In a 480 V three-phase WYE system, the ratio of line-to-line voltage to line-to-neutral voltage is approximately which value?

In a 480 V three-phase WYE system, the ratio of line-to-line voltage to line-to-neutral voltage is approximately which value?

• A. 1.0
• B. 1.73
• C. 2.0
• D. 1.41

Answer: (B)

In a balanced three-phase WYE system, the line-to-line voltage is the vector difference between two phase voltages that are 120 degrees apart. The magnitude of that difference is √3 times the line-to-neutral (phase) voltage, so the ratio of line-to-line to line-to-neutral voltages is √3, about 1.73. Therefore, for a 480 V line-to-line system, the ratio remains approximately 1.73. The other numbers don’t match the geometric relationship created by the 120-degree phase angles in a WYE connection.

In a balanced three-phase WYE system, the line-to-line voltage is the vector difference between two phase voltages that are 120 degrees apart. The magnitude of that difference is √3 times the line-to-neutral (phase) voltage, so the ratio of line-to-line to line-to-neutral voltages is √3, about 1.73. Therefore, for a 480 V line-to-line system, the ratio remains approximately 1.73. The other numbers don’t match the geometric relationship created by the 120-degree phase angles in a WYE connection.