# EN 60076-19:2015

(Main)## Power transformers - Part 19: Rules for the determination of uncertainties in the measurement of the losses on power transformers and reactors

## Power transformers - Part 19: Rules for the determination of uncertainties in the measurement of the losses on power transformers and reactors

To illustrate the procedures that should be applied to evaluate the uncertainty affecting the measurements of no-load and load losses during the routine tests on power transformers.

## Leistungstransformatoren - Teil 19: Regeln für die Bestimmung von Unsicherheiten in der Messung der Verluste von Leistungstransformatoren und Drosselspulen

## Transformateurs de puissance - Partie 19: Règles pour la détermination des incertitudes de mesure des pertes des transformateurs de puissance et bobines d’inductance

La CEI/TS 60076-19:2013, qui est une Spécification Technique, présente les procédures qu'il convient d'appliquer pour évaluer l'incertitude qui affecte les mesures des pertes à vide et des pertes dues à la charge lors d'essais individuels de série de transformateurs de puissance. Même si la présente spécification prête une attention particulière aux transformateurs, elle peut être également utilisée, le cas échéant, pour les mesures des pertes des bobines d'inductance, à l'exception des grandes bobines d'inductance à très faible facteur de puissance.

## Močnostni transformatorji - 19. del: Pravila za določanje negotovosti meritve izgub močnostnih transformatorjev in dušilk

Ta evropski standard opisuje postopke, ki naj bi se uporabljali za ocenjevanje negotovosti, ki vpliva na meritve izgub močnostnih transformatorjev brez obremenitve in z obremenitvijo med rutinskimi preskusi.

### General Information

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### Standards Content (Sample)

SLOVENSKI STANDARD

01-oktober-2015

0RþQRVWQLWUDQVIRUPDWRUMLGHO3UDYLOD]DGRORþDQMHQHJRWRYRVWLPHULWYHL]JXE

PRþQRVWQLKWUDQVIRUPDWRUMHYLQGXãLON

Power transformers - Part 19: Rules for the determination of uncertainties in the

measurement of the losses on power transformers and reactors

Leistungstransformatoren - Teil 19: Regeln für die Bestimmung von Unsicherheiten in

der Messung der Verluste von Leistungstransformatoren und Drosselspulen

Transformateurs de puissance - Partie 19: Règles pour la détermination des incertitudes

de mesure des pertes des transformateurs de puissance et bobines d’inductance

Ta slovenski standard je istoveten z: EN 60076-19:2015

ICS:

29.180 Transformatorji. Dušilke Transformers. Reactors

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60076-19

NORME EUROPÉENNE

EUROPÄISCHE NORM

August 2015

ICS 29.180

English Version

Power transformers - Part 19: Rules for the determination of

uncertainties in the measurement of the losses on power

transformers and reactors

(IEC/TS 60076-19:2013 , modified)

Transformateurs de puissance - Partie 19: Règles pour la Leistungstransformatoren - Teil 19: Regeln für die

détermination des incertitudes de mesure des pertes des Bestimmung von Unsicherheiten in der Messung der

transformateurs de puissance et bobines d'inductance Verluste von Leistungstransformatoren und Drosselspulen

(IEC/TS 60076-19:2013 , modifiée) (IEC/TS 60076-19:2013 , modifiziert)

This European Standard was approved by CENELEC on 2015-06-25. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization

Comité Européen de Normalisation Electrotechnique

Europäisches Komitee für Elektrotechnische Normung

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 60076-19:2015 E

Foreword

This document (EN 60076-19:2015) consists of the text of IEC/TS 60079:2013 prepared by

IEC/TC 14 "Power transformers", together with the common modifications prepared by

CLC/TC 14 "Power transformers".

The following dates are fixed:

(dop) 2016-06-25

• latest date by which this document has to be

implemented

at national level by publication of an identical

national standard or by endorsement

(dow) 2018-06-25

• latest date by which the national standards

conflicting with this document

have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the

subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying

any or all such patent rights.

This document has been prepared under a mandate given to CENELEC by the European

Commission and the European Free Trade Association.

Endorsement notice

The text of the International Standard IEC/TS 60079:2013 was approved by CENELEC as a

European Standard with agreed common modifications.

COMMON MODIFICATIONS

Introduction

Modify the first paragraph as follows:

The losses of the transformers (no- load and load losses) are object of guarantee and penalty

in the majority of the contracts and play an important role in the evaluation of the total

(service) costs and therefore in the investments involved. Furthermore, regional regulations,

such as the European Union directive for EcoDesign, may also pose requirements on

establishment of reliable values for losses.

