Problem 2 A 23-kVA, 2300/230-V, 60-Hz, step down transformer has the following resistance and leakage- reactance values: R1=40, R2=0.04N, X1=12N, and X2=0.120. The transformer is operating at 75% of its rated load. If the power factor of the load is 0.866 leading. Determine the efficiency of the transformer.

A method for determining the equivalent network of a nonideal transformer consists of two tests: the open-circuit test and the short-circuit test. The open-circuit test, shown in figure (a), is usually done by applying rated voltage to the primary side of the transformer while leaving the secondary side open. The current into the primary side is measured, as is the power dissipated. The short-circuit test, shown in figure (b), is performed by increasing the primary voltage until rated current is going into the transformer while the secondary side is short-circuited. The current into the transformer, the applied voltage, and the power dissipated are measured. The equivalent circuit of a transformer is shown in figure (c), where rw and Lw represent the winding resistance and inductance, respectively, and rc and Lc represent the losses in the core of the transformer and the inductance of the core. The ideal transformer is also included in the model. With the open-circuit test, we may…

E 16. If a 0.6 accuracy class current transformer has a phase angle ß of + 10' at 100% rated current, the ratio correction factor is A. 1.005. B. 0.989. C. 1.007. D. 0.995. bru

A 20 kVA, 2000/200-V, 50-Hz transformer has a high voltage winding resistance of 0.2 2 and a leakage reactance of 0.242. The low voltage winding resistance is 0.05 2 and the leakage reactance is 0.02 2. Find the equivalent winding resistance, reactance and impedance referred to the (i) high voltage side and (ii) the low-voltage side. (Draw the related equivalent circuits)