In a 3-wire 3-phase corner-grounded delta system, how many conductors are considered grounded for protection purposes?

In a 3-wire 3-phase corner-grounded delta system, how many conductors are considered grounded for protection purposes?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (A)

In a corner-grounded delta, grounding is applied at a single corner of the delta. That means only the conductor at that grounded corner is connected to earth for protection purposes, while the other two phase conductors remain ungrounded with respect to earth. This single-point grounding provides a defined fault path to ground through that corner and helps protect the system by limiting fault conditions and guiding protection schemes. Therefore, one conductor is considered grounded for protection purposes.

In a corner-grounded delta, grounding is applied at a single corner of the delta. That means only the conductor at that grounded corner is connected to earth for protection purposes, while the other two phase conductors remain ungrounded with respect to earth. This single-point grounding provides a defined fault path to ground through that corner and helps protect the system by limiting fault conditions and guiding protection schemes. Therefore, one conductor is considered grounded for protection purposes.