GB/T 4207-2022Method for the determination of the proof and the comparative tracking indices of solid insulating materials (English PDF)

Foreword

This Document was drafted as per the rules specified in GB/T 1.1-2020 Directives for

Standardization - Part 1.Rules for the Structure and Drafting of Standardizing Documents.

This Document replaced GB/T 4207-2012 Method for the Determination of the Proof and the

Comparative Tracking Indices of Solid Insulating Materials. Compared with GB/T 4207-2012,

the major technical changes of this Document are as follows besides the structural adjustment

and editorial modifications.

a) Add "Description of influence of material composition and surface condition on

measurement results" (see Clause 1 of this Edition);

b) Add normative reference of "ISO 4287" (see Clause 2 of this Edition);

c) Delete the five normative references of "GB/T 17037.1-1997, GB/T 17037.3-2003, IEC

104, ISO 293.1986 and ISO 295.1991" (see Clause 2 of the 2012 Edition);

d) Change the notes on the definition of the term "electrical tracking failure" (see 3.2 of this

Edition; 3.2 of the 2012 Edition);

e) Change the notes on the definition of the term "comparative tracking index"; and add

Notes 1 and 4 (see 3.5 of this Edition; 3.5 of the 2012 Edition);

f) Add the term and definition of "deionized water" (see 3.8 of this Edition);

g) Change the content of the "principle" note (see Clause 4 of this Editon; Clause 4 of the 2012 Edition);

h) Change the documents that can be referred to for the sample processing technology in

"Specimen"; and add the technical content of Notes 6 and 7 (see Clause 5 of this Edition;

Clause 5 of the 2012 Edition);

i) Change the definition of ambient temperature in "Environmental Conditions", from

"23°C+/-5 °C" to "(23+/-2) °C"; and add the requirement to start the test time (see 6.1 of

this Edition; see 6.1 of the 2012 Edition);

j) Change the description of "Solution A"; delete the requirement for the conductivity of

deionized water used to configure the solution; and add Note 2 (see 7.3 of this Edition;

1 Scope

This Document specifies the method of test for the determination of the proof and comparative

tracking indices of solid insulating materials on pieces taken from parts of equipment and on

plaques of material using alternating voltage.

2 Normative References

The provisions in following documents become the essential provisions of this Document

through reference in this Document. For the dated documents, only the versions with the dates

indicated are applicable to this Document; for the undated documents, only the latest version

(including all the amendments) is applicable to this Document.

3 Terms and Definitions

For the purposes of this Document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses.

Water for analytical laboratory use in accordance with ISO 3696, Grade 3, or equivalent quality.

4 Principle

The upper surface of the test specimen is supported in a horizontal plane and subjected to an

electrical stress via two electrodes. The surface between the electrodes is subjected to a

succession of drops of electrolyte either until the over-current device operates, or until a

persistent flame occurs, or until the test period has elapsed.

5 Test Specimen

Any approximately flat surface may be used, provided that the area is sufficient to ensure that

during the test no liquid flows away from the test electrodes.

6 Test Specimen Conditioning

Unless otherwise specified, the test specimens shall be conditioned for a minimum of 24 h at

(23 +/- 2) °C, with (50 +/- 10) % RH. Once the test specimen has been removed from the

conditioning chamber (see 7.7) the test shall be started within 30 minutes.

7 Test Apparatus

Drops of the test solution shall fall on to the specimen surface at intervals of (30 +/- 5) s. The

drops shall fall approximately centrally between the two contact areas of the electrodes from a

height of (35 +/- 5) mm.

8 Basic Test Procedure

After each test, clean the electrodes with an appropriate solvent and then rinse and dry them

with de-ionized water. If necessary, restore their shape, polish if necessary, and give a final

rinse and dry before the next test.

9 Determination of Erosion

When required, specimens which have not failed at the 50-drop point shall be cleaned of any

debris or loosely attached degradation products and placed on the platform of a depth gauge.

The maximum depth of erosion of each specimen shall be measured in millimeters to an

accuracy of 0.1 mm, using a 1.0 mm nominal diameter probe having a hemispherical end. The

result is the maximum of the five measured values.

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