MeterValue data type

MeterType

The two possible meter types are:

  1. S0 - Charge station
  2. EVSE

Unit

The following are possible units defined in OCPP.

Allowable values of the optional "unit" field of a Value element, as used in MeterValues.req and
StopTransaction.req messages. Default value of "unit" is always "Wh

UnitDescriptionNote
wHWatt-hours (energy). Default.Common
kWhkiloWatt-hours (energy).
varhVar-hours (reactive energy).
kvarhkilovar-hours (reactive energy).
WWatts (power).
kWkilowatts (power).
VAVoltAmpere (apparent power).
kVAkiloVolt Ampere (apparent power).
varVars (reactive power).
AAmperes (current).Common
VVoltage (r.m.s. AC).Common
kvarkilovars (reactive power).
CelsiusDegrees (temperature).Common
FahrenheitDegrees (temperature)
KDegrees Kelvin (temperature).
PercentPercentage

Measurand

OCPP defines different measurands that can be passed on through meter values.

The key value in most cases is the Energy.Active.Import.Register or simply 'Energy (consumed)" as represented in the EvPortal.

Value DescriptionDescriptionUsed in GFX
Current.ExportInstantaneous current flow from EV
Current.ImportInstantaneous current flow to EVYes
Current.OfferedMaximum current offered to EV
Energy.Active.Export.RegisterEnergy exported by EV (Wh or kWh)
Energy.Active.Import.RegisterEnergy imported by EV (Wh or kWh)Yes
Energy.Reactive.Export.RegisterReactive energy exported by EV (varh or kvarh)
Energy.Reactive.Import.RegisterReactive energy imported by EV (varh or kvarh)
Energy.Active.Export.IntervalEnergy exported by EV (Wh or kWh)
Energy.Active.Import.IntervalEnergy imported by EV (Wh or kWh)
Energy.Reactive.Export.IntervalReactive energy exported by EV. (varh or kvarh)
Energy.Reactive.Import.IntervalReactive energy imported by EV. (varh or kvarh)
FrequencyInstantaneous reading of powerline frequencyYes
Power.Active.ExportInstantaneous active power exported by EV. (W or KW)
Power.Active.ImportInstantaneous active power imported by EV. (W or KW)Yes
Power.FactorInstantaneous power factor of total energy flowYes
Power.OfferedMaximum power offered to EVYes
Power.Reactive.ExportInstantaneous reactive power exported by EV. (var or kvar)
Power.Reactive.ImportInstantaneous reactive power imported by EV. (var or kvar)
RPMFan speed in RPMYes
SoCState of charge of charging vehicle in percentageYes
TemperatureTemperature reading inside Charge Point.Yes
VoltageInstantaneous AC RMS supply voltageYes

Context

Meter Values can be sent by the Charge Station at different moments.

Typically there are Meter Values at the beginning and end of a Transaction:

  • Transaction.Begin
  • Transaction.End

Meter Values can be sent based either:

  • Sample.periodic - meter values are sent only during an active session
  • Sample.Clock - meter values are sent every clock aligned interval, e.g. every 15mins, regardless of an ongoing transaction or not.
ValueDescription
Interruption.BeginValue taken at start of interruption.
Interruption.EndValue taken when resuming after interruption.
OtherValue for any other situations.
Sample.ClockValue taken at clock aligned interval.
Sample.PeriodicValue taken as periodic sample relative to start time of transaction.
Transaction.BeginValue taken at end of transaction.
Transaction.EndValue taken at start of transaction.
TriggerValue taken in response to a TriggerMessage.req

Phase

Value
L1
L2
L3
N
L1N
L2N
L3N
L1L2
L2L3
L3L1
None

📘

Filtering on phases

If a Charge Station has three phases, typically it will send 4 metervalues relating to kWh:

  • L1
  • L2
  • L3
  • none

In most cases, Users are not interested in the individual phase, but the 'total' of the Charge Station.
To select the 'total', you should filter on 'none'

Format

  • Raw
  • SignedData

Location

  • Cable
  • EV
  • Inlet
  • Outlet
  • Body