Preview |
Foreword 1
1 Scope 1
2 Normative References 1
3 Terms and Definitions 2
3.1 General definitions 2
3.2 Additional definitions for measuring current transformers 5
3.3 Additional definitions for protective current transformers 6
4 Normal and Special Service Conditions 7
4.1 Normal service conditions 7
4.2 Special service conditions 8
4.3 Earthquakes 9
4.4 System earthing 9
5 Ratings 9
5.1 Standard values of rated primary currents 9
5.2 Standard values of rated secondary currents 9
5.3 Rated continuous thermal current 9
5.4 Standard values of rated output 9
5.5 Short-time current ratings 10
5.6 Limits of temperature rise 10
6 Design Requirements 11
6.1 Insulation requirements 11
6.2 Mechanical requirements 16
6.3 General requirements of structure 16
7 Classification of Tests 17
7.1 Type tests 17
7.2 Routine tests 18
7.3 Special tests 18
8 Type Tests 18
8.1 Short-time current tests 18
8.2 Temperature-rise test 19
8.3 Impulse tests on primary winding 19
8.4 Wet test for outdoor type transformers 20
8.5 Radio interference voltage measurement 21
8.6 Insulation thermal stability test 22
9 Routine Tests 22
9.1 Verification of terminal markings 22
9.2 Power-frequency withstand tests on primary windings and partial discharge measurement 22
9.3 Power-frequency withstand tests between sections of primary and secondary windings and on secondary windings 24
9.4 Inter-turn overvoltage test 25
9.5 Measurement of capacitance and dielectric dissipation factor 25
9.6 Insulation oil performance test 26
9.7 Sealing performance test 26
10 Special Tests 26
10.1 Chopped impulse test on primary winding 26
10.2 Mechanical tests 26
10.3 Transmitted overvoltages measurement 27
11 Markings 30
11.1 Terminal markings 30
11.2 Rating plate markings 30
12 Packaging, Storage & Transportation and Attachment Paper 32
12.1 Packaging 32
12.2 Storage & transportation 32
12.3 Attachment paper 32
12.4 Other 32
13 Additional Requirements for Measuring Current Transformers 32
13.1 Accuracy class designation for measuring current transformers 32
13.2 Limits of current error and phase displacement for measuring current transformers 32
13.3 Extended current ratings 34
13.4 Type tests for accuracy of measuring current transformers 34
13.5 Routine tests for accuracy of measuring current transformers 34
13.6 Instrument security factor 34
13.7 Marking of the rating plate of a measuring current transformer 34
14 Additional Requirements for Protective Current Transformers 35
14.1 Standard accuracy limit factors 35
14.2 Accuracy classes for protective current transformer 35
14.3 Limits of errors for protective current transformers 35
14.4 Type and routine tests for current error and phase displacement of protective current transformers 35
14.5 Type tests for composite error 36
14.6 Routine tests for composite error 36
14.7 Marking of the rating plate of a protective current transformer 36
15 Additional Requirements for Class PR Protective Current Transformers 37
15.1 Standard accuracy limit factors 37
15.2 Accuracy classes for class PR protective current transformers 37
15.3 Limits of error for class PR protective current transformers 37
15.4 Type and routine tests for current error and phase displacement of class PR protective current transformers 37
15.5 Marking of rating plate of class PR current transformers 38
16 Additional Requirements for Class PX Protective Current Transformers 38
16.1 Specification of performance for class PX protective current transformers 38
16.2 Insulation requirements for class PX protective current transformers 38
16.3 Type tests for class PX protective current transformers 38
16.4 Routine tests for class PX protective current transformers 39
Annex A (Informative) 41
Contrast of Clause and Article of Numbering of this Standard and IEC 60044-1: 2003 41
Annex B (Informative) 43
The Technical Differences and Reasons between this Standard and IEC 60044-1: 2003 43
Annex C (Normative) Protective current transformers 46
C.1 Vector diagram 46
C.2 Turns correction 46
C.3 The error triangle 47
C.4 Composite error 47
C.5 Direct test for composite error 48
C.6 Alternative method for the direct measurement of composite error 49
C.7 Use of composite error 50
Annex D (Informative) 52
The Altitude in IEC 60044-1: 2003 and Rated Insulation Level of Primary Winding 52
D.1 Altitude 52
D.2 Rated insulation levels for primary windings 52
D.3 Power-frequency withstand voltage of primary winding insulation 54
D.4 Chopped lighting impulse withstand voltages 54
Annex E (Normative) Chopped lightning impulse withstands voltage 55
Annex F (Normative) The permissible value of dielectric dissipation factor of transformer 56
Annex G (Informative) Multiple chopped impulse test 57
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1 Scope
This Standard applies to newly manufactured current transformers for use with electrical measuring instruments and electrical protective devices at frequencies from 15 Hz to 100 Hz.
Although the requirements relate basically to transformers with separate windings, they are also applicable, where appropriate, to autotransformers.
Clause 13 covers the requirements and tests, in addition to those in clauses 4 to 11, which are necessary for current transformers for use with electrical measuring instruments.
Clause 14 covers the requirements and tests, in addition to those in clauses 4 to 11 that are necessary for current transformers for use with electrical protective relays and in particular for forms of protection in which the prime requirement is the maintenance of accuracy up to several times the rated current.
For certain protective systems, where the current transformer characteristics are dependant on the overall design of the protective equipment (for example high-speed balanced systems and earth-fault protection in resonant earthed networks), additional requirements are given in clause 15 for class PR transformers and in clause 16 for class PX transformers.
Clause 15 covers the requirements and tests in addition to those in clauses 4 to 11 that are necessary for current transformers for use with electrical protective relays, and in particular for forms of protection in which the prime requirement is the absence of remanent flux.
Clause 16 covers the requirements and tests in addition to those in clauses 4 to 11 that are necessary for current transformers for use with electrical protective relays, and in particular for forms of protection for which knowledge of the transformer’s secondary excitation characteristic, secondary winding resistance, secondary burden resistance and turns ratio is sufficient to assess its performance in relation to the protective relay system with which it is to be used.
Current transformers intended for both measurement and protection shall comply with all the clauses of this standard.
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