Which feature is included in a CSP transformer that is not present in a conventional transformer?

The correct answer highlights a distinct feature found in a CSP transformer that differentiates it from a conventional transformer. The external operating handle for opening and closing the secondary allows for more convenient and safer operation. This feature facilitates the ability to disconnect the transformer from the secondary side while still connected to the primary, which is particularly beneficial in utility operations where personnel may need to perform maintenance or troubleshooting without shutting down the entire system.

In contrast, conventional transformers typically do not have such an easily accessible mechanism, requiring other means to disrupt the secondary circuit. This added functionality in CSP transformers can enhance safety and reliability in electrical systems, especially in outdoor or remote installations.

The other choices do not accurately represent unique aspects of CSP transformers compared to conventional transformers. Lower voltage ratings, higher resistance coils, and less insulation do not specifically define the operational capabilities or safety features typical of a CSP transformer, making the first choice the most relevant and correct one.