Transformer Turns Ratio & Sizing Calculator mechanism

Model scope

The core ideal-transformer relationships are standard, but the instrument fails its stated feature set because % regulation has no defined formula and required VA sizing is conflated with load apparent power. The honest-label text appropriately discloses ignored losses, but the UI must explicitly identify all results as ideal-model values and must not imply a certified or thermally sufficient transformer rating.

• The turns-ratio identity a=N1/N2=V1/V2=I2/I1 is correct only for an ideal transformer with RMS AC quantities, negligible losses, and consistent primary/secondary labeling.
• No formula is provided for the claimed % regulation estimate. In the stated ideal model, regulation would conventionally be 0%, but that assumption and the regulation definition are not specified; a real-transformer regulation estimate requires additional parameters.
• VA=V·I correctly computes apparent power, but it does not by itself determine a required transformer VA rating. A sizing rating normally requires a design margin, duty cycle, temperature/thermal constraints, and possibly inrush considerations.
• The input alternatives are underspecified: the spec does not state how to derive missing V2 from N1,N2 and V1, or missing current from a supplied VA, nor how conflicting simultaneous inputs are handled.

Units and conventions

• V1 and V2 are RMS AC voltages in volts, measured on consistently labeled primary and secondary windings.
• I1 and I2 are RMS currents in amperes; N1 and N2 are winding turns and therefore dimensionless counts.
• The transformer operates at the same frequency on both windings and is modeled as ideal, so V1/V2=N1/N2 and I2/I1=N1/N2.
• VA is apparent power in volt-amperes, calculated using RMS voltage multiplied by RMS current, with power factor excluded.
• A supplied load current is treated as secondary load current I2; a supplied VA value is treated as secondary apparent load power unless explicitly stated otherwise.
• A current ratio or voltage ratio must not use a zero denominator, and all voltage, current, and turns inputs must be positive for normal transformer operation.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "V1_V": 120,
    "V2_V": 12,
    "load_current_A": 5
  },
  "expected_outputs": {
    "ratio_a": 10,
    "secondary_voltage_V": 12,
    "secondary_current_A": 5,
    "primary_current_A": 0.5,
    "required_VA": 60
  },
  "working": "a=V1/V2=120/12=10. I1=I2/a=5/10=0.5 A. VA=V2·I2=12·5=60 VA."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The zero-turn secondary input produces an undefined ratio and must be rejected. Signed-voltage inputs also expose an unresolved polarity/sign convention: signed and magnitude interpretations produce different ratio and current signs.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json