Marquel World Information Technology

Page 1

Comparison of Standards – ANSI / IEEE and IEC
Prepared by the Task Force under the Standards Subcommittee
IEEE Transformers Committee
March 2011
TF Chair: H. Jin Sim
TF Members: Vinay Mehrotra
Ajith Varghese
Hali Moleski
Richard Marek
Bill Henning
Hasse Nordman
Jim Thompson
The comparisons below are based on the latest published standards unless identified otherwise. It is the directive of the Standards
Subcommittee to publish this comparison study each time a major standard (IEEE C57.12.00, C57.12.90, or IEC 60076-1) is approved and
published. The purpose of this study is to provide list of major differences between IEEE and IEC standards to the members of the group
working on these documents. In addition to these major documents, we will include comparisons of other standards and guides commonly
used for Power Transformers. It is hoped that the readers would consider harmonizing the standards as best as they can as they develop
these standards for the industry.
Page 2

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Scope 1.1 Single and polyphase transformers
with voltage of 601V or higher in the
highest voltage winding are
governed by the standard.
1.1 Single phase transformers with
rated power less than 1 KVA and
three phase power transformers
less than 5 KVA are not governed
by this standard.
Scope 1.1 The standard does not apply to the
following
Instrument transformers, step
voltage and induction voltage
regulators, arc transformers, rectifier
transformers, specialty transformers,
grounding transformers, mobile
transformers and mine transformers
1.1 The standard does not apply to
following
Transformers with no winding
with rated voltage higher than
1000V, instrument transformers,
traction transformers mounted on
rolling stock, starting
transformers, testing transformers
and welding transformers,
explosion-proof and mining
transformers, transformer for deep
water applications.
When IEC standards are not
available for such categories of
transformers, this part of IEC
60076 may still be applicable.
Word usage 1.2 Paragraph on usage of words shall,
must, should and may in the
specification.
- -
Definitions 3 Reference to C57.12.80 3 Definitions included in standard
Page 3

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Cooling air temperature limit 4.1.2.1
4.1.2.3
For air cooled ambient air
temperature shall not exceed 40°C,
and average temperature of air for
any 24 hr period not to exceed 30°C.
For water cooled ambient
temperature of cooling water not
exceed 30°C and average
temperature for any 24 hr period not
exceed 25°C. Minimum water
temperature shall not be lower than
1°C, unless it includes antifreeze
suitable for -20°C operation.
1.2.2 b) Ambient air not below -25°C and
not above +40°C. For water
cooled water temperature at inlet
not exceeding +25°C.
Liquid temperature limit 4.1.2.2 Not lower than -20°C when
operating
Not addressed
Supply voltage 4.1.4 Harmonic content not addressed. 1.2.2 c) The total harmonic content not
exceeding 5% and an even
harmonic content not exceeding
1%.
Load current 4.1.5 Harmonic factor not exceed 0.05 pu 1.2.2 d) Harmonic content of load current
not exceeding 5% of rated current.
Operation above rated voltage or below
rated frequency
4.1.6, 4.1.6.1 Under full load secondary voltage
and volts /Hz not exceed 105% of
rated, at power factor >.8 &
frequency at least 95% of rated.
4.4.3 Maximum over-fluxing (volts /Hz)
within prescribed Um, of 5%. At
K times rated current (0≤ K ≤ 1)
the over-fluxing will be limited to
(U*fr/ Ur*f) * 100 ≤ 110 -5K
Installation environment - Not addressed 1.2.2 (f) Pollution rate normal (IEC 60137
and IEC 60815), ground
acceleration level is below 2 m/s2)
Max ambient air temperature in an
enclosure ( acoustic enclosure) not
supplied by manufacturer 40°C. Page 4

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Max continuous transformer operating
voltage
4.1.6.2 Limits specified in C84.1 - Not addressed
Step down operation 4.1.8 Unless specified designed for step
down operation.
- Not addressed
Unusual service conditions
Insulation Level 4.3.2.1 Dielectric strength correction factors
in Table1 for altitudes > than 1000m
1.2.1 External insulation at high altitude
in IEC 60076-3 for oil immersed
transformers and IEC 60076-11
for dry type transformers.
Scott-connected or T-connected
transformers
5.3.2 Arrangements used to accomplish
specified.
- Not addressed
Rated KVA 5.4.1 The output that can be delivered at
rated secondary voltage and rated
frequency without exceeding
specified temperature-rise
4.1.1(NOTE) The apparent power input to the
transformer. The power delivered
by the secondary under rated
loading differs from rated power.
Highest system voltage 5.5.1 Listed in Table 4 4.6 Reference to IEC 60076-3 for
highest system voltage.
Transport - Not addressed 4.7.4 Transformer shall be designed to
withstand a constant acceleration
of 1g in all directions.
Categories for tapping voltage variations - Not addressed 5.2 Constant flux voltage variation,
variable flux voltage variation &
combined voltage variation
described.
Rating of transformer taps 5.5.3 Transformers with LTC may have
reduced capacity taps unless
specified otherwise.
5.3 All taps shall be full power taps
except when specified otherwise.
Specification of taps in enquiry and order - Not addressed 5.4 Necessary data required - which
winding tapped , number of steps
and tapping step, category of
voltage variation and whether
maximum current limitation applies.
Page 5

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Specification for short circuit impedance - Not addressed 5.5 For transformers with tapping
range exceeding ± 5% from
principal tapping, impedance
values to be given at principal
tapping and the extreme tapping
exceeding 5%.
Load loss and temperature rise - Not addressed 5.6 For tapping range within ±5% or
rated power not above 2500 KVA
load loss guarantee and
temperature rise refer to principal
tapping. For tapping range > ±5%
or rated power above 2500 KVA
the losses shall be guaranteed at
principal as well as any other
tapping stated and “ maximum
current tapping” to be selected for
temp. rise test.
Connections and phase displacement
symbols
5.7.2 a) Connections are designated as
delta , Y and zig zag. Reference to
C57.12.70 for connection
arrangements.
b) The phasor diagram is oriented
with phase 1 pointing halfway
between 7 and 8 o’clock.
6 Connections indicated by Y, D or Z
for high voltage and y, d or z for
intermediate and low voltage. The
winding connection letter for LV and
intermediate winding is immediately
followed by its phase displacement
clock number. Open windings not
connected together in the transformer
are indicated as III (HV), or
iii(intermediate or low voltage).
Existence of stabilizing winding is
indicated by a symbol +d after
symbols of loadable windings.
b) The high voltage winding phasor
diagram is oriented with phase 1
pointing at 12 o’clock.
Page 6

