IEEE Std C57.163 pdf free download

IEEE Std C57.163 pdf free download.Establishing Power Transformer Capability while under Geomagnetic Disturbances.
3. Definitions
For the purposes of this document, the following terms and definitions apply. For other terms, the standard transformer terminology available in IEEE Std C57. I 2.8OTNI shall apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.4
geoelectric field: The electric field within the earth. A geomagnetic disturbance of sufficient intensity and duration changes the earth’s magnetic field thereby inducing atypical electric fields in the earth. The horizontal field near the surface of the earth, typically measured in V/km and characterized by the earth surface potentials, induces the flow of geomagnetically induced currents in power systems.
geomagnetic disturbance (GNID): A disturbance of the magnetic field of the earth caused by the ejection of plasma from the sun, due to coronal mass ejections (CME) and high speed solar wind streams, and its interaction with the earth’s magnetic field. The changing magnetic field induces voltages in the loops formed by transmission lines, groundcd-ye transformers, and the paths through earth between the transformer neutrals. The changing magnetic field induces the changes in the geoelectric field and the earth and surface potentials, resulting in the flow of geomagnetically induced current (GIC).
quasi-dc potentials: The potentials existing in geoelectric field, characterized by relatively slowly time- varying values of same polarity. Quasi-dc potentials are also commonly referred to as earth surface potentials.
T-beam: A T-shapcd beam used in shell form transformers. T-bcams arc typically made of non-magnetic steel and are located at the bottom and may also be at the top of the core, supporting the core passing through the coils and the winding assembly.
temperature gradient: In transformers, temperature gradients are most frequently used to indicate the difference between the temperature the core, winding, or other transformer components and adjacent oil temperature in kelvin (K) in response to a change in loading.
tie-plates: Structural members typically utilized in core form transformers to tie the top and bottom core yokes and clamping structures together. which maintain clamping force on the windings. They are also known as flitch plates or tic-bars.
4. Background
Geomagnetic disturbance (GMD) is a naturally occurring phenomenon of a disturbance in the earth’s magnetic field that starts with activity in the sun. Various events can occur on the surface of the sun, which can produce strong and complex magnetic fields. Sunspots, which are relatively cool areas shielded by complex magnetic fields, can give rise to solar flares and coronal mass ejections (CME). The CME can be visualized as an enormous ball of plasma that travels outward into space. When a CME is directed toward the earth, it interacts with the earth’s magnetic field. One effect is to direct charged particles toward the earth’s magnetic poles where, upon impacting the upper atmosphere, cause the phenomenon commonly known as the northern lights (aurora borealis), and southern lights (aurora australis). When a CME interacts with the magnetosphere, the movement of the geomagnetic field relative to the conductive ionosphere increases the magnitude of’ currents flowing 100 km to 150 km above the earth’s surface in the e’Ic’ctroje’ts. which are currents in the order of millions of amperes. These electrojet currents induce quasi-dc potential in series with the transmission lines, which in turn drives the flow of geomagnetically induced current (GIC) wherever there is a path for them to flow. It is the GIC that flows in the transmission lines which affects the power grid, i.e., the transmission systems and the power transformers. This flow is depicted in Figure 1.IEEE Std C57.163 pdf download.