ASTM D3638-21

Standard Test Method for Comparative Tracking Index of Electrical Insulating Materials

SIGNIFICANCE AND USE
5.1 Electrical equipment can fail as a result of electrical tracking of insulating material that is exposed to various contaminating environments and surface conditions. This method is an accelerated test which at relatively low test voltages, provides a comparison of the performance of insulating materials under wet and contaminated conditions. The comparative tracking index is not related directly to the suitable operating voltage in service.  
5.2 When organic electrical insulating materials are subjected to conduction currents between electrodes on their surfaces, many minute tree-like carbonaceous paths or tracks are developed near the electrodes. These tracks are oriented randomly, but generally propagate between the electrodes under the influence of the applied potential difference. Eventually a series of tracks spans the electrode gap, and failure occurs by shorting of the electrodes.  
5.3 The conditions specified herein are intended to produce a condition conducive to the formation of surface discharges and possible subsequent tracking. Test conditions are chosen to accelerate a process that is reproducible. Consequently, they rarely reproduce the varied conditions found in actual service. Therefore, while tracking tests serve to differentiate materials under given conditions, results of tracking tests cannot be used to infer either direct or comparative service behavior of an application design. Rather, the results provide a tool for judging the suitability of materials for a given application. The suitability can only be verified through testing the design in actual end use or under conditions which simulate end use as closely as possible.  
5.4 The results have been used for insulation coordination of equipment with rated voltage up to 1000 Vac or 1500 Vdc connected to low-voltage supply systems (higher voltages permitted in internal circuits). The complete principles of insulation coordination involve the consideration of the combination of clearanc...
SCOPE
1.1 This test method evaluates in a short period of time the low-voltage (up to 600 V) track resistance or comparative tracking index (CTI) of materials in the presence of aqueous contaminants.  
1.2 The values stated in metric (SI) units are to be regarded as standard. The inch-pound equivalents of the metric units are approximate.  
1.3 This test method is technically equivalent to the version of IEC Publication 112 cited in 2.2. However, the 2007 version of IEC 60112 Fourth Edition yields numerical CTI values that are very likely to differ significantly from this test method.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 31-Dec-2020
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.12 - Electrical Tests

