Design and Implementation of Van de Graaff Generator

The paper proposes a design and implementation of Van de Graaff generator whose output voltage is 80.28 KV. To calculate the generated output voltage we have use the sphere gap method. A Van de Graaff generator is an electrostatic generator as it works on a principle of electrostatics. A Van de Graaff generator is used to generate a high DC voltage. It was first developed by Robert Jemison Van de Graaff in 1929, in USA and carries his name along 1931. This generator uses a moving belt to build up very high voltages on a hollow metal globe which is located on top of the generator. The potential difference that is developed in modern Van de Graaff generator reach about 5 megavolts. A Van de Graaff generator that we design and built that is intended to be used in schools and colleges for teaching the basics principles of Electrostatics and Electromagnetics as well as many other applications. Nowadays many schools and colleges laboratories and many museums use this type of generators for electrostatics demonstrations.

PLL-BASED 3? INVERTER CIRCUIT FOR MICROGRID SYSTEM OPERATED BY ELECTROSTATIC GENERATOR

A current source control based PLL (phase lock loop) technique is one of the most efficient methods for modern 3? synchronized grid power systems. When an inverter circuit is driven by an electrostatic generator with wind power, it encounters some problems, such as static and dynamic turn-on-off switching losses, unbalanced source voltage, low continuous current, higher frequency harmonic distortion, phase angle imbalance, etc. To solve these problems, a series of connected switching inverter modules technique is proposed. It is not only a traditional inverter system, but it also works as a low-frequency ripple current inverter with lower switch losses. A new topology of phase synchronous inverter (PSI) is designed using a PLL current source controller. The input voltage source of the PSI is a high DC voltage from an electrostatic generator (ESG). The modified ESG is capable of generating the HVDC and a continuous moderate amount of current. The proposed switching topology of the inverter is able to control the microgrid power as well as reduce the dynamic and static switching loss. It also reduces the high-frequency harmonic distortion and improves the phase angle error. The output LCL lowpass filter scheme of the inverter is designed to reduce the total harmonic distortion of 1.62%. The PSI circuit is designed and simulated using MATLAB software. In the developed system, the input voltage of 8 k , microgrid frequency of 50Hz, switching frequency of the carrier of 10 kHz, and modulation index of 0.85 are considered to be implemented. The proposed novel microgrid connected PSI switching module design technique has significantly enhanced the power stability. The overall system efficiency improved by 95.52%. ABSTRAK: Sumber-arus terkawal berdasarkan teknik PLL (fasa litar kunci) adalah satu kaedah cekap bagi sistem moden tenaga grid selaras 3?. Apabila litar songsang (inverter) digerak menggunakan penjana elektrostatik bersama tenaga angin, ia mengalami masalah seperti kehilangan tenaga statik dan dinamik suis hidup-mati, sumber voltan yang tidak seimbang, kurang arus terus, gangguan harmoni frekuensi tinggi, ketidak-seimbangan sudut fasa, dan sebagainya. Bagi menyelesaikan masalah ini, teknik modul suis bersiri dihubung bersama inverter telah dicadangkan. Ini bukan semata-mata teknik lama sistem inverter, tetapi ia juga berfungsi sebagai arus tidak tetap frekuensi-rendah dengan kurang kehilangan tenaga pada suis inverter. Topologi baru fasa inverter tetap (PSI) ini telah direka menggunakan kawalan sumber arus PLL. Sumber voltan masuk PSI ini telah digunakan daripada voltan DC tinggi penjana elektrostatik (ESG). ESG yang diubah suai ini dapat menghasilkan HVDC dan arus terus yang sederhana. Topologi suis inverter yang dicadang ini dapat mengawal kuasa mikrogrid serta mengurangkan kehilangan dinamik dan statik suis. Ia juga mengurangkan gangguan harmoni frekuensi tinggi dan memperbaiki ketidak-seimbangan sudut fasa. Skim tapisan signal keluar yang rendah pada LCL inverter ini direka bagi mengurangkan total gangguan harmoni sebanyak 1.62%. Litar PSI ini direka dan disimulasi menggunakan perisian MATLAB. Dalam sistem yang dibangunkan ini, 8 kVDCvoltan masuk, 50Hz frekuensi mikrogrid, 10 kHz frekuensi suis angkutan dan 0.85 indeks modulasi telah dipertimbangkan untuk kegunaan. Teknik baru modul suis PSI mikrogrid bersambung yang dicadangkan ini mempunyai kepentingan dalam menstabilkan kuasa dan memperbaiki kecekapan sistem keseluruhan sebanyak 95.52%.

