Improving the reliability of electric motors during startup using electroosmotic drying of insulation

The article considers the actual problem of electric motors (EM) operation associated with wetting of winding insulation. The condition of wet insulation is getting worse due to aggressive environment of premises of agro-industrial complex, and some workshops in industry. It is noted that together with humidification, the effect of insulation “steaming” occurs after EM is put into operation. In this case, the insulation resistance R sharply decreases and its breakdown may occur, after which a major overhaul of EM is required. A new method for EM drying based on the electrokinetic phenomenon of electroosmosis has been developed. Under the influence of electric field forces, moisture is extruded from insulation capillaries onto the surface of EM winding and stator iron. R increases, and EM becomes ready to turn on. Under further operation, EM is heated and moisture evaporates into the environment. It is shown how electroosmotic drying (EOD) and the developed device (DEOD) help to get rid of the effect of insulation “steaming” and thereby ensure trouble-free EM operation.

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Improving the efficiency of electroosmotic drying of electric motors insulation

E3S Web of Conferences ◽

10.1051/e3sconf/202017801061 ◽

2020 ◽

Vol 178 ◽

pp. 01061 ◽

Cited By ~ 1

Author(s):

Alexandr Nemirovskiy ◽

Galina Kichigina ◽

Irina Sergievskaya ◽

Alexey Udaratin ◽

Aleksandr Alyunov ◽

...

Keyword(s):

Electrical Equipment ◽

Hydrogen Ions ◽

State University ◽

Electric Motors ◽

Ion Hydration ◽

Actual Problem ◽

Penetration Ability ◽

Electrokinetic Phenomenon ◽

Positively Charged ◽

Pulsed Voltage

The actual problem of electric motors (EM) operation associated with wetting of windings insulation is considered. A new method of EM drying based on electrokinetic phenomenon of electroosmosis was developed at the Department of Electrical Equipment of Vologda State University. It was shown that water molecules can take part in formation of non-mobile hydrated positively charged hydrogen ions. In this case, hydrogen ions become bound, lose their mobility and ability to take part in the process of electroosmotic drying (EOD). EOD efficiency is drastically reduced. It was proved that it is possible to prevent ion hydration, increase their mobility, penetration ability and, thereby, increase the EOD efficiency by applying a pulsed voltage component to the EOD process with a duty factor of 4. As a result, a new EOD method was developed using a pulsed voltage component that increases the speed of EM insulation drying by three times.

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A Novel MOS-Channel Diode Embedded in a SiC Superjunction MOSFET for Enhanced Switching Performance and Superior Short Circuit Ruggedness

Electronics ◽

10.3390/electronics10212619 ◽

2021 ◽

Vol 10 (21) ◽

pp. 2619

Author(s):

Jongwoon Yoon ◽

Kwangsoo Kim

Keyword(s):

Electric Field ◽

Switching Time ◽

Short Circuit ◽

Oxide Thickness ◽

Shielding Effect ◽

Figures Of Merit ◽

Switching Performance ◽

Turn On ◽

Reverse Recovery Time ◽

Tcad Simulations

In this study, a novel MOS-channel diode embedded in a SiC superjunction MOSFET (MCD SJ-MOSFET) is proposed and analyzed by means of numerical TCAD simulations. Owing to the electric field shielding effect of the P+ body and the P-pillar, the channel diode oxide thickness (tco) of MCD can be set to very thin while achieving a low maximum oxide electric field (EMOX) under 3 MV/cm. Therefore, the turn-on voltage (VF) of the proposed structure was 1.43 V, deactivating the parasitic PIN body diode. Compared with the SJ-MOSFET, the reverse recovery time (trr) and the reverse recovery charge (Qrr) were improved by 43% and 59%, respectively. Although there is a slight increase in specific on-resistance (RON), the MCD SJ-MOSFET shows very low input capacitance (CISS) and gate to drain capacitance (CGD) due to the reduced active gate. Therefore, significantly improved figures of merit RON × CGD by a factor of 4.3 are achieved compared to SJ-MOSFET. As a result, the proposed structure reduced the switching time as well as the switching energy loss (ESW). Moreover, electro-thermal simulation results show that the MCD SJ-MOSFET has a short circuit withstand time (tSC) more than twice that of the SJ-MOSFET at various DC bus voltages (400 and 600 V).

