Transformer transformation ratio calculation method: The induced potential in the primary winding of the transformer and the secondary winding of the transformer is proportional to the number of turns of the winding. The ratio of the input voltage of the primary winding to the output voltage of the secondary winding is equal to their turns ratio, and the ratio K is called the transformer. ratio coefficient. In the transformer, the ratio of the primary side electromotive force E1 to the secondary side E2 is called the transformation ratio of the transformer, which is represented by k, that is, k=E1/E2.
Error calculation method: when the general transformation ratio is greater than 3, the error should be less than 0.5%; when the transformation ratio is less than or equal to 3, the error should be less than 1%. Since the resistance and leakage reactance of the secondary winding of the current transformer are relatively small, generally 1~15, as long as the excitation current I0 is controlled within a suitable range (mA level), the difference between U2 and E2 will be caused by the difference between U2 and E2. The error can be ignored, and very high accuracy can be obtained by measuring the transformation ratio of the current transformer by the voltage method.
Error range: The voltage ratio error of the power transformer is: the standard is ±0.5% (or ±1/10 of the actual impedance percentage of the transformer. Take the lower of the two). Electromagnetic design should be controlled within ±0.3% at least, preferably within ±0.25%.