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D3638 − 21
Standard Test Method for
Comparative Tracking Index of Electrical Insulating
1
Materials
This standard is issued under the fixed designation D3638; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
4
1. Scope* 2.2 IEC Publications:
IEC 112Method for the determination of the proof and the
1.1 This test method evaluates in a short period of time the
comparative tracking indices of solid insulating materials
low-voltage (up to 600 V) track resistance or comparative
IEC60112Methodforthedeterminationoftheproofandthe
tracking index (CTI) of materials in the presence of aqueous
comparative tracking indices of solid insulating materials
contaminants.
IEC 60664-1Insulation coordination for equipment within
1.2 The values stated in metric (SI) units are to be regarded
low-voltage supply systems – Part 1: Principles, require-
asstandard.Theinch-poundequivalentsofthemetricunitsare
ments and tests, 2020 Edition 3.0
5
approximate.
2.3 2.3 ANSI/UL Publication:
ANSI/UL 840Standard for Insulation Coordination Includ-
1.3 This test method is technically equivalent to the version
ing Clearances and Creepage Distances for Electrical
ofIECPublication112citedin2.2.However,the2007version
rd
Equipment. January 6, 2005, 3 edition
of IEC 60112 Fourth Edition yields numerical CTI values that
are very likely to differ significantly from this test method.
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 track, n—a partially conducting path of localized
responsibility of the user of this standard to establish appro-
deterioration on the surface of an insulating material.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. 3.1.2 tracking, n—the process that produces tracks as a
result of the action of electric discharges on or close to an
1.5 This international standard was developed in accor-
insulation surface.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3.1.3 tracking, contamination, n—tracking caused by scin-
Development of International Standards, Guides and Recom-
tillations that result from the increased surface conduction due
mendations issued by the World Trade Organization Technical
to contamination.
Barriers to Trade (TBT) Committee.
3.1.4 tracking resistance, n—the quantitative expression of
the voltage and the time required to develop a track under the
2. Referenced Documents
specified conditions.
2
2.1 ASTM Standards:
3.1.5 For other terminology, refer to Terminology D1711.
D1711Terminology Relating to Electrical Insulation
3.2 Definitions of Terms Specific to This Standard:
D6054Practice for Conditioning Electrical Insulating Mate-
3.2.1 comparative tracking index, n—an index for electrical
3
rials for Testing (Withdrawn 2012)
insulating materials which is arbitrarily defined as the numeri-
cal value of that voltage which will cause failure by tracking
when the number of drops of contaminant required to cause
1
This test method is under the jurisdiction of ASTM Committee D09 on failure is equal to 50.
Electrical and Electronic Insulating Materials and is the direct responsibility of
3.2.1.1 Discussion—The voltage value is obtained from a
Subcommittee D09.12 on Electrical Tests.
plot of the number of drops required to cause failure by
Current edition approved Jan. 1, 2021. Published February 2021. Originally
tracking versus the applied voltage.
approved in 1977. Last previous edition approved in 2012 as D3638–12. DOI:
10.1520/D3638-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from International Electrotechnical Commission (IEC), 3, rue de
Standards volume information, refer to the standard’s Document Summary page on Varembé, 1st floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, https://
the ASTM website. www.iec.ch.
3 5
The last approved version of this historical standard is referenced on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
www.astm.org. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D3638 − 21
3.2.2 failure, n—an attribute of an electrical circuit
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D3638 − 12 D3638 − 21
Standard Test Method for
Comparative Tracking Index of Electrical Insulating
1
Materials
This standard is issued under the fixed designation D3638; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method evaluates in a short period of time the low-voltage (up to 600 V) track resistance or comparative tracking
index (CTI) of materials in the presence of aqueous contaminants.
1.2 The values stated in metric (SI) units are to be regarded as standard. The inch-pound equivalents of the metric units are
approximate.
1.3 This standard test method is technically equivalent to the version of IEC Publication 112 cited in 2.2. However, the 2007
version of IEC 60112 Fourth Edition yields numerical CTI values that are very likely to differ significantly from this standard.test
method.
1.4 This standard does not purport to address all of the safety problems,concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
D1711 Terminology Relating to Electrical Insulation
3
D6054 Practice for Conditioning Electrical Insulating Materials for Testing (Withdrawn 2012)
4
2.2 IEC Publication:Publications:
IEC 112 Recommended Method for Determining the Comparative Track Index of Solid Insulating Materials Under Moist
Conditions, 1971 Second Editionthe determination of the proof and the comparative tracking indices of solid insulating
materials
IEC 60112 Recommended Method for Determining the Comparative Track Index of Solid Insulating Materials Under Moist
1
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.12 on Electrical Tests.
Current edition approved Jan. 1, 2012Jan. 1, 2021. Published February 2012February 2021. Originally approved in 1977. Last previous edition approved in 20072012 as
D3638 – 07.D3638 – 12. DOI: 10.1520/D3638-12.10.1520/D3638-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
4
Available from the International Electrotechnical Commission, Geneva, Switzerland.International Electrotechnical Commission (IEC), 3, rue de Varembé, 1st floor, P.O.
Box 131, CH-1211, Geneva 20, Switzerland, https://www.iec.ch.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D3638 − 21
Conditions, 2007 Fourth Editionthe determination of the proof and the comparative tracking indices of solid insulating
materials
IEC 60664-1 Insulation coordination for equipment within low-voltage supply systems – Part 1: Principles, requirements and
tests, 2020 Edition 3.0
5
2.3 2.3 ANSI/UL Publication:
ANSI/UL 840 Standard for Insulation Coordination Including Clearances and Creepage Distances for Electrical Equipment.
rd
January 6, 2005, 3 edition
3. Terminology
3.1 Definitions:
3.1.1 track—track, n—a partially conducting path of localized deterioration on the surface of an insulating material.
3.1.2 tracking—tracking, n—the process that produces tracks as a result of the action of electric discharges on or close to an
insulation surface.
3.1.3 tracking, contamination—contamination, n—tracking caused by scintillations that result from the increased surface
conduction due to contamination.
3.1.4 tracking resistance—resistance, n—the quantitative expression of the voltage and the
...