Test Cell For Polarization And Depolarization Current Test Of Transformer Insulation Oil

2012 ◽  
Author(s):  
Nor Asiah Muhamad ◽  
Toan Phung ◽  
Trevor Blackburn
Keyword(s):  
The Other ◽  
Depolarization Current ◽  
Dc Voltage ◽  
Current Test ◽  
Long Duration ◽  
A Cell ◽  
Run Up ◽  
Paper Insulation ◽  
Transformer Insulation ◽  
Insulation Oil

Polarisasi dan depolarisasi Arus (PDA) analisis biasanya digunakan untuk menentukan kadar air dalam di antara penebat minyak–kertas dan juga konduktiviti minyak di dalam pemboleh ubah. Pengukuran PDA ke atas pemboleh ubah di tapak dilakukan dengan menyuntikkan Voltan DC pada satu sisi pemboleh ubah dan pengukuran arus akak dilalukan pada sisi yang lain, di mana semasa pemdukuran dijalankan pemboleh ubah ini harus dipisahkan dari operasi. Ujian PDC biasanya berjalan sehingga 10000s untuk polarisasi dan harus menunggu 10000s lagi untuk pengukuran depolarisasi. Kerana tempoh ujian yang lama, aplikasi kaedah ini untuk memantau pemboleh ubah yang sedang beroperasi menjadi kurang popular. Dalam kajian ini, sel direka dan dibangunkan untuk melakukan ujian PDA pada sampel minyak penebat. Pola PDA minyak penebat diperoleh dengan ujian menggunakan sel tersebut didapati memiliki pola yang sama dengan ujian dilakukan di tapak. Ramalan kondisi pemboleh ubah dalam perkhidmatan dapat dilakukan dengan melakukan ujian PDA pada sampel minyak penebat yang diambil dari tangki pemboleh ubah dan kemudian membandingkan polanya, tahap konduktiviti dan nilai pemuat berkadar terhadap pola asal PDA minyak penebat tersebut. Kata kunci: Polarisasi; depolarisasi; minyak penebat; pemboleh ubah dan sel Polarization and Depolarization Current (PDC) analysis is normally used to determine the water content in the oil–paper insulation barrier and also oil conductivity inside the transformers. PDC measurement onsite was performed by injecting the DC Voltage at one side of the transformer and current measurement will be carried at the other side of the transformer, in which the transformers are required to be isolated from services to be tested. PDC test normally run up to 10000s for polarization and had to wait for other 10000s for depolarization measurement. Because of the long duration of the test, applications of this method to monitor transformer on service become less popular. In this research, a cell was designed and developed to perform PDC on insulation oil samples. The PDC pattern of insulation oil obtained by testing using the cell was found to have same pattern with the test done onsite. Predictions for transformers in service can be made by performing PDC tests on oil samples taken from the transformer tank and then comparing its pattern, conductivity level and measured capacitance value against a PDC fingerprint. Key words: Polarization; depolarization; oil insulation; transformer; cell

Measurement of Noise inside the Compartment and Vibration on both Sides of Elastomeric Powertrain Mounts of Passenger Car

2013 ◽  
Vol 471 ◽  
pp. 59-63
Author(s):  
Mohd Noor Arib Rejab ◽  
Roslan Abd Rahman ◽  
Raja Ishak Raja Hamzah ◽  
Jawaid Iqbal Inayat Hussain ◽  
Nazirah Ahmad ◽  
...  
Keyword(s):  
Fast Response ◽  
Sound Level ◽  
Measurement Noise ◽  
The Other ◽  
Vibration Level ◽  
Test Conditions ◽  
Exhaust Noise ◽  
Run Up ◽  
Level Meter ◽  
High Level

This paper presents an evaluation on elastomeric mount used to isolate vibration from powertrain to chassis or structure vehicle. The assessments started with measurement of noise inside compartment, and exhaust noise. This is followed by the measurement of vibration on both sides of elastomeric mounts. The noise in the compartment and exhaust noise is measured according to BS 6086: 1981 and BS ISO 5130: 2007. The noise in the compartment and vibration is tested in three conditions. Firstly, engine is run-up with load (driving at second gear); secondly, without load; and thirdly, without load but hanging. A microphone is fixed at the ear of the mannequin. The fast response and A weighting sound level meter were used for measurement noise in the compartment and exhaust noise. The vibration is measured in terms of acceleration on both sides of each elastomeric powertrain mounts. Two accelerometer transducers are fixed on both sides of powertrain elastomeric mounts. One side was identified as a source of vibration and the other as receiver of vibrations. The results showed that the pattern of overall vibration level on source and receiver increased from 1050 RPM (idling) to 4000 RPM on all test conditions. Vibration transmitted to chassis or receiver structure was analyzed using transmissibility concept. By evaluating test condition of engine run-up without load, informed that the front and rear mounts showed a high level transmissibility contributing to structure-borne noise.

