scholarly journals Partial Discharges in Insulating Systems of Low Voltage Electric Motors Fed by Power Electronics—Twisted-Pair Samples Evaluation

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 768 ◽  
Author(s):  
Marek Florkowski ◽  
Barbara Florkowska ◽  
Pawel Zydron
Keyword(s):  
Electric Field ◽  
Power Electronics ◽  
Low Voltage ◽  
Partial Discharges ◽  
Mutual Position ◽  
Electric Motors ◽  
Dynamic Activity ◽  
Twisted Pair ◽  
Common System ◽  
Different Diameters

Power electronics switching devices currently represent the dominant technology for supplying low voltage (LV) electric motors. The fast switching processes exert a different class of stress on dielectric insulating materials than standard sinusoidal excitations. Such stresses result in an increase in the dynamic activity of the working electric field, which in turn lead to an increased likelihood of partial discharges (PD). The stator design of low voltage motor is often in form of random-wound windings, where the magnet wires (copper or aluminum round wires coated with thin layer of insulation) form a common system of coils with not precisely defined mutual position of particular turns, resulting in various turn-to-turn and coil-to-coil voltage distributions. Pulse Width Modulated (PWM) voltage waveforms from modern electronic inverters are characterized by very short rise times and presence of repetitively occurring overvoltages that can significantly stress the insulation of feeding cables and motors. These factors influence the inception and dynamics of PD and processes of space charge accumulation in electrical insulation. In this paper investigations performed on round magnet wire twisted-pair samples representing LV motor random-wound winding elements are presented. Special attention was afforded to the twist configurations, observed breakdown voltage and PD activity. To describe the field conditions for the formation of PD in the turn-to-turn insulation system, the results of numerical simulations of electric field distributions for winding wires with different diameters, modeled using the COMSOL program, were analyzed. PD created in the insulating systems of model twisted-pair systems were registered and analyzed using the phase resolved partial discharge analysis (PRPDA) method.

scholarly journals Using the Method of Harmonic Distortion Analysis in Partial Discharge Assessment in Mineral Oil in a Non-Uniform Electric Field

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4830
Author(s):  
Alper Aydogan ◽  
Fatih Atalar ◽  
Aysel Ersoy Yilmaz ◽  
Pawel Rozga
Keyword(s):  
Electric Field ◽  
Leakage Current ◽  
High Voltage ◽  
Partial Discharge ◽  
Harmonic Distortion ◽  
Mineral Oil ◽  
Significant Rise ◽  
Partial Discharges ◽  
Uniform Electric Field ◽  
Different Diameters

In high-voltage equipment, it is vital to detect any failure in advance. To do this, a determination of the partial discharges occurring at different voltage types as well as at different electrode configurations is essential for observing the oil condition. In this study, an experimental setup consisting of a needle–semi-sphere electrode configuration immersed in mineral oil is prepared for laboratory experiment. In such a way, a non-uniform electric field is created and the leakage currents are monitored from the grounded electrode. A total of six different electrode configurations are analyzed during the tests by the use of hemispheres of different diameters as grounded electrodes and copper and steel pointed (medical) needle high-voltage electrodes. In the experiments, the partial discharges occurring at four different voltage levels between 5.4 and 10.8 kV are measured and recorded. The effect of the different electrode configurations and voltage levels on the harmonic distortion are noted and discussed. It is experimentally confirmed that it is possible to measure the leakage current caused by the partial discharges of the corona type in oil at the different metal points, creating high-voltage electrodes and different electric field distributions based on the proposed non-invasive measurement technique. The studies showed that there is a significant rise of even harmonic components in the leakage current during the increase in the partial discharge intensity with the 5th harmonic as dominant.

scholarly journals Insulation Life Span of Low-Voltage Electric Motors—A Survey

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1738
Author(s):  
Vanessa Neves Höpner ◽  
Volmir Eugênio Wilhelm
Keyword(s):  
Life Span ◽  
Electric Motor ◽  
Low Voltage ◽  
Frequency Converter ◽  
Rate Of Change ◽  
High Rate ◽  
Switching Frequency ◽  
Electric Motors ◽  
Frequency Converters ◽  
High Switching Frequency

The use of static frequency converters, which have a high switching frequency, generates voltage pulses with a high rate of change over time. In combination with cable and motor impedance, this generates repetitive overvoltage at the motor terminals, influencing the occurrence of partial discharges between conductors, causing degradation of the insulation of electric motors. Understanding the effects resulting from the frequency converter–electric motor interaction is essential for developing and implementing insulation systems with characteristics that support the most diverse applications, have an operating life under economically viable conditions, and promote energy efficiency. With this objective, a search was carried out in three recognized databases. Duplicate articles were eliminated, resulting in 1069 articles, which were systematically categorized and reviewed, resulting in 481 articles discussing the causes of degradation in the insulation of electric motors powered by frequency converters. A bibliographic portfolio was built and evaluated, with 230 articles that present results on the factors that can be used in estimating the life span of electric motor insulation. In this structure, the historical evolution of the collected information, the authors who conducted the most research on the theme, and the relevance of the knowledge presented in the works were considered.