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Standard reference temperature 5.9 For load losses 85 °C and for no load
losses 20°C
10.1 b) Reference temperature 75°C for
oil filled transformers.
Insulation levels 5.10 Dielectric insulation levels for Class
I and Class II transformers included.
- Not addressed.
Coordination of insulation levels 5.10.2.1 &5.10.2.2 BIL levels, BSL levels included. - Not addressed
Winding, oil, metallic and hot spot
temperature rises
5.11.1.1,5.11.1.3
5.11.1.4
Winding, oil and hot spot
temperature rises above ambient
65°C, 65°C and 80°C. Metallic parts
in contact with current carrying
conductors limited to 80°C.
- Not addressed.
Nameplate information 5.12.2 Three categories
Nameplate A transformer 500KVA
and below and HV BIL less than
150KV
Nameplate B transformer 500KVA
and below not covered above
Nameplate C transformers above
500KVA
7.1 There are no categories.
Nameplate information 5.12.2 Conductor material (for each
winding), installation and operating
instructions reference, step-up
operation suitability and have a
statement for no PCB.
7.1 Not required.
Nameplate information 5.12.2 Not required 7.3 b) Impedance values for extreme taps
for transformers with tapping
range > ±5%
Schematic representation of windings 5.12.3 Schematic representation of single
and three phase windings included.
- Not included. Page 7

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Bushings, CTs and thermometer well 6.1, 6.3, 6.4 Electrical characteristic of bushing
below 34.5 KV included. BCTs to
have ID to accommodate bushings
per C57.19.01. Drawing and
dimensions of thermometer well
included.
- Not addressed
Tank pressure requirements 6.5 For sealed transformer tank pressure
under normal condition not to
exceed 2 atmospheres (14.7 psi .
- Not addressed.
External clearances between transformer
live parts
6.8 Minimum clearance between live
parts of different phases included in
table 11.
- Not addressed.
Short-circuit requirements 7.0 Short circuit duration, calculations
for symmetrical, asymmetrical
currents, temperature during short
circuit and details of system
characteristics included.
- Not addressed.
Dimensioning of neutral connection - Not addressed 8.2 Dimensioned for earth –fault
current for non single phase
loading, for loading between
phase and neutral dimensioned for
load current and earth-fault
current.
Load rejection of generator transformer - Not addressed 4.3 During load rejection able to
withstand 1.4 times rated voltage
for 5s at the transformer terminals.
Liquid preservation system 6.6.2 Types specified reference to
C57.12.80 for description.
8.3 Different liquid preservation
systems described. Free breathing
or conservator, diaphragm, inert
gas pressure, sealed –tank system
and sealed. Page 8

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
DC currents in neutral circuits - Not addressed 8.4 The sources of DC current and the
consequences of DC currents in
the neutral described.
Center of gravity - Not addressed 8.5 Center of gravity markings on two
adjacent sides of the transformer
Thermal duplicate temperature-rise data 8.5 Criteria for thermal duplicate. - Not addressed.
Tolerance for losses 9.3 No load losses +10%
Total losses +6%
9(1) Component losses +15%
(provided that the tolerance for
total losses is not exceeded)
Total losses +10%
Tolerances ratio 9.1 Transformer at no load
0.5% of the nameplate voltage.
When the volts per turn of the
winding exceeds 0.5% of the
nameplate voltage, the turns ratio of
the winding shall be to the nearest
turn.
9(2) At no load on principal tapping
Lower of
a) ± 0.5 % of specified ratio
b) ±1/10 of actual percentage
impedance on the
principal tapping
Other taps (same pair) ± 0.5% of
design value of turns ratio
Other taps(further pairs) ± 0.5%
of design value of turns ratio Page 9

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Tolerances impedance 9.2 Two winding transformer
Impedance of transformer > 2.5%
Tolerance ±7.5%
Impedance ≤ 2.5% , Tolerance ±10%
Three winding, zig –zag winding
and auto-transformers tolerance
±10%
9(3) & (4) Two winding transformer
a) Principal tapping
Impedance value is ≥ 10%
tolerance ±7.5%
Impedance value <10%
Tolerance ±10%
Any other tapping of the pair
Impedance value is ≥ 10%
tolerance ±10.0%
Impedance value <10%
Tolerance ±15%
Multi-winding & auto transformer
Principal tapping ±10% of
specified value
Any other tapping of the pair
±10% of the design value for that
tapping
Other pairs of winding , to be
agreed but ≥ 15%
Tolerance no- load current - Not addressed 9 (5) +30% of the declared value
Tests on on-load tap-changers- operation
test
- Not addressed 10.7 Operational tests on the LTC with
the transformer energized and deenergized.
Check of core and frame insulation 8.2 Table 18 Measurement of insulation resistance
between core and ground at 500 V
DC for 1 min.
10.12 Where core and frame connections
are not accessible test at 500V DC
for 1 min before active part is
installed in the tank.
When the core and frame
connections are accessible the
insulation shall be tested at
2500V DC for 1 min after
transformer is filled with liquid. Page 10

Comparison of Standards – ANSI / IEEE and IEC
C57.12.00-2010 with IEC 600076-1 (2000)
Vinay Mehrotra / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
C57.12.00-2010 IEC 60076-1
Leak , vacuum and pressure test on tank - Not addressed 10.8,
10.9,10.10
Details of leak, vacuum and
pressure test with deflection
included.
Electromagnetic compatibility - Not addressed 11 Transformers considered as
passive elements in respect to
emission of, immunity to
electromagnetic disturbances.
High frequency switching transients - Not addressed 12 Lightly loaded and /or low power
factor transformers with vacuum
and SF6 interrupters may subject
the transformer to high frequency
transients.
Informative Annexes- Facilities for
condition monitoring and environmental
and safety considerations
- Not addressed Annex F &
Annex G
Facilities for future fitting of
condition monitoring systems to
transformers and environmental
and safety considerations
included.
Page 11

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
Test General
- Routine Test C57.12.00
Table 18
Class I ( 69 KV and below) :
Ratio-Polarity
winding Resistance
Positive Seq Impedance , Load loss
No load loss and current
Low frequency Dielectric Tests
Operation of all devices
Leak test
Class II (115 KV through 765KV):
Ratio-Polarity
winding Resistance
Insulation PF
Core Megger
Winding Megger
Positive Seq Impedance , Load loss
Zero Sequence Test
Partial Discharge ,
Lightning Impulse
Low frequency Dielectric Tests
Low frequency test on control wiring
/ CT
Operation of all devices
Leak test
DGA
>=345KV : Switching Impulse
IEC 60076-1
10.1.1 &
IEC60076-3
Ratio Polarity
Winding Resistance
Zp , Load loss
No load loss and current
Routine Dielctric Tests *
Tests of Tapchanger
*
Um <=72.5 KV
Short duration AC ( ACSD )
Separate source
72.5 KV < Um <=170
Lightning Impulse
Short duration AC ( ACSD )
Separate source
170 KV < Um <=300
Lightning Impulse
Switching / ACSD
Long duration AC ( ACLD )
Separate source
Um >=300
Lightning Impulse
Switching
Long duration AC ( ACLD )
Separate source
Page 12

