Mutual Inductance / Coupled Coil 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-5

Evidence ID

t5-136

Ledger rows

1

No ledger note is attached.

Review findings

The formulas M = k*sqrt(L1*L2), Ltotal(aiding) = L1 + L2 + 2M, and Ltotal(opposing) = L1 + L2 - 2M are standard under the stated unit and polarity assumptions. Review is required because the input-unit policy, k sign/range, physical constraints, and honest user-facing limitations are not specified.

Formula and scope findings

• The algebraic formulas are standard, but the sign convention for k is unspecified. If k is a nonnegative coupling magnitude, M is normally reported as a magnitude and the aiding/opposing choice supplies the sign. If k may be signed, the interaction between the sign of M and the aiding/opposing mode must be defined explicitly.
• The specification does not state that L1 and L2 must be positive finite self-inductances, or that the coupling coefficient must satisfy 0 <= k <= 1 for passive coupled coils.

Unit assumptions

• L1 and L2 must use the same inductance unit before multiplication or addition; M and Ltotal use that same unit.
• k is dimensionless.
• sqrt(L1*L2) has the same inductance unit as L1 and L2 because both inductances use the same unit.
• The test vector with mixed H and mH explicitly converts all values to henries before calculation.
• Aiding and opposing refer to the relative winding-polarity/current-reference convention, not merely a numerical label.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The specification leaves the handling of negative inductances, signed coupling coefficients, and invalid square-root arguments unspecified. It can also produce different results if the sign of k and the aiding/opposing switch are both used to encode winding orientation.

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": {
    "L1": 0.004,
    "L1_unit": "H",
    "L2": 0.009,
    "L2_unit": "H",
    "k": 0.5,
    "connection": "series aiding"
  },
  "expected_outputs": {
    "M": 0.003,
    "M_unit": "H",
    "Ltotal": 0.019,
    "Ltotal_unit": "H"
  },
  "working": "M = k*sqrt(L1*L2) = 0.5*sqrt(0.004*0.009) = 0.5*sqrt(0.000036) = 0.5*0.006 = 0.003 H. Ltotal(aiding) = L1 + L2 + 2M = 0.004 + 0.009 + 2(0.003) = 0.004 + 0.009 + 0.006 = 0.019 H."
}

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-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json