The GICTransformer model is used in combination with the GICLine model for the calculation of geomagnetically induced current (GIC). The GICLine model contains the source representing the induced voltage. Transformers with a connection to ground provide a return path for the resulting current.

Power transformers are represented by their dc equivalent circuits, and only windings with connection to ground are included in the analysis. The model is a resistor network for the purposes of computing GIC in transformers. Only frequency domain models are necessary.