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
- Design Test / Type Tests Table 21 Sound Test
Temperature rise
Pressure Test
10.1.1 2 Temperature rise
Dielectric type test
- Other tests / Special Tests Table 21 Class I :
Insulation PF
Core Megger
Winding Megger
Short circuit ,
Sound Test ,
Single Ph excitation test
Switching Impulse,
FOW,
Low frequency test on control wiring
/ CT
Temperature rise
DGA
Class II :
Short circuit ,
Sound Test ,
Switching Impulse ( < 345KV )
FOW
Temperature rise
10.1.1 Sound Test
Insulation PF
Zo
Short circuit
Control losses
Harmonics
Megger and/or Tan delta
Page 13

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Tolerances
Ratio C57.12.00
9.1
1. Within +/-0.5 % of Name
plate for all
2. for Volts per turn exceed
0.5 % of NP voltage , turn
ratio of winding shall be the
nearest turn
IEC60076-1: 1993
9
Rated tap :
Lower of
a) +/0 0.5 % of declared ratio
b) +/- 1/10
th
of actual
impedance of Rated tap
Other Tap : agreement between
supplier and buyer but not lower
than a and b
Impedance C57.12.00-
9.2
Two wdg with
Z > 2.5 % = +/- 7.5 %
Z < 2.5 % = +/- 10 %
Three / Zig Zag , Auto
Z > 2.5 % = +/- 7.5 %
Z < 2.5 % = +/- 10 %
( of specified values )
IEC60076-1: 1993
9
Two wdg / first pair of multi wdg
( Principal Tap )
Z > 10 % = +/- 7.5 %
Z < 10 % = +/- 10 %
Two wdg /first pair of multi wdg
( other Tap )
Z > 10 % = +/- 10 %
Z < 10 % = +/- 15 %
Auto / second pair of multi wdg (
Principal Tap ) = +/- 10 %
Auto / second pair of multi wdg (
other Taps ) = +/- 15 %
(of declared values )
Losses C57.12.00-2006
9.3
No load – not to exceed 10 % of
specified
Load loss – not to exceed 6 %
Not a criteria for rejection
IEC60076-1: 1993
9
Total losses : + 10 % with
individual components less than +
15%
No load current No mention +30 % of declared values


Page 14

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
General
Test Sequence C57.12.90 sec 4.3 &
sec 10.1.5.1
Lightning impulse and switching
impulse ( when required ) shall
precede low frequency .
Having Heat run and losses ahead of
dielectric has advantage of low risk
of damage , but sequence is flexible
Ratio C57.12.00 sec 8.3.1 At all position of DETC to Rated
LTC
All LTC position to Rated DETC
IEC 60076-1
10.3
Measure for each tapping
C57.12.90 sec 6. Detailed method of how to test
polarity and phase relationships is
included

Resistance Measurement
Test environment C57.12.90-2006
5.1.2
Measure cold resistance after
minimum 3 hours with no excitation
and current in winding. ( 1 hr for trf
with pumps )
Top & BTM difference shall not
exceed 5 degree
IEC60076-1: 1993
10.2.3
Measure cold resistance after 3
hour minimum with no excitation
Measurement method 5.3 Bridge and Volt-amp method No methodology specified

Loss Accuracy requirement C57.12.90/C57.12.00
9.4
Correction for Temp and phase angle
error is provided
Page 15

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements


No load test
Waveform correction C57.12.90- 8.3 PC (Tm) = Pm /(P1+kP2 )
K = (RMS volt / Average Volt )
2
P1:P2 = 0.5
IEC60076-1: 1993
10.5
P0
= Pm (1+d )
d= ( RMS volts – Average Volt )
/RMS volts
Maximum Waveform correction C57.12.90-
8.3
Max magnitude of correction : 5 % IEC60076-1: 1993
10.5
Max difference in Voltmeter
reading shall be below 3 %
Ambient for No Load test C57.12.90-
8.4
Average oil within +/- 10 deg of
reference temp ( 20
0
C ).
Difference between top and Bottom
oil temp does not exceed 5
0
C
Empirical formula is provided for
correction outside the range
IEC60076-1: 1993
10.5
Approximately at factory ambient
temp
No Temperature correction
Measurement of harmonics No Requirements IEC60076-1: 1993
10.6
Required to be measured as
percentage of fundamental
components – No limits
Frequency for testing C57.12.90-
8.2.4
Test source frequency shall be under
+/- 0.5 % of rated frequency.
Correction for 50/60 Hz in Annex B
IEC60076-1: 1993
10.5
Rated frequency – No tolerance
specified.
Excitation current C57.12.90-
8.5
Expressed in per unit or % of rated
line current ( lowest rating )
Page 16

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Load loss & Impedance
Min Load current IEC60076-1: 1993
10.4
50 % of rated current
Ambient conditions for test C57.12.90-
9.3
Top and Btm Oil difference not to
exceed 5
0
c.
Frequency of test source within +/-
0.5 % of nominal
IEC60076-1: 1993
10.4
Top and Btm Oil difference shall
be small
Impedance on Other Taps C57.12.00-
Table 19
Extreme tap measurement required
on first unit.
IEC60076-1: 1993
10.4
If tapping range exceed +/- 5 % ,
impedances on two extreme taps
are also required
Methods of measurement C57.12.90
9.3
Detailed Methodology provided References IEC 60606
Zero Sequence Test
Unit of measure C57.12.90-2006
9.5.1
Reported in % of KVA base IEC60076-1: 1993
10.7
Expressed in ohms per phase
Test procedure for windings with
two neutral
C57.12.90-2006
9.5.3
Minimum of three tests are specified
to arrive Z1 , Z2 , Z3
IEC60076-1: 1993
10.7
Testing based on agreement
between manufacturer and
purchaser.
Page 17

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Tests on Tap changer No Test Procedure and acceptance
criteria is defined
IEC60076-1: 1993
10.8
Deenergized 8 cycles ; denergised
85 % Aux Voltage 1 cycle ;
energized 1 cycle ; rated current –
10 opeartions across
reversing/coarse-fine tap
EMC No Test Procedure and acceptance
criteria is defined.
IEC60076-1: 1993
11
Transformer is considered as
passive but accessories may be .
But no guideline of handling or
test required is provided.
Insulation Power factor Test C57.12.90-
10.10
Test Procedure is outlined , no limits
Measure between 10 and 40 C (
close to 20 ) . temp Correction factor
removed from 2010 std
Not listed
Insulation Resistance Test C57.12.90-
10.11
Test Procedure is outline , no limits
Correction table for Temp is
included
Not listed
Single Phase Excitation Test No Procedure is outlined , though it
is listed as other test in C57.12.00
Not listed
Control wiring megger Table 1.5 KV AC 60 Hz , CT @ 2.5 KV IEC60076-3: 2000
9.0
2 KV for 1 minute
Page 18