Modify the third and fourth paragraphs as follows:

Corrections and uncertainties are also considered in IEC 60076-8 where some general

indications are given for their determination.

This European Standard deals with the measurement of the losses that from a measuring

point of view consist of the estimate of a measurand and the evaluation of the uncertainty that

affects the measurand itself. The procedures can also be applied to loss measurements on

power transformers and reactors as evaluation of the achievable performance of a test facility

in the course of prequalification processes, as estimations of achievable uncertainty in the

enquiry stage of an order or prior to beginning final testing at manufacturer´s premises and for

evaluations of market surveillance measurements.

Add before the fifth paragraph:

Evaluation of uncertainty in testing is often characterized as “top-down” or “bottom-up”, where

the first one relies on inter-laboratory comparisons on a circulated test object to estimate the

dispersion and hence the uncertainty. The latter method instead relies on the formulation of a

model function, where the test result y is expressed as a function of input quantities. This

function is often the formula used for the calculation of the result. The “bottom-up” method is

applied in this Document.

Replace the sixth paragraph by:

It is recommended that guarantee and penalty calculations should refer to the best estimated

values of the losses without considering the measurement uncertainties, based on a shared

risk concept, where both parties are aware of and accept the consequences of non-negligible

measurement uncertainty.

In cases where the losses are required to conform to stated tolerance limits, it is

recommended that the estimated uncertainty is less than the tolerance limit. This situation will

occur for example in market surveillance activities. In lieu of other specifications it can be

noted that 3 % is often used as estimate for the required uncertainty.

Modify the eighth paragraph as follows:

Standards mentioned in the text but not indispensable are listed at the end of the document.

Replace the last paragraph by:

This European document is based on IEC/TS 60076-19. The technical content of the TS was

not changed, but small numerical mistakes and consistent use of symbols in Annex A were

corrected. The introduction was modified to enhance clarity.

1 Scope

Modify the first paragraph as follows:

This European Standard illustrates the procedures that should be applied to evaluate the

uncertainty affecting the measurements of no-load and load losses during the routine tests on

power transformers.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any

amendments) applies.

EN 60076-1:2011, Power transformers – Part 1: General (IEC 60076-1:2011)

EN 60076-2:2011, Power transformers – Part 2: Temperature rise for liquid-immersed

transformers (IEC 60076-2:2011)

Annex A

(informative)

Example of load loss uncertainty evaluation

for a large power transformer

A.4 Model function of the measurand and deviation correction (see 7.2)

A.4.2 Correction of known systematic deviations

Modify the paragraph after the first equation as follows:

The remaining corrective term is given by the following equation: (erroneous K replaced by

C

F )

D

Replace the second and the third equations by the following ones:

F =

∆

1−(∆ −∆ )⋅ tanϕ

ϕV ϕC

P = k ⋅ k ⋅ P ⋅ F

2 CN VN W ∆

A.5 Results of the measurements

A.5.1 Load loss measurements

Modify the paragraph after Table A.2 as follows:

The estimate of the phase angle between voltage and current results (see 7.2 and A.6.1):

Replace the first equation by:

P 6,625 0,09 0,11 180

W

ϕarccos −∆+∆ arccos − + 88⋅ ,782−0,11588,670°

ϕϕVC

IU 3,608×86,60 100 100 π

MM

Modify the paragraph after the first equation as follows:

The corresponding tanϕ is therefore equal to 43,087.

Replace the second equation by:

F 1,0943

∆

1− (0,09 /100+⋅0,11/100) 43,087

1− ∆ +∆ ⋅ tanϕ

( )

ϕϕVC

= ==

= = = =

Replace the third equation by:

P= k⋅ k⋅⋅PF= 60⋅200⋅6,625⋅1,0943=86 997 W

2 CN VN W D

Add after the third equation:

NOTE This result differs slightly from the result obtained with the full formula given in clause A.4.1 because of

the simplifications introduced in A.4.2.

A.6 Estimates of the single contributions to the uncertainty budget

A.6.3 Instrument transformer phase displacement uncertainties (see 10.3)

Replace the first, second and third equations by the following ones:

0,02

u = = 0,011 5 crad

∆ϕC

0,010

u 0,005 8 crad

∆ϕV

Add after the second equation:

and

22 2 2

u uu+= 0,0115+ 0,005 8 0,012 9

∆ϕ ∆∆ϕϕVC

NOTE In some cases, in the calibration certificates the uncertainty is directly indicated with a given confidence

level and therefore the standard uncertainties can be directly obtained from these data.