scholarly journals Extended Use for the Frequency Response Analysis: Switching Impulse Voltage Based Preliminary Diagnosis of Potential Sources of Partial Discharges in Transformer

2020 ◽  
Vol 10 (22) ◽  
pp. 8283
Author(s):  
Kamalaselvan Arunachalam ◽  
Balasubramanian Madanmohan ◽  
Rajesh Rajamani ◽  
Natarajan Prabaharan ◽  
Hassan Haes Alhelou ◽  
...  
Keyword(s):  
Frequency Response ◽  
Low Voltage ◽  
Partial Discharges ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Potential Sources ◽  
Impulse Voltage ◽  
Before And After ◽  
Test Voltage ◽  
Low Capacitance

The Frequency Response Analysis approach (FRA) is useful in the fault diagnosis of transformers. However, its usefulness in diagnosing any potential sources of Partial Discharge (PD) in transformers has not been thoroughly investigated so far. In this work, the use of Impulse voltage-based FRA (IFRA) in diagnosing inter-turn shorts and potential sources of PD were investigated on a 315 kVA, 11 kV/433 V transformer. Inter-turn shorts and PD sources were emulated and the usefulness of IFRA in their diagnosis was investigated while using switching impulse voltage at different magnitude levels as the test signals. For emulating the inter-turn shorts and the PDs, special tappings were provided on one of the 11 kV windings through the low capacitance bushings. Low voltage impulse was successful in diagnosing the inter-turn shorts, but unsuccessful in identifying the sources of PDs. During the test condition, the test voltage was adjusted with the presence of artificially created PD sources. The frequency response of the transformer before and after the inception of PD was observed and analyzed in this article. The FRA results demonstrated that the switching impulse voltage based IFRA approach at moderate voltages could be useful in diagnosing the presence of the potential sources of PDs.

Fundamental Study of Cannabidiol Effect on MCF-7 with Low Voltage Pulse Electric Field

2021 ◽  
Author(s):  
Nur Adilah Abd Rahman ◽  
Muhammad Mahadi Abdul Jamil ◽  
Mohamad Nazib Adon ◽  
Ahmad Basri Zainal ◽  
Farideh Javid ◽  
...  
Keyword(s):  
Electric Field ◽  
Voltage Pulse ◽  
Low Voltage ◽  
Pulse Electric Field ◽  
Fundamental Study ◽  
Pulse Electric ◽  
Mcf 7

scholarly journals Implementation of Buck-Boost Converter as Low Voltage Stabilizer at 15 V

2019 ◽  
Vol 9 (4) ◽  
pp. 2230
Author(s):  
Suwarno Suwarno ◽  
Tole Sutikno
Keyword(s):  
Power Electronics ◽  
Wind Power ◽  
Output Voltage ◽  
Low Voltage ◽  
Input Voltage ◽  
Boost Converter ◽  
Voltage Stabilizer ◽  
Voltage Regulator ◽  
Output Current ◽  
Converter Design

<p>This paper presents the implementation of the buck-boost converter design which is a power electronics applications that can stabilize voltage, even though the input voltage changes. Regulator to stabilize the voltage using PWM pulse that triger pin 2 on XL6009. In this design of buck-boost converter is implemented using the XL6009, LM7815 and TIP2955. LM7815 as output voltage regulator at 15V with 1A output current, while TIP2955 is able to overcome output current up to 5A. When the LM7815 and TIP2955 are connected in parallel, the converter can increase the output current to 6A.. Testing is done using varied voltage sources that can be set. The results obtained from this design can be applied to PV (Photovoltaic) and WP (Wind Power), with changes in input voltage between 3-21V dc can produce output voltage 15V.</p>

Microgrid Model on Homer Software

2021 ◽  
Vol 9 (VI) ◽  
pp. 757-760
Author(s):  
Mohd Ahamad
Keyword(s):  
Power Generation ◽  
Power Electronics ◽  
Life Cycle Cost ◽  
Low Voltage ◽  
High Reliability ◽  
Low Cost ◽  
Local Area ◽  
New Paradigm ◽  
Power Sources ◽  
Wide Range

A new concept in power generation is a microgrid. The Microgrid concept assumes a cluster of loads and microsources operating as a single controllable system that provides power to its local area. This concept provides a new paradigm for defining the operation of distributed generation. The microsources of special interest for MGs are small (<100-kW) units with power electronic interfaces. These sources are placed at customers sites. They are low cost, low voltage and have a high reliability with few emissions. Power electronics provide the control and flexibility required by the MG concept. A properly designed power electronics and controllers insure that the MG can meet the needs of its customers as well as the utilities. The goal of this project is to build a complete model of Microgrid including the power sources, their power electronics, and a load and mains model in THE HOMER. The HOMER Micropower Optimization Model is a computer model developed by the U.S. National Renewable Energy Laboratory (NREL) to assist in the design of micropower systems and to facilitate the comparison of power generation technologies across a wide range of applications. HOMER models a power system’s physical behavior and its life-cycle cost, which is the total cost of installing and operating the system over its life span. HOMER allows the modeler to compare many different design options based on their technical and economic merits. It also assists in understanding and quantifying the effects of uncertainty or changes in the inputs.

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