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Dielectric Test General
Ambient C57.12.90-10.1.5.2 Temp assumed at normal operating
condition or condition of routine test
IEC60076-3: 2000
4
Approximately at ambient , but not
lower than 10
0
C
Dielectric level for unit in service Class I : 85 % of test level or 150 %
operating stress .
Class II : Not more than 150 % - 5
min; 140 % -12 min ; 130 % - 36
min ; 120 % -120 min
IEC60076-3: 2000
9.0
80 % of Original Value

Applied Voltage
( Separate source )
C57.12.90-2006
10.6.
No significant difference except
Voltage levels
( Note : Test levels and BILs
comparisons are covered under
C57.12.00 comparison )
IEC60076-3: 2000
11.0
No significant difference except
Voltage levels
Page 19

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Induce Test
Duration
Class I IEEE / ACSD IEC
C57.12.90
10.7.1
7200 cycle ( same as IEC only for 60
Hz )
Min test time : Not specified ( max
test freq )
Max Test time : 60 sec
IEC60076-3: 2000
12.1
120 X Rated Freq / Test frequency,
Min test time : 15 sec
Theoretical Max test time : 120
sec ( when Rated freq and test
frequency are same )
Class II C57.12.90
10.8.5
PD Acceptance limit :500 pC @
approx Ph-Ph Volts of 1.5 X Um
IEC60076-3: 2000
12.2.2
PD Acceptance limit :300 pC @
ph-ph Volts of 1.3 X Um ( 1.2 Um
incase of Um > 420 KV)
PD Acceptance limit :100 pC @
1.1 X Um
Non Uniform Insulated windings Not defined IEC60076-3: 2000
12.2.2
Two tests required :
1. Phase to Earth
2. Phase to phase


Page 20

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Impulse
Lightning Sequence ( Line ) IEEE C57.12.90
10.3
Line RFW, CW , CW , FW IEC60076-3: 2000
13.2
RFW , FW , FW , FW
Impulse Tap IEEE C57.12.90
10.3.2.4
Minimum effective turns in the
winding under test.
IEC60076-3: 2000
8.0
Tapping range is +/- 5 % or less :
Principal Tap
Tapping range is larger than +/- 5
%: Principal Tap & two extremes
Lightning Sequence ( Neutral ) IEEE C57.12.90
10.3.3
Line RFW, FW , FW
( for 200 BIL and above per IEEE
C57.12.00 5.10.7.1)
IEC60076-3: 2000
7.4.2 /7.4.3
Directly Earthed Neutral : Not
Recommended
Not directly earthed : Impulse
verified by either direct method
and indirect method.
Chopping time C57.12.00-2006
Table 6
> 110 BIL : Min 3 us ;
125 BIL : Min 2.3
< =110 BIL class 2: Min 2 us
95 BIL class I : Min 1.8us
< 95 BIL class I : 1.5 us
IEC60076-3: 2000
14.2
Between 2 and 6 microsecond
Switching Sequence IEEE C57.12.90
10.2.1
Line RSS, SS , SS IEC60076-3: 2000
14.2
RSS , SS , SS, SS
Switching Sequence ( polarity ) IEEE C57.12.90
10.2.2.1
negative IEC60076-3: 2000
15.1
negative Page 21

Comparison of Standards – ANSI / IEEE and IEC – Transformer Testing
C57.12.00-2010 section 8 & 9 and C57.12.90-2010 with IEC 600076-1 (2000) and IEC60076-3(2000)
Ajith Varghese / Waukesha Electric Systems
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Sound Test C57.12.90-
13
60076-10 (2001-
05)

Test Method C57.12.90-
13.1.1
Sound Pressure levels – A weighted,
octave , discrete frequency
60076-10 (2001)
sec 5.0
Both Sound Pressure and Sound
Intensity are Valid and is to be agreed
between manufacturer and purchaser
Load Condition C57.12.90-
13.3.3
No Load 60076-10 (2001)
sec 6.1
To be agreed between manufacturer
and purchaser
Test Tap C57.12.90-
13.3.4
Principal unless agreed differently 60076-10 (2001)
sec 6.2
Principal unless agreed differently
Measurement contour C57.12.90-
13.4.1
0.3 m for sound producing surface
2 m for fans
One measurement at half height for
2.4 m and below ; two at 1/3 and 2/3
for higher.
Microphone 2 meter apart ; min 4
60076-10 (2001)
sec 8
0.3 m for sound producing surface
2 m for fans
One measurement at half height for
2.5 m and below ; two at 1/3 and 2/3
for higher.
Microphone 2 meter apart ; min 6
Rated / Reduced Current Test No methodology provided 60076-10 (2001)
sec 6.3
Load test by short Circuiting one
winding .
Log addition of NL and Load sound
to arrive at sound during operation .
Not Required if “ 39+ 18 ( log MVA
) ” is 8 dB lower than guarantee
Sound Intensity Measurement Not defined 60076-10 (2001)
sec 12
Allow sound intensity measurement
Sound Power level Not defined 60076-10 (2001)
sec 12
Formula is provide to estimate Sound
Power level based on pressure or
intensity measurement
Ambient sound correction C57.12.90-
13.3.1(table 7)
Allows 0 to -1.6db correction for
ambient to transformer sound
difference of 10 to 5 db
C57.12.90-2006
13.4.1
If the difference is between 3db and 8
db , correction is applied based on
formula involving ambient to tested
sound level and environmental
correction factor k which depend of
sound reflection from surfaces.. Max
allowable K is 7 db.
Page 22

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standards Requirements Standard Requirements
C57.130/D17
(2006)
61181
(2007)
- Scope of document 1.1 Mineral-oil filled transformers &
reactors
1 Mineral-oil filled new power transformers,
reactors ad instrument transformers
- Factory tests 1.2 y Factory temperature rise tests
(C57.12.90)
y No data from overload temperature
rise tests – may or may not be
applicable. (IEEE C57.119)
1 y Temperature-rise (heat run), overloading
tests – power transformers & reactors
y Impulse tests – instrument transformers
- Basis of gas levels – Data 1.2
6.3
y 95% confidence with “limited
database”
y Oil volume and voltage rating were
not factors taken into account
1
2
Annex A
y References CIGRE reports
y References other IEC documents
y Gas generation rates given are values
observed in 90% of the xfmrs tested
-Use of standard 1.2 y Guidance document – acceptable
levels should be made by user and
manufacturer
y Trial use
1 y Specifically for long-term dielectric tests
y electrical and acoustic methods more
sensitive than DGA before and after
short-term dielectric tests
- Oil sample collection 3 Sample in accordance with ASTM
D3613, duplicates are preferred
4.1 Sample in accordance with IEC 60567,
duplicates are preferred
- Oil sample containers 4.2 y Gas-tight glass syringe fitted with threeway sampling cock
y Other containers that conform to IEC
60567
- Oil sample location 5.2 Near the direct path of the cooling oil. If
not possible, the bottom drain valve
4.3 y Power xfmrs – ground level pipes
circulating oil through radiators
y NOT BOTTOM VALVE of TANK
- Drain amount before sample collection 4.3 y Syringe - At least 2 liters
y Bottles – twice the volume of bottle or 5
liters
Page 23

