IEC 61643-351:2016

IEC 61643-351 ®
Edition 1.0 2016-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Components for low-voltage surge protective devices –
Part 351: Performance requirements and test methods for telecommunications
and signalling network surge isolation transformers (SIT)

Composants pour parafoudres basse tension –
Partie 351: Exigences de performance et méthodes d'essai pour les
transformateurs d'isolement contre les surtensions dans les réseaux de
signalisation et de télécommunications

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IEC 61643-351 ®
Edition 1.0 2016-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Components for low-voltage surge protective devices –

Part 351: Performance requirements and test methods for telecommunications

and signalling network surge isolation transformers (SIT)

Composants pour parafoudres basse tension –

Partie 351: Exigences de performance et méthodes d'essai pour les

transformateurs d'isolement contre les surtensions dans les réseaux de

signalisation et de télécommunications

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.040.99 ISBN 978-2-8322-3717-5

– 2 – IEC 61643-351:2016 © IEC 2016
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols, abbreviations and acronyms . 7
3.1 Terms and definitions . 7
3.2 Symbols . 10
3.3 Abbreviations and acronyms . 12
4 Service conditions . 12
4.1 Temperature range . 12
4.2 Humidity . 12
4.3 Altitude . 12
4.4 Microclimate . 12
5 SIT surge conditions . 13
5.1 SIT surge mitigation . 13
5.2 Common-mode surges . 14
5.3 Differential-mode surges . 14
6 Characteristics . 15
6.1 Characteristic measurement . 15
6.2 Input winding to output winding capacitance . 15
6.3 Insulation resistance (IR) . 16
6.4 Signal SIT voltage-time product . 18
7 Ratings . 19
7.1 Rated impulse withstand voltage . 19
7.2 Signal SIT rated winding direct current . 22
8 Identification . 24
8.1 General . 24
8.2 Datasheet . 24
8.3 Marking . 24
Annex A (informative)  1,2/50 impulse . 25
Bibliography . 26

Figure 1 – Symbol for two-winding SIT . 10
Figure 2 – Symbol for a two-winding SIT with polarity indication . 11
Figure 3 – Symbol for a two-winding SIT with electric screen . 11
Figure 4 – SIT with centre tapped windings . 11
Figure 5 – Common-mode surge conditions for SIT . 13
Figure 6 – Common-mode surge conditions for SIT with an electric screen . 14
Figure 7 – Test circuit to measure SIT internal-winding capacitance . 15
Figure 8 – Test circuit to measure the internal-winding capacitance of SIT with an
electric screen . 16
Figure 9 – Test circuit to measure the insulation resistance of SIT . 17
Figure 10 – Test circuit to measure the insulation resistance of SIT with an electric
screen . 17
Figure 11 – Test circuit to measure SIT voltage-time product . 18

Figure 12 – Generator and SIT secondary voltage waveforms . 18
Figure 13 – SIT rated impulse voltage test circuit . 19
Figure 14 – Rated impulse voltage test circuit for SIT with an electric screen . 20
Figure 15 – Construction of pass/fail template from the 1,2/50 open-circuit waveform . 20
Figure 16 – Pass/fail template and test waveforms . 21
Figure 17 – Winding conductor temperature rise test circuit . 23
Figure A.1 – 1,2/50 time periods and voltage amplitudes . 25

Table 1 – Classification of microclimate condition . 12
Table 2 – Impulse withstand test voltage for rated impulse voltage . 22
Table A.1 – 1,2/50 voltage impulse generator parameters . 25

– 4 – IEC 61643-351:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPONENTS FOR LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 351: Performance requirements and test methods
for telecommunications and signalling network surge
isolation transformers (SIT)
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-
governmen
...