Safe even during a solar storm At a NERC conference, Siemens engineers provide proof for the high degree of safety of Siemens power transformers siemens.com/energy/transformers During a conference of the North American Electric Reliability Corporation’s (NERC) Geomagnetic Disturbance Task Force (GMDTF) in Atlanta, the Siemens Global Technology Center (GTC) offered proof of how Siemens power transformers can withstand solar storms. The engineers provided details of their studies on the impact of geomagnetically induced currents (GICs). The GMDTF, a specialist body within the nonprofit organization NERC, deals with all issues relating to GICs and their effect on the power transmission system. Due to continuously changing solar activity, the density of electrically charged particles in the earth’s ionosphere and magnetosphere fluctuates as well. These particles influence the earth’s magnetic field. In the event of a so-called solar storm, the sun emits an especially large amount of particles, which causes GICs – currents that travel from the grounded neutral of a transformer through the high-voltage windings into the transmission lines. Power transformers are a strategic element in all power transmission grids because they supply longdistance lines and complex integrated networks, so they must withstand GICs as well as low-value direct currents. At the NERC GMDTF conference, the Siemens engineers presented their findings on the GIC capability of Siemens Power Transformers and provided valid figures for the transformers’ risk of failure in the event of a solar storm. Suitable simulation models and special tests at the high-voltage lab were used to perform the studies that proved that thermal overload caused by GIC events is noncritical for a wide range of power transformers. This is due to the long time constants of the stressed components in relation to the short duration of the event. Siemens can thus provide transmission system operators with transformers that are sufficiently protected against the dangers caused by GICs. According to the simulation results, the temperature rise in the transformers is not critical. Siemens AG Energy Sector Power Transmission Division Transformators Martin Stoessl martin.stoessl@siemens.com Publisher and copyright 2014: Siemens AG Energy Sector Freyeslebenstrasse 1 91058 Erlangen, Germany Answers for energy.