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standard Requirements Standard Requirements
C57.130/D17
(2006)
61181
(2007)
- Sampling frequency 5.3 y Before the temperature rise test
y After the load is shut down or 2 to 6
hours after the load is shut down.
y Intermediate sampling during test
4.4 y Thermal tests on power xfmrs – before
& after test. Intermediate sample
frequency is left to the user to decide.
y Suggested stages of sampling
- After filling xfmr with oil
- 1 day to 1 week after filling
- Before start of thermal test
- Every 2 hrs during test
- End of test
- 24+ hrs after test is complete
y Impulse tests on instrument xfmrs –
before chopped lightning-impulse test
and 72 hrs after the test
- Sample labeling 4.5 y Identification of equipment
y Date and time of sampling
y Nature of factory test
y Sampling point
y Top oil temperture
- Sample storage 6 Samples should be analyzed asap,
preferably within 24 hours.
4.6
6
y Shield from direct sunlight
y Samples should be analyzed asap and
no later than seven days after sampling
Page 24

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standard Requirements Standard Requirements
C57.130/D17
(2006)
61181
(2007)
- factors affecting gassing rate during thermal
tests
5 y Design of windings, leads, magnetic
circuit and structural elements
y Oil to cellulose ratio
y Paper type
y Oil type
y Paints, glues, material of some xfmrs
y Cooling method and efficiency
y Test duration
- Gases to measure during DGA 3 y Hydrogen
y Methane
y Ethane
y Ethylene
y Acetylene
y Carbon monoxide
y Carbon dioxide
y Oxygen
y Nitrogen
6 y Hydrogen
y Hydrocarbons
y Carbon monoxide
y Carbon dioxide
y Oxygen
y Nitrogen
- Acceptable concentrations 3 y Acetylene must be none detected
- Detection limits for factory tests y 6 y Hydrogen 2 ul/l
y Hydrocarbons 0.1
y Carbon monoxide 5
y Carbon dioxide 10
y Oxygen 500
y Nitrogen 2000
- Analysis methods 4 ASTM 3612 6 IEC 60567 gas chromatography
Several adaptations are recommended from
the 60567 methods (Toepler and partial
degassing)
Page 25

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standard Requirements Standard Requirements
C57.130/D17 61181
- Determination of generated component
concentrations
6.1 Initial minus final concentration in ppm
y {H2}=H2 initial – H2 final
y {HC}= (CH4+C2H4+C2H6)initial
-
(CH4+C2H4+C2H6)final
y {CO}=CO initial – CO final
y {CO2}=CO2 initial – CO2 final
Annex B 90% typical gas concentration increases
observed in chopped lightning-impulse
tests (ul/l)
y H2 15
y CH4
4
y C2H4
1
y C2H6
1.5
y C2H2
0.5
y CO 15
- Determination of average generation rates 6.2 Generation rates are determined by
dividing the volume (ppm) of each
component by the heat run interval in
hours (tf
– t0)
y [H2]={H2}/t
f – t0
y [HC]={HC}/t
f – t0
y [CO]={CO}/t
f – t0
y [CO2]={CO2}/tf – t0
Annex A Note: IEC includes acetylene in the
hydrocarbon total and state that it is
typically not generated during the tests
Cn = CH4+C2H4+C2H6+C2H2
- Application of Gas generation rate
guidelines
6.3 Applicable to xfmrs built in accordance
with IEEE stds
y 65°C AWR
y 65°C TOR
y 80°C HSR with an average ambient
temp of 30°C

- Gas generation rate guidelines 6.3 Condition 1 (no problem detected)
ppm/hr
y [H2] <0.8
y [HC] <0.5
y [CO] <2.0
y [CO2] <20.0
Annex A 90% typical rates of gas in modern power
transformers during thermal tests
ul/l/h
y H2 0.1 – 1.3
y Cn
0.04 – 0.3
y Cn + H2
0.1 – 1.6
y CO 0.4 – 2
y CO2 5 – 18
Page 26

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standard Requirements Standard Requirements
C57.130/D17
(2006)
61181
(2007)
6.3 Condition 2 (possible problem)
Test duplicate sample. Investigate cause
by reviewing temperature rise results.
Extend test duration.
y [H2] ≥0.8, <1.5
y [HC] ≥0.5, <1.0
y [CO] ≥2.0, <5.0
y [CO2] ≥20.0, <40.0
Annex A 90% typical rates of gas in modern shell
type transformers during thermal tests
ul/l/h
y H2 0.1 – 1.3
y Cn
0.04 – 0.3
y Cn + H2
0.1 – 1.6
y CO 4
y CO2 5 – 18
6.3 Condition 3 (certain problem)
Mfg and customer conference. A
thermal fault exists. Corrective action
and repeat temperature rise tests.
y [H2] ≥1.5
y [HC] ≥1.0
y [CO] ≥5.0
y [CO2] ≥40.0
Annex A 90% typical rates of gas in modern special
cases (material compatibility problems
such as paint) during thermal tests
ul/l/h
y H2 0.7
y Cn
0.5
y Cn + H2
2.2
y CO 5
y CO2 20
Report should include the following 7 y Testing laboratory
y Identification of equipment tested
y Sampling location
y DGA results on each sample, in ul/l or
umol/l (total volume of gas, oxygen
and nitrogen may conveniently be
expressed in percent of oil volume)
y Rate of generation of gases in ul/l/h
Page 27

Comparison of Standards – IEEE and IEC
DGA during Factory (Temperature Rise) Tests of Mineral Oil Immersed Electrical Equipment
H Moleski / SD Myers Inc.
Subject Issue IEEE IEC
Standard Requirements Standard Requirements
C57.130/D17
(2006)
61181
(2007)
Follow up of cases with problems during or
after put back in service. Core-type power
transformers (ul/l/h)
Annex A Cn+H2 Total # # problem cases
y <0.5 215 1
y 0.5 – 1 36 1
y 1 – 2 21 4
y 2 – 5 12 4
y 5 – 10 4 2
y >10 3 3
Page 28