LONG DURATION ECHOES FROM AURORA, METEORS, AND IONOSPHERIC BACK-SCATTER

1953 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
D. W. R. McKinley ◽  
Peter M. Millman
Keyword(s):  
Long Range ◽  
High Frequency ◽  
The Other ◽  
Very High Frequency ◽  
Long Duration ◽  
E Region ◽  
Very High ◽  
Visual Observations

In the course of the Ottawa meteor program some unusual echoes have been detected on 33 Mc. Echoes from the aurora are discussed and correlated with visual observations. Two mechanisms of radio reflections from the aurora have been proposed but the data here presented are insufficient to favor one over the other. On Aug. 4, 1948, six extremely long duration meteor echoes were observed which may have been due to abnormal ionospheric conditions. From time to time since August, 1948, a weak semipermanent echo has been recorded, usually appearing at a range of about 80 km., and enduring up to an hour. It is suggested that this echo is due to back-scatter from the same sources in the lower E-region that are presumed to be responsible for long-range very high frequency propagation.

scholarly journals MICRURGICAL STUDIES IN CELL PHYSIOLOGY

1926 ◽  
Vol 10 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Paul Reznikoff
Keyword(s):  
Heavy Metals ◽  
Metal Cation ◽  
Surface Membrane ◽  
The Other ◽  
Contractile Vacuole ◽  
Toxic Action ◽  
Cell Physiology ◽  
Relative Toxicity ◽  
A Cell

I. Plasmalemma. 1. The order of toxicity of the salts used in these experiments on the surface membrane of a cell, taking as a criterion viability of amebæ immersed in solutions for 1 day, is HgCl2, FeCl3> AlCl3> CuCl2> PbCl2> FeCl2. Using viability for 5 days as a criterion, the order of toxicity is PbCl2> CuCl2> HgCl2> AlCl3> FeCl3> FeCl2. 2. The rate of toxicity is in the order FeCl3> HgCl2> AlCl3> FeCl2> CuCl2> PbCl2. 3. The ability of amebæ to recover from a marked tear of the plasmalemma in the solutions of the salts occurred in the following order: AlCl3> PbCl2> FeCl2> CuCl2> FeCl3> HgCl2. II. Internal Protoplasm. 4. The relative toxicity of the salts on the internal protoplasm, judged by the recovery of the amebæ from large injections and the range over which these salts can cause coagulation of the internal protoplasm, is in the following order: PbCl2> CuCl2> FeCl3> HgCl2> FeCl2> AlCl3. 5. AlCl3 in concentrations between M/32 and M/250 causes a marked temporary enlargement of the contractile vacuole. FeCl2, FeCl3, and CuCl3 produce a slight enlargement of the vacuole. 6. PbCl2, in concentrations used in these experiments, appears to form a different type of combination with the internal protoplasm than do the other salts. III. Permeability. 7. Using the similarity in appearance of the internal protoplasm after injection and after immersion to indicate that the surface is permeable to a substance in which the ameba is immersed, it is concluded that AlCl3 can easily penetrate the intact plasmalemma. CuCl2 also seems to have some penetrating power. None of the other salts studied give visible internal evidence of penetrability into the ameba. IV. Toxicity. 8. The toxic action of the chlorides of the heavy metals used in these experiments, and of aluminum, is exerted principally upon the surface of the cell and is due not only to the action of the metal cation but also to acid which is produced by hydrolysis.

scholarly journals Numerical Simulation of a Textured and Untextured Photovoltaic Solar Cell: Comparative study

2021 ◽  
Vol 03 (01) ◽  
pp. 104-114
Author(s):  
Karim Salim ◽  
◽  
M.N Amroun ◽  
K Sahraoui ◽  
W Azzoui ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Solar Cell ◽  
Comparative Study ◽  
Silicon Solar Cell ◽  
The Other ◽  
Surface Parameters ◽  
Cell Efficiency ◽  
Photovoltaic Solar Cell ◽  
A Cell

Increasing the efficiency of solar cells relies on the surface of the solar cell. In this work, we simulated a textured silicon solar cell. This simulation allowed us to predict the values of the surface parameters such as the angle and depth between the pyramids for an optimal photovoltaic conversion where we found the Icc: 1.783 (A) and Vco: 0.551 (V) with a cell efficiency of about 13.56%. On the other hand, we performed another simulation of a non-textured solar cell to compare our values and found Icc: 1.623 (A) and Vco: 0.556 (V) with an efficiency of about 12.76%.

