A 40KVA 6000V/240V power transformer has the following parameters.
Resistance of primary winding = 10Ω
Resistance of secondary winding = 0.017Ω
Reactance referred to primary side = 35Ω
Evaluate
(a) the primary voltage and power factor required to circulate full load current when the secondary is short-circuited;
(b) the percentage voltage regulation for load of 33kVA at 0.65 leading power factor.
a) a: 6000/240 = 25
Reap: 10 + 25(0.017)
= 20.625Ω
Xea p: Xp: 35Ω
S: Ip Yp
= Ip(6000)
Ip= 6.67A
Ep: Ip(Zea)
= 6.67(40625)
= 270.83V
P.f= cosd
= cos59.45
= 0.508 (lagging)
b) VR= |Ep|-|Np|
|Np|
Ep= Ip(Zea)
((a)270.83V, 0.508, (b) -1.15%)