IEC TR 63139:2018

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
• ICS: 29.140.01 - Lamps in general
• Technical Committee: TC 34 - Lighting
• Drafting Committee: WG 7 - TC 34/WG 7
• Current Stage: PPUB - Publication issued
• Start Date: 19-Oct-2018
• Completion Date: 12-Oct-2018

Overview

IEC TR 63139:2018 is a Technical Report from IEC TC 34 (Lamps and related equipment) that explains insulation coordination for modern lighting technologies. It clarifies how to treat the mathematical addition of working voltages, insulation between circuits, and the use of Protective Extra Low Voltage (PELV) when assessing insulation requirements in luminaires and controlgear-particularly for LED light sources and controllable products. The report supports practical decisions on creepage distances, clearances and circuit insulation when a first-failure condition occurs.

Key topics and requirements

• Mathematical addition of working voltages

  • Provides a reproducible method to combine supply and output working voltages for insulation design when basic insulation within controlgear fails.
  • Covers combinations such as AC/AC (same or different frequency), AC/DC and DC/DC scenarios and refers to specific calculation approaches (see Table 1 of the TR).
  • Rationale: direct measurement of fault voltages is often impractical, so conservative mathematical addition is used for design and testing.

• Insulation between circuits

  • Explains required insulation levels between active parts and accessible conductive parts based on controlgear input/output insulation classification and luminaire insulation class (referencing IEC 60598-1 and IEC 61347-1 tables).
  • Describes failure scenarios (input/output failure, earth/equipotential bonding faults, insulation failures between outputs and conductive parts) and their implications for protective requirements.

• Use of PELV

  • Describes how PELV can increase immunity and reliability in electronic circuits used with LEDs and details safety consequences.
  • Discusses PELV characteristics and requirements in relation to SELV and touch-current/protective conductor considerations.

• Insulation between LV supply and control line conductors

  • Highlights the importance of separating low-voltage supply and control conductors in complete installation systems to maintain safety under fault conditions.

Practical applications - who uses this standard

• Lighting manufacturers and controlgear designers assessing creepage distances and clearances for LED luminaires.
• Safety and compliance engineers preparing designs or test plans against IEC 60598-1 and IEC 61347-1 requirements.
• Test laboratories evaluating insulation under simulated fault conditions.
• Standards committees and product certification bodies updating requirements for controllable lighting products.

Related standards

• IEC 60598-1:2014 (luminaire safety) - Annex X explanations referenced.
• IEC 60598-1:2014/AMD1:2017 - related amendments.
• IEC 61347-1:2015 (controlgear safety) - Clause 15 and Table 6 cross-referenced.

Keywords: IEC TR 63139:2018, insulation coordination, mathematical addition of working voltages, PELV, TC 34 standards, LED lighting, controlgear, creepage distances, clearances, insulation between circuits.

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

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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
– 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
E
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

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLANATION OF THE MATHEMATICAL ADDITION
OF WORKING VOLTAGES, INSULATION BETWEEN CIRCUITS
AND USE OF PELV IN TC 34 STANDARDS

FOREWORD
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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.

– 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
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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.

– 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.

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.

– 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
DC
TT
u t dt ()U sinωt + U dt
() ( )
1 DC
∫∫
22 00
U ut
()
TT
2 T TT
U 2UU 1
1 221 DC
sin ωωt dt ++ sin t dt U dt (2)
( ) ( )
DC
∫ ∫∫
T TT
0 00
= = ==
==
=
=
=
=
=
=
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

U
2 2
UU+ (4)
DC
And thus,
U
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
...