Transformer Turns Ratio & Sizing Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Electrical & Electronics Engineering — Circuits, Power Systems, Electronics Lab

Tranche

tranche-4

Evidence ID

t4-054

Ledger rows

1

No ledger note is attached.

Review findings

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.

Formula and scope findings

• 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.

Unit assumptions

• 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.

Boundary hardening

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.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "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."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

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