Characteristics Of The Wye Connection

Question 1

If the magnitudes of the phase voltages of a three-phase, four wire, wye connected system are 300 volts, what are the magnitudes of the line voltages?

Answer 1

520V

Question 2

If the magnitudes of the line voltages of a three-phase, four wire, wye connected system are 400 volts, what are the magnitudes of the phase voltages?

Answer 2

231V

Question 3

In a purely resistive, balanced Y-connected system, what is the magnitude of the phase angles between the line voltages and the line currents?

Answer 3

30°

Question 4

What is the mathematical relationship between the line currents and the phase currents in a Y-connected system?

Answer 4

I(line) = I(phase)

Question 5

What is the mathematical relationship between the line voltages and the phase voltages in a Y-connected system?

Answer 5

E(line) = √3 x E(phase)

Question 6

What are four reasons for grounding the neutral in a three-phase, four wire, wye-connected system?

Answer 6

• Reduction in the magnitude of transient overvoltages
• Improved lighting protection
• Easier location and correction of ground faults
• More effective system and equipment fault protection
• Extended life of electrical insulation
• Increased personnel and equipment safety