SIST EN 60076-19:2015

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

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.

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

• Status: Published
• Publication Date: 21-Sep-2015
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: ETR - Power transformers
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 15-Sep-2015
• Due Date: 20-Nov-2015
• Completion Date: 22-Sep-2015
• Directive: 2009/125/EC - Directive 2005/32/EC of the European Parliament and of the Council of 6 July 2005 establishing a framework for the setting of ecodesign requirements for energy-using products and amending Council Directive 92/42/EEC and Directives 96/57/EC and 2000/55/EC of the European Parliament and of the Council
• Mandate: M/495 - Standardisation mandate to CEN, CENELEC and ETSI under Directive 2009/125/EC relating to harmonised standards in the field of Ecodesign
• Ref Project: EN 60076-19:2015 - Power transformers - Part 19: Rules for the determination of uncertainties in the measurement of the losses on power transformers and reactors

Relations

• Revised: SIST EN IEC 60076-19:2023 - Power transformers - Part 19-1: Rules for the determination of uncertainties in the measurement of the losses of power transformers
• Effective Date: 23-Jan-2018

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60076-19:2015
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
SIST EN 60076-19:2015 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60076-19:2015

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SIST EN 60076-19:2015


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

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SIST EN 60076-19:2015
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.
2

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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.
3

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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)

4

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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:
1
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:
11
F 1,0943
∆
1− (0,09 /100+⋅0,11/100) 43,087
1− ∆ +∆ ⋅ tanϕ
( )
ϕϕVC
5


= ==
= = = =

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EN 60076-19:2015 (E)

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.
6

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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
3
0,010
u 0,005 8 crad
∆ϕV
3

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
7


= =
==

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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)
2
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
1
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:
8


= ==
= ==
= =

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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:
2
P= P−⋅I R= 86 997− 69 500=17 497 W
aN22 2
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 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
2
t+θ t+θ (t+θ )
2 r 2
The reported loss at the reference temperature is thus given by:
2
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:
9


=== = ==

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t+θ
2
2 r
For I R loss: I R u 1,196 ⋅ 69 500 ⋅=0,35 /100 291 W
N 2
NR22
t+θ
2
t+θ
2

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
2
(t+θ )
2
The combined absolute standard uncertainty is given by:
2 2 2 2 2 2 22

u (1,196 I Ru )+ (0,836 u )+ (0,004 6 I Ru ) 291+ 616+ 320 753 W
LL N 2 R2 Pa2 N 2 θ 2

The expanded absolute uncertainty is obtained as:

Uu2  2 ⋅ 0,753 1,51 kW
LL LL
which corresponds to a coverage probability of approximately 95 %.
The relative standard uncertainty is then:

u 753
LL
u 100 100 0,77 %
LL
P 97 749
LL
and the expanded relative uncertainty:
Uu=2 =2×≈0,77 1,5 %
LL LL
which corresponds to a level of confidence of approximately 95 %.
A.10 Presentation of the results
Modify the second and fourth paragraphs and replace the first and second equations as
follows:
If the uncertainty is given in relative value, the load loss at reference temperature 75 °C is
expressed as follows:
97,7 kW±1,5 %
97,7 kW±1,5 kW
The text shall be also completed with the indication of the coverage factor that for the
example made was k = 2 (coverage factor of about 95 %).
10


= ==
= ==
= = =
==
=

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NOTE The probability that the loss is higher than (97,7+1,5) kW is therefore 2,5 %.
11

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Annex B
(Informative)

Example of load loss uncertainty evaluation
for a distribution transformer
B.4 Model function of the measurand (see 7.2)
Modify the first paragraph as follows:
The model function for load loss referred to rated current and ambient temperature is the
following (considering that no voltage transformer is used):
Replace the first, second, third and the fourth equations by the following ones:
2
 
ε P I
 
C W N
P = k 1+ ⋅ ⋅
 
CN  
2
100 1+∆ tanϕ k × I
 
ϕC CN M
 

 
P
W
 
ϕ=ϕ +∆ = arccos +∆
M ϕC ϕC
 
I U
 M M

1

1+∆ tanϕ
ϕC

2
 
P I
W N
P = k ⋅ ⋅
2 CN  
1+∆ tanϕ k × I
ϕC  CN M
B.5 Results of the measurements
Replace the first, second and the third equations as follows:
 
 
P 337,5 0,035 180
W
 
 
ϕ= arccos +∆ = arccos + ⋅ = 83,63+ 0,02= 83,65 °
ϕC
 
 
I ⋅U 100 π
4,812⋅ 3⋅ 365,0
 M M
 

1 1
F = = = 0,997
∆
0,035
1+∆ tanϕ
ϕC
1+ ⋅ 8,99
100

12

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P = k ⋅ P ⋅ F = 40 ⋅ 337,5 ⋅ 0,997=13 460 W
2 CN W ∆
B.6 Estimate of the single contributions to the uncertainty formation
Modify the title of B.6.2 as follows:
B.6.2 Power meter (see 10.5)
Replace the first, second and the third equations by the following ones:
0,57
u = = 0,33 %
PW
3

0,42

u = = 0,24 %
IM
3

0,25
u = = 0,14 %
UM
3
B.6.3 Current transformers (see 10.3)
Modify the second paragraph and Table B.3, second row, last cell, as follows:
For the type of transformer under test the values of the ratio error and displacement error
given by the calibration certificate can be considered, as indicated in Table B.3. Uncertainty
statements have been given as standard uncertainty in the table.
Table B.1 – Calibration of the current transformers
Ratio error Phase displacement
(%) (centiradians)
Rated ratio Accuracy class
u
ε u Value
c ∆ϕ
c
200/5 0,1 0,0 0,01 0,01
+ 0,035
NOTE The errors reported in the table are those measured including burden and connections corresponding to
the instrument used.