Comparison of Standards – ANSI / IEEE and IEC – High Temperature Liquid-Immersed Transformers
R. P. Marek / DuPont Energy Solutions
Subject Issue ANSI / IEEE IEC
Standards Description / Requirements Standard Description / Requirements
Std 1276 TS60076-14
General Title Guide Title Technical Specification (similar to
IEEE “Trial Use” document)
Scope Applies to power transformers
insulated with mineral oil
Scope Applies to standard and convertor
transformers larger than 1 kVA,
insulated with mineral oil, silicone
oil or ester liquid
Definitions Not defined 3.5 conventional
adjective that refers to temperature
rise limits and insulation materials
applied in systems
consisting of mineral oil and nonthermally upgraded paper
3.5 high-temperature: Used to describe
materials, insulation systems, and
transformers that are designed to
operate at a maximum hottest-spot
temperature above 120 °C.
3.7 high-temperature
refers to temperature rise limits
and insulation materials applied in
systems consisting of solid
materials and/or liquid operating at
higher temperatures than
conventional
3.6 high-temperature insulation
system: An insulation system
composed of all high-temperature
solid insulation materials, with or
without high-temperature fluids.
Not defined
Page 29

Comparison of Standards – ANSI / IEEE and IEC – High Temperature Liquid-Immersed Transformers
R. P. Marek / DuPont Energy Solutions
Subject Issue ANSI / IEEE IEC
Standards Description / Requirements Standard Description / Requirements
Std 1276 TS60076-14
3.8 hybrid high-temperature insulation
system: An insulation system
usually composed of hightemperature solid insulation material
adjacent to winding conductors and
cellulose materials in the areas
where the maximum temperature at
rated load does not exceed 120 °C.
This system typically uses
conventional mineral oil as the
insulating liquid.
3.8 hybrid insulation system
high-temperature solid insulation
material adjacent to all winding
conductors either bare or insulated
(including all conductor insulation,
spacers, strips and cylinders in
direct contact with the winding
conductor) and cellulose-based
materials in lower temperature
areas where thermal class 105
limits are met
Not defined 3.9 semi-hybrid insulation system
high-temperature materials used
only for conductor insulation
Not defined 3.10 mixed insulation system
high-temperature solid insulation
material adjacent to the winding
conductors located in the hotter
regions (including all conductor
insulation and, if necessary,
spacers, strips and
cylinders in contact with these
conductors) and cellulose-based
materials in the rest of the winding
and other lower temperature areas
where thermal class 105 limits are
met
Page 30

Comparison of Standards – ANSI / IEEE and IEC – High Temperature Liquid-Immersed Transformers
R. P. Marek / DuPont Energy Solutions
Subject Issue ANSI / IEEE IEC
Standards Description / Requirements Standard Description / Requirements
Std 1276 TS60076-14
Not defined 3.11 homogeneous insulation system
high-temperature insulation used
in all areas exposed to
temperatures higher than would be
suitable for conventional insulation
systems together with hightemperature insulating liquid
Insulation information No equivalent Table 1 Typical properties of solid
insulation materials
5.6 High-temperature solid and wire
insulation and their interaction with
mineral oil
and other high-temperature fluids
Table 2 Typical enamels for wire
insulation
No equivalent Table 3 Typical performance
characteristics of unused
insulating liquids
Temperature limits Table 1 Maximum temperature limits for
various (hybrid) insulation
systems
Table 4a Temperature limits for
transformers with mineral oil or
alternative liquid operated at 60
K top liquid temperature rise
a. Maximum temperature rise
limits
No equivalent Table 4b b. Maximum overload
temperature limits
Page 31

Comparison of Standards – ANSI / IEEE and IEC – High Temperature Liquid-Immersed Transformers
R. P. Marek / DuPont Energy Solutions
Subject Issue ANSI / IEEE IEC
Standards Description / Requirements Standard Description / Requirements
Std 1276 TS60076-14
No equivalent Table 5a Temperature limits for
transformers with homogeneous
high-temperature insulation
systems
a. Maximum temperature rise
limits
No equivalent Table 5b b. Maximum overload
temperature limits
Insulation-system temperature ratings for
high-temperature rise systems
5.2 Bubble generation Annex A Calculation of bubble generation
temperature
Aging test procedure for material
qualification
5.4 Defines TUK life curve for cellulose
and criteria for paper and enamel
3.6 thermally upgraded paper (TUP)
…
Loading information 6.0 Loading guides for high-temperature
transformers
8.4 Overload
Transformer accessories and compatibility No equivalent – not necessary since
all accessories interface with mineral
oil operating at normal temperatures
7.0 General notes about hightemperature application
No equivalent 8.0 Special design considerations
- General notes on hightemperature application
- maximum permissible short
circuit temperature for category I
transformers with high-temperature
liquids covered by Table 5 is 350
°C.
Required information 7.0 Description of high-temperature
transformers – mostly for repair units
9.1 Information to be provided by the
purchaser
Page 32

Comparison of Standards – ANSI / IEEE and IEC – High Temperature Liquid-Immersed Transformers
R. P. Marek / DuPont Energy Solutions
Subject Issue ANSI / IEEE IEC
Standards Description / Requirements Standard Description / Requirements
Std 1276 TS60076-14
No equivalent 9.2 Information to be provided by the
manufacturer
Nameplate information 8.0 Nameplate information
Additional information required for
high-temperature
10.0 Rating plate and additional
information
Testing 9.0 Heat run test and average winding
temperature
11.0 Testing
Gas analysis Annex A Gas analysis No equivalent
Page 33

C57.131-1995 Vs. IEC 60214-1 Comparison
Bill Henning / Waukesha Electric Systems
Synonyms
IEEE C57.131
(Revision)
IEC 60214-1
(Current Version)
Definition
Arcing switch Diverter switch A switching device used in conjunction with a tap selector to
carry, make, and break current in circuits that have already
been selected.
Arcing tap switch Selector switch A switching device capable of carrying current and also
breaking and making current while selecting a tap position. It,
thereby, combines the duties of a diverter switch and a tap
selector.
De-energized tap
changer (DETC)
Off-circuit tap changer A device for changing the tap of a winding, suitable for
operation only when the transformer is de-energized.
Externally mounted tap
changer
Air environment tap
changer
A tap changer mounted in a container outside the main
transformer tank and immersed in its own insulating liquid.
Internally mounted tap
changer
liquid environment tap
changer
A tap changer mounted inside the main transformer tank and
immersed in the insulating liquid of the transformer
Load tap changer
(LTC)
On-load tap changer
(OLTC)
A device for changing the tap of a winding, suitable for
operation while the transformer is energized or on load.
Reversing switch Reversing change-over
selector
A change-over selector that connects one or the other end of
the tap winding to the main winding. Page 34

