UnitSymbol

Class Description

The derived units defined for usage in the CIM. In some cases, the derived unit is equal to an SI unit. Whenever possible, the standard derived symbol is used instead of the formula for the derived unit. For example, the unit symbol Farad is defined as “F” instead of “CPerV”. In cases where a standard symbol does not exist for a derived unit, the formula for the unit is used as the unit symbol. For example, density does not have a standard symbol and so it is represented as “kgPerm3”. With the exception of the “kg”, which is an SI unit, the unit symbols do not contain multipliers and therefore represent the base derived unit to which a multiplier can be applied as a whole.
Every unit symbol is treated as an unparseable text as if it were a single-letter symbol. The meaning of each unit symbol is defined by the accompanying descriptive text and not by the text contents of the unit symbol.
To allow the widest possible range of serializations without requiring special character handling, several substitutions are made which deviate from the format described in IEC 80000-1. The division symbol “/” is replaced by the letters “Per”. Exponents are written in plain text after the unit as “m3” instead of being formatted as “m” with a superscript of 3 or introducing a symbol as in “m^3”. The degree symbol “°” is replaced with the letters “deg”. Any clarification of the meaning for a substitution is included in the description for the unit symbol.
Non-SI units are included in list of unit symbols to allow sources of data to be correctly labelled with their non-SI units (for example, a GPS sensor that is reporting numbers that represent feet instead of meters). This allows software to use the unit symbol information correctly convert and scale the raw data of those sources into SI-based units.
The integer values are used for harmonization with IEC 61850.

