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A 9375 kVA, 13,800 kV, 60 Hz, two pole, Y-connected synchronous generator is delivering rated current at rated voltage and unity PF. Find the armature resistance and synchronous reactance given that the filed excitation voltage is 11935.44 V and leads the terminal voltage by an angle 47.96°.
A cylindrical rotor machine is delivering active power of 0.8 p.u. and reactive power of 0.6 p.u. at a terminal voltage of 1 p.u. If the power angle is 20°, compute the excitation voltage and the machine’s synchronous reactance.
The no load current If is needed to supply the no load
losses and to magnetize the transformer core.
Z2’ is the load impedance
referred to the primary
V1: Primary voltage (supply)
I1 : Primary current.
V2: Secondary voltage (load)
I2: : Secondary current
The no load current ranges from 1% to 3% of the full load current.
Therefore, the circuit can be simplified to circuit (b).
P1 : The input power (Primary) = V1I1 cosf1
P2 : The output power (Secondary) = V2I2 cosf2
PL is the power loss in the transformer = Pcopper + Piron
A 100-kVA, 400/2000 V, single-phase transformer has the following parameters
R1 = 0.01 R2 = 0.25 ohms
X1 = 0.03 ohms X2 = 0.75 ohms
The transformer supplies a load of 90 kVA at 2000 V and 0.8 PF lagging.