Safety of transformers, reactors, power supply units and combinations thereof - Part 2-8: Particular requirements and tests for transformers and power supply units for bells and chimes

IEC 61558-2-8:2010 deals with the safety of bell and chime transformers and power supply units incorporating bell and chime transformers. Transformers incorporating electronic circuits are also covered by this standard. This second edition cancels and replaces the first edition published in 1998. It constitutes a technical revision. The main changes consist of updating this part in accordance with IEC 61558-1:2005. This part has the status of a group safety publication in accordance with IEC Guide 104. The attention of National Committees is drawn to the fact that equipment manufacturers and testing organizations may need a transitional period following publication of a new, amended or revised IEC publication in which to make products in accordance with the new requirements and to equip themselves for conducting new or revised tests. It is the recommendation of the committee that the content of this publication be adopted for implementation nationally not earlier than 12 months from the date of publication. In the meantime, the previous edition can still be ordered by contacting your local IEC member National Committee or the IEC Central Office.
This publication is to be read in conjunction with IEC 61558-1:2005.

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et des combinaisons de ces éléments - Partie 2-8: Règles particulières et essais pour les transformateurs et blocs d'alimentation pour sonneries et carillons

La CEI 61558-2-8:2010 traite de la sécurité des transformateurs pour sonneries et carillons et des blocs d'alimentation incorporant des transformateurs pour sonneries et carillons. Les transformateurs incorporant des circuits électroniques sont également couverts par la présente norme. Cette deuxième édition annule et remplace la première édition publiée en 1998. Elle constitue une révision technique. Les principales modifications comprennent la mise à jour de la présente partie conformément à la CEI 61558-1:2005. La présente partie a le statut de publication groupée de sécurité conformément au Guide CEI 104. L'attention des Comités Nationaux est attirée sur le fait que les fabricants d'appareils et les organismes d'essai peuvent avoir besoin d'une période transitoire après la publication d'une nouvelle publication CEI, ou d'une publication amendée ou révisée, pour fabriquer des produits conformes aux nouvelles exigences et pour adapter leurs équipements aux nouveaux essais ou aux essais révisés. Le comité recommande que le contenu de cette publication soit entériné au niveau national au plus tôt 12 mois après la date de publication. Pendant ce temps, l'édition précédente peut toujours être commandée auprès du Comité National CEI de votre pays ou auprès du bureau Central de la CEI.
Cette publication doit être lue conjointement avec la CEI 61558-1:2005.

General Information

Status
Published
Publication Date
28-Jun-2010
Current Stage
PPUB - Publication issued
Start Date
29-Jun-2010
Completion Date
29-Jun-2010
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IEC 61558-2-8
Edition 2.0 2010-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-8: Particular requirements and tests for transformers and power supply
units for bells and chimes
Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des
combinaisons de ces éléments –
Partie 2-8: Règles particulières et essais pour les transformateurs et blocs
d’alimentation pour sonneries et carillons
IEC 61558-2-8:2010
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
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---------------------- Page: 2 ----------------------
IEC 61558-2-8
Edition 2.0 2010-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-8: Particular requirements and tests for transformers and power supply
units for bells and chimes
Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des
combinaisons de ces éléments –
Partie 2-8: Règles particulières et essais pour les transformateurs et blocs
d’alimentation pour sonneries et carillons
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX
ICS 29.180 ISBN 978-2-88912-036-9
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – 61558-2-8 © IEC:2010
CONTENTS

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

1 Scope...............................................................................................................................5

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

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

4 General requirements .......................................................................................................6

5 General notes on tests......................................................................................................6

6 Ratings.............................................................................................................................6

7 Classification ....................................................................................................................7

8 Marking and other information...........................................................................................7

9 Protection against electric shock.......................................................................................8

10 Change of input voltage setting .........................................................................................8

11 Output voltage and output current under load ....................................................................8

12 No-load output voltage......................................................................................................9

13 Short-circuit voltage..........................................................................................................9

14 Heatingss .........................................................................................................................9

15 Short-circuit and overload protection ...............................................................................10

16 Mechanical strength........................................................................................................10

17 Protection against harmful ingress of dust, solid objects and moisture.............................10

18 Insulation resistance, dielectric strength and leakage current ..........................................10

19 Construction ...................................................................................................................10

20 Components ...................................................................................................................12

21 Internal wiring .................................................................................................................12

22 Supply connection and other external flexible cables or cords..........................................12

23 Terminals for external conductors ...................................................................................12

24 Provisions for protective earthing ....................................................................................12

25 Screws and connections .................................................................................................13

26 Creepage distances, clearances and distances through insulation ...................................13

27 Resistance to heat, fire and tracking ...............................................................................13

28 Resistance to rusting ......................................................................................................13

Annexes................................................................................................................................14

Annex F Requirements for manually operated switches which are parts of transformer

assemblies............................................................................................................................14

Bibliography ..........................................................................................................................14

---------------------- Page: 4 ----------------------
61558-2-8 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –
Part 2-8: Particular requirements and tests
for transformers and power supply units for bells and chimes
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.