Attributes

Name Type Description
deg Plane angle in degrees.
rad Plane angle in radians (m/m).
sr Solid angle in steradians (m2/m2).
Gy Absorbed dose in grays (J/kg).
Bq Radioactivity in becquerels (1/s).
degC Relative temperature in degrees Celsius.
In the SI unit system the symbol is °C. Electric charge is measured in coulomb that has the unit symbol C. To distinguish degree Celsius from coulomb the symbol used in the UML is degC. The reason for not using °C is that the special character ° is difficult to manage in software.
Sv Dose equivalent in sieverts (J/kg).
F Electric capacitance in farads (C/V).
C Electric charge in coulombs (A·s).
S Conductance in siemens.
H Electric inductance in henrys (Wb/A).
ohm Electric resistance in ohms (V/A).
J Energy in joules (N·m = C·V = W·s).
N Force in newtons (kg·m/s²).
Hz Frequency in hertz (1/s).
lx Illuminance in lux (lm/m²).
lm Luminous flux in lumens (cd·sr).
Wb Magnetic flux in webers (V·s).
T Magnetic flux density in teslas (Wb/m2).
Pa Pressure in pascals (N/m²). Note: the absolute or relative measurement of pressure is implied with this entry. See below for more explicit forms.
m2 Area in square metres (m²).
m3 Volume in cubic metres (m³).
mPers Velocity in metres per second (m/s).
mPers2 Acceleration in metres per second squared (m/s²).
m3Pers Volumetric flow rate in cubic metres per second (m³/s).
mPerm3 Fuel efficiency in metres per cubic metres (m/m³).
kgm Moment of mass in kilogram metres (kg·m) (first moment of mass). Note: multiplier “k” is included in this unit symbol for compatibility with IEC 61850-7-3.
kgPerm3 Density in kilogram/cubic metres (kg/m³). Note: multiplier “k” is included in this unit symbol for compatibility with IEC 61850-7-3.
m2Pers Viscosity in square metres / second (m²/s).
WPermK Thermal conductivity in watt/metres kelvin.
JPerK Heat capacity in joules/kelvin.
ppm Concentration in parts per million.
rotPers Rotations per second (1/s). See also Hz (1/s).
radPers Angular velocity in radians per second (rad/s).
WPerm2 Heat flux density, irradiance, watts per square metre.
JPerm2 Insulation energy density, joules per square metre or watt second per square metre.
SPerm Conductance per length (F/m).
KPers Temperature change rate in kelvins per second.
PaPers Pressure change rate in pascals per second.
JPerkgK Specific heat capacity, specific entropy, joules per kilogram Kelvin.
cosPhi Power factor, dimensionless.
Note 1: This definition of power factor only holds for balanced systems. See the alternative definition under code 153.
Note 2 : Beware of differing sign conventions in use between the IEC and EEI. It is assumed that the data consumer understands the type of meter in use and the sign convention in use by the utility.
Vs Volt seconds (Ws/A).
V2 Volt squared (W²/A²).
As Ampere seconds (A·s).
A2 Amperes squared (A²).
A2s Ampere squared time in square amperes (A²s).
VPerHz Magnetic flux in volt per hertz.
HzPers Rate of change of frequency in hertz per second.
character Number of characters.
charPers Data rate (baud) in characters per second.
kgm2 Moment of mass in kilogram square metres (kg·m²) (Second moment of mass, commonly called the moment of inertia). Note: multiplier “k” is included in this unit symbol for compatibility with IEC 61850-7-3.
dB Sound pressure level in decibels. Note: multiplier “d” is included in this unit symbol for compatibility with IEC 61850-7-3.
WPers Ramp rate in watts per second.
lPers Volumetric flow rate in litres per second.
dBm Power level (logarithmic ratio of signal strength , Bel-mW), normalized to 1mW. Note: multiplier “d” is included in this unit symbol for compatibility with IEC 61850-7-3.
h Time in hours, hour = 60 min = 3600 s.
min Time in minutes, minute = 60 s.
none Dimension less quantity, e.g. count, per unit, etc.
V Electric potential in volts (W/A).
W Real power in watts (J/s). Electrical power may have real and reactive components. The real portion of electrical power (I²R or VIcos(phi)), is expressed in Watts. See also apparent power and reactive power.
VA Apparent power in volt amperes. See also real power and reactive power.
VAr Reactive power in volt amperes reactive. The “reactive” or “imaginary” component of electrical power (VIsin(phi)). (See also real power and apparent power).
Note: Different meter designs use different methods to arrive at their results. Some meters may compute reactive power as an arithmetic value, while others compute the value vectorially. The data consumer should determine the method in use and the suitability of the measurement for the intended purpose.
Wh Real energy in watt hours.
VAh Apparent energy in volt ampere hours.
VArh Reactive energy in volt ampere reactive hours.
m Length in metres.
kg Mass in kilograms. Note: multiplier “k” is included in this unit symbol for compatibility with IEC 61850-7-3.
s Time in seconds.
A Current in amperes.
