IEC 61643-312:2013

IEC 61643-312 ®
Edition 1.0 2013-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Components for low-voltage surge protective devices –
Part 312: Selection and application principles for gas discharge tubes

Composants pour parafoudres basse tension –
Partie 312: Principes de choix et d’application pour les tubes à décharge de gaz

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IEC 61643-312 ®
Edition 1.0 2013-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Components for low-voltage surge protective devices –

Part 312: Selection and application principles for gas discharge tubes

Composants pour parafoudres basse tension –

Partie 312: Principes de choix et d’application pour les tubes à décharge de gaz

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 31.100; 33.040.99 ISBN 978-2-83220-740-6

– 2 – 61643-312 © IEC:2013
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and symbols . 6
3.1 Terms and definitions . 6
3.2 Symbols . 10
4 Service conditions . 10
4.1 General . 10
4.2 Low temperature . 10
4.3 Air pressure and altitude . 10
4.4 Ambient temperature . 10
4.5 Relative humidity . 11
5 Mechanical requirements and materials . 11
5.1 General . 11
5.2 Robustness of terminations . 11
5.3 Solderability . 11
5.4 Radiation . 11
5.5 Marking . 11
6 General . 11
7 Construction . 12
7.1 Design . 12
7.2 Description . 12
7.3 Fail-short (failsafe) . 13
8 Function . 14
8.1 Protection principle . 14
8.2 Operating mode . 14
8.3 Response behaviour . 14
8.3.1 Static response behavior . 14
8.3.2 Dynamic response behavior . 14
8.4 Fail-short (failsafe) . 15
9 Applications . 16
9.1 Protective circuits . 16
9.1.1 General . 16
9.1.2 2-point (signal line) protection . 16
9.1.3 3-point protection . 17
9.1.4 5-point protection . 18
9.2 Telephone/fax/modem protection . 19
9.3 Cable TV/coaxial cable protection . 19
9.4 AC line protection . 20
Bibliography . 21

Figure 1 – Voltage and current characteristics of a GDT . 8
Figure 2 – Symbol for a two-electrode GDT . 10
Figure 3 – Symbol for a three-electrode GDT . 10
Figure 4 – Example of a two-electrode GDT . 12

61643-312 © IEC:2013 – 3 –
Figure 5 – Example of a three-electrode GDT . 12
Figure 6 – Failsafe construction of a three-electrode GDT using a solder pill as
sensitive spacer . 13
Figure 7 – Failsafe construction of a three-electrode GDT, using a plastic foil as
sensitive spacer . 13
Figure 8 – Typical response behaviour of a 230 V GDT . 15
Figure 9 – Spark-over voltages versus response time . 15
Figure 10 – Current through the GDT versus response time of fail-short (failsafe) . 16
Figure 11 – 2-point (Signal line) protection . 17
Figure 12 – 3-point protection using two-electrode GDTs . 17
Figure 13 – 3-point protection using three-electrode GDTs . 17
Figure 14 – 3-point protection using two-electrode GDTs with fail-short . 18
Figure 15 – 3-point protection using three-electrode GDTs with fail-short . 18
Figure 16 – 5-point protection using two-electrode GDTs . 18
Figure 17 – 5-point protection using three-electrode GDTs . 18
Figure 18 – 5-point protection using two-electrode GDTs with fail-short . 19
Figure 19 – 5-point protection using three-electrode GDTs with fail-short . 19
Figure 20 – Telephone/fax/modem protection using two-electrode GDTs . 19
Figure 21 – Telephone/fax/modem protection using three-electrode GDTs . 19
Figure 22 – Cable TV/ coaxial cable protection . 20
Figure 23 – AC line protection . 20

– 4 – 61643-312 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPONENTS FOR LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 312: Selection and application principles for gas discharge tubes

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the In
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