The correct answer is: B. generator transformer of the power plant
Overfluxing protection is a type of transformer protection that is used to prevent the transformer from being overloaded. This type of protection is typically used on generator transformers, as these transformers are more susceptible to overfluxing than other types of transformers.
Overfluxing can occur when the transformer is overloaded, or when the voltage applied to the transformer is too high. When overfluxing occurs, the magnetic field in the transformer becomes too strong, which can damage the transformer.
Overfluxing protection typically works by using a current transformer to measure the current flowing through the transformer. If the current exceeds a certain threshold, the overfluxing protection will trip the transformer off, preventing it from being damaged.
Other types of transformers, such as distribution transformers and auto-transformers, are less susceptible to overfluxing. This is because these transformers are typically not operated at the same high voltages as generator transformers. Additionally, these transformers are typically not connected to the same large power systems as generator transformers. As a result, the risk of overfluxing is much lower for these types of transformers.
Therefore, overfluxing protection is typically only recommended for generator transformers.