Materials Effect on Shielding Effectiveness

Saadi, H.; Oussaid, Rachid

doi:10.1109/icspc.2007.4728490

Cited by 11 publications

(9 citation statements)

References 5 publications

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“…According to Schelkunoff's approach when an electromagnetic plane wave is incident on a shielding material a part of the wave energy is reflected at the interface with the shield, as a result of the difference in impedance between the incident wave and the shield [8,46]. This primary mechanism, defined as reflection loss, requires the presence of charge carriers in the material, i.e.…”

Section: The Shielding Mechanismmentioning

confidence: 99%

“…The absorption loss is the result of the heat generated in the shield and is related to the interaction of electric and/or magnetic dipoles with the electromagnetic field. In addition a third part of the electromagnetic radiation is attenuated by multiple reflections, which take place at various surfaces or interfaces in the shield, this third mechanism can be disregarded for SE calculations if the shield thickness is much greater than the skin depth [46], when the absorption loss is ≥ 15 dB [22]. Finally the last part of the electromagnetic field is transmitted through the material, so that the effectiveness of the shield can be viewed as the ratio expressed in dB of the electric (magnetic) incident field intensity to the intensity of the electric (magnetic) field that is transmitted through the shield:…”

Section: The Shielding Mechanismmentioning

confidence: 99%

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Electromagnetic shielding effectiveness of carbon fibre reinforced composites

Munalli

Dimitrakis

Chronopoulos

et al. 2019

Composites Part B: Engineering

158

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This paper reports results on the shielding effectiveness parameter of laminated epoxy composites with carbon fibre reinforcements. Measurements of shielding effectiveness were carried out with a coaxial transmission line testing chamber according to ASTM 4935 standard and epoxy-matrix composites with continuous carbon-fibres were proven to be an excellent electromagnetic interference shielding material, where a composite slab made of 4 layers of prepregs provided more than 99.9% of electromagnetic attenuation. It was found that the reflection mechanism of the shielding material was mainly influenced by the fibre volume ratio, and that an increase in the number of layers of the composite resulted in higher shielding effectiveness due to a greater absorption mechanism. Calculations of the shielding effectiveness parameter of the material used were made by means of commercial electromagnetic simulation tools, having determined experimentally the overall resistivity of the composite. The findings presented in this work suggest that in presence of a greater number of interfaces at different impedance the separate modelling of matrix and fibres at mesoscopic scale must be taken into account.

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Section: The Shielding Mechanismmentioning

confidence: 99%

Section: The Shielding Mechanismmentioning

confidence: 99%

Electromagnetic shielding effectiveness of carbon fibre reinforced composites

Munalli

Dimitrakis

Chronopoulos

et al. 2019

Composites Part B: Engineering

158

View full text Add to dashboard Cite

show abstract

“…2. Because the propagation of the electromagnetic waves is mainly along the surface of cables, a part of radiated disturbance's energy can be reflected when the electromagnetic waves encounter the copper mesh, which can decrease the radiated EMI [20], [21]. 3) For the reason of the EMI produced by the TRV is serious, and the transient process of arc voltage is the key cause of the large transient EMI, some measures should be taken to reduce the overvoltage caused by TRV.…”

Section: B Measures To Suppress the Emimentioning

confidence: 99%

EM Measurements Between MV Switching Sources and Colocated Sensitive Circuit

Huang

Ruan

et al. 2015

IEEE Trans. Electromagn. Compat.

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With the development and increasing use of intelligent vacuum circuit breaker (VCB), the electromagnetic compatibility problem between VCBs and their low-voltage electronic equipment is becoming increasingly prominent. Switching operations of circuit breakers are known to be serious sources of electromagnetic interference (EMI) to their secondary equipment, which can lead to the control and protection devices display error and malfunction. Hence, it is very important to study the EMI problem of the secondary equipment (such as current transformer (CT), PT, and controller) caused by the operations of circuit breakers. This paper carried out the tests of a 10 kV medium-voltage outdoor polemounted switch by a synthetic test circuit with large current and high impulse voltage sources, and collected the current signals of the secondary circuit at the same time, then obtained the frequency and energy distributions of the disturbance signals, caused by the breaking operation of pole-mounted switch, by time and frequency characteristic analysis with the wavelet analysis. Results show that the secondary side of the CT and the feeder terminal unit (FTU) controller are bearing EMI when pole-mounted switch is in operation and the distribution of the frequency spectrum is wide. The most serious disturbance appears at the time of arc current passing zero and the frequency distribution is mainly in 7.81-15.63 MHz. The EMI caused by transient recovery voltage is mainly distribution in 31.25-125.0 MHz. The maximum amplitude of disturbance pulses is about 4.5 times as large as that of the normal case. The results can provide a reference to the measures against the EMI for the pole-mounted switch's FTU controller. Index Terms-Current transformer (CT), electromagnetic interference (EMI), feeder terminal unit (FTU), frequency distribution, pole-mounted switch, synthetic test, transient recovery voltage (TRV), wavelet analysis.

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“…Por otra parte, en el estudio de Saadi (2007) [4] sobre apantallamiento se realizó un análisis teórico de la eficiencia de blindaje magnético con diversos materiales, donde se tienen en cuenta las variables de reflexión y absorción de estos y su respuesta cuando son sometidos a la influencia de ondas electromagnéticas y verifican su eficiencia por medio de resultados del software Matlab . En este estudio se incluyen las características de los materiales, considerándolos ideales, donde se evidencia la necesidad de comparar con datos obtenidos por una práctica donde se evalue qué tan aproximados son los datos arrojados por el software con los datos reales.…”

Section: Introductionunclassified

Estudio de blindaje magnético en materiales conductores en función de la frecuencia.

2016

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Se describe el efecto de un campo magnético uniforme en materiales conductores, y cómo estos apantallan el campo que los atraviesa. Con el fin de crear dicho campo,se energiza una bobina que encierra el material apantallador y la bobina sensor de campo magnético, mediante una señal sinusoidal producida por un generador de señales con una tensión de 10 [Vp]. La medida del campo magnético se realiza de manera indirecta ubicando una bobina como sensor en el centro de una bobina de diámetro mayor, realizando la medida de tensión en el sensor, de tal manera que al colocar un material apantallador que encierre la bobina se reduzca el campo magnético en su interior y, por ende, la tensión inducida en la bobina. Los materiales apantalladores que se emplearon fueron: acero, aluminio, hierro y cobre, la eficiencia de estos materiales fue estudiada en un rango de frecuencias de 60-100.000 Hz, obteniendo como resultado que el material más eficiente desde 60- 12.000 Hz es el hierro, y para 32.000-100.000 es el cobre.

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Materials Effect on Shielding Effectiveness

Cited by 11 publications

References 5 publications

Electromagnetic shielding effectiveness of carbon fibre reinforced composites

Electromagnetic shielding effectiveness of carbon fibre reinforced composites

EM Measurements Between MV Switching Sources and Colocated Sensitive Circuit

Estudio de blindaje magnético en materiales conductores en función de la frecuencia.

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