1 Scope
This Standard applies to single-phase and three-phase oil-immersed power transformers (including auto-transformers), with the exception of certain small and special transformers, as defined in the scope of GB 1094.1. It identifies transformer windings to their highest voltage for equipment Um associated with their corresponding rated insulation levels and details the relevant applicable dielectric tests and minimum external clearances in air between live parts of bushings and to objects at earth potential.
For categories of power transformers and reactors which have their own standards, this Standard is applicable only to the extent in which it is specifically called up by cross reference in the other standards.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB 311.1-1997 Insulation Co-ordination for High Voltage Transmission and Distribution Equipment (neq IEC 60071-1:1993)
GB/T 311.7-1988 Application Guide for Insulation Co-ordination of High Voltage Transmission and Transformation Equipment (neq IEC 60071-2:1976)
GB/T 813-1989 Oscilloscopes and Peak Voltmeters for Impulse Tests (neq IEC 60790:1984)
GB 1094.1-1996 Power Transformers — Part 1: General (eqv IEC 60076-1:1993)
GB/T 2900.15-1997 Electrotechnical Terminology — Transformer, Instrument Transformer, Voltage Regulator and Reactor [neq IEC 60050(421):1990, IEC 60050(321):1986]
GB/T 4109-1999 Technical Specification of High Voltage Bushing (eqv IEC 60137:1995)
GB/T 7354-1987 Partial Discharge Measurements (neq IEC 60270:1981)
GB/T 7449-1987 Guide to the Lightning Impulse and Switching Impulse testing of Power Transformers and Reactors (eqv IEC 60722:1982)
GB/T 16896.1-1997 Digital Recorders for Measurements in High-voltage Impulse Tests – Part 1: Requirements for Digital Recorders (eqv IEC 61083-1:1991)
GB/T 16927.1-1997 High voltage test techniques — Part 1: General Test Requirements (eqv IEC 60060-1:1989)
GB/T 16927.2-1997 High Voltage Test Techniques — Part 2: Measuring Systems (eqv IEC 60060-2:1994)
IEC 61083-2:1991 Digital Recorders for Measurements in High-voltage Impulse Tests — Part 2: Evaluation of Software Used for the Determination of the Parameters of Impulse Waveforms
CISPR 16-1:1993 Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods — Part 1: Radio Disturbance and Immunity Measuring Apparatus
3 Definitions
Foreword III
IEC Foreword IV
IEC Introduction VI
1 Scope
2 Normative References
3 Definitions
4 General
5 Highest Voltage for Equipment and Insulation Level
6 Rules for Some Particular Transformers
7 Insulation Requirements and Dielectric Tests – Basic Rules
7.1 General
7.2 Insulation requirements
7.3 Dielectric tests
7.4 Insulation requirements and tests for the neutral terminal of a winding
8 Tests on a Transformer Having a Tapped Winding
9 Repeated Dielectric Tests
10 Insulation of Auxiliary Wiring
11 Separate Source AC Withstand Voltage Test
12 Induced AC Voltage Tests (ACSD, ACLD)
12.1 General
12.2 Short-duration induced AC withstand voltage test (ACSD) for transformers with uniformly insulated high-voltage windings
12.3 Short-duration AC withstand voltage test (ACSD) for transformers with non-uniformly insulated high-voltage windings
12.4 Long-duration induced AC voltage test (ACLD) with non-uniformly and/or uniformly insulated high-voltage windings
13 Lightning Impulse (LI) Test
13.1 General
13.2 Test sequence
13.3 Test connections
13.4 Records of test
13.5 Test criteria
14 Test With Lightning Impulse Chopped on the Tail (LIC)
14.1 General
14.2 Chopping gap and characteristics of the chopping
14.3 Test sequence and test criteria
15 Switching Impulse Test (SI)
15.1 General
15.2 Test sequence and records
15.3 Test connections
15.4 Test criteria
16 External Clearances in Air
16.1 General
16.2 Bushing clearance requirements as determined by transformer insulation withstand voltages
Appendix A (Informative) Application Guide for Partial Discharge Measurements During induced A.C. Withstand Voltage test on Transformers According to 12.2, 12.3 and
Appendix B (Informative) Overvoltage Transferred from the High-voltage Winding to a Low-voltage Winding
Appendix C (Informative) Information on Transformer Insulation and Dielectric Tests to be Supplied with an Enquiry and with an Order
Appendix D (Normative) Test Voltages for ACSD Test
Appendix E (Informative) Adoption Explanation
