IEC TS 62367:2004

Safety aspects for xDSL signals on circuits connected to telecommunication networks (DSL: Digital Subscriber Line)

This technical specification addresses the safety implications of having xDSL signals on circuits in equipment connected to a TELECOMMUNICATION NETWORK, and gives rules for dealing with such equipment in the context of the IEC 60950 series

General Information

• Status: Published
• Publication Date: 26-Jan-2004
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 35.020 - Information technology (IT) in general
• Technical Committee: TC 108 - Safety of electronic equipment within the field of audio/video, information technology and communication technology
• Drafting Committee: MT 2 - TC 108/MT 2
• Current Stage: PPUB - Publication issued
• Start Date: 15-Mar-2004
• Completion Date: 27-Jan-2004

Standards Content (Sample)

TECHNICAL IEC
SPECIFICATION
TS 62367
First edition
Pre-Standard
2004-01
Safety aspects for xDSL signals on circuits
connected to telecommunication networks
(DSL: Digital Subscriber Line)
Reference number
IEC/TS 62367:2004(E)
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
Consolidated editions
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
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TECHNICAL IEC
SPECIFICATION
TS 62367
First edition
Pre-Standard
2004-01
Safety aspects for xDSL signals on circuits
connected to telecommunication networks
(DSL: Digital Subscriber Line)
 IEC 2004  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail]  Web: www.iec.ch
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Commission Electrotechnique Internationale M
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – TS 62367  IEC:2004(E)
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms, definitions and abbreviations .6
4 xDSL signals on circuits connected to telecommunication networks.7
Annex A (informative) xDSL telecommunication systems .8
A.1 Introduction .8
A.2 General description .8
A.3 Peak-to average ratio and CF.9
A.4 CF distribution.10
A.5 Line termination impedance.12
A.6 Measurement of xDSL parameters.12
Bibliography.13
Figure A.1 – Typical configuration of an xDSL system.8
Figure A.2 – Typical xDSL (VDSL) signal in the time-domain .9
Figure A.3 – Probability of symbol with CF >x .11
Figure A.4 – Inter-arrival time of symbol with CF > x (DMT-symbol rate = 4 kHz) .11

TS 62367  IEC:2004(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY ASPECTS FOR XDSL SIGNALS ON CIRCUITS
CONNECTED TO TELECOMMUNICATION NETWORKS
(DSL: DIGITAL SUBSCRIBER LINE)
FOREWORD
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all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development, or where, for any other reason, there is
the future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC-TS 62367, which is a technical specification, has been prepared by IEC technical
committee 108: Safety of electronic equipment within the field of audio/video, information
technology and communication technology.
This technical specification is a pre-standard publication which may be updated in the future
as an International Standard.
– 4 – TS 62367  IEC:2004(E)
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
108/61/DTS 108/90/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, terms defined in 1.2 of IEC 60950-1are printed in SMALL CAPITALS.
The committee has decided that the contents of this publication will remain unchanged until
2007. At this date, the publication will be
• transformed into an International Standard;
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
TS 62367  IEC:2004(E) – 5 –
INTRODUCTION
xDSL signals are high-speed telecommunication signals that may be present on a
telecommunication line, together with:
– analogue PSTN (Public Switched Telephone Network);
– ISDN (Integrated Services Digital Network) signals; or
– a d.c. power-feeding component.
An xDSL signal is characterised by an amplitude of the order of 3 V r.m.s. with superimposed
spikes having very short duration (about 1 μs) and peak values not exceeding 30 V.
When combined with other services as above, the peak voltage can very occasionally exceed
the limits for a TNV-3 CIRCUIT. However the excursions above these limits consist of these very
short duration spikes.
There are no published documents from IEC on the effect of such spikes on the human body,
but experience with xDSL is that the safety risk, if any, is very small because of:
– the low power of the spikes; and
– the limited accessibility of TNV circuits.
The amplitude and probability of the spikes have been calculated as follows:
– amplitude up to 15V/1μs with a probability of occurrence of one every few seconds to
every few minutes;
– amplitude up to 20V/1μs with a probability of occurrence of one every few hours;
– amplitude up to 27V/1μs with a probability of occurrence of one every few years.
Annex A gives more detail on the operation of xDSL telecommunication systems.

– 6 – TS 62367  IEC:2004(E)
SAFETY ASPECTS FOR XDSL SIGNALS ON CIRCUITS
CONNECTED TO TELECOMMUNICATION NETWORKS
(DSL: DIGITAL SUBSCRIBER LINE)
1 Scope
This technical specification addresses the safety implications of having xDSL signals on
circuits in equipment connected to a TELECOMMUNICATION NETWORK, and gives rules for dealing
with such equipment in the context of the IEC 60950 series.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60950 (all parts), Information technology equipment – Safety
IEC 60950-1 (all parts), Information technology equipment – Safety – Part 1: General
requirements
3 Terms and definitions, and abbreviations
For the purposes of this document, the terms and definitions in the IEC 60950 series and the
following abbreviations apply.
ADSL Asymmetric Digital Subscriber Line
CF Crest Factor
CO Central Office
CPE Customer Premises Equipment
DMT Discrete Multi Tone
DSL Digital Subscriber Line
HDSL High Speed Digital Subscriber Line
IEC International Electrotechnical Commission
ISDN Integrated Services Digital Network
ITU International Telecommunication Union
ITU-T Telecommunication Standardization Sector of ITU
NT Network Termination
PAR Peak to Average Ratio
PSTN Public Switched Telephone Network
QAM Quadrature Amplitude Modulation
RSS Remote Signal Source
SDSL Symmetric Digital Subscriber Line
TNV Telecommunication Network Voltage
VDSL Very-high-bit-rate Digital Subscriber Line

TS 62367  IEC:2004(E) – 7 –
4 xDSL signals on circuits connected to telecommunication networks
Based on the information presented in Annex A, it is recommended that for equipment within
the scope of the IEC 60950 series of standards, the following rules be applied for xDSL
signals on circuits connected to telecommunication networks.
Rule 1: Circuits carrying xDSL signals are classified as either TNV-1 CIRCUITS or TNV-3
CIRCUITS, depending on the normal operating voltage of the circuit.
Rule 2: When
a) assessing the voltages in circuits carrying xDSL signals with respect to the limits in 2.3.1
of IEC 60950-1, and when
b) determining the WORKING VOLTAGE of insulation in accordance with the IEC 60950 series,
the voltage of xDSL signals is regarded as zero and has no impact on the classification of the
circuits.
– 8 – TS 62367  IEC:2004(E)
Annex A
(informative)
xDSL telecommunication systems
A.1 Introduction
This annex describes the structure of xDSL signals, and explains why it is considered that
there is no shock hazard associated with xDSL signals.
xDSL is a general expression for high-speed telecommunication signals such as ADSL
(Asymmetric Digital Subscriber Line), VDSL (Very-high-bit-rate DSL), HDSL (High-Speed-
DSL), SDSL (Symmetric DSL), etc. (see Figure
...