Explanation of the mathematical addition of working voltages, insulation between circuits and use of PELV in TC 34 standards

IEC TR 63139:2018(E) is related to the insulation coordination in TC 34 standards and provides explanations on mathematical addition of working voltages, insulation between circuits, use of protective extra low voltage (PELV) and insulation between LV supply and control line conductors in order to cover new technologies associated with the use of LED light sources and controllable products.
It describes in which way the addition of supply voltages and working voltages can be arranged for an assessment of the electrical insulation requirements (e.g. creepage distances and clearances) in a system if a first failure occurs.

General Information

Status
Published
Publication Date
18-Oct-2018
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
19-Oct-2018
Ref Project

Buy Standard

Technical report
IEC TR 63139:2018 - Explanation of the mathematical addition of working voltages, insulation between circuits and use of PELV in TC 34 standards
English language
20 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC TR 63139
Edition 1.0 2018-10
TECHNICAL
REPORT
colour
inside
Explanation of the mathematical addition of working voltages, insulation
between circuits and use of PELV in TC 34 standards
IEC TR 63139:2018-10(en)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2018 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, 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

either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC

copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or

your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes

International Standards for all electrical, electronic and related technologies.
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org

The stand-alone application for consulting the entire The world's leading online dictionary of electronic and

bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in

Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional

documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical

iPad. Vocabulary (IEV) online.

IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary

The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and

variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of

committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been

and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc

details all new publications released. Available online and If you wish to give us your feedback on this publication or

also once a month by email. need further assistance, please contact the Customer Service

Centre: sales@iec.ch.
---------------------- Page: 2 ----------------------
IEC TR 63139
Edition 1.0 2018-10
TECHNICAL
REPORT
colour
inside
Explanation of the mathematical addition of working voltages, insulation
between circuits and use of PELV in TC 34 standards
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ISBN 978-2-8322-6163-7
ICS 29.140.01

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 63139:2018 © IEC 2018
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 Mathematical addition of working voltages ....................................................................... 6

5 Insulation between circuits............................................................................................... 9

5.1 General ................................................................................................................... 9

5.2 Insulation requirements between active parts and accessible conductive

parts ....................................................................................................................... 9

5.3 Possible failure conditions .................................................................................... 11

6 Circuits analysis ............................................................................................................ 13

7 Use of PELV .................................................................................................................. 15

7.1 General ................................................................................................................. 15

7.2 Characteristics of PELV (protective extra low voltage) circuits .............................. 16

7.3 Requirements for PELV circuits in addition to SELV .............................................. 16

7.3.1 Voltage limitations ......................................................................................... 16

7.3.2 Touch current and protective conductor current ............................................. 17

7.4 Summary of the proposed changes to IEC 60598-1 and IEC 61347-1 .................. 18

8 Insulation between LV supply and control line conductors ............................................. 18

Bibliography .......................................................................................................................... 20

Figure 1 – Input/output failure simulation ................................................................................ 8

Figure 2 – Examples of controlgear with different insulation systems .................................... 11

Figure 3 – Condition A: failure between input and output circuits .......................................... 11

Figure 4 – Condition B: earth failure/equipotential bonding failure (interruption of the

connection continuity) ........................................................................................................... 12

Figure 5 – Condition C: insulation failure between output circuits and accessible

earthed metal part................................................................................................................. 12

Figure 6 – Condition D: insulation failure between output circuit to conductive parts

which are connected together (equipotential bonding) ........................................................... 12

Figure 7 – Condition E: insulation failure between output circuit and different

conductive parts not connected together (no equipotential bonding) ..................................... 13

Figure 8 – PELV circuit in the most adverse condition (touch voltage is the sum of U

and U )................................................................................................................................. 17

Figure 9 – PELV circuit with a person located in an equipotential location (touch

voltage is U only) ................................................................................................................ 17

Table 1 – Addition of voltages ................................................................................................. 8

Table 2 – Insulation requirements between active parts and accessible conductive

parts ..................................................................................................................................... 10

Table 3 – Circuit analysis overview ....................................................................................... 13

---------------------- Page: 4 ----------------------
IEC TR 63139:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLANATION OF THE MATHEMATICAL ADDITION
OF WORKING VOLTAGES, INSULATION BETWEEN CIRCUITS
AND USE OF PELV IN TC 34 STANDARDS
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 International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

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. However, a

technical committee may propose the publication of a Technical Report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".

IEC TR 63139, which is a Technical Report, has been prepared by IEC technical committee

34: Lamps and related equipment.
The text of this Technical Report is based on the following documents:
DTR Report on voting
34/415/DTR 34/493A/RVDTR

Full information on the voting for the approval of this Technical Report can be found in the

report on voting indicated in the above table.
---------------------- Page: 5 ----------------------
– 4 – IEC TR 63139:2018 © IEC 2018

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 6 ----------------------
IEC TR 63139:2018 © IEC 2018 – 5 –
INTRODUCTION

This document provides background information to the following subjects being introduced

into IEC TC 34 standards to cover new technologies associated with the use of LED light

sources and controllable products.
This document consists of the following subdivisions:
Clause 4 – Mathematical addition of working voltages;
Clause 5 – Insulation between circuits;
Clause 6 – Use of protective extra low voltage (PELV);
Clause 7 – Insulation between LV supply and control line conductors.
---------------------- Page: 7 ----------------------
– 6 – IEC TR 63139:2018 © IEC 2018
EXPLANATION OF THE MATHEMATICAL ADDITION
OF WORKING VOLTAGES, INSULATION BETWEEN CIRCUITS
AND USE OF PELV IN TC 34 STANDARDS
1 Scope

This document is related to the insulation coordination in TC 34 standards and provides

explanations on mathematical addition of working voltages, insulation between circuits, use of

protective extra low voltage (PELV) and insulation between LV supply and control line

conductors in order to cover new technologies associated with the use of LED light sources

and controllable products.

