Public evidence

electrical.watts_to_va

Machine-checked verification for calculation version 1.3.1 · tier engine_tested

Open calculator API Capability Download JSON CVP Manifest MCP Review policy

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· Sinusoidal PF; optional factor scales result · Protocol · Schema · Production report

Declared partition coverage: PASS · 3/3 declared partitions (w-va, va-w, invalid-domain)
Versions: Calculation 1.3.1 · CVP protocol 1.0.0-proposed
CVP identity: 5/5 property · digest c927268aa5e1

Verification

Legacy regression suite: 16/16 calculation tests · Production surface contract 4/4

Three distinct suites: educational examples on the calculator page, this legacy regression count (16/16 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

This calculator CURRENT · Public schema 1.3.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Calculation version 1.3.1. CVP 1.0.0-proposed. 2/2 golden · 2/2 CVP boundary · 2/2 invalid · 5/5 property · 1/1 cross-interface · 1/1 CVP contract. digest c927268aa5e1.

Golden (oracle-backed) 2 / 2
CVP boundary 2 / 2
Invalid input 2 / 2
Property 5 / 5
Cross-interface 1 / 1
CVP contract 1 / 1
Interfaces PASS · UI (SSR) / REST / MCP
Interface claim ui-ssr is query-result HTML, not a live browser session.
Assurance Engineering

release artifacts aligned PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS

Fingerprint sha256:bb77c72a7e6a3706c4f972d201d7105ddf1bd94157d14ddaacba60c8adcc7063

Input schema sha256:7b6c952cbb6fc0459a203690db986cfdc7c776a850c8892addf86e30f1adcdb6 · Output schema sha256:9f90e949875b4de22527a32e88ea7a9bef5d533c1a2aa6bc4c406a0d08fa0089 · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: watts-to-va
Engine: watts-va
Engine build: 2026-09-10
Evidence core: 2026-09-10T22:48:17.762Z
Rendered: 2026-09-16T22:03:43.707Z
Last reviewed: —

Assumptions

PF in (0, 1] — required (not optional)
No voltage/phase required once P (or S) and PF are known

Limitations

Not for voltage/current→VA (use amps-to-va)
PF must be in (0, 1] — PF=0 → POWER_FACTOR_OUT_OF_RANGE (not a soft zero)
Roadmap model op: real_from_S_pf / apparent_from_P_pf

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

IEC 60050 — International Electrotechnical Vocabulary — Apparent power (IEV 131-11-41)
Supports: S (VA) is apparent power; distinct from active power P (W); unit volt-ampere (VA)
IEC 60050 — International Electrotechnical Vocabulary — Power factor (IEV 131-11-46)
Supports: λ = |P| / S; S = P / λ and P = S × λ
IEEE Std 1459-2025 — Apparent power from real power and power factor · 2025-05-16 · errata checked
Supports: S(VA) = P(W) / PF; P = S × PF
BIPM SI Brochure (9th edition, version 4.01) — SI units for watt and volt-ampere · 2026-06 · DOI
Supports: W and VA unit relationships
NIST Guide to the SI (SP 811) — Watt and volt-ampere
Supports: SI power unit relationships

Legacy published checks

Golden and boundary cases from the legacy Evidence JSON. CVP property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the Manifest — including SKIP when a suite has no vectors.

ID	Kind	Status	Detail
`1000W-0.8`	golden	pass	Expected 1250 · Actual 1250
`500W-0.67`	golden	pass	Expected 746.2687 · Actual 746.2686567164179
`1000W-1`	golden	pass	Expected 1000 · Actual 1000
`va-to-w`	golden	pass	Expected 1000 · Actual 1000
`linear-2x-w`	golden	pass	Expected 2500 · Actual 2500
`inverse-half-pf`	golden	pass	Expected 2500 · Actual 2500
`hard-zero-pf`	boundary	pass	Expected POWER_FACTOR_OUT_OF_RANGE · Actual POWER_FACTOR_OUT_OF_RANGE
`soft-zero-w`	golden	pass	Expected 0 · Actual 0
`5000W-0.9`	golden	pass	Expected 5555.5556 · Actual 5555.555555555556
`2500VA-to-w`	golden	pass	Expected 2000 · Actual 2000
`missing-pf`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`property-w-va`	property	pass	1000 W / 0.8 → 1250 VA
`property-linear-P`	property	pass	2P → 2S
`property-inverse-pf`	property	pass	½PF → 2S
`property-roundtrip`	property	pass	VA→W recovers P
`property-named-fields`	property	pass	P/power_factor ≡ a/b