This article shows a transmission line model developed directly in the phase domain. The proposed model is based on the relationships between the phase currents and voltages at both the sending and receiving ends of a single-phase line. These relationships, established using an ABCD matrix, were extended to multi-phase lines. The proposed model was validated by using it to represent a transmission line during short-and open-circuit tests. The results obtained with the proposed model were compared with results obtained with a classical model based on modal decomposition. These comparisons show that proposed model was correctly developed. © 2013 Taylor and Francis Group, LLC.411111001113Hofmann, L., Series expansions for line series impedances considering different specific resistances, magnetic permeabilities, and dielectric permittivities of conductors, air, and ground (2003) IEEE Trans. Power Delivery, 18 (2), pp. 564-570. , AprilBudner, A., Introduction of frequency-dependent line parameters into an electromagnetic transients program (1970) IEEE Trans. Power Apparat. Syst., 89 (1), pp. 88-97. , JanuaryWedepohl, L.M., Nguyen, H.V., Frequency-dependent transformation matrices for untransposed transmission lines using newton-raphson method (1996) IEEE Transactions on Power Systems, 11 (3), pp. 1538-1546Chen, C.T., (1984) Linear System Theory and Design, , New York: CBS College Publishing. Chap. 2Kurokawa, S., Daltin, R.S., Prado, A.J., Pissolato, J., An alternative modal representation of a symmetrical nontransposed three-phase transmission line (2007) IEEE Transactions on Power Systems, 22 (1), pp. 500-501. , DOI 10.1109/TPWRS.2006.889117Marti, J.R., Accurate modeling of frequency-dependent transmission lines in electromagnetic transient simulations (1982) IEEE Trans. Power Apparat. Syst., PAS-101 (1), pp. 147-155. , JanuaryGustavsen, B., Semlyen, A., Simulation of transmission line transients using vector fitting and modal decomposition (1998) IEEE Trans. Power Delivery, 13 (2), pp. 605-614. , AprilGustavsen, B., Modal domain based modeling of parallel transmission lines with emphasis on accurate representation of mutual coupling effects (2012) IEEE Trans. Power Delivery, 27 (4), pp. 2159-2167. , October