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Magnetic resonance imaging (MRI) is the largest application of superconductivity. Field uniformity is important requirement to MRI magnet. Method of polynomial expansion is used in calculation of magnetic field of MRI magnet. Strategically arrangements of unshielded and shielded multiple coils are deduced on base of eliminating low order coefficients of coils. Shifts of coils along axial direction...
This paper discusses magnetic field of electric power lines and mitigation of passive shielding. Magnetic field is calculated by two-dimension method. It shows elliptically polarized resultant magnetic field for three-phase power lines. Traces of magnetic field vector at positions 1.5m above the ground are presented to show variation of rms and direction of semi-major axis. Induced current in passive...
Transmission line pulse (TLP) can be used in immunity test of electrostatic discharge. Waveform of TLP especially its rising time is very important to the test. In the paper, Factors influencing on waveform of TLP are studied. A model based on principle of TLP is established. It's then simulated. Influences of transmission line, relay, load and grounding wire on waveform of TLP are studied respectively...
This paper discusses electric field under overhead lines with a nearby building. Surface charge method is used. Planer triangle surface charge element is chosen. Electric potential and electric field strength produced by a planer triangle surface charge are presented. And analytical expression is deduced. Then electric field of 220kV double circuit overhead lines with a nearby building is calculated...
This paper discusses influence of sloping ground on electric field under overhead lines. Sloping ground is first transformed into flat ground by use of conformal mapping. Then the analytical expression of electric field is obtained by mirror method. The calculation method of electric field with sloping ground is verified by an example with analytical result. At last, electric field under overhead...
This paper deals with the calculation of the power-frequency electric field generated by the extra high voltage transmission lines. When the ground surface under the transmission line is not flat, the traditional charge simulation method cannot be used to calculate the electric field. In the paper, we present the use of surface charge method (SCM) for this purpose. A two-dimensional electric field...
High voltage overhead lines produce intense electric field and induce current in human body which may be hazard to human health. To study electric field of overhead lines and human body, a mixed method utilizing both finite element method and surface charge method is first presented. It can be used to complex structure and open domain. Merged matrix equation is deduced and an example of electric field...
Electrostatic discharge is a well-known electromagnetic interference. Its transient field can affect operation of electronic equipment. In the paper, the transient electromagnetic field of indirect electrostatic discharge through vertical coupling plane is numerically simulated by using the FDTD method. An expression of pulse function is used as the electrostatic discharge current. Configuration with...
In electric field generated by ultra high voltage overhead lines, electric charges are induced at surface of human body. These electric charges alter electric field of human body and adjoining space. In order to study the influence of human body, a human body model is placed under ultra high voltage overhead lines and electric field produced by the overhead lines is calculated. Charge simulation method...
In order to research the electromagnetic interference (EMI) in substation, this paper describes constitution of analysis model of EMI in substation secondary cable via which EMI can couple to substation secondary system. Substation cable is modeled by transmission line theory and calculated by finite difference time domain (FDTD) method. External electromagnetic field, lightning strike and busbar...
This paper describes electromagnetic transient in busbar of air insulted substation due to switch operation. Transmission line model and lumped parameter model are used to model high voltage bus. Interference of transient in busbar to secondary cable via CCVT is model by coupling capacitor. Simulation results show reflections of electromagnetic wave during propagation in busbar have influence on electromagnetic...
This paper describes constitution of analysis model of electromagnetic interference in substation secondary system. Substation cable is the key part of the model. It's modeled by transmission line model or multi-conductor transmission line model. Electromagnetic interference couples to secondary system via substation cable. External electromagnetic field, ground potential difference and busbar interference...
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