I have a three phase three winding transformer like that shown in Fig 1 (attached)
I have got the following data for this transformer
Leakage reactance for winding (#1+#2)
Leakage reactance for winding(#1+#3)
Leakage reactance for winding(#2+#3)
And I have the turns ratio of course.
This is very simple model with only the leakage reactances considered and no magnetising path or coupling between phases modelled.
My question is I want to know how I could get the current - Voltage relationships between the three coils for this transformer (For each phase).
With two windings in the secondary and the leakage reactances given as above i am a bit confused how to come up with the relationships and draw the equivalent circuit.
Any assistance would be much appreciated.
Attached you will find the equivalent circuit. The voltages are approximately related by:
V1/N1 = V2/N2 and V1/N1 = V3/Nt
More accurate relations can be derived considering the actual equivalent circuit parameters.
Consider the Z1, Z2 and Z3 are the impedances of the three winding transformers. These impedances are considered as the base for performing the short circuit test. For the short-circuit test, the two winding is short circuit and the third winding is kept open.
The open circuit test is carried out to determine the core loss, magnetising impedance and turn ratios. In open circuit test the voltmeter, ammeter and wattmeter are connected in low voltage winding. The secondary side is kept open, and the voltmeter is connected.
Since the high voltage side is opened the current drawn by the primary is no load current and I0 measured by the ammeter A. The magnetising impedance may be found by exciting current winding 1 with both winding 2 and 3 be open circuit