Prueba de Relación de Transformación (TTR) a transformador de potencia 5 MVA, 115000 - 13800 Voltios

The number of turns in a transformer's windings is always the same, so the ratio of the number of turns of the primary coil to the secondary coil remains unchanged throughout the transformer's useful life. Np/Ns = Vp/Vs = Is/Ip Where: Np: Number of turns of the primary winding coil. Ns: Number of turns of the secondary winding coil. Vp: Primary winding voltage. Line-to-neutral voltage. Vs: Secondary winding voltage. Line-to-neutral voltage. Ip: Primary winding current. Is: Secondary winding current. The TTR test measures the ratio of turns of the primary coil to the secondary coil. This measurement is performed using the voltages and currents applied to the primary coil and their corresponding values ​​obtained in the secondary coil. The results of the transformer ratio test must not exceed 0.5% with respect to: Standard 1: Adjacent coils, or Standard 2: Calculated theoretical ratio. Thus, the transformer ratio test can reveal: Damage to the insulation between turns or a short circuit between turns. Open turns or lack of electrical continuity. High resistance in the transformer's internal connections (bushing, fuse, tap changer, or TAP). Through the transformer ratio test, it is also possible to determine the polarity of the equipment. Knowing the polarity of single-phase transformers is important when installing three-phase transformers in groups. Theoretical Transformation Ratio Calculation The theoretical transformation ratio serves as a reference to determine whether the measured transformation ratio is within the allowable variation, which is less than 0.5%. The theoretical transformation ratio in single-phase transformers is calculated by dividing the line-to-neutral voltage of the primary coil by the line-to-neutral voltage of the secondary coil. In three-phase transformers, calculating the theoretical ratio is not as straightforward because not all transformers have access to the neutral of the primary and/or secondary windings.