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Determination of Estimated, Consumed and Remaining Lifetimes of Paper - Oil Transformers Insulation Based on Winding Insulation Resistance

2018 IEEE International Conference on High Voltage Engineering and Application (ICHVE) ◽

10.1109/ichve.2018.8642211 ◽

2018 ◽

Author(s):

P. V. Notingher ◽

G. Tanasescu

Keyword(s):

Insulation Resistance ◽

Winding Insulation

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Justification of the active method of protecting the insulation of submersible electric motors

E3S Web of Conferences ◽

10.1051/e3sconf/201912402003 ◽

2019 ◽

Vol 124 ◽

pp. 02003

Author(s):

V. A. Trushkin ◽

O. N. Churlyaeva ◽

R. V. Kozichev

Keyword(s):

Physical Properties ◽

Electrical Breakdown ◽

Electrical Equipment ◽

Working Environment ◽

Operating Parameters ◽

Insulation Resistance ◽

Electric Motors ◽

Electrically Conductive ◽

Active Method ◽

Conductive Properties

The article provides an analysis of the properties of the working environment of submersible electrical equipment. The influence of the operating parameters of electrical equipment on the physical properties of the fluid (its electrically conductive properties) is considered. Mathematical confirmation of the implementation of electroosmosis in the capillaries of the insulation of submersible electric motors is given. The rationale for the active method of protecting submersible electrical equipment from reducing insulation resistance and preventing electrical breakdown is given.

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Field emitters with low turn on electric field based on carbon fibers

Applied Surface Science ◽

10.1016/j.apsusc.2006.12.115 ◽

2007 ◽

Vol 253 (14) ◽

pp. 5980-5984 ◽

Cited By ~ 4

Author(s):

Qilong Wang ◽

Hui Mu ◽

Xiaobing Zhang ◽

Wei Lei ◽

Jinchan Wang ◽

...

Keyword(s):

Electric Field ◽

Carbon Fibers ◽

Turn On ◽

Field Emitters

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SiC-MOSFET Structure Enabling Fast Turn-On and -Off Switching

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.1097 ◽

2012 ◽

Vol 717-720 ◽

pp. 1097-1100 ◽

Cited By ~ 1

Author(s):

Shiro Hino ◽

Naruhisa Miura ◽

Akihiko Furukawa ◽

Shoyu Watanabe ◽

Yukiyasu Nakao ◽

...

Keyword(s):

Electric Field ◽

Equivalent Circuit ◽

High Speed ◽

Equivalent Circuit Model ◽

Circuit Model ◽

Turn On ◽

Model Based ◽

Switching Losses ◽

High Speed Switching

High speed switching is desired to reduce switching losses of SiC-MOSFETs. In order to realize SiC-MOSFETs capable of high speed switching, we numerically evaluated the electric field induced in SiC-MOSFETs during switching using an equivalent circuit model. Based on the evaluation, we designed a SiC-MOSFET, which successfully demonstrated high speed switching with a dV/dt of over 70 V/ns.

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Optimization of Dry Construction Mix with the Addition of Biochar from Reclaimed Rice Straw in the Agro-Industrial Complex

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/937/3/032071 ◽

2021 ◽

Vol 937 (3) ◽

pp. 032071

Author(s):

A Smolyanichenko ◽

Y Shcherban ◽

S Stel’makh ◽

A Khalyushev ◽

Y Zherebtsov

Keyword(s):

Rice Straw ◽

Physical And Mechanical Properties ◽

Average Density ◽

Optimal Dosage ◽

Industrial Complex ◽

Mathematical Planning ◽

Actual Problem ◽

Chemical Studies ◽

Physical And Chemical ◽

By Products

Abstract Currently, the actual problem is the disposal of various by-products of the agro-industrial complex. This direction practically does not develop, but is solved only by burning them, which leads to air pollution. The article contains physical and chemical studies of a byproduct from rice production, namely rice straw. In the process of recycling rice straw at a temperature of 600°C, biochar is formed, which can be used as a micro-filling additive for dry mortar. Using the method of mathematical planning of the experiment (FFE 2k), optimization was carried out and the optimal composition of the dry mortar was obtained, containing up to 10% of biochar. It has been established that the introduction of biochar in the optimal dosage improves the physical and mechanical properties of the dry mortar in comparison with the control composition on average by: average density – 3%, water absorption – 17%, compressive strength – 12%, tensile strength at bending – 24%, adhesion strength – 55%..

