies. The conclusion is that high frequency residual current changes the tripping threshold of RCDs and in some cases this threshold can be many times higher than for frequency 50 Hz.…”

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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Frequency behavior of the residual current devices

Cited by 4 publications

References 1 publication

A comparative study on AC/DC analysis of an operational low voltage distribution system

A comparative study on AC/DC analysis of an operational low voltage distribution system

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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