Power Transmission Lines
Purpose:
The purpose of these experiments[1] was to measure the exciting current and determine the core losses in a transformer using the open circuit test (experiment # 2) and to determine the equivalent circuit of a transformer by using the short circuit method (experiment # 3).
Introduction:
In order to determine the equivalent circuit parameters of a transformer two simple tests are used, namely the open-circuit test
(experiment #2) and the short-circuit test (experiment #3). By performing these simple tests the values for the equivalent circuit of a transformer (see Figures 1 &2). If it is desired to find the parameter of the exact equivalent circuit (see Figure 3) it is customary to assume R1=a2R2 and
X1=a2X2. By making this assumption we can decompose the values of the equivalence resistance and reactance into the primary (winding 1 or high voltage side) and secondary (winding 2 or low-voltage side) components.
Figure 1 – Approximate Equivalent Circuit of a Transformer
Figure 2 – Approximate Equivalent Circuit of a Transformer
Figure 3 – Exact equivalent circuit of a Transformer in phasor form
Experiments # 2 & 3
[1]
During the open-circuit test, the transformer rated voltage is applied to the low voltage side of the transformer with the high-voltage side as shown in Figure 6. Since the high-voltage side is open, the input current Ioc is equal to the exciting current through the shunt excitation branch as shown in the equivalent circuit in Figure 4. Because this current is very small, about 5% of rated value, the voltage drop across the low-voltage winding and the winding copper losses are neglected. The magnitude of the admittance of the shunt excitation branch of the equivalent circuit referred to the low voltage side is calculated by using the following formulas:
1) admittance
|Yo2| = Ioc/Voc
2) phase angle of the admit
-θo2 = - cos-1(Poc/VocIoc)
3) complex admittance
Yo2 = |Yo2|/-θo2 = Gc2 –
The purpose of these experiments[1] was to measure the exciting current and determine the core losses in a transformer using the open circuit test (experiment # 2) and to determine the equivalent circuit of a transformer by using the short circuit method (experiment # 3).
Introduction:
In order to determine the equivalent circuit parameters of a transformer two simple tests are used, namely the open-circuit test
(experiment #2) and the short-circuit test (experiment #3). By performing these simple tests the values for the equivalent circuit of a transformer (see Figures 1 &2). If it is desired to find the parameter of the exact equivalent circuit (see Figure 3) it is customary to assume R1=a2R2 and
X1=a2X2. By making this assumption we can decompose the values of the equivalence resistance and reactance into the primary (winding 1 or high voltage side) and secondary (winding 2 or low-voltage side) components.
Figure 1 – Approximate Equivalent Circuit of a Transformer
Figure 2 – Approximate Equivalent Circuit of a Transformer
Figure 3 – Exact equivalent circuit of a Transformer in phasor form
Experiments # 2 & 3
[1]
During the open-circuit test, the transformer rated voltage is applied to the low voltage side of the transformer with the high-voltage side as shown in Figure 6. Since the high-voltage side is open, the input current Ioc is equal to the exciting current through the shunt excitation branch as shown in the equivalent circuit in Figure 4. Because this current is very small, about 5% of rated value, the voltage drop across the low-voltage winding and the winding copper losses are neglected. The magnitude of the admittance of the shunt excitation branch of the equivalent circuit referred to the low voltage side is calculated by using the following formulas:
1) admittance
|Yo2| = Ioc/Voc
2) phase angle of the admit
-θo2 = - cos-1(Poc/VocIoc)
3) complex admittance
Yo2 = |Yo2|/-θo2 = Gc2 –