DC railways and the magnetic fields they produce—the geomagnetic context

DC railways and the magnetic fields they produce—the geomagnetic context

DC electric railways produce magnetic fields, not only from the intended traction currents, but also from unintended earth-leakage currents; these fields, particularly those from the leakage currents, are becoming an increasing problem for geomagneticians. This paper introduces the relevant properties of DC-railway tractionpower circuits, and the various ways in which earth-leakage currents are...

Ferrohydrodynamic instabilities in DC magnetic fields

Ferrofluid instabilities in DC magnetic fields for an Isopar-M based ferrofluid with saturation magnetization of about 400 Gauss. a) 1200 Gauss 5 mm diameter magnet behind small ferrofluid droplet surrounded by propanol to prevent ferrofluid wetting of 1 mm gap glass plates; Peak pattern with magnetic field perpendicular to ferrofluid layer. The peaks initiate in a hexagonal array when the magn...

Nanoparticle temperature estimation in combined ac and dc magnetic fields.

The harmonics produced by the nonlinear magnetization of superparamagnetic nanoparticles have been utilized in a number of budding medical devices. Here we expand on an earlier technique for quantitatively measuring nanoparticle temperature in a purely ac field by including the presence of a static field. The ability to quantify nanoparticle temperature by tracking changes in the 4th/2nd harmon...

Effects of DC Magnetic Bias on the Magnetic and Sound Fields of Transformer

DC bias current flowing into the neutral point of power transformer will seriously affect the normal operation of AC power system. In this paper, exciting current, harmonic component of the excitation current, magnetic flux density and noise of transformer were analyzed when the transformer is in the no-load operation state based on field-circuit coupled method. Through the calculation and anal...

Geomagnetic Fields, their Fluctuations and Health Effects