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Analysis of depolymerization of insulating compositions of electric motor windings based on ultrasonic radiation

Vestnik MGTU ◽

10.21443/1560-9278-2021-24-4-361-371 ◽

2021 ◽

Vol 24 (4) ◽

pp. 361-371

Author(s):

A. I. Kashin ◽

A. E. Nemirovsky

Keyword(s):

Electric Motor ◽

Software Systems ◽

Electric Motors ◽

Optimal Parameters ◽

Fundamental Study ◽

Environmental Friendliness ◽

Stator Windings ◽

Working Solution ◽

Insulation Systems ◽

Winding Insulation

This work is a continuation of the fundamental study on implementing an innovative method of repairing electric motors using ultrasound. A study of the method of dismantling windings based on ultrasound has been carried out for the purpose of energy efficiency, environmental friendliness and less time spent on the repair cycle of electric motors in terms of removing the stator winding. The investigated dismantling method is optimal for a number of technical issues in comparison with the existing methods for dismantling electric motor windings. In the work, the main focus is on the material of the winding insulation. Lacquer and compound types of insulation of industrial electric motors, which are the main ones everywhere, have been analyzed. The analysis of the impregnating electrical insulating compositions of the stator windings of electric motors and the influence of ultrasound on them during dismantling of the windings of electric motors at different levels of influence of forcing factors: duration and power of ultrasonic action, concentration and temperature of the working solution. The applied mathematical software systems for calculation and modeling guarantee the reliability and rationality of the results of the experiments obtained during the work. A system of equations has been modeled and models of the effect of useful factors relative to each other have been constructed, the results obtained have been optimized and the optimal parameters of both varnish and compound insulation systems have been identified. The optimal parameters of the investigated types of insulation show encouraging results on many important points: duration, energy consumption, environmental friendliness.

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Ultra-Violet Electroluminescence of ZnO Nanorods/MEH-PPV Heterojunctions by Optimizing Their Thickness and Using AZO as a Transparent Conductive Electrode

Materials ◽

10.3390/ma12182976 ◽

2019 ◽

Vol 12 (18) ◽

pp. 2976 ◽

Cited By ~ 1

Author(s):

S. Wageh ◽

Su-Ling Zhao ◽

Xiao-Yi Xie ◽

Song Gao ◽

Ahmed Al-Ghamdi

Keyword(s):

Electric Field ◽

Zno Nanorods ◽

Ultra Violet ◽

Hole Injection ◽

Band Edge Emission ◽

Edge Emission ◽

Transparent Conductive Electrode ◽

Pronounced Increase ◽

Turn On ◽

Dc Bias

In this paper, a series of ITO/ZnO/ZnO nanorods/MEH-PPV/Al were prepared with different thicknesses of MEH-PPV that were changed from 15, 10 to 7 nm. The electric field in the devices was analyzed. An increase in the electric field on ZnO made hole injection easy and the electrons tunnel fast through thinner MEH-PPV to ZnO. This made the carriers prefer to recombine inside the ZnO layer, and the emission of ZnO was predominant under direct current (DC) bias. Furthermore, another device was fabricated with the structure of AZO (Al-doped ZnO)/ZnO/ZnO nanorods/MEH-PPV/Al. Ultra-violet (UV) electroluminescence (EL) at 387 nm from ZnO band edge emission was realized under DC bias. The turn-on voltage of the devices having AZO as the electrode is lower than that of ITO, and the EL power is enhanced. This work also studies the effect of inserting LiF underneath the Al electrode and above the layer of MEH-PPV. The LiF film inserted caused an obvious decrease in turn-on voltage of the devices and a pronounced increase in the EL power. The mechanism of electroluminescence enhancement is also discussed.

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