Showcasing Science

Teylers Museum was founded in 1784 and soon thereafter became one of the most important centres of Dutch science. The Museum’s first director, Martinus van Marum, famously had the world’s largest electrostatic generator built and set up in Haarlem. This subsequently became the most prominent item in the Museum’s world-class, publicly accessible, and constantly growing collections. These comprised scientific instruments, mineralogical and palaeontological specimens, prints, drawings, paintings, and coins. Van Marum’s successors continued to uphold the institution’s prestige and use the collections for research purposes, while it was increasingly perceived as an art museum by the public. In the early twentieth century, the Nobel Prize laureate Hendrik Antoon Lorentz was appointed head of the scientific instrument collection and conducted experiments on the Museum’s premises. Showcasing Science: A History of Teylers Museum in the Nineteenth Century charts the history of Teylers Museum from its inception until Lorentz’ tenure. From the vantage point of the Museum’s scientific instrument collection, this book gives an analysis of the changing public role of Teylers Museum over the course of the nineteenth century.

A Novel Design of Static Electrostatic Generator for High Voltage Low Power Applications Based on Electric Field Manipulation by Area Geometric Difference

An electrostatic generator is an electromechanical device that produces static charges at high voltage and low current. This technology is mature enough, as it has existed for many centuries. Nevertheless, the working principle of most of the commonly used electrostatic generators is still based on typical mechanical methods, which consequently makes them bulky and limits their controllability on the generated charges, e.g., Van de Graaff generator that uses the friction between two different materials to generate electrostatic charges. In this paper, a novel design of a static electrostatic generator (SEG) is presented based on a completely different idea compared to existing electrostatic generators, which offers several potential benefits. The idea originates from the study of a parallel plates capacitor—for instance, if a voltage is applied to two plates of a capacitor, then according to Gauss’s law, both of the plates must have an equal and opposite charge. Suppose one of the plates has a different geometry, with a shorter length than the other, then the number of the charges on both plates will not be equal. Thus, by manipulating the geometrical area of the device, a different number of charges will be generated on both metal conductors. Therefore, a different number of charges are generated on both conductors; hence, by connecting both conductor plates of the capacitance, excess charges will remain on the device. The proposed idea was assessed with computer simulations using finite element and finite difference methods for a variety of different scenarios to determine the optimal design of the proposed device. The device offers several advantages over traditional electrostatic generators, such as that it can generate either positive or negative charges by merely reversing the polarity of the DC source; additionally, it is very simple, lightweight, and easy to manufacture. In particular, the principal advantage of the proposed device is that it is a static one, and no mechanical movement is required to produce charges. Further, the design is general enough and scalable. The simulation results demonstrate the performance of the proposed device.

HIGH PRECISION SIMULATION ON SURFACE POTENTIAL OF CELLULAR ELECTRETS BY CHARGE SIMULATION METHOD

Surface potential is one of the key properties of charge retain ability and energy storage performance of cellular electrets. Based on charge simulation method (CSM), a high precision simulation algorithm of surface potential of functional dielectrics is proposed in this paper, which can be applied to the simulations of cellular polypropylene after high-voltage corona discharge. In order to validate the modeling, the surface potential of insulating polymer after corona discharge is measured by an electrostatic measurement system and compared with simulation results based on CSM and finite element method (FEM). The result shows that the numerical simulation based on CSM is well consistent with the experimental data, which indicates that the modeling based on CSM can be used in the calculation and analysis of charge storage ability of capacitor and electrostatic generator based on functional electrets. Moreover, as simulation based on CSM has higher precision than FEM, investigation of surface charge storage ability and prediction of electrostatic hazards of insulating dielectrics could be realized by using CSM.