A.6.4 Power analyzer uncertainties (see 10.5)

Modify the first paragraph as follows:

According to the manual for the instrument used, the accuracy on power measurement is

obtained by the combination of a number of terms:

Modify the third paragraph after the first equation as follows:

The accuracy determined in accordance with the above relation resulted in ±0,91 %.

Modify the paragraph before the last equation as follows:

According to the manual for the instrument used, the accuracy for voltage measurement is

±0,18 %, which corresponds to the following standard uncertainty:

A.6.5 Corrective term uncertainty (see 10.3.2)

Modify the first paragraph as follows:

The uncertainty u related to the phase displacement correction can be evaluated with the

F∆

following simplified relations:

Replace the first and the second equations by the following ones:

u ≈ u ⋅ tanϕ

F∆ ∆ϕ

= =

==

u 0,012 9⋅=tanϕ 0,012 9⋅43,087 0,56 %

F∆

A.6.6 Uncertainty of the resistance at temperature θ (see 10.8)

Modify the first paragraph as follows:

The standard uncertainty due to the measuring instruments is assumed equal to 0,35 % and

that attributable to the winding temperature estimate equal to 2 K, with the latter deemed to

be negligible.

A.7 Uncertainty of the load loss measured at ambient temperature (see 7.4)

Modify the first paragraph and Table A.4, fifth row, last cell, as follows:

The uncertainties that affect the load loss at ambient temperature can be estimated using the

results of the previous elaborations and are summarized in Table A.4.

Table A.4 – Uncertainty contributions

Quantity Estimate Standard uncertainty Sensitivity Uncertainty

coefficient contribution

(%)

CT ratio error η u 1 -

C C

VT ratio error 1 -

η u

V V

Power meter 1 0,53

u

P

P

W

Phase displacement 1 0,56

u

F∆

1−(∆ϕv−∆ϕc)tanϕ

Ampere meter I u 2 0,24

M IM

Replace the equation by:

22 2 2 2 2

u= uu+ + u= 0,53+ 0,56+ 0, 24= 0,81 %

P2 P F∆ IM

A.8 Expanded uncertainty of the measured load loss (see 7.4)

Replace the first and second equations by the following ones:

Uu2 2 ⋅ 0,81 1,61 %

PP22

U 1,61

P2

UP 86,997 1,4 kW

P22

100 100

Modify the second paragraph after Equation 2 as follows:

= ==

= ==

= =

If the uncertainty is given in relative value, the load loss at ambient temperature 24,2 °C is to

be expressed as follows:

Replace the third and the fourth equations by the following ones:

87,0 kW±1,6 %

87,0 kW± 1,4 kW

Modify the last paragraph as follows:

The result shall be also completed with the indication of the coverage factor, which for the

example made was k = 2 (confidence level of about 95 %).

A.9 Uncertainty for reported load loss at reference temperature (see 7.5)

Replace the text under A.9 as follows:

The additional loss at ambient temperature is given by:

P= P−⋅I R= 86 997− 69 500=17 497 W

aN22 2

The absolute uncertainty of the measured loss and I R loss are obtained as follows:

N

u 0,80 u 0,35

P2 R2 2

uP 86 997 696 W and u IR 69 500 243 W

P22 R22N

100 100 100 100

The absolute uncertainty of the additional loss at temperature θ is given by (see Table 3):

2 2 2 2 2

u = u + (I R ⋅ u ) = 696 + 243 = 737 W

Pa2 P2 N 2 R2

The reported load loss at reference temperature is calculated for copper conductors with

t=235, reference temperature θ = 75 °C and ambient temperature θ = 24,2 °C is given by:

r 2

t+θ t+θ

t+θ

r 2 2 2

r

=1,196 = 0,836 I R ≅ 0,004 6 I R

N 2 N 2

t+θ t+θ (t+θ )

2 r 2

The reported loss at the reference temperature is thus given by:

P=1,196 IR+ 0,836 P= 83 122+14 627= 97 749 W

LL N 22a

The various contributions to the absolute uncertainty are calculated according to Table 4:

=== = ==

t+θ

2 r

For I R loss: I R u 1,196 ⋅ 69 500 ⋅=0,35 /100 291 W

N 2

NR22

t+θ

t+θ

For additional loss: u 0,836 ⋅ 737 616 W

Pa2

t+θ

r

t+θ

r 2

For mean winding temperature:

I R u = 0,004 6 x⋅ 69 500= 320 W

N r θ 2

(t+θ )

The combined absolute standard uncertaint

**...**

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