Three-Phase Power Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-with-binding-errata

Evidence ID

t4-042

Effect

Computation or source lookup only

Input and validation requirements

• Division by √3 is safe, but any inverse calculation such as current=power/(voltage·PF) requires explicit zero-voltage and zero-PF handling.
• PF values outside [0,1] are invalid if PF is an unsigned magnitude; the implementation must reject them or define signed-PF semantics.
• PF=0 makes calculations that divide by PF undefined, even though direct P, Q, and S calculations remain valid.
• Q sign is indeterminate unless leading or lagging behavior is provided; silently assuming lagging would produce misleading results.
• Unbalanced loads, non-sinusoidal waveforms, phase-to-neutral versus line-to-line voltage confusion, and peak-versus-RMS inputs can produce incorrect results.
• Connection type must be validated before applying wye/delta voltage and current conversions.

Required corrections

[
  {
    "vector": 3,
    "field": "S_VA, Q_var",
    "wrong": 4782.860228,
    "correct": 4780.4602,
    "cause": "used √3≈1.7329 in S (her own Vph used the correct 1.73205)"
  },
  {
    "vector": 4,
    "field": "S_VA, Q_var",
    "wrong": "S 3600, Q 2160",
    "correct": "S 1800, Q 1080",
    "cause": "S doubled; contradicts her own correct P=1440 at PF 0.8"
  }
]

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "connection": "wye",
    "VL_V": 400,
    "IL_A": 10,
    "PF": 0.8,
    "reactive_behavior": "lagging"
  },
  "expected_outputs": {
    "VPh_V": 230.940108,
    "IPh_A": 10,
    "P_W": 5542.562585,
    "Q_var": 4156.921939,
    "S_VA": 6928.20323
  },
  "working": "VPh=VL/√3=400/1.732050807=230.940108 V. For wye, IPh=IL=10 A. P=√3·VL·IL·PF=1.732050807·400·10·0.8=5542.562585 W. S=√3·VL·IL=1.732050807·400·10=6928.20323 VA. |sinθ|=√(1−0.8²)=√0.36=0.6; lagging gives positive Q, so Q=S·0.6=6928.20323·0.6=4156.921939 var."
}

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
• tranche errata record