S-E-12—Specifications for the approval of type of electricity meters equipped with loss compensation functions

Category: Electricity
Issue date:
Effective date:
Revision number: N/A
Supersedes: N/A


Table of contents


1.0 Scope

These specifications apply to electricity meters having legal unit of measure values that are compensated for power transformer losses and/or line losses.

2.0 Authority

These specifications are issued under the authority of section 12 of the Electricity and Gas Inspection Act.

3.0 References

4.0 Definitions

Actual current
(courant réel)

The current as determined from the meter's approved I2h function.

Actual voltage
(tension réelle)

The voltage as determined from the meter's approved V2h function.

Attestation
(attestation)

A binding document which solemnly declares in writing that a particular requirement of this document has been complied with and that this conclusion is an accurate representation of the facts as attested to by the signatory.

Blondel's theorem
(théorème de Blondel)

In a system of N conductors, N-1 meter elements, properly connected, will correctly measure the power or energy taken. The connection must be such that all potential coils have a common tie to the conductor in which there is no current coil.

Copper loss
(perte dans le cuivre)

The active and reactive power losses of the transformer or power line at actual load current (also known as copper loss or winding loss for power transformers).

Core loss
(perte dans le noyau)

The active and reactive power consumed by the transformer's windings or power line at the actual voltage with no load current (also known as core loss or iron loss).

Full load loss (var)
(perte à pleine charge [en voltsampères réactifs])

The reactive power consumed by the transformer's windings or power line at full load current.

Full load loss (watt)
(perte à pleine charge [en watts])

The active power consumed by the transformer's windings or power line at full load current.

Iron loss
(perte dans le fer)

The active and reactive power consumed by the transformer's windings or power line at the actual voltage with no load current (also known as core loss or iron loss).

Load loss
(perte due à la charge)

The active and reactive power losses of the transformer or power line at actual load current (also known as copper loss or winding loss for power transformers).

Load loss (var)
(perte due à la charge [en voltsampères réactifs])

The reactive power consumed by the transformer's windings or power line at actual load current.

Load loss (watt)
(perte par la charge [en watts])

The active power consumed by the transformer's windings or power line at actual load current.

Load percent of short-circuit impedance
(pourcentage de la charge de l'impédance en court-circuit)

The short-circuit impedance of the power transformer expressed as a percentage of the primary voltage required to circulate full load current in the short-circuited secondary winding to the rated primary voltage.

Loss compensation
(compensation des pertes)

A means for establishing a legal unit of measure when the metering point and the point of service are physically separated resulting in measurable losses. These losses may be used to adjust meter registration for a final (compensated) legal unit of measure.

No-load loss
(perte à vide)

The active and reactive power consumed by the transformer's windings or power line at the actual voltage with no load current (also known as core loss or iron loss).

No-load loss (var)
(perte à vide [en voltsampères réactifs])

The reactive power consumed by the transformer's windings or power line at the actual voltage with no load current.

No-load loss (watt)
(perte à vide [en watts])

The active power consumed by the transformer's windings or power line at the actual voltage with no load current.

No-load percent excitation current
(pourcentage du courant d'excitation à vide)

The percentage of a full load current that flows through the line terminals of a power transformer when all other windings are open circuited and rated voltage is applied.

Percent impedance
(pourcentage d'impédance)

The voltage drop on full load due to the winding resistance and leakage reactance expressed as a percentage of the rated voltage.

Rated (apparent) power
(puissance nominale [apparente])

The nominal volt-ampere power rating of the transformer as provided in the test sheet (typically provided in megavolt-amperes).

Rated current
(courant nominal)

The current at rated power of the transformer as provided in the test sheet.

Rated voltage
(tension nominale)

The voltage at rated power of the transformer as provided in the test sheet.

Test sheet
(feuille d'essai)

The source of the power transformer and/or power line technical information. The data can come from test sheets, reports or other acceptable sources.

Winding loss
(perte aux enroulements)

The active and reactive power losses of the transformer or power line at actual load current (also known as copper loss or winding loss for power transformers).

5.0 Approval requirements

5.1 General

5.1.1 Compensated registrations

Electricity meters that provide registrations which are compensated for power transformer losses and/or line losses are to do so in accordance with these requirements.

5.1.2 Registration of compensated and uncompensated legal units of measure

Meters that provide registrations which are compensated for power transformer losses and/or line losses must provide compensated and uncompensated legal units of measure in one or more separate approved registers.

5.1.3 Inclusion of an identifier

Compensated legal unit of measure registrations are to include an identifier which facilitates distinction between compensated and uncompensated legal units of measure. "COMP" is the recommended identifier.