scholarly journals Partial Discharge Process and Characteristics of Oil-Paper Insulation under Pulsating DC Voltage

2016 ◽  
Vol 11 (2) ◽  
pp. 436-444 ◽  
Author(s):  
Lianwei Bao ◽  
Jian Li ◽  
Jing Zhang ◽  
Tianyan Jiang ◽  
Xudong Li
Keyword(s):  
Partial Discharge ◽  
Discharge Process ◽  
Dc Voltage ◽  
Paper Insulation

scholarly journals Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 336
Author(s):  
Yu Shang ◽  
Qiang Liu ◽  
Chen Mao ◽  
Sen Wang ◽  
Fan Wang ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Moisture Content ◽  
Charge Carriers ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Stable Operation ◽  
Polarization Current ◽  
Depolarization Current ◽  
Moisture Condition ◽  
Dc Voltage

Cellulose insulation polymer material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

Tandem Conveyor Queues

1989 ◽  
Vol 3 (4) ◽  
pp. 517-536
Author(s):  
F. Baccelli ◽  
E.G. Coffman ◽  
E.N. Gilbert
Keyword(s):  
Boundary Value Problem ◽  
Joint Distribution ◽  
Queueing System ◽  
The Other ◽  
Riemann Boundary Value Problem ◽  
Riemann Boundary ◽  
Special Cases ◽  
A Cell ◽  
Service Times ◽  
Input Position

This paper analyzes a queueing system in which a constant-speed conveyor brings new items for service and carries away served items. The conveyor is a sequence of cells each able to hold at most one item. At each integer time, a new cell appears at the queue's input position. This cell holds an item requiring service with probability a, holds a passerby requiring no service with probability b, and is empty with probability (1– a – b). Service times are integers synchronized with the arrival of cells at the input, and they are geometrically distributed with parameter μ. Items requiring service are placed in an unbounded queue to await service. Served items are put in a second unbounded queue to await replacement on the conveyor in cells at the input position. Two models are considered. In one, a served item can only be placed into a cell that was empty on arrival; in the other, the served item can be placed into a cell that was either empty or contained an item requiring service (in the latter case unloading and loading at the input position can take place in the same time unit). The stationary joint distribution of the numbers of items in the two queues is studied for both models. It is verified that, in general, this distribution does not have a product form. Explicit results are worked out for special cases, e.g., when b = 0, and when all service times are one time unit (μ = 1). It is shown how the analysis of the general problem can be reduced to the solution of a Riemann boundary-value problem.

Analyse de la morphogenèse du pied des Oiseaux à l'aide de mélanges cellulaires interspécifiques

Development ◽  
1973 ◽  
Vol 29 (1) ◽  
pp. 175-196
Author(s):  
Par Marie-Paule Pautou
Keyword(s):  
Cell Suspension ◽  
The Other ◽  
Composite Type ◽  
A Cell ◽  
Species Specific ◽  
Host Embryo

Morphogenesis of the feet of birds, studied in limbs developed from reaggregated heterospecific mesoderm Experiments were undertaken to determine whether species-specific characters of chick and duck mesodermal leg-bud cells are retained after dissociation and reaggregation in homoand heterospecific mixtures. Prospective zeugopod and autopod mesoderm from chick and/or duck leg buds were isolated, dissociated into a cell suspension and pelleted by centrifugation. The reaggregated mesoderm was packed into a leg-bud ectodermal jacket; the recombined leg bud was then grafted on the wing stump of a host embryo. Recombinants whose mesoderm was a homospecific reaggregate developed into typical chick or duck leg parts according to the specific origin of the mesodermal component; the feet of nearly all these legs lacked antero-posterior polarity. Recombinants containing heterospecific reaggregates were also capable of forming reasonably organized leg structures. The foot was not, as a rule, of the specific type expected of the majority component. In a mixture of 75% chick mesoderm cells and 25% duck mesoderm cells, the feet which developed were either of chick type or of composite chick/duck type, where typical chick areas were next to typical or aberrant (steganoid) duck areas. When the ratio was reversed (25% chick, 75% duck), the majority of the feet were again of chick type or of composite chick/duck type, the typical duck phenotype being exceptional. Even in a mixture of 10% chick cells and 90% duck cells, duck-type feet were not obtained. They were all of composite type: half of their interdigital zones were of chick type, the other half were occupied, in most cases, by underdeveloped, indented webbing or by one or several discrete flaps, and, in a few cases, by normal webbing. The vast majority of the feet developed from heterospecific mesoderm were characterized by the profusion of the toes, which were not polarized along the a–p axis.

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