| This depicts in simplistic form the construction and operation of a large power transformer and how it's magnetic circuit operation can be disrupted by GIC flow. Under normal operation a transformer uses a magnetic circuit to transform voltage from one voltage level to another by linking magnetic flux between windings via a steel core. The presence of GIC (even though small in comparison to normal load current in the transformer) overwhelms the magnetic circuit of the transformer which will cause flux to exit the core steel where it can impinge on other structures in the transformer, such as windings, orvtank surfaces, and can lead to the creation of damaging hot spots. GIC in transformers, and the saturation this causes is the root-cause of all other power system problems that can occur due to geomagnetic storms. |
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