Two transformers are connected in parallel. These transformers do not ...
Introduction:
When two transformers are connected in parallel, they are expected to share the load in proportion to their kVA ratings. However, if the transformers have unequal percentage impedance, the loading may not be proportional to their kVA ratings. This can lead to various issues and inefficiencies in the system.
Explanation:
When transformers are connected in parallel, their voltage ratios and turns ratios should be the same to ensure proper sharing of the load. However, the percentage impedance of the transformers may vary due to differences in their design and construction. The percentage impedance is a measure of the internal impedance of the transformer and affects the voltage regulation and fault current capability.
Effect on loading:
When transformers with different percentage impedances are connected in parallel, the one with lower impedance will tend to draw more current and share a larger portion of the load. This is because a transformer with lower impedance will have a lower voltage drop and therefore a higher output voltage, causing it to draw more current. On the other hand, a transformer with higher impedance will have a higher voltage drop and a lower output voltage, resulting in it drawing less current and sharing a smaller portion of the load.
Consequences of unequal loading:
The unequal loading of transformers can lead to various issues, including:
1. Overloading: The transformer with lower impedance may be overloaded while the one with higher impedance operates at a lower load. This can result in overheating and reduced lifespan of the overloaded transformer.
2. Inefficiency: When transformers are not loaded in proportion to their kVA ratings, the overall system efficiency decreases. The transformers may operate at different load factors, resulting in suboptimal performance and increased energy losses.
3. Voltage regulation: The voltage regulation of the system may be affected due to unequal loading. The transformer with lower impedance will have better voltage regulation, while the one with higher impedance may experience larger voltage drops under load.
Conclusion:
In conclusion, when transformers with unequal percentage impedances are connected in parallel, the loading may not be proportional to their kVA ratings. This can lead to problems such as overloading, decreased efficiency, and voltage regulation issues. Therefore, it is important to consider the percentage impedance when connecting transformers in parallel to ensure proper load sharing and optimal system performance.
Two transformers are connected in parallel. These transformers do not ...
- When two transformers with different percentage impedances are connected in parallel, their individual impedance values determine how the load is shared between them. Transformers with lower impedance will draw more current than those with higher impedance for the same applied voltage and load conditions.
- This results in an unequal distribution of load between the transformers, and their loading is not in proportion to their kVA ratings. The transformer with lower impedance will carry a higher percentage of the total load, while the one with higher impedance will carry a relatively smaller percentage of the total load.
- This unequal loading can lead to several issues, such as one transformer being overloaded, decreased efficiency, and potential overheating problems in the overloaded transformer. Therefore, it is generally preferred to connect transformers with similar impedance values in parallel to ensure a more balanced and efficient operation.
- Hence, the correct answer is D: loading of the transformers not in proportion to their kVA ratings.
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