What distinguishes a two bushing transformer from a CSP transformer?

The distinction between a two bushing transformer and a CSP (Continuous Service Power) transformer lies primarily in the design features related to internal protections. A two bushing transformer is characterized by its relatively simple design, which typically does not incorporate internal fusing. This absence of internal fusing is significant because it affects how the transformer is protected against faults and overloads. In contrast, CSP transformers often come with built-in fusing or other protection mechanisms that help manage fault conditions more effectively.

This key difference in internal fusing reflects on the operational reliability and safety of the transformers. By not having internal fusing, a two bushing transformer may rely more heavily on external protective devices to manage fault scenarios, while CSP transformers have more integrated solutions for such situations.

The other aspects mentioned, such as the number of windings, size of the core, and output voltage, can vary among different designs but are not as definitive in differentiating these specific transformer types as the feature of internal fusing. Thus, the lack of internal fusing is what clearly distinguishes a two bushing transformer from a CSP transformer.