It describes in which way the addition of supply voltages and working voltages can be

arranged for an assessment of the electrical insulation requirements (e.g. creepage distances

and clearances) in a system if a first failure occurs.

Furthermore the actual failure scenarios given in IEC 60598-1:2014 and IEC 60598-

1:2014/AMD1:2017, Annex X and IEC 61347-1:2015, Clause 15 are explained in greater

detail and the rationale behind the protective requirement for each situation is given (e.g.

possible LV primary to ELV secondary does not lead to an overburden of the insulation in the

second circuit).

This document also describes the possibility to increase immunity and reliability of electronic

circuits, used in combination with LEDs, with the use of PELV and the associated safety

consequences for this system.

The insulation between LV supply and control line conductors is also important and this

document explains why this is an essential safety consideration for a complete installation

system.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Mathematical addition of working voltages

Insulation requirements between live parts and accessible conductive parts as function of the

controlgear input/output insulation classification and the insulation class of the luminaire are

given in IEC 60598-1:2014, Table X.1 and IEC 61347-1:2015, Table 6.

Insulation requirements in TC 34 standards are based on a hazard assessment with the

assumption that a certain failure will occur.
---------------------- Page: 8 ----------------------
IEC TR 63139:2018 © IEC 2018 – 7 –

The required insulation is normally based on the working voltage U , but in some specific

OUT

failure cases when the basic insulation between supply and output of a controlgear fails, the

supply voltage should be added to U . For controlgear with double or reinforced insulation

OUT
between primary (U ) and secondary (U ) this type of failure is not expected.
SUPPLY OUT

In case of failure of the basic insulation within the controlgear the following assumptions are

made:
• there is an increased output voltage,

• the luminaire remains working, and the increased voltage is present for a time long

enough to create a conduction track across the insulation (known as tracking).

For 50/60 Hz transformers inside the controlgear, this failure condition results in the addition

of the voltages that can be calculated by the simple summation of the two values. In

electronic controlgear this situation may result in a more complex summation due to the

complexity of the oscillating circuit that may influence the result.

The best method to check the output voltage in case of insulation failure is to measure the

output voltage directly on a sample of controlgear with the fault simulated. The failure of the

insulation and the output voltage should be measured against earth (or zero potential). This

method has been found not to be practical due to the following reasons:
• differing supply conditions (voltage/frequency);
• difficulty in simulating exactly the failure condition;
• difficulty in making accurate and reproducible measurements.

For the above mentioned reasons the mathematical calculation of the sum of the voltages has

been found to be more appropriate, reproducible and easy to calculate, even if the result may

in some cases be lower than the real measurement. Designing and testing the insulation

properties of the output circuit with an increased voltage value is considered as a necessary

safety provision to cover this first failure condition which can occur inside basic insulated

controlgear.

The approximation given by the mathematical calculation is considered to provide sufficient

severity, compared to the possible practical failure voltage, to ensure the safety of the product

through its lifetime. With the selected formula most of the expected failure cases are covered.

Higher voltages occurring in very rare cases will not have any serious impact.

The formulas to be used for combining the input and output voltages of the controlgear, with

basic insulation between supply and output, are given in Table 1.
---------------------- Page: 9 ----------------------
– 8 – IEC TR 63139:2018 © IEC 2018
Table 1 – Addition of voltages
U U Phase relationship Voltage calculation for insulation design
supply OUT
AC AC Same frequency and no phase shift U = U + U
AC1 AC2
AC AC Same frequency and with phase shift
U U+U+2 UU cosϕ
AC1 AC2 AC1 AC2
AC AC Different frequency
UU+U
AC1 AC2
AC DC No phase shift
U UU+
AC DC
DC AC No phase shift
U UU+
AC DC
DC DC No phase shift UU+U
DC1 DC2
NOTE 1 Voltages in the table are RMS values.
NOTE 2 The AC and DC calculation is typical for LED applications.

Figure 1 shows the simulation of the possible fault between input and output terminals (red

line) with the mathematical calculation providing the expected output voltage that may occur.

Controlgear
U U
supply out
IEC
Figure 1 – Input/output failure simulation

For background information, the formula U UU+ (line 4 of Table 1) for the specific

AC DC

case of a combination of an AC and DC voltage is derived from the following Formulas (1) to

(5). It may be regarded as a showcase for any of the formulas from Table 1.
U is the RMS value (U ) of the voltage u(t)
RMS
U U ut() (1)
RMS

In the particular case given, u(t) consists of an AC (sinusoidal) part with peak voltage U and

frequency ω and a DC part U . It can be derived that
u t dt ()U sinωt + U dt
() ( )
1 DC
22 00
U ut
2 T TT
U 2UU 1
1 221 DC
sin ωωt dt ++ sin t dt U dt (2)
( ) ( )
∫ ∫∫
T TT
0 00
= = ==
---------------------- Page: 10 ----------------------
IEC TR 63139:2018 © IEC 2018 – 9 –
Evaluating this integral yields
11U 2 UU 1
22tT tT
1 1 DC
U=t− sinωωt cos t ││−+ cosωt UT (3)
( ) ( ) ( )
t 0 t 0 DC
2 T ωωTT
2 2
UU+ (4)
And thus,
2 22
U= +=U UU+ (5)
DC AC DC
5 Insulation between circuits
5.1 General

New requirements have been added to those in IEC 60598-1 and IEC 61347-1 concerning the

requirements for insulation between diffe
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.