Which statement is true of a balanced wye-connected source or load?
- Line voltage equals phase voltage, and line current is 1.732 times phase current
- Line voltage and line current are both 1.732 times the phase values
- Line voltage and line current are both equal to the phase values
- Line voltage is 1.732 times phase voltage, and line current equals phase current
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D. Line voltage is 1.732 times phase voltage, and line current equals phase current
In a wye, each line conductor is in series with one winding, so line and phase current are the same, while two windings 120° apart are between any two lines, making line voltage 1.732 × phase voltage. The first wrong choice describes a delta.
Reference: Wye connection: E line = 1.732 × E phase; I line = I phase
Which statement is true of a balanced delta-connected source or load?
- Line voltage equals phase voltage, and line current is 1.732 times phase current
- Line voltage is 1.732 times phase voltage, and line current equals phase current
- Line voltage and line current are both 1.732 times the phase values
- Line voltage and line current are both equal to the phase values
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A. Line voltage equals phase voltage, and line current is 1.732 times phase current
In a delta, each winding is connected directly across two lines, so line and phase voltage are the same, while each line feeds two windings 120° apart, making line current 1.732 × phase current. The first wrong choice describes a wye.
Reference: Delta connection: E line = E phase; I line = 1.732 × I phase
Each winding of a wye-connected transformer secondary produces 277 V. What is the line-to-line voltage? (Use 1.732.)
Answer in V.
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479.8 V
E line = E phase × 1.732 = 277 × 1.732 = 479.8 V (nominally 480 V).
Reference: Wye connection: E line = 1.732 × E phase