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

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2044
Author(s):  
Stanislaw Czapp
Keyword(s):  
Power Systems ◽  
Electric Shock ◽  
Low Voltage ◽  
Wide Spectrum ◽  
Residual Current ◽  
Motor Speed ◽  
Earth Fault ◽  
Fault Currents ◽  
Wide Range ◽  
Sinusoidal Waveform

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.

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

2017 ◽  
Vol 66 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Stanislaw Czapp ◽  
Krzysztof Dobrzynski ◽  
Jacek Klucznik ◽  
Zbigniew Lubosny ◽  
Robert Kowalak
Keyword(s):  
High Frequency ◽  
Low Voltage ◽  
Current Transformer ◽  
Residual Current ◽  
Fault Current ◽  
Earth Fault ◽  
Fault Currents ◽  
Proper Operation ◽  
Current Device ◽  
A Current

Abstract For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

scholarly journals Development of a Range of Modified Multifunctional Residual Current Systems and Their Industrial Implementation

2022 ◽  
Vol 1211 (1) ◽  
pp. 012020
Author(s):  
O К Nikolsky ◽  
T M Khalina
Keyword(s):  
Electric Shock ◽  
New Technology ◽  
Residual Current ◽  
Leakage Currents ◽  
Fault Currents ◽  
Industrial Implementation ◽  
Industrial Use ◽  
Current Systems

Abstract The developments of the AltSTU have been reviewed in the area of creating a new technology for preventing technogenic hazards based on the residual current devices. The residual current devices are intended for protecting people from electric shock in case of contact with conductive parts of the electric appliances and shall facilitate reduction of fire risks caused by a prolonged flow of leakage currents and fault currents resulting from them. The results of creating different modifications of protective trip circuits and their industrial use are provided.

scholarly journals An Open Hardware Design for Internet of Things Power Quality and Energy Saving Solutions

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 627 ◽  
Author(s):  
Eduardo Viciana ◽  
Alfredo Alcayde ◽  
Francisco Montoya ◽  
Raul Baños ◽  
Francisco Arrabal-Campos ◽  
...  
Keyword(s):  
Power Systems ◽  
Open Source ◽  
Power Quality ◽  
Low Voltage ◽  
Renewable Energy Sources ◽  
Hardware Design ◽  
Operating Conditions ◽  
Monitoring And Control ◽  
Open Hardware ◽  
Wide Range

An important challenge for our society is the transformation of traditional power systems to a decentralized model based on renewable energy sources. In this new scenario, advanced devices are needed for real-time monitoring and control of the energy flow and power quality (PQ). Ideally, the data collected by Internet of Thing (IoT) sensors should be shared to central cloud systems for online and off-line analysis. In this paper openZmeter (oZm) is presented as an advanced low-cost and open-source hardware device for high-precision energy and power quality measurement in low-voltage power systems. An analog front end (AFE) stage is designed and developed for the acquisition, conditioning, and processing of power signals. This AFE can be stacked on available quadcore embedded ARM boards. The proposed hardware is capable of adapting voltage signals up to 800 V AC/DC and currents up to thousands of amperes using different probes. The oZm device is described as a fully autonomous open-source system for the computation and visualization of PQ events and consumed/generated energy, along with full details of its hardware implementation. It also has the ability to send data to central cloud management systems. Given the small size of the hardware design and considering that it allows measurements under a wide range of operating conditions, oZm can be used both as bulk metering or as metering/submetering device for individual appliances. The design is released as open hardware and therefore is presented to the community as a powerful tool for general usage.

scholarly journals Behavior of Residual Current Devices at Frequencies up to 50 kHz

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1785
Author(s):  
Stanislaw Czapp ◽  
Hanan Tariq
Keyword(s):  
Electric Shock ◽  
High Frequency ◽  
Pulse Width Modulation ◽  
Low Voltage ◽  
Residual Current ◽  
Indirect Contact ◽  
Additional Protection ◽  
Operating Current ◽  
Low Voltage Circuits ◽  
Frequency Components

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.

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

Cucurbitacins as Anticancer Agents: A Patent Review

2019 ◽  
Vol 14 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Hidayat Hussain ◽  
Ivan R. Green ◽  
Muhammad Saleem ◽  
Khanzadi F. Khattak ◽  
Muhammad Irshad ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Wide Spectrum ◽  
Biological Effects ◽  
Therapeutic Effects ◽  
Cytotoxic Effects ◽  
Natural Sources ◽  
Oh Groups ◽  
Drug Candidates ◽  
The Past ◽  
Wide Range

Background: Cucurbitacins belong to a group of tetracyclic triterpenoids that display a wide range of biological effects. In the past, numerous cucurbitacins have been isolated from natural sources and many active compounds have been synthesized using the privileged scaffold in order to enhance its cytotoxic effects. Objective: his review covers patents on the therapeutic effects of natural cucurbitacins and their synthetic analogs published during the past decade. By far, the majority of patents published are related to cancer and Structure-Activity Relationships (SAR) of these compounds are included to lend gravitas to this important class of natural products. Methods: The date about the published patents was downloaded via online open access patent databases. Results: Cucurbitacins display significant cytotoxic properties, in particular cucurbitacins B and D which possess very potent effects towards a number of cancer cells. Numerous cucurbitacins isolated from natural sources have been derivatized through chemical modification at the C(2)-OH and C(25)- OH groups. Most importantly, an acyl ester of the C(25)-OH and, iso-propyl, n-propyl and ethyl ether groups of the C(2)-OH demonstrated the most increased cytotoxic activity. Conclusion: The significant cytotoxic effects of natural and semi-synthetic cucurbitacins make them attractive as new drug candidates. Moreover, cucurbitacins have the capability to form conjugates with other anticancer drugs which will synergistically enhance their anticancer effects. The authors believe that in order to get lead compounds, there should be a greater focus on the synthesis of homodimers, heterodimers, and halo derivatives of cucurbitacins. In the opinion of the authors the analysis of the published patents on the cucurbitacins indicates that these compounds can be developed into a regimen to treat a wide spectrum of cancers.

Study on the Residual Current Protection Device Technology

2014 ◽  
Vol 8 (1) ◽  
pp. 404-411 ◽  
Author(s):  
Guo Rongyan ◽  
Zhang Honghui
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Residual Current ◽  
Electrical Safety ◽  
Protective Device ◽  
Protection Device ◽  
Voltage Distribution ◽  
The People ◽  
Safety Protection ◽  
Device Technology

As an important electrical safety protection device in low voltage distribution system, residual current protection device is to protect the insulation line leakage fault; the electric shock of the people plays an important role in fault. From the protection characteristics of residual current protective device to points, those can be divided into, residual current protection device for residual pulsating direct current and residual dc, according to the residual sinusoidal alternating current.

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