K Temperature in kelvins.
mol Amount of substance in moles.
cd Luminous intensity in candelas.
Q Quantity power, Q.
Qh Quantity energy, Qh.
ohmm Resistivity, ohm metres, (rho).
APerm A/m, magnetic field strength, amperes per metre.
V2h Volt-squared hour, volt-squared-hours.
A2h Ampere-squared hour, ampere-squared hour.
Ah Ampere-hours, ampere-hours.
count Amount of substance, Counter value.
ft3 Volume, cubic feet.
m3Perh Volumetric flow rate, cubic metres per hour.
gal Volume in gallons, US gallon (1 gal = 231 in3 = 128 fl ounce).
Btu Energy, British Thermal Units.
l Volume in litres, litre = dm3 = m3/1000.
lPerh Volumetric flow rate, litres per hour.
lPerl Concentration, The ratio of the volume of a solute divided by the volume of the solution. Note: Users may need use a prefix such a ‘µ’ to express a quantity such as ‘µL/L’.
gPerg Concentration, The ratio of the mass of a solute divided by the mass of the solution. Note: Users may need use a prefix such a ‘µ’ to express a quantity such as ‘µg/g’.
molPerm3 Concentration, The amount of substance concentration, (c), the amount of solvent in moles divided by the volume of solution in m³.
molPermol Concentration, Molar fraction, the ratio of the molar amount of a solute divided by the molar amount of the solution.
molPerkg Concentration, Molality, the amount of solute in moles and the amount of solvent in kilograms.
sPers Time, Ratio of time. Note: Users may need to supply a prefix such as ‘µ’ to show rates such as ‘µs/s’.
HzPerHz Frequency, rate of frequency change. Note: Users may need to supply a prefix such as ‘m’ to show rates such as ‘mHz/Hz’.
VPerV Voltage, ratio of voltages. Note: Users may need to supply a prefix such as ‘m’ to show rates such as ‘mV/V’.
APerA Current, ratio of amperages. Note: Users may need to supply a prefix such as ‘m’ to show rates such as ‘mA/A’.
VPerVA Power factor, PF, the ratio of the active power to the apparent power. Note: The sign convention used for power factor will differ between IEC meters and EEI (ANSI) meters. It is assumed that the data consumers understand the type of meter being used and agree on the sign convention in use at any given utility.
rev Amount of rotation, revolutions.
kat Catalytic activity, katal = mol / s.
JPerkg Specific energy, Joules / kg.
m3Uncompensated Volume, cubic metres, with the value uncompensated for weather effects.
m3Compensated Volume, cubic metres, with the value compensated for weather effects.
WPerW Signal Strength, ratio of power. Note: Users may need to supply a prefix such as ‘m’ to show rates such as ‘mW/W’.
therm Energy, therms.
onePerm Wavenumber, reciprocal metres, (1/m).
m3Perkg Specific volume, cubic metres per kilogram, v.
Pas Dynamic viscosity, pascal seconds.
Nm Moment of force, newton metres.
NPerm Surface tension, newton per metre.
radPers2 Angular acceleration, radians per second squared.
JPerm3 Energy density, joules per cubic metre.
VPerm Electric field strength, volts per metre.
CPerm3 Electric charge density, coulombs per cubic metre.
CPerm2 Surface charge density, coulombs per square metre.
FPerm Permittivity, farads per metre.
HPerm Permeability, henrys per metre.
JPermol Molar energy, joules per mole.
JPermolK Molar entropy, molar heat capacity, joules per mole kelvin.
CPerkg Exposure (x rays), coulombs per kilogram.
GyPers Absorbed dose rate, grays per second.
WPersr Radiant intensity, watts per steradian.
WPerm2sr Radiance, watts per square metre steradian.
katPerm3 Catalytic activity concentration, katals per cubic metre.
d Time in days, day = 24 h = 86400 s.
anglemin Plane angle, minutes.
anglesec Plane angle, seconds.
ha Area, hectares.
tonne Mass in tons, “tonne” or “metric ton” (1000 kg = 1 Mg).
bar Pressure in bars, (1 bar = 100 kPa).
mmHg Pressure, millimetres of mercury (1 mmHg is approximately 133.3 Pa).
M Length, nautical miles (1 M = 1852 m).
kn Speed, knots (1 kn = 1852/3600) m/s.
Mx Magnetic flux, maxwells (1 Mx = 10-8 Wb).
G Magnetic flux density, gausses (1 G = 10-4 T).
Oe Magnetic field in oersteds, (1 Oe = (103/4p) A/m).
Vh Volt-hour, Volt hours.
WPerA Active power per current flow, watts per Ampere.
onePerHz Reciprocal of frequency (1/Hz).
VPerVAr Power factor, PF, the ratio of the active power to the apparent power. Note: The sign convention used for power factor will differ between IEC meters and EEI (ANSI) meters. It is assumed that the data consumers understand the type of meter being used and agree on the sign convention in use at any given utility.
ohmPerm Electric resistance per length in ohms per metre ((V/A)/m).
kgPerJ Weight per energy in kilograms per joule (kg/J). Note: multiplier “k” is included in this unit symbol for compatibility with IEC 61850-7-3.
JPers Energy rate in joules per second (J/s).

Relationships

Inherits from

  • None

Descendant classes

  • No descendant classes

Leaf/Root class

IsLeaf IsRoot
False False

Associations

None