B.6.4 Corrective term uncertainty (see 10.3.2)
Replace the equation by:
u
∆
ϕC
u ≈ ⋅ tanϕ⋅100= 0,01 ⋅ 8,99= 0,09 %
F∆
100
13

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B.7 Uncertainty of the load loss measured at ambient temperature (see 7.4)
Modify Table B.4, third row as follows:

Table B.2 – Uncertainty contribution
Quantity Estimate Standard uncertainty Sensitivity Uncertainty
coefficient contribution
Power meter P u 1 0,33 %
W P
1

Phase displacement u 1 0,09 %
F∆
1+∆ tanϕ
ϕC
Ampere meter I u 2 0,48 %
M IM

Modify the second paragraph and replace the equation as follows:
The combined uncertainty of load loss P measured at ambient temperature is given by:
LL
2 2 2 2 2 2
u = u + u + u = 0,33 + 0,09 + 0,48 = 0,59 %
LL P F∆ I
B.8 Expanded uncertainty of the load loss (see 7.4)
Replace the first and second equations by the following ones:
U = 2 u = 2 ⋅ 0,59=1,18 %
LL LL
U 1,18
LL

U = P = 13,5= 0,16 kW
LL LL
100 100
Modify the last paragraph as follows:
The result shall be also completed with the indication of the coverage factor that for the
example made was k = 2 (coverage factor of about 95 %).
14

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Bibliography
Replace the bibliography by:
EN 61869-1, Instrument transformers – Part 1: General requirements (IEC 61869-1)
EN 61869-2, Instrument transformers – Part 2: Additional requirements for current
transformers (IEC 61869-2)
EN 61869-3, Instrument transformers – Part 3: Additional requirements for inductive voltage
transformers (IEC 61869-3)
EN ISO/IEC 17025:2005, General requirements for the competence of testing and calibration
laboratories (ISO/IEC 17025:2005)
CLC/TR 50462:2008, Rules for the determination of uncertainties in the measurement of the
losses on power transformers and reactors
15

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SIST EN 60076-19:2015



IEC/TS 60076-19

®


Edition 1.0 2013-03




TECHNICAL



SPECIFICATION





SPÉCIFICATION



TECHNIQUE












Power transformers –

Part 19: Rules for the determination of uncertainties in the measurement of the

losses on power transformers and reactors




Transformateurs de puissance –

Partie 19: Règles pour la détermination des incertitudes de mesure des pertes


des transformateurs de puissance et bobines d’inductance













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX W


ICS 29.180 ISBN 978-2-83220-693-5



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Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60076-19:2015
– 2 – TS 60076-19 © IEC:2013
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Symbols . 8
4.1 General symbols . 8
4.2 Symbols for uncertainty . 9
5 Power measurement, systematic deviation and uncertainty . 10
5.1 General . 10
5.2 Model function . 10
5.3 Measuring systems . 10
6 Procedures for no-load loss measurement . 11
6.1 General . 11
6.2 Model function for no-load losses at reference conditions . 11
6.3 Uncertainty budget for no-load loss . 12
7 Procedures for load loss measurement . 13
7.1 General . 13
7.2 Model function for load loss measurement at rated current . 13
7.3 Reporting to rated current and reference temperature . 14
7.4 Uncertainty budget for the measured power P reported to rated current . 14
2
7.4.1 General . 14
7.4.2 Uncertainties of measured load loss power P at ambient temperature
2
θ . 14
2
7.5 Uncertainty budget for reported load loss at reference temperature . 15
8 Three-phase calculations . 16
8.1 Power measurement . 16
8.2 Reference voltage . 17
8.3 Reference current. 17
9 Reporting . 17
9.1 Uncertainty declaration . 17
9.2 Traceability . 17
10 Estimate of corrections and uncertainty contributions . 18
10.1 Instrument transformers . 18
10.2 Uncertainty contributions of ratio error of instrument transformers . 18
10.3 Uncertainty contribution of phase displacement of instrument transformers . 19
10.3.1 General . 19
10.3.2 Complete reference procedure . 19
10.3.3 Class index procedure . 20
10.4 Voltage and current measurements . 21
10.5 Power meter . 21
10.6 Correction to sinusoidal waveform . 22
10.7 Winding temperature at load loss measurement . 23
10.8 Winding resistance measurement . 23
Annex A (informative) Example of load loss uncertainty evaluation for a large power
transformer . 25

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SIST EN 60076-19:2015
TS 60076-19 © IEC:2013 – 3 –
Annex B (Informative) Example of load loss uncertainty evaluation for a distribution
transformer . 33
Bibliography . 37

Table 1 – Measured no-load loss uncertainties . 12
Table 2 – Measured load loss uncertainties at ambient temperature . 15
Table 3 – Absolute uncertainty of the additional losses at temperature θ . 15
2
Table 4 – Absolute uncertainty of load losses P reported at reference temperature . 16
LL
Table 5 – Procedures for the determination of phase displacement uncertainties . 19
Table A.1 – Transformer ratings . 25
Table A.2 – Loss measurement results (one phase) . 27
Table A.3 – Calibration of voltage and current transformers . 27
Table A.4 – Uncertainty contributions. 29
Table B.1 – Transformer ratings . 33
Table B.2 – Measured quantities . 34
Table B.3 – Calibration of the current transformers . 35
Table B.4 – Uncertainty contribution . 36

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SIST EN 60076-19:2015
– 4 – TS 60076-19 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

POWER TRANSFORMERS –

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

FOREWORD
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