. C57.131-1995 Vs. IEC 60214-1 Comparison
Bill Henning / Waukesha Electric Systems
The definition of step voltage given in IEC 214 (1989) and IEC 60214-1 is: “The step voltage is the voltage between adjacent tap changer
terminals.”
IEEE C57.131-1995 provides a slightly different definition of the term step voltage, shown below.
Rated step voltage (according to C57.131-1995):
For each value of rated through current, the highest permissible voltage between successive tap positions.
NOTE : Step voltage of resistance type LTCs means tap to tap voltage (no bridging position).
The IEC definition clearly defines step voltage in terms adjacent (tap changer) terminals, while the IEEE definition refers to tap positions. This
ambiguity is being addressed in the current revision of C57.131.
Key Differences between C57.131-1995 and IEC 60214-1
Terminology: Fluid versus Liquid
IEC 60214-1 uses the term liquid whereas C57.131-1995 uses fluid in all references to the insulating medium.
Scope
In addition to LTCs, IEC 60214-1 covers de-energized tap changers (DETCs). C57.131-1995 does not cover de-energized tap changers.
Short Circuit Current Test
IEC 60214-1 places a tolerance of ±10% on the 2 second duration of the test current. C57.131-1995 requires a 2 second duration but does not place
on tolerance on the duration.
Transition Impedance Test
IEC 60214-1 provides a limit of 350 ºC for the resistor in internally mounted LTCs and a limit of 400 ºC for externally mounted LTCs. C57.131-
1995 places a limit of 350 ºC period. (No distinction between internally or externally mounted LTCs) Page 35

C57.131-1995 Vs. IEC 60214-1 Comparison
Bill Henning / Waukesha Electric Systems
Mechanical Endurance Test
IEC 60214-1 states that at least 50,000 tap change operations shall be carried out on the change-over selector. C57.131-1995 gives this number as 15,
625 operations of the change-over selector.
Tightness Test
IEC 60214-1 specifies a tightness test to assure that dissolved gases due to arcing in the tap changer compartment do not enter the transformer main
tank and effect DGA results. C57.131-1995 does not require this test.
Auxiliary Circuits Insulation Test
IEC 60214-1 requires that this test be done at 2.0 kV. C57.131-1995 requires that this test be done at 1.5 kV.
C57.131 Annex Information
Annex A Switching Duty Relating to Load Tap Changers with Resistor Transition
This annex shows phasor diagrams of the voltages and currents during tap change operations for flag cycle and pennant cycle types. A table (Table
A.1 Duty on Main and Transition Contacts for Resistance Type LTCs) indicates the current and voltage magnitudes, corresponding to the phasor
diagrams, for the current switched and the recovery voltages across the various contacts during tap change operations for flag cycle and pennant
cycle, arcing switch and arcing tap switch constructions. These tables for C57.131-1995 and IEC60214-1 are identical, except that IEC60214-1 has
one additional major row for a selector switch with asymmetrical pennant cycle (1 resistor). C57.131-1995 does not contain this row of information.
Page 36

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standards Requirements Standard Requirements
Temperature Rise Limits C57.12.00-2010
C57.12.90-2010
IEC 60076-2:
2011
- Tap position 5.11.1.1 Max. average winding temperature rise
tapping = Highest loss tapping
Ditto for the winding hot-spot rise
6.2 - Tapping range ≤ ±5% and Sr ≤
833 kVA/phase:
Principal tapping
- Tapping range >±5% or Sr > 833
kVA/phase:
Max. temperature rise tapping
- Ambient temperature Not addressed.
In other parts of IEEE: 30 °C
6.2 20 °C yearly average
- Top oil rise 5.11.1.4 65 K 6.2 60 K
- Average winding rise, non-upgraded insulation
* ON and OF
* OD
Not addressed
Not addressed
6.2
6.2
65 K
70 K
- Average winding rise, upgraded insulation
* ON and OF
* OD
5.11.1.1
5.11.1.1
65 K
65 K
6.2
6.2
65 K
70 K
- Winding hot-spot rise
* non-upgraded insulation
* upgraded insulation 5.11.1.1
Not addressed
80 K
6.2
6.2
78 K
78 K
- Rises of metallic parts other than
windings
5.11.1.3 - Parts in contact with current
carrying conductor insulation: 80 K
- Other parts: “shall not attain
excessive temp. rises at rated load”
6.2 “...shall not reach temperatures which
will cause damage to adjacent parts or
undue aging of the insulation liquid.”
- Reduction of Temperature Rise Limits
* Altitude correction for over 1000 m 11.4.3 Temperature rises increased by Equation
(32)
6.3.1 - Limit reduced by 1 K / 400 m for
...AN
- Limit reduced by 1 K / 250 m for
...AF
* Elevated ambient temperatures Not addressed 6.2 Limits reduced by the same amount as
the excess of 20 °
- 10 K for amb. temp. 30 °C etc.
Page 37

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Temperature Rise Test, Ambient
Temperature
C57.12.90-2010 IEC 60076-2:
2011
- Test room air temperature, ..AN, ..AF 11.3.1.1 Air between 10 °C and 40 °C 7.2.1 - Air between 10 °C and “the
maximum ambient temperature for
which the transformer is designed”
- Cooling water temperature, ..WF 11.3.1.2 Water between 20 °C and 30 °C 7.2.2 Water between 5 °C and “the
maximum water temperature for
which the transformer is designed”
- Number of sensors, ..AN, ..AF 11.3.1.1 At least 3 sensors 7.2.1 At least 4 sensors (for large units 6
sensors)
- Height level of sensors, ..AN; ..AF 11.3.1.1 “about mid-height of the transformer”
“1 m to 2 m from the transformer”
7.2.1 ...AN: “about halfway up the cooling
surfaces and about 2 m from the
perimeter of tank and cooling
surfaces”
...AF: “in the air at about 0.5 m from
the intake of the coolers”
- Location of sensors, ..WF 11.3.1.2 “the temperature of the incoming and
outgoing water, shall be measured”
7.2.2 “temperature shall be measured at the
intake of the cooling equipm.”
Temperature Rise Test, Total Loss Phase C57.12.90-2010 IEC 60076-2:
2011
- Steady state criterion 11.3.2 Top liquid temperature rise variation
below 2.5 % or 1 K, whichever is
greater, during consequtively 3 h
7.3.2 Change of top liquid temperature
below 1 K / h during 3 h
- Measurement of top oil temperature 11.3.2 One sensor 50 mm below top liquid
surface
7.4.1 - Measurement in the pockets:
< 6.7 MVA / phase ⇒ 1 pocket
6.7 MVA / phase ≤ Sr < 33 MVA
/ phase ⇒ 2 pockets
≥ 33 MVA / phase ⇒ 3 pockets
- Or by agreement:
As an average of the pockets and
the liquid in the centre of the
pipes to the cooling equipment
Page 38

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Temperature Rise Test, Total Loss Phase C57.12.90-2010 IEC 60076-2:
2011
- Measurement of bottom oil temperature
* Transformers with external coolers


* Transformers without external coolers
(plain or corrugated tanks)
11.3.2

11.3.2
One sensor in an inlet pipe from a
common header or from one radiator in
the middle of the bank
“thermocouples on the tank wall at the
elevation of the bottom of the winding”
7.4.2

7.4.2
Sensors fitted in one or several bottom
pipes (if there are more than one pipe)
Not addressed
- Determination of average oil temperature
rise
* Transformers with external coolers

