 This paper presents a novel approach for estimating the electrical parameters in single-phase distribution transformers. The authors used a non-linear programming, NLP, model to represent the parametric estimation problem, which was solved using the sine cosine algorithm, a combinatorial optimization technique. The results showed that the proposed NLP model accurately estimates the electrical behavior of the transformers under various load conditions. Additionally, the simulation results were compared with those obtained using the GAMS optimization package. This article was authored by Sarah Yulieth Bokenegra, Oscar Danilo Montoya, and Alexander Molina.