What defines a delta to wye transformer?

Question

Options

• ATakes in three-phases and ground; outputs three-phases and ground
• BTakes in three-phases, neutral, and ground; outputs three-phases and ground
• CTakes in three-phases and ground; outputs three-phases, neutral, and ground
• DTakes in three-phases, neutral, and ground; outputs three-phases, neutral, and ground

• A
  4% (1)
• B
  9% (2)
• C
  83% (19)
• D
  4% (1)

Explanation

Option C is correct because a delta-to-wye transformer is named for its input and output winding configurations: the delta (input) side connects three-phase lines with no neutral, only a ground, while the wye (output) side creates a center point that serves as the neutral, producing three-phases, neutral, and ground. Option A is wrong because it describes a delta-to-delta configuration, where neither side has a neutral. Option B describes a wye-to-delta connection (neutral present on input, absent on output), which is the reverse. Option D describes a wye-to-wye configuration, where both sides carry a neutral.

Memory tip: Think of the transformer name as describing the journey from input to output. Delta has no neutral (just three corners of a triangle), and wye creates one (the center point of the Y shape). Delta-to-wye means you start without a neutral and end with one.

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