International standard IEC 61558-2-8 has been prepared by IEC technical committee 96:

Transformers, reactors, power supply units and combinations thereof.

This second edition cancels and replaces the first edition published in 1998. It constitutes a

technical revision. The main changes consist of updating this part in accordance with

IEC 61558-1:2005.

This part has the status of a group safety publication in accordance with IEC Guide 104: 1997,

The preparation of safety publications and the use of basic safety publications and group

safety publications.
---------------------- Page: 5 ----------------------
– 4 – 61558-2-8 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
96/354/FDIS 96/361/RVD

Full information on the voting for the approval of this standard 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.

This part is intended to be used in conjunction with the latest edition of IEC 61558-1 and its

amendments. It is based on the second edition (2005) of that standard.

This part supplements or modifies the corresponding clauses in IEC 61558-1, so as to convert

that publication into the IEC standard: Particular requirements and tests for transformers and

power supply units for bell and chime.

A list of all parts of the IEC 61558 series, under the general title: Safety of transformers,

reactors, power supply units and combinations thereof, can be found on the IEC website.

Future standards in this series will carry the new general title as cited above. Titles of existing

standards in this series will be updated at the time of the next edition.

Where a particular subclause of Part 1 is not mentioned in this part, that subclause applies as

far as is reasonable. Where this part states "addition", "modification" or "replacement", the

relevant text of Part 1 is to be adopted accordingly.
In this part, the following print types are used:
– requirements proper: in roman type;
– test specifications: in italic type;
– explanatory matters: in smaller roman type.
In the text of this part, the words in bold are defined in Clause 3.

Subclauses additional to those in Part 1 are numbered starting from 101; supplementary

annexes are entitled AA, BB, etc.

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

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

the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

NOTE The attention of National Committees is drawn to the fact that equipment manufacturers and testing

organizations may need a transitional period following publication of a new, amended or revised IEC publication in

which to make products in accordance with the new requirements and to equip themselves for conducting new or

revised tests.

It is the recommendation of the committee that the content of this publication be adopted for implementation

nationally not earlier than 12 months from the date of publication.
---------------------- Page: 6 ----------------------
61558-2-8 © IEC:2010 – 5 –
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –
Part 2-8: Particular requirements and tests
for transformers and power supply units for bells and chimes
1 Scope
Replacement:

This part of IEC 61558 deals with the safety of bell and chime transformers and power

supply units incorporating bell and chime transformers. Transformers incorporating

electronic circuits are also covered by this standard.
NOTE 1 Safety includes electrical, thermal and mechanical aspects.

Unless otherwise specified, from here onward, the term transformer covers bell and chime

transformers and power supply units incorporating bell and chime transformers.

This part is applicable to stationary, single-phase, air-cooled (natural or forced) independent

or associated dry-type transformers. The windings may be encapsulated or non-
encapsulated.
This standard is applicable to transformers and power supply (linear).

This standard used in combination with part 2-16 for switch mode power supply (SMPS) units

is also applicable to power supplies with internal operating frequencies higher than 500 Hz.

Where the two requirements are in conflict, the most severe takes precedence.

The rated supply voltage does not exceed 250 V a.c., and the rated supply frequency and

does not exceed 500 Hz. This standard is applicable to transformers and linear power supply

units with internal operating frequency not exceeding 500 Hz.
The rated output shall not exceed 100 VA.

The no-load output voltage does not exceed 33 V a.c. or 46 V ripple-free d.c., and the rated

output voltage does not exceed 24 V a.c., or 33 V ripple-free d.c.

Bell and chime transformers are generally intended to supply domestic sound signalling

equipment and other similar devices where the load is applied for short periods of time.

NOTE 2 A partial load may be applied for illumination purposes.

This part is not applicable to external circuits and their components intended to be connected

to the input terminals and output terminals of the transformers.

