China
Africa
Explore chapters and articles related to this topic
Magnetic Circuits
Published in Zeki Uğurata Kocabiyikoğlu, Electromechanical Energy Conversion, 2020
A magnetic core is a magnetic material with a high permeability used to confine and guide magnetic fields in electromechanical and magnetic devices (electromagnets, transformers, electrical machines). It is in fact analogous to conductive wires in electrical circuits. Up until now, we dealt with magnetic circuits which are excited by DC sources. We did not consider the effects of AC in magnetic circuits. Transformers and electrical machines, and many other types of electromechanical devices operate from AC source rather than DC. Therefore, we must look into the effects of AC on the magnetic cores. When magnetic core is subjected to time-varying flux densities (AC), there are two causes of power loss in the form of heat in the iron core: hysteresis losseddy current loss.
Power Quality and Equipment Protection
Published in Ramesh Bansal, Power System Protection in Smart Grid Environment, 2019
Abhishek Chauhan, J. J. Justo, T. Adefarati, Ramesh Bansal
Harmonics sources are classified into three subcategories: (a) magnetic core equipment like motors, generators and transformers; (b) arc welding and arc furnaces; and (c) power electronics and electronics equipment.
Magnetic Cores
Published in Colonel Wm. T. McLyman, Transformer and Inductor Design Handbook, 2017
There are two types of construction for magnetic cores, core type and shell type. The shell type construction is shown in Figure 3-3, and the core type construction is shown in Figure 3-4. In the shell type, shown in Figure 3-3, the core surrounds the coil. Here, the magnetic fields are around the outside of the coil. The advantage of this configuration is that it requires only one coil. In the core type of construction, shown in Figure 3-4, the coils are outside of the core. A good example of this is a toroid, where the coil is wound on the outside of a core.
The losses and temperature comparison in three-phase distribution transformer with various assembly core designs
Published in Australian Journal of Electrical and Electronics Engineering, 2018
There are many articles, standards and reports of manufactures that have been produced from researches to highlight and focus on the problems in joint design for three-phase transformer cores (Soda and Enokizono 2000; Cinar, Alboyaci, and Sengul 2014; Haidar and Al-Dabbagh 2013; Ahmad & Fauzi 2010; Isa et al. 2016). A very small variation of flux density (B) could have a significant impact on the magnetic core performance, especially in the T-joint area (Alyozbaky et al. 2018; Shilyashki et al. 2014a). In general, there are a number of techniques to reduce transformer losses and among them are three important ways to reduce losses in transformers. The first way is to use better core material; another way is to improve the cooling medium and methods; and the third one is to improve the distribution of flux by changing the geometry of the core design. This study focuses on the third solution because it is more economical than the first and second methods since the economic factor is an important aspect that transformer designers take into consideration when making a decision.
Design and Fabrication of a Low-Cost Mobile Antenna for Low VHF
Published in IETE Journal of Research, 2021
Mahmood Rafaei-Booket, Sina Hasibi-Taheri
The windings of coaxial cable on the core are relatively few to avoid parasitic effects while enough to raise the magnitude of the impedance and choke off non-TL current over the high-frequency end of the operational frequency range. In addition, the magnetic core is chosen to exhibit relatively high permeability and moderate loss characteristics. Such a balun can be employed at high-power levels over a bandwidth 30∼108 MHz. The circuit schematic of the balun is depicted in Figure 4(b). In this figure, the unbalanced terminals of balun are attached to input terminals of constructed high-impedance coaxial TL (H2 in Figure 1). Using handheld spectrum analyzer, the impedance matching of mentioned structure is measured from balanced terminals of the balun.
Inductance calculations for coils with an iron core of arbitrary axial position
Published in Electromagnetics, 2019
Yuanzhe Zhu, Baichao Chen, Yao Luo, Runhang Zhu
Based on the method in Section 2, the magnetic vector and the mutual inductor for the multi-coil system can be calculated easily. In this section, a double-coil system is taken as an example, according to which the formulas for more coils can be deduced. Figure 3 is the longitudinal section schema of a double-coil system with an iron core. The magnetic core is a cylinder of relative permeability μr, radius r0 and length 2h0, around which coil 1 (with constant current density J1, turns N1, inner and outer radii a1, a2, and length 2h1) and coil 2 (with constant current density J2, turns N2, inner and outer radii b1, b2, and length 2h2) is placed coaxially. The central cross-section of the core, the coil 1 and the coil 2 are set to plane z = 0, z = d1, and z = d2, respectively (dm> 0 and dm< 0 correspond to the planes above and beneath z = 0, respectively). The whole domain is also truncated by a perfectly conductive coaxial circular shell of radius a and infinite length. The same as Section 2, d1and d2 can be set to arbitrary values, and Figure 3 shows only one of the situations . The whole region is also divided into three parts in z-direction, so the magnetic vector A is divided into , accordingly. And A2 is split into .