Interturn short circuits represent a common yet insidious winding insulation failure in oil-immersed transformers during operation. Due to the typically small number of shorted turns, such faults may prove difficult to detect early through conventional protection methods. However, once an oil gap breakdown occurs at the shorted location, localized arcing can easily develop, resulting in significant instantaneous energy release. Under specified assumptions, this paper derives expressions for the induced voltage and equivalent impedance of short-circuited turns based on the equivalent circuit of a typical three-winding transformer. Consequently, formulas for calculating arc current and arc energy are obtained. Using typical transformer parameters, illustrative analyses of arc energy are conducted for different short-circuited turn counts and arc duration conditions. To support theoretical derivation, the paper qualitatively verifies arc length, voltage, and gas generation phenomena through inter-electrode gap discharge experiments in air and oil discharge observations. Results indicate that within the adopted model and parameter range, arc energy increases with both short-circuit turn ratio and arc duration, while gas bubble volume in oil exhibits consistent variation trends with discharge energy. The theoretical derivations and experimental verifications presented herein provide insights into understanding the localized energy release caused by inter-turn short circuits.