A single phase transformer rated 1.2kV/120V, 7.2kVA has primary-referred parameters
Req= r1+ a r2= 1Ω and Xeq = x1+ a2 x2 = 4Ω when neglecting exciting current. At rated voltage its core loss may be assumed to be 40W for all the load curent.
(a) Determine the efficiency and regulation of the transformer when it delivers 7.2 kVA at
V2=120V and power factor of 0.8 lagging.
(b)Repeat (a) at power factor of 0.8 leading.
(c)Determine maximum efficiency of the transformer at rated voltage and 0.8 power factor, and
determine the kVA load level at which the maximum efficiency occurs.