Transformers covered by this part are used only in applications where double or reinforced

insulation between circuits is required by the installation rules or by the end product standard.

NOTE 3 Normally, the transformers are intended to be used with equipment to provide voltages different from the

supply voltage for the functional requirements of the equipment. The protection against electric shock may be

provided (or completed) by other features of the equipment, such as the body. Parts of output circuits may be

connected to the input circuits or to protective earth.
---------------------- Page: 7 ----------------------
– 6 – 61558-2-8 © IEC:2010

This part is applicable to transformers associated with specific equipment, to the extent

decided upon by the relevant IEC technical committees.
NOTE 4 Attention is drawn to the following:

- measures to protect the enclosure and the components inside the enclosure against external influences such

as fungus, vermin, termites, solar-radiation, and icing should also be considered;

- the different conditions for transportation, storage, and operation of the transformer should also be considered;

- additional requirements in accordance with other appropriate standards and national rules may be applicable to

transformers intended for use in special environments, such as tropical environment.

NOTE 5 Future technological development of transformers may necessitate a need to increase the upper limit of

the frequencies, until then this part may be used as a guidance document.
2 Normative references
This clause of Part 1 is applicable except as follows:
Addition:

IEC 61558-1:2005, Safety of power transformers, power supplies, reactors and similar products

– Part 1: General requirements and tests
3 Terms and definitions
This clause of Part 1 is applicable except as follows:
Addition:
3.1.101
bell and chime transformer

single-phase safety isolating transformer specifically intended to supply household sound

signalling equipment and other similar devices
4 General requirements
This clause of Part 1 is applicable.
5 General notes on tests
This clause of Part 1 is applicable.
6 Ratings
Replacement:

6.101 The rated output voltage shall not exceed 24 V a.c. or 33 V ripple-free d.c..

For independent transformers, this output voltage limitation applies even when output

windings, not intended for interconnection, are connected in series.
6.102 The rated output shall not exceed 100 VA.
---------------------- Page: 8 ----------------------
61558-2-8 © IEC:2010 – 7 –

6.103 The rated supply frequency and the internal operating frequencies shall not exceed

500 Hz.
6.104 The rated supply voltage shall not exceed 250 V a.c.

Compliance with the requirements 6.101 to 6.104 is checked by inspection of the marking.

7 Classification
This clause of Part 1 is applicable except as follows:
7.2 Replacement:
According to short-circuit protection or protection against abnormal use:
– inherently short-circuit proof transformers;
– non-inherently short-circuit proof transformers;
– fail-safe transformers.
7.4 Replacement:
According to their mobility:
– fixed transformers.
7.5 Replacement:
According to their duty-type:
– short-time duty cycle;
– intermittent duty cycle.
NOTE A partial load for illumination may be applied continuously.
Addition:
7.101 According to the method of mounting:
– mounting in a distribution assembly;
– mounting in sound signalling devices (bells, chimes, buzzers, etc.);
– mounting on an outlet box or cabinet;
– flush mounted;
– surface mounted.
8 Marking and other information
This clause of Part 1 is applicable except as follows:
8.1 h) Replacement:

The transformers shall be marked with one of the graphical symbols shown in 8.11;

---------------------- Page: 9 ----------------------
– 8 – 61558-2-8 © IEC:2010
8.11 Addition:
Symbol or graphical symbol Explanation or title Identification
Fail-safe bell and chime transformer Based on
Symbol
IEC 60417-
5013 (2009-
05)
Short-circuit proof bell and chime
IEC 60417-
transformer (inherently or non-inherently)
5013 (2009-
05)
9 Protection against electric shock
This clause of Part 1 is applicable except as follows:
Addition:

9.101 Protection against accidental contact with windings and hazardous live parts of the

input circuit shall be ensured while connecting conductors to the output terminals.

Compliance is checked by inspection and by the application of the standard test finger shown

in Figure 2. It shall not be possible to touch windings or hazardous live parts of the input

circuit with the test finger.
10 Change of input voltage setting
This clause of Part 1 is applicable.
11 Output voltage and output current under load
This clause of Part 1 is applicable except as follows:
11.1 Replacement

When the transformer is connected to the rated supply voltage, at the rated supply

frequency, and loaded with an impedance resulting in the rated output at the rated output

voltage and, for a.c. current, at the rated power factor, the output voltage shall not differ from

the rated value by more than:

a) 15 % for the output voltage of inherently short-circuit proof transformers with one

rated output voltage;

b) 15 % for the highest output voltage of inherently short-circuit proof transformers

with more than one rated output voltage;

c) 20 % for the other output voltages of inherently short-circuit proof transformers with

more than one rated output voltage;
d) 15 % for the output voltages of other transformers.