5.1.4 Power transformer loss compensation conditions

Power transformer loss compensation can be applied under the following service conditions:

  1. The meter is installed on the primary or secondary side of a two-winding power transformer or a series of two-winding transformers.
  2. The meter is installed on the primary side of a power transformer having two or more windings.
  3. The installed meter complies with Blondel's theorem.

5.1.5 Application of line loss compensation

Line loss compensation can be applied for single phase or polyphase service conditions.

5.1.6 Addition and subtraction of loss compensation

Loss compensation is to be added or subtracted based on the point of delivery and direction of energy flow.

5.2 Loss compensation determinable parameters

Pursuant to the requirements of this document, the following parameters (or equivalents) are permitted for use in determining loss compensated legal units of measure.

5.2.1 Transformer loss parameters

% EXC
(No-load) percent (%) excitation current of the power transformer (ratio of no-load test current from the transformer sheet data at rated voltage to full load current)
%Z
Percent impedance (%) of the power transformer (ratio of full load test voltage from transformer sheet data at test current to rated voltage)
CTR
Current transformer ratio of the instrument transformers supplying current to the meter
VTR
Voltage transformer ratio of the instrument transformers supplying voltage to the meter
Elements
Number of meter elements
Iact
Actual current (derived from measured I2h value)
Irated
Rated current (on the metered side of transformer)
LVCu
Load loss (var) of power transformer at metered current (var copper loss)
LVCuFL
Full load loss (var) (typically calculated from test sheet data)
LVFe
No-load loss (var) of power transformer at metered voltage (var iron loss)
LVFeNL
No-load loss (var) (typically calculated from test sheet data)
LWCu
Load loss (watts) of power transformer at metered current (copper or winding losses)
LWCuFL
Full load loss (watts) (from test sheet data or adjusted for in-use tap))
LWFe
No-load loss (watts) of power transformer at metered voltage (iron or core losses)
LWFeNL
No-load loss (watt) (from test sheet data)
Vact
Actual metered voltage (derived from measured V2h value)
Vrated
Rated voltage (on the metered side of transformer)
VAphase
Per phase VA rating of power transformer
VATXtest (VArated)
Rated (apparent) power of transformer

5.2.2 Power line loss parameters

n
Number of conductors
L
Conductor (line) length (units compatible with conductor resistance)
r
Conductor resistance per unit length
rt
Conductor resistance per unit length (corrected for climatic influence)
PLLv
Power line load loss (var)
PLLW
Power line load loss (watt)
PNLLW
Power line no-load loss (watt)
PNLLv
Power line no-load loss (var)
PLLWt
Power line loss based on climatic influences (watts)
xl
Inductive reactance for service length of conductor
Gl
Conductance for service length of conductor
Bl
Susceptance for service length of conductor

5.3 Requirements for loss compensation

5.3.1 Submitting loss compensation functions for approval

Electricity meters submitted for approval of type having loss compensation functions must determine loss values pursuant to the requirements of these specifications.

5.3.2 Use of approved I2h and V2h values

Meters are to use approved I2h and V2h values in the determination of loss values as required below.

5.3.3 Application of loss equations

The loss equations identified herein must apply with regard to power transformers used, power lines, service conditions and meter configurations.

5.4 Transformer loss compensation

5.4.1 Parameters that can be included for compensation

Transformer loss compensation can include compensation for the following:

Iron or core losses

  1. No-load loss (watt)
  2. No-load loss (var)

Copper or winding losses

  1. Load loss (watt)
  2. Load loss (var)

5.4.2 Application of models for transformer losses

Where applicable, the following models are to be applied for transformer losses:

  1. No-load loss (watt) is proportional to (Vact)2
  2. No-load loss (var) is proportional to (Vact)4
  3. Load loss (watt) is proportional to (Iact)2
  4. Load loss (var) is proportional to (Iact)2

5.4.3 Determination of Vact and Iact

Vact and Iact will be determined from approved V2h and I2h quantities. Where applicable, transformer ratios must be applied for values that are metered on the secondary side of transformers.

5.4.4 Period of integration

Unless otherwise noted, loss values established pursuant to the equations of sections 5.5 and 5.6 must be integrated over the same period as the energy legal units of measure to which they are being applied.

5.4.5 Compensated demand values

Compensated demand values must be established on the basis of compensated energy values.

5.4.6 Compliance

Compliance with the requirements of these specifications must be established on the basis of both functionality testing and written attestations of compliance.

5.4.7 Attestations

Attestations of compliance must originate from an authorized signing authority that has been appropriately designated by the device manufacturer to represent it for these purposes as part of the pattern approval process.

