In a 480 V three-phase WYE system, what is the line-to-neutral voltage?

In a 480 V three-phase WYE system, what is the line-to-neutral voltage?

• A. 277 V
• B. 480 V
• C. 347 V
• D. 208 V

Answer: (A)

In a three-phase WYE system, the line-to-line (phase-to-phase) voltage is √3 times the line-to-neutral (phase) voltage. So with a line-to-line value of 480 V, the line-to-neutral voltage is 480 divided by √3, which is about 277 V. This is why 277 V is the correct line-to-neutral voltage for a 480 V WYE system. The other numbers don’t fit this relationship: 480 V is the line-to-line value, not the line-to-neutral. 347 V would come from a 600 V line-to-line system (600/√3 ≈ 347 V). 208 V corresponds to a different common system (such as 120/208 V), where the line-to-neutral is 120 V and the line-to-line is 208 V.

In a three-phase WYE system, the line-to-line (phase-to-phase) voltage is √3 times the line-to-neutral (phase) voltage. So with a line-to-line value of 480 V, the line-to-neutral voltage is 480 divided by √3, which is about 277 V. This is why 277 V is the correct line-to-neutral voltage for a 480 V WYE system.

The other numbers don’t fit this relationship: 480 V is the line-to-line value, not the line-to-neutral. 347 V would come from a 600 V line-to-line system (600/√3 ≈ 347 V). 208 V corresponds to a different common system (such as 120/208 V), where the line-to-neutral is 120 V and the line-to-line is 208 V.