* Transformers without external coolers
(plain or corrugated tanks)
11.3.2
11.3.2
Top oil temperature rise – 0.5 x (Top
pipe – Bottom pipe)
Top oil temperature rise – 0.5 x (Tank
surface at winding top – Tank surface at
winding bottom)
7.4.2
7.4.2
Average of top and bottom oil
temperature rises
0.8 x Top oil temperature rise
- Multi-winding transformers Not addressed 7.2.3 Supply the losses of 3 windings into 2
or 3 windings to obtain the oil
temperature rises
Temperature Rise Test, Rated Current
Phase
C57.12.90-2010 IEC 60076-2:
2011
- Average winding temperature
measurement
11.2.2 Shall be made on all phases 7.6 Shall be made on one phase
(preferably middle limb)
Page 39

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Temperature Rise Test, Rated Current
Phase
C57.12.90-2010 IEC 60076-2:
2011
- Warm Resistance Curve, shutdown
procedure
11.2.2 - The first valid resistance value has
to be taken within 4 min. after
shutdown
- At least four resistance
measurements shall be made on
one terminal pair
- Fans and cooling water shall be
shut off. Oil pumps may be shut off
or left running
7.6
and
7.7
- No minimum time for the first
valid value is given in the main
body. Annex C (informative)
recommends:
* within 2 min. for transf. < 33
MVA / phase
* within 3 min. for transf . ≥ 33
MVA / phase to 167 MVA /
phase
* within 4 min. for transf . ≥ 167
MVA / phase
- If fans and pumps are operating
during the test, they should be
maintained during the
measurements
- Determination of average winding rise 11.3.3 - Average winding rise can be either
based on the gradient to top oil or
to average oil
- Factors 234.5 °C for Cu and 225.0
°C for Al
(up to 230 °C for alloyed Al)
7.6 - Average winding rise is based on
average oil rise
- Factors 235 °C for Cu and 225
°C for Al
Page 40

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Temperature Rise Test, Rated Current
Phase
C57.12.90-2010 IEC 60076-2:
2011
- Determination of winding hot-spot rise 5.11.1.1 a) Direct measurement by a
“sufficient number of direct reading
sensors”
b) Direct measurement on an exact
duplicate transformer
c) Calculation by a thoroughly
verified method
7.10 * Rated power < 6.7 MVA / phase
neither calculation nor direct
measurement is required
* Rated power ≥ 6.7 MVA / phase
calculation is necessary. If
agreed, direct measurement can
be made as a special test
* For strategic asset or specific
operating condition (e.g. nuclear
power plant) both calculation
and direct measurement can be
made and the results compared
Calculation: Annex B (informative)
Measurement: Annex E (informative)
Temperature Rise Test, Supplied Values C57.12.90-2010 IEC 60076-2:
2011
- Supplied loss 11.4.2 Not less than 80 % of the required total
loss
7.13 Within ±20 % from target loss
(By agreement ≥ - 30 %)
- Supplied current 11.4.1 Not less than 85 % of rated winding
current
7.13 Within ±10 % from target current
(By agreement ≥ - 15 %)
- Supplied frequency different from
transformer frequency
11.4.4
and
B.3
Permitted: Formulas for frequency
conversion 50/60 Hz given
Not addressed
Page 41

Comparison of Standards – ANSI / IEEE and IEC – Temperature Rise
H Nordman / ABB Transformers
Subject Issue ANSI / IEEE IEC
Standard Requirements Standard Requirements
Temperature Rise Test, Corrections C57.12.90-2010 IEC 60076-2:
2011
- Liquid exponent n 11.4.2 * 0.8 for ONAN
* 0.9 for ONAF, OFAF, OFWF
* 1.0 for ODAF, ODWF
7.13 * 0.8 for ONAN Distribution
transformers ≤ 833 kVA/phase
* 0.9 for ONAN; ONAF Medium
and Large Power transformers
> 833 kVA/phase
* 1.0 for OFAF, OFWF
* 1.0 for ODAF, ODWF
- Winding exponent y = 2m 11.4.1 * 1.6 for ONAN
* 1.6 for ONAF, OFAF, OFWF
* 2.0 for ODAF, ODWF
7.13 * 1.6 for ONAN
* 1.6 for ONAF, OFAF, OFWF
* 2.0 for ODAF, ODWF
- Hot-spot exponent z Not addressed 7.13 * 1.6 for ONAN, ONAF, OFAF,
OFWF Medium and Large
Power Transformers > 833
kVA/phase
* 2.0 for ODAF, ODWF
- Correction for supply frequency different
from transformer frequency
11.4.4
and
B.3
Formulas for frequency conversion 50/60
Hz given
Not addressed
Temperature Rise Test, DGA as a Special
Test according to agreement
C57.12.90-2010 IEC 60076-2:
2011
- Procedure and permissible limits Not addressed 7.12 Guidance given in Annex D
(informative)
Page 42

IEC 60296 and IEC 60422 Comparison to IEEE C57.106-2006
Jim Thompson / T&R Service Company
Table 2 of IEC 60296, “Fluids for electrotechnical applications – Unused mineral insulating oils for transformers and switch gear,” uses 30 ppm
moisture in oil as a minimum acceptance value for new mineral oil delivered in bulk tanks and 40 ppm moisture as a minimum acceptance value for
new mineral oil delivered in drums. The C57.106-2006 at Table 1 uses a minimum acceptance value of 25 ppm.
Figure 1 of IEC 60422 “Mineral Insulating Oils in electrical equipment – Supervision and maintenance guidance” contains a formula with no
reference for moisture solubility versus temperature and also a curve for aged oil for the same. The C57.106-2006 provides two references in
section in section 4.5 for published papers to find an equation for solubility and makes reference to the fact that aged oil will have different solubility.
Table 3 of IEC 60422 uses minimum acceptance moisture in oil values for new mineral oil in equipment of 20 ppm for < 72.5 KV equipment, < 10
ppm for 72.5 KV to 170 KV equipment and < 10 ppm for > 170 KV equipment. The C57.106-2006 at Table 5 uses a minimum acceptance value for
new oil of 20 ppm for < or = 69 KV equipment ; 10 ppm for > 69 KV and < 230 KV equipment; and 10 ppm for 230 KV and above equipment. The
C57.106-2006 at Tables 7 and 8 for circuit breakers provide guidelines of 25 ppm for new shipments and 20 ppm after filling. The C57.106-2006 at
Table 5 uses a minimum acceptance value for service aged oil of 35 ppm for < or = 69 KV equipment ; 25 ppm for > 69 KV and < 230 KV
equipment; and 20 ppm for 230 KV and above equipment – and 25 ppm for circuit breakers.
Additional Notes:
IEC 60422 appears to be an acceptance criterion while C57.106-2006 is a guide with all of the precautionary statements clearly stating as
such.
IEC 60422 contains references to C57.106-2002 and a memo should be sent to the IEC committee that a new guide has been published on
June of 2007 (IEEE C57.106-2006).