IEC TS 60695-2-20:2024
(Main)Fire hazard testing - Part 2-20: Glowing/hot-wire based test methods - Hot-wire ignition test (HWI) method - Apparatus, verification, test method and guidance
Fire hazard testing - Part 2-20: Glowing/hot-wire based test methods - Hot-wire ignition test (HWI) method - Apparatus, verification, test method and guidance
IEC TS 60695-2-20:2024, which is a technical specification, describes a test method that applies to solid electrical insulating materials of which test specimens can be provided. The test measures the time required to ignite a test specimen when it is affected by heat from an electrically heated wire wound around the test specimen. The test method can be used to provide classifications which can be used for quality assurance, the preselection of materials of products as described in IEC 60695-1-30, or to verify the required minimum classification of materials used in end products. This fourth edition cancels and replaces the third edition published in 2021. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
Removed all text which was related to drip or dripping, since in this 4th edition only ignition is taken into consideration for determination of the classification level;
Title changed: "Hot wire coil test method" is now "Hot wire ignition (HWI) test method".
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IEC TS 60695-2-20 ®
Edition 4.0 2024-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Fire hazard testing –
Part 2-20: Glowing/hot wire based test methods – Hot-wire coil ignition (HWI)
test method test method – Apparatus, verification, test method and guidance
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IEC TS 60695-2-20 ®
Edition 4.0 2024-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Fire hazard testing –
Part 2-20: Glowing/hot wire based test methods – Hot-wire coil ignition (HWI)
test method test method – Apparatus, verification, test method and guidance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.40; 29.020 ISBN 978-2-8327-0038-9
– 2 – IEC TS 60695-2-20:2024 RLV © IEC 2024
CONTENTS
FOREWORD . 4
INTRODUCTION . 2
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Principle . 11
5 Apparatus . 12
5.1 Test chamber . 12
5.2 Heater wire . 12
5.3 Power supply and test circuit . 13
5.4 Test specimen fixture . 13
5.5 Test specimen winding and pressing . 13
5.6 Conditioning chamber . 15
5.7 Timing device . 15
5.8 Micrometer . 15
5.9 Measuring scale . 15
6 Test specimens . 15
6.1 Test specimen preparation . 15
6.2 Test specimen dimensions . 15
7 Conditioning . 17
7.1 Requirements . 17
7.2 Test specimen conditioning . 17
7.3 Heater wire conditioning . 17
7.4 Test conditions . 17
8 Test procedure . 17
8.1 Verification of the heater wire . 17
8.1.1 General . 17
8.1.2 Apparatus Test circuit for the verification . 17
8.1.3 Determination of the test current, I . 18
c
8.1.4 Calculation of test current, I . 19
c
8.2 Determination of time to ignite, IT . 20
9 Observations and measurement . 23
10 Evaluation of test results – Assigning an HWI PLC classification . 24
11 Test report . 24
Annex A (informative) Guidance on how to effectively wind the heater wire on to the
test specimen . 25
Annex B (normative) Hot Wire coil Ignition test (HWCT HWI) – Performance level
category (PLC) classes . 26
B.1 General . 26
B.2 Reporting a classification . 26
Annex C (informative) Calibration curve to determine test current (I ) in a spreadsheet
c
program . 27
Annex D (informative) Precision data .
D.1 General .
D.2 Results of preliminary inter-laboratory round robin .
D.3 Evaluation of test results .
Bibliography . 33
Figure 1 – Test fixture arrangement (example) . 11
Figure 2 – Test specimen winding pattern . 12
Figure 3 – Test specimen fixture (example). 13
Figure 4 – Heater wire winding device (Example) . 14
Figure 5 – Test circuit arrangement for the heater wire calibration verification . 18
Figure 6 – Heater wire marking and connection . 19
Figure 7 – Calibration curve . 20
Figure 8 – Decision tree . 23
Figure A.1 – Illustration of type a) behaviour . 25
Figure A.2 – Illustration of type b) behaviour . 25
Figure C.1 – Calibration curve in a spreadsheet program used to determine I . 27
c
Table 1 – Nominal thickness tolerances . 16
Table 2 – Heater wire verification lengths . 18
Table B.1 – Hot Wire coil Ignition test (HWCT HWI) – Performance level category
(PLC) classes . 26
Table D.1 – Results for material 1A .
Table D.2 – Results for material 1B .
Table D.3 – Results for material 2A .
Table D.4 – Results for material 2B .
Table D.5 – Results for material 3 .
Table D.6 – Results for material 4 .
Table D.7 – Occurrence of PLC classes in the round robin .
– 4 – IEC TS 60695-2-20:2024 RLV © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 2-20: Glowing/hot wire based test methods –
Hot-wire coil ignition (HWI) test method –
Apparatus, verification, test method and guidance
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