1 Scope and object
This part of GB/T 16935 deals with insulation coordination for equipment within low-voltage systems. It applies to equipment for use up to 2 000 m above sea level having a rated voltage up to a.c. 1 000 V with rated frequencies up to 30 kHz, or a rated voltage up to d.c. 1 500 V.
This part specifies the requirements for clearances, creepage distances and solid insulation for equipment based upon their performance criteria. It includes methods of electric testing with respect to insulation coordination.
The minimum clearances specified in this part do not apply where ionized gases occur. Special requirements for such situations may be specified at the discretion of the relevant technical committee.
This part does not deal with distances
— through liquid insulation;
— through gases other than air;
— through compressed air.
Note 1: Insulation coordination for equipment within low-voltage systems with rated frequencies above 30 kHz is given in IEC 60664-4.
Note 2: Higher voltages may exist in internal circuits of the equipment.
Note 3: Guidance for dimensioning for altitudes exceeding 2 000 m is given in Table A.2.
The object of this basic safety standard is to guide technical committees responsible for different equipment in order to rationalize their requirements so that insulation coordination is achieved.
It provides the information necessary to give guidance to technical committees when specifying clearances in air, creepage distances and solid insulation for equipment.
Care should be taken to see that manufacturers and technical committees are responsible for application of the requirements, as specified in this basic safety publication, or make reference to it, where necessary, in standards for equipment within their scope.
In the case of missing specified values for clearances, creepage distances and requirements for solid insulation in the relevant product standards, or even missing standards, this part is applicable.
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2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of GB/T 16935. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB 156-2003 Standard voltages (neq IEC 60038-1983)
GB/T 1408.1-2006 Electrical strength of insulating materials — Test methods — Part 1: Tests at power frequencies (idt IEC 60243-1:1998)
GB/T 2421-1999 Environmental testing for electric and electronic products — Part 1: General and guidance (idt IEC 60068-1:1988)
GB/T 2423.2-2001 Environmental testing for electric and electronic products — Part 2: Test methods — Tests B: Dry heat (idt IEC60068-2-2:1974)
GB/T 2423.3-2006 Environmental testing for electric and electronic products - Part 2: Testing method test Cab: Damp heat Steady state (idt IEC 60068-2-78:2001)
GB/T 2423.22-2002 Environmental testing for electric and electronic products — Part 2: Test methods — Test N: Change of temperature (idt IEC 60068-2-14:1984)
GB/T 2900.5-2002 Electrotechnical terminology — Insulating solids, liquids and gases (eqv IEC 60050 (212):1990)
GB/T 2900.57-2002 Electrotechnical terminology — Generation,transmission and distribution of electricity — Operation (eqv IEC 60050(604):1987)
GB/T 4207-2003 Method for determining the comparative and the proof trackin indices of solid insulating materials under moist conditions (idt IEC 60112:1979)
GB/T 7354-2003 Partial discharge measurements (idt IEC 60270:2000)
GB/T 11021-1989 Thermal evaluation and classification of electrical insulation (eqv IEC 60085:1984)
GB/T 16499-1996 Guide to the drafting of electrical safety standards (eqv IEC Guide 104:1984)
GB/T 17045-2006 Protection against electric shock — Common aspects for installation and equipment (idt IEC 61140:2001)
GB/T 17627.1-1998 High-voltage test techniques for low-voltage equipment — Part 1: Definitions, test and procedure requirements (eqv IEC 61180-1:1992)
GB/T 17627.2-1998 High-voltage test techniques for low-voltage equipment — Part 2: Measuring system and test equipment (eqv IEC 61180-2:1994)
Foreword II
1 Scope and object
2 Normative References
3 Terms and Definitions
4 Basis for Insulation Coordination
5 Requirements and Dimensioning Rules
6 Tests and Measurements
Appendix A (Informative) Basic Data on Withstand Characteristics of Clearances
Appendix B (Informative) Nominal Voltages of Supply Systems for Different Modes of Overvoltage Control
Appendix C (Normative) Partial Discharge Test Methods
Appendix D (Informative) Additional Information on Partial Discharge Test Methods
Appendix E (Informative) Comparison of Creepage Distances Specified in Table F.4 and Clearances in Table A
Appendix F (Normative) Tables
Bibliography
