Transformers

[a61iacla]

Can anyone define the terms Equivalent Resistance and Equivalent Reactance within a transformer.
Also can anyone express for Equivalent resistance, referred to the primary, of a single-phase transformer in which the actual resistance of the primary and secondary windings are R1 and R2 ohms respectively, and the number of terms on these windings N1 and N2 respectively.

This infomation on the above would be much appreciated,and would help in the completing of my HNC (UK).

 

[230842]

Equivalent resistance or reactance (impedance in general) is the resistance value that primary "feels" when a resistor is connected on the secondary, or is the quotient of voltage and current of primary for a connected secondary resistor.

Equivalent impedances can eassily be obtained by multiplying its real value by de number of turns ratio to the square.
Let's say that primary and secondary winding impedances are Z1 (R1, X1) and Z2 (R2, X2) respectively and their number of turns are N1 and N2 respectively. The equivalent impedance referred to primary side is:
Zp = Z1 + Z2*(N1/N2)^2
And referred to the secondary side:
Zs = Z1*(N2/N1)^2 + Z2

Both equivalent impedances are rated by the number of turns rate to the square:
Zp/Zs = (N1/N2)^2 Julian