scholarly journals Measurement Techniques for Electromagnetic Shielding Behavior of Braided-Shield Power Cables: An Overview and Comparative Study

2019 ◽  
Vol 19 (5) ◽  
pp. 213-221
Author(s):  
Peng Hu ◽  
Zhongyuan Zhou ◽  
Jinpeng Li ◽  
Xiang Zhou ◽  
Mingjie Sheng ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Equivalent Circuit Model ◽  
Qualitative Evaluation ◽  
Reduction Factor ◽  
Power Cables ◽  
Testing Methods ◽  
Transfer Impedance ◽  
Impedance Testing ◽  
Overview Analysis ◽  
Symmetrical Communication

Abstract More and more EMC tests have shown that the radiated emission problems of the equipment under test mainly concentrate on the intercon- nected power cables and cable connectors. Measurement of shielding performance is a prerequisite for quantitative and qualitative evaluation of the frequency-dependent characteristic of braided-shield power cables and cable connectors. Due to the asymmetric geometric structures of these cable assemblies, compared with the coaxial and symmetrical communication cables, the commonly used transfer impedance testing methods may not be suitable. In view of this, several improved simple and effective measurement methods, including transfer impedance and shield reduction factor testing methods, were proposed in recent years. These methods, based on the equivalent circuit model of the characteristic parameters, provide good repeatability for the measurement of shielding performance. This paper presents an overview analysis of various measurement techniques for shielding performance of power cables and cable connectors, highlights some of its equivalence principle in measurement setups, and showcases a brief comparison between transfer impedance and shield reduction factor.

scholarly journals Electromagnetic Shielding Performance Measurement for Braided-Shield Power Cables at Low Frequency Regimes

2020 ◽  
Vol 20 (5) ◽  
pp. 224-229
Author(s):  
Zhongyuan Zhou ◽  
Peng Hu ◽  
Xiang Zhou ◽  
Mingjie Sheng ◽  
Peng Li ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Measurement Techniques ◽  
Low Frequency ◽  
Reduction Factor ◽  
Electromagnetic Shielding ◽  
Power Cables ◽  
Transfer Impedance ◽  
Factor Method ◽  
Definition Of ◽  
Ground Loop

AbstractAlthough various measurement techniques have been applied to both qualitative and quantitative evaluation for the electromagnetic shielding performance of braided-shield power cables, the existing measurements cannot directly assess the low-frequency shielding performance (typically below 100 kHz) due to factors such as ground-loop effects and dynamic range problem in measurement. To solve these, an improved shield reduction factor method, based on gain (T/R) rather than scattering parameters, is proposed to evaluate the shielding performance of braided-shield power cables from 25 Hz to 1 MHz. In this work, we highlight the implementation of measurement setup to avoid the effects of ground-loop and stray electromagnetic field. Meanwhile, the test cell is simplified according to the definition of the shield reduction factor in order to obtain the gain (T/R) parameters, which can be used to calculate transfer impedance as well. From the measurements we present more intuitive evaluation of shielding behavior of braided-shield power cables at low frequency regimes, and showcase a detailed comparative discussion between transfer impedance and shield reduction factor. The proposed shield reduction factor method is expected to be a useful way for the evaluation of the low frequency shielding performance of braided-shield cables.

Investigation of Concrete Slabs under Impact Load

2011 ◽  
Vol 82 ◽  
pp. 398-403 ◽  
Author(s):  
Anja Hummeltenberg ◽  
Birgit Beckmann ◽  
Tony Weber ◽  
Manfred Curbach
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Impact Load ◽  
Compressive Strain ◽  
Measurement Techniques ◽  
Qualitative Evaluation ◽  
Concrete Slabs ◽  
Vehicle Impact ◽  
Measurement Results ◽  
Extent Of Damage

The behaviour of concrete slabs under dynamic load such as rock fall or vehicle impact isinvestigated in this work. The aim of this study is to enlarge the knowledge concerning thesubsequent reinforcing of concrete slabs and its inuence on their behaviour under impact load.Therefore, the results of the drop tower experiments with standard concrete, high performanceconcrete (HPC) and ultra-high performance concrete (UHPC) are compared and interpreted.The analysis of the test results focuses on the qualitative evaluation of the protective e ectand on the quantitative evaluation of measurement results. Regarding the protective e ect, theinuence of the additional steel stirrup reinforcement is rather small. In contrast, the subsequentfabric reinforcement prevents the perforation of the concrete slabs. The behaviour of steel fabricand carbon fabric is compared. Although particular di erences in fracture behaviour are seen,both types of fabric reinforcement obviate total punch-through and, hence, vastly enhance theprotective performance. Comparing the stamping cones and analysing the extent of damage, theprotective capacity of di erent concrete slabs is evaluated. Within the quantitative evaluationof the measurement results, the evolution of strains and strain rates is being considered. Onthe top side of the concrete slabs, the strain is measured as tensile strain in the rst spellafter load application, turning into compressive strain later on. The evolution of strains andstrain rates indicates wave propagation. Beside the strain results, special attention is paid tothe correlation of di erent measurement techniques. The results of strain gauges, accelerometer,load cells and photogrammetry are contextualised and therefore show the change from the localmaterial behaviour to the global structure response in temporal sequence.

scholarly journals Methods of Assessing Degradation of Supercapacitors by Using Various Measurement Techniques

2019 ◽  
Vol 9 (11) ◽  
pp. 2311 ◽  
Author(s):  
Stanislaw Galla ◽  
Arkadiusz Szewczyk ◽  
Janusz Smulko ◽  
Patryk Przygocki
Keyword(s):  
Measurement Method ◽  
Measurement Techniques ◽  
Qualitative Evaluation ◽  
Measurement Methods ◽  
Qualitative Assessment ◽  
Non Invasive ◽  
Measurement Results ◽  
Qualitative Analyses ◽  
Invasive Measurement

This article presents the qualitative analyses of the construction of supercapacitor samples. The analyses are based on the suggested thermographic measurements as well as the technique of testing the inherent noise of the investigated element. The indicated assessment methods have been referred to the currently used parameters for the qualitative evaluation of supercapacitors. The approach described in this paper, which introduces additional parameters assessing worn out of supercapacitors, can be included in the so-called non-invasive measurement methods, which allow the assessment of the condition of the sample under test. This article presents the applied measurement stands and verifies of the applicability of measurement methods in relation to the currently used parameters allowing for the qualitative assessment of supercapacitors. The measurement method presented in this article was used to study prototypes of supercapacitors. The measurement results allow for more accurate characterization of the observed element. Conducted tests revealed, at the same time, that one of the proposed evaluation methods, based on measurements of inherent noise of tested supercapacitors, is a method predicting their degradation.

Hardness Testing of Metals—Contactless and Other Nondestructive Methods

2011 ◽  
pp. 91-118
Author(s):  
T. Polzin ◽  
K. Herrmann
Keyword(s):  
Hardness Testing ◽  
Testing Methods ◽  
Contact Impedance ◽  
Nondestructive Methods ◽  
Advantages And Disadvantages ◽  
Scratch Hardness ◽  
Impedance Testing ◽  
Hardness Values

Abstract This chapter discusses the characteristics, advantages, and disadvantages of nondestructive hardness testing methods for metals, including electromagnetic impulse testing, photothermal testing, scratch hardness testing, and ultrasonic contact impedance testing. It also discusses the use of ultrasound to determine the depth of hardening in a metal or alloy. The chapter reviews methods used to check and calibrate hardness testing machines and indenters and the use of hardness reference blocks for verification and calibration of test machines. It also addresses conversion of hardness values determined by one method to equivalent values for a different method.

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