IEC TS 60695-2-20:2021
(Main)Fire hazard testing - Part 2-20: Glowing/hot-wire based test methods - Hot wire coil test method - Apparatus, verification, test method and guidance
Fire hazard testing - Part 2-20: Glowing/hot-wire based test methods - Hot wire coil test method - Apparatus, verification, test method and guidance
IEC TS 60695-2-20:2021 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. If the test specimen drips, the time at which this occurs is also recorded.
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 basic safety publication is intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. The requirements, test methods or test conditions of this basic safety publication will not apply unless specifically referred to or included in the relevant publications.
This third edition of IEC TS 60695-2-20 cancels and replaces the second edition of IEC TS 60695-2-20 published in 2004. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
– Contents page added
– Updated Scope (Clause 1)
– Updated Terms and Definitions, added new relevant terms (Clause 3)
– Updated Principle (Clause 4)
– Updated Apparatus (Clause 5; recommendation to change the power source from a.c. to d.c. with a constant current output. Reason for this recommendation: d.c. technology is easier to obtain and to handle, which has been found to improve the Repeatability and Reproducibility of the test.
– Updated Test specimen dimensions (6.2)
– Revised Test procedure (Clause 8)
– Revised Observations and measurements (Clause 9)
– Revised Evaluation of test results (Clause 10)
– Revised Test report (Clause 11)
– Revised Annex A: Deletion of conformational test; Guidance on verification of the heater wire winding before testing
– Addition of normative Annex B: HWCT PLC Classes
– Addition of informative Annex C: Calibration curve to determine test current (Ic) in a spreadsheet program
– Addition of informative Annex D: Precision data
It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC Guide 51.
This basic safety publication is intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
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Standards Content (Sample)
IEC TS 60695-2-20 ®
Edition 3.0 2021-04
TECHNICAL
SPECIFICATION
colour
inside
Fire hazard testing –
Part 2-20: Glowing/hot wire based test methods – Hot-wire coil test method –
Apparatus, verification, test method and guidance
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IEC TS 60695-2-20 ®
Edition 3.0 2021-04
TECHNICAL
SPECIFICATION
colour
inside
Fire hazard testing –
Part 2-20: Glowing/hot wire based test methods – Hot-wire coil test method –
Apparatus, verification, test method and guidance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.40, 29.020 ISBN 978-2-8322-9707-0
– 2 – IEC TS 60695-2-20:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 7
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 . 14
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 . 16
7.1 Requirements . 16
7.2 Test specimen conditioning . 16
7.3 Heater wire conditioning . 16
7.4 Test conditions . 16
8 Test procedure . 17
8.1 General . 17
8.2 Apparatus . 17
8.3 Determination of the test current, I . 17
c
8.4 Calculation of test current, I . 18
c
8.5 Determination of time to ignite, IT and/or time to drip, DT . 18
9 Observations and measurement . 20
10 Evaluation of test results . 21
10.1 Assigning a HWCT PLC classification . 21
10.2 Precision data . 21
11 Test report . 21
Annex A (informative) Guidance on how to effectively wind the heater wire on to the
test specimen . 22
Annex B (normative) Hot wire coil test (HWCT) – Performance level category (PLC)
classes . 23
B.1 General . 23
B.2 Reporting a classification . 23
Annex C (informative) Calibration curve to determine test current (I ) in a spreadsheet
c
program . 24
Annex D (informative) Precision data . 25
D.1 General . 25
D.2 Results of preliminary inter-laboratory round robin . 25
D.3 Evaluation of test results . 28
Bibliography . 30
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 heater wire calibration . 17
Figure 6 – Calibration curve . 18
Figure 7 – Decision tree . 20
Figure A.1 – Illustration of type a) behaviour . 22
Figure A.2 – Illustration of type b) behaviour . 22
Figure C.1 – Calibration curve in a spreadsheet program used to determine I . 24
c
Table 1 – Nominal thickness tolerances . 16
Table B.1 – Hot wire coil test (HWCT) – Performance level category (PLC) classes . 23
Table D.1 – Results for material 1A . 26
Table D.2 – Results for material 1B . 26
Table D.3 – Results for material 2A . 26
Table D.4 – Results for material 2B . 27
Table D.5 – Results for material 3 . 27
Table D.6 – Results for material 4 . 28
Table D.7 – Occurrence of PLC classes in the round robin . 29
– 4 – IEC TS 60695-2-20:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 2-20: Glowing/hot wire based test methods –
Hot-wire coil test method –
Apparatus, verification, test method and guidance
FOREWORD
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