Compliance is checked by measuring the output voltage 2 min after the transformer is

connected to the rated supply voltage, at the rated supply frequency, and loaded with an

impedance resulting in the rated output, at the rated output voltage and the rated power

factor.

For transformers with more than one rated supply voltage, the requirement is applicable for

each of the rated supply voltages.
---------------------- Page: 10 ----------------------
61558-2-8 © IEC:2010 – 9 –

For transformers with multiple output windings, the loads are applied to every multiple

section simultaneously, unless otherwise declared.
12 No-load output voltage
This clause of Part 1 is applicable except as follows:
Addition:

The no-load output voltage is measured when the transformer is connected to the rated

supply voltage at the rated supply frequency at ambient temperature.

12.101 The no-load output voltage shall not exceed 33 V a.c. or 46 V ripple free d.c.. The

output voltage limitation applies even when independent output windings, not intended for

interconnection, are connected in series.

12.102 The difference between the no-load output voltage and the output voltage under

load shall not be excessive.

The difference between the no-load output voltage measured in this clause and the output

voltage under load measured during the test of Clause 11, expressed as a percentage of the

latter voltage, shall not exceed 100 %.
U – U
no-load
load
NOTE The ratio is defined as follows: × 100 %
load
where U is the no-load output voltage and U is the output voltage under load.
no-load load

Compliance with the requirements of 12.101 and 12.102 is checked by measuring the no-load

output voltage at the ambient temperature when the transformer is connected to the rated

supply voltage at the rated frequency.
13 Short-circuit voltage
This clause of Part 1 is applicable.
14 Heatingss
This clause of Part 1 is applicable except as follows:
14.1 Replacement of the second paragraph by the following:
Temperatures are determined under the following conditions.
Replacement of the tenth paragraph by the following:
Transformers are supplied at rated supply voltage and loaded with an impedance Z

producing rated output at the rated output voltage and, for a.c. current, at the rated power

factor. The value of output current is measured after 1 min. Then the supply voltage is

increased by 10 % and the output impedance is adjusted so that the new impedance Z’ gives

the same output current than the value measured before. Transformers are submitted to 20

cycles of 1 min operation with the impedance Z’ and 5 min operation with 5 times the

impedance Z’. Temperature rises are measured during the last cycle.
---------------------- Page: 11 ----------------------
– 10 – 61558-2-8 © IEC:2010
Addition:

Addition of the following footnote to table “f“ to "external enclosures" in Table 1:

f The external enclosure of a transformer only includes the parts accessible to the standard test finger when

mounted in accordance with 14.1.
Addition of the following footnote to table “g“ to "supports" in Table 1:

g Support includes any area of the black painted plywood support, but excludes any metal parts of the mounting

system (rails, outlet boxes, etc.).
15 Short-circuit and overload protection
This clause of Part 1 is applicable except as follows:
Addition:

15.101 The maximum short-circuit output current shall not exceed 10 A, measured 5 s after

applying the short-circuit, the transformer being supplied with 1,1 times the rated supply

voltage.
16 Mechanical strength
This clause of Part 1 is applicable except as follows:
Replacement:
16.2 The impact hammer shall have an energy of (0,2 ± 0,05) J.
17 Protection against harmful ingress of dust, solid objects and moisture
This clause of Part 1 is applicable.
18 Insulation resistance, dielectric strength and leakage current
This clause of Part 1 is applicable.
19 Construction
This clause of Part 1 is applicable except as follows:
Replacement:

19.1 The input and output circuits shall be electrically separated from each other, and the

construction shall be such that there is no possibility of any connection between these circuits,

either directly or indirectly, through other conductive parts, except by deliberate action.

Compliance is checked by inspection and measurements, taking Clauses 18 and 26 into

consideration.

19.1.1 The insulation between input and output winding(s) shall consist of double or

reinforced insulation (rated for the working voltage).
---------------------- Page: 12 ----------------------
61558-2-8 © IEC:2010 – 11 –
In addition, the following applies:

– for class I transformers not intended for connection to the mains supply by means of a

plug, the insulation between the input windings and the body connected to earth shall

consist of at least basic insulation rated for the input voltage. The insulation between

the output windings and the body connected to earth, shall consist of at least basic

insulation (rated for the output voltage);
– for class I transformers intended for co
...

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