CIM ApparentPower vs QUDT ComplexPower

[VladimirAlexiev]

cim:ApparentPower  a qudt:QuantityKind ;
  qudt:applicableUnit cim:UnitSymbol.VA;
  skos:broader quantitykind:ComplexPower. # ApparentPower is a sub-concept of ComplexPower
cim:UnitSymbol.VA skos:exactMatch unit:V-A

But is it true?

• In QUDT, unit:V-A applies to quantitykind:ComplexPower
• If you google "ApparentPower vs ComplexPower", you can find electrical textbooks that define them as follows:
  • ComplexPower is the vector sum of real power and reactive power.
  • ApparentPower is the magnitude of complex power.
• Despite the name ComplexPower: units apply to magnitudes, not to vectors
• QUDT defines ComplexPower as "under sinusoidal conditions, is the product of the phasor U representing the voltage between the terminals of a linear two-terminal element or two-terminal circuit and the complex conjugate of the phasor I representing the electric current in the element or circuit"
• CIM defines ApparentPower as "Product of the RMS value of the voltage and the RMS value of the current."
• To me (not being an electrical engineer), these definitions are "close enough"

Questions:

• is it skos:broader or maybe even skos:exactMatch
• Do we need to submit ApparentPower as a new QuantityKind to QUDT?

[griddigit-ci]

Looks good, but we need to dive in definitions. The complex power can be expressed as P+jQ where P is the active and Q reactive power. the S - apparent power we exchange is the module of this

the complex power can be expressed as sqrt(P^2+Q^2)<ctan(Q/P), where the < is the angle part. I think we do not want the angle but just the module

We need to see an example of ComplexPower in QUDT maybe that will get clearer

[VladimirAlexiev]

QUDT refers to https://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-11-39, and has these details (in addition to those above):

  qudt:latexDefinition "$\\underline{S} = \\underline{U}\\underline{I^*}$, where $\\underline{U}$ is voltage phasor and $\\underline{I^*}$ is the complex conjugate of the current phasor."^^qudt:LatexString ;
  qudt:latexSymbol "$\\underline{S}$"^^qudt:LatexString ;

So it also calls it S. Even though it talks of complex numbers, the unit V-A applies to magnitudes, not to vectors. So it has to be the same thing.

[VladimirAlexiev]

Answered in https://github.com/qudt/qudt-public-repo/issues/970: QUDT has ApparentPower (I overlooked it). Fixed that section.

[steveraysteveray]

By the way, @VladimirAlexiev, this topic happens to be what I used in explaining how we compute qudt:applicableUnit triples. See https://github.com/qudt/qudt-public-repo/wiki/Advanced-User-Guide#4-computing-applicable-units-for-a-quantitykind