The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage side (low-voltage winding short circuited) gives readings of 4.53 kV, 321 A, and 77.5 kW. An open-circuit test is conducted from the low-voltage side and the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW. (a) Calculate the equivalent series impedance of the transformer as referred to the high-voltage terminals. (b) Calculate the equivalent series impedance of the transformer as referred to the low-voltage terminals. (c) Making appropriate approximations, draw a T equivalent circuit for the transformer. (d) Determine the efficiency of the transformer if it is supplying rated load (unity power factor) at rated voltage at its low-voltage terminals. Use the open-circuit and short-circuit measurements for the computation of the total power losses
Three-Phase Transformers
Three-segment transformers are a type of transformer used to transform voltages of electrical systems into three ranges. Two type transformers are shell-type transformer and core type transformer. In brief, it could be described because of the exquisite kinds of configurations.
Transformer
Ever since electricity has been created, people have started using it in its entirety. We see many types of Transformers in the neighborhoods. Some are smaller in size and some are very large. They are used according to their requirements. Many of us have seen the electrical transformer but they do not know what work they are engaged in.
The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage side (low-voltage winding short
circuited) gives readings of 4.53 kV, 321 A, and 77.5 kW. An open-circuit test is conducted from
the low-voltage side and the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW.
(a) Calculate the equivalent series impedance of the transformer as referred to the high-voltage
terminals.
(b) Calculate the equivalent series impedance of the transformer as referred to the low-voltage
terminals.
(c) Making appropriate approximations, draw a T equivalent circuit for the transformer.
(d) Determine the efficiency of the transformer if it is supplying rated load (unity power factor)
at rated voltage at its low-voltage terminals. Use the open-circuit and short-circuit measurements for the computation of the total power losses
- The transformer is a static device that transfers power from one circuit to another circuit without a change in frequency.
- As the transformer does not change the frequency of the system, it can be treated as a constant frequency device.
- As a transformer transfers almost the same amount of power from one circuit to another circuit, it can be treated as a constant power device.
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