A 4000 V/2000 V, 60 Hz single phase transformer has a total impedance ...
Concept:
Consider a two winding single phase transformer as shown below,
N1 = primary winding turns
N2 = secondary winding turns
V1 = primary winding voltage
V2 = secondary winding voltage
I1 = current through the primary winding
I2 = current through the secondary winding
Transformation ratio: It is defined as the ratio of the secondary voltage to the primary voltage. It is denoted by k.
K=N2N1=V2V1=I1I2" tabindex="0">K=N2N1=V2V1=I1I----- (1)Transformer equivalent circuit with respect to secondary can be represented a show below
Where R02 = Effective resistance referred to the secondary side of the transformer.
R02 = R2 + R1' ........ (2)
R1' = Primary winding resistance as referred to the secondary side.
R1' = R1 × k2 ......... (3)
Similarly, the effective resistance referred to the primary side of the transformer is given as,
R01 = R1 + R2'
R2' = Secondary winding resistance as referred to the primary side.
R2' = R2 / k2
Calculation:
Given total impedance of the transformer referred to primary R01 = 60 Ω
Transformation ratio k = V2 / V1 = 2000 / 4000 = 0.5
Total impedance of the transformer referred to secondary when primary and secondary windings have negligible resistances is given as
R02 = R01 × k2
= 60 / 4 = 15 Ω
Apply the voltage division rule to find voltage across the load
VL = 2000 × 20 / (15 + 20)
VL = 1143 V