5.5 Transformer loss equations

5.5.1 No-load loss (watt)

LWFe= [LWFe]_NL ×(V_act/V_rated)^2

Where:

LWFe = No-load loss (watts) at metered voltage

LWFeNL = No-load loss (watts) (from test sheet data)

Vact = Actual metered voltage (derived from measured V2h value)

Vrated = Rated voltage (transformer)

5.5.2 No-load loss (var)

LVFe= [LVFe]_NL ×(V_act/V_rated)^4

Where:

LVFe = No-load loss (var) at metered voltage

LVFeNL = No-load loss (var) (derived from test sheet data)

Vact = Actual metered voltage (derived from measured V2h value)

Vrated = Rated voltage (transformer)

5.5.3 Formula for LVFeNL

Where LVFeNL is not available, the following can be used to determine this value:

LVFe_NL= √((VA_(TXtest) ×(%EXC)/100)^2−(LWFe_(NL))^2)

Where:

VATXtest = Rated VA of power transformer (from transformer sheet data)

%EXC = No-load percent (%) excitation current

5.5.4 Load loss (watt)

LWCu= [LWCu]_FL ×(I_act/I_rated)^2

Where:

LWCu = Load loss (watts) at metered current

LWCuFL = Full load loss (watts) (from test sheet data or adjusted for in-use tap)

Iact = Actual current (derived from measured I2h)

Irated = Rated transformer current

5.5.5 Load loss (var)

LVCu= [LVCu]_FL ×(I_act/I_rated)^2

Where:

LVCu = Load loss (var) at metered current

LVCuFL = Full load loss (var) (calculated from test sheet data)

Iact = Actual current (derived from measured I2h)

Irated = Rated transformer current

Where LVCuFL is not available, the following can be used to determine this value:

LVCu_FL=√((VA_(TXtest) ×(%Z)/100)^2−(LWCu_(FL))^2)

Where:

VATXtest = Rated VA of power transformer

%Z = Voltage drop on full load due to the winding resistance and leakage reactance expressed as a percentage of the rated voltage (from test sheet data)

5.5.6 Total transformer loss value applied to watts

The total transformer loss value applied to watts must be the combination of values established by 5.5.1 and 5.5.4 above.

5.5.7 Total transformer loss value applied to volt-amperes reactive

The total transformer loss value applied to volt-amperes reactive must be the combination of values established by 5.5.2 and 5.5.5 above.

5.5.8 Total transformer loss value applied to VA

The total transformer loss value applied to VA must be the vectorial sum of the watt and var values established by 5.5.6 and 5.5.7 above.

5.6 Power line losses

5.6.1 Application of models for power line losses for meters

When applicable, the following models are to be applied for power line losses for meters:

  1. Load loss (watt) is proportional to (Iact)2
  2. Load loss (var) is proportional to (Iact)2
  3. No-load loss (watt) is proportional to (Vact)2
  4. No-load loss (var) is proportional to (Vact)2

5.6.2 Determination of Vact and Iact

Vact and Iact will be determined from approved V2h and I2h quantities.

5.6.3 Equations for power line application of losses

For power line applications, the following equations are to be used, as applicable, when determining line losses:

  1. Line loss (watt)

    PLLW= (I_(act))^2 ×r×L

    Where:

    PLLW = (Power) line loss (watt)

    Iact = Actual current (derived from measured I2h)

    r = Resistance per unit length or resistance (corrected for climatic influences) per unit length

    L = Conductor length

  2. Line loss (var, inductive)

    PLLv=(I_(act))^2 ×x_i ×L

    Where:

    PLLv = (Power) line loss (var)

    Iact = Actual current (derived from measured I2h)

    xi = Inductive reactance per unit length or inductive reactance (corrected for climatic influences per unit length)

    L= Conductor length

  3. No-load loss (watt)

    PNLLw=(V_(act))^2 ×G_(l)

    Where:

    PNLLw = (Power) line load loss (watt)

    Vact = Actual voltage (derived from measured V2h)

    Gl = Shunt conductance for service length of conductor

  4. No-load loss (var)

    PNLLv=(V_(act))^2 ×B_(l)

    Where:

    PNLLv = (Power) line no-load loss (var)

    Vact = Actual voltage (derived from measured V2h)

    Bl = shunt susceptance for service length of conductor

5.6.4 Total line loss value applied to VA

The total line loss value applied to VA must be the vectorial sum of the watt and var values established by 5.6.3 above.

5.7 Combination of transformer losses and line losses

5.7.1 Total watt loss value

The total loss value applied to watts must be the combination of values established by 5.5.6 and 5.6.3 a) and c) above.

5.7.2 Total var loss value

The total loss value applied to volt-amperes reactive must be the combination of values established by 5.5 7 and 5.6.3 b) and d) above.

5.7.3 Total VA loss value

The total loss value applied to VA must be the vectorial sum of the watt and var values established by 5.7.1 and 5.7.2 above.

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