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IEC 60947-7-4
Edition 2.0 2019-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
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IEC 60947-7-4
Edition 2.0 2019-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-6451-5
– 2 – IEC 60947-7-4:2019 RLV IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 9
4 Classification . 10
5 Characteristics . 10
5.1 Summary of characteristics . 10
5.2 Type of PCB terminal block . 10
5.3 Rated and limiting values . 11
5.3.1 Rated voltages . 11
5.3.2 Rated current . 11
5.3.3 Standard cross-sections . 11
5.3.4 Maximum cross-section . 12
5.3.5 Connecting capacity . 12
6 Product information . 13
6.1 Marking . 13
6.2 Additional information . 14
7 Normal service, mounting and transport conditions . 14
8 Constructional and performance requirements . 14
8.1 Constructional requirements . 14
8.1.1 Clamping units . 14
8.1.2 Mounting and installation . 15
8.1.3 Clearances and creepage distances . 15
8.1.4 Terminal identification and marking . 15
8.1.5 Resistance to abnormal heat and fire . 16
8.1.6 Maximum cross-section and connecting capacity . 16
8.2 Performance requirements . 16
8.2.1 Temperature-rise (current-temperature derating) . 16
8.2.2 Dielectric properties . 16
8.2.3 Short-time withstand current . 16
8.2.4 Contact resistance . 17
8.2.5 Ageing tests . 17
8.3 Electromagnetic compatibility (EMC) . 17
9 Tests . 17
9.1 Kinds of test . 17
9.2 General . 17
9.3 Verification of mechanical characteristics . 18
9.3.1 General . 18
9.3.2 Attachment of the PCB terminal block on its support . 18
9.3.3 Vacant . 19
9.3.4 Verification of the maximum cross-section and connecting capacity . 19
9.3.5 Verification of maximum cross-section (special test with gauges) . 19
9.4 Verification of electrical characteristics . 20
9.4.1 General . 20
9.4.2 Verification of clearances and creepage distances . 20
9.4.3 Dielectric tests . 20
9.4.4 Verification of contact resistance . 21
9.4.5 Temperature-rise test (current-temperature derating) . 23
9.4.6 Short-time withstand current test . 25
9.4.7 Ageing tests . 26
9.5 Verification of thermal characteristics. 30
9.6 Verification of EMC characteristics . 31
9.6.1 General . 31
9.6.2 Immunity . 31
9.6.3 Emission . 31
Annex A (informative) Structure of a PCB terminal block . 32
Annex B (informative) Additional information to be specified between the manufacturer
and the user . 33
B.1 Additional information available on request of the user . 33
B.2 Information for testing in addition to those mentioned above . 33
Annex C (informative) Examples of PCBs and PCB terminal blocks for high-current
application . 34
C.1 Layout of high-current PCBs (schematic diagram) . 34
C.2 High-current PCB terminal blocks . 35
Bibliography . 36
Figure 1 – Test assembly for the measurement of contact resistance and temperature-rise . 23
Figure 2 – Example of wiring structure of a multi-tier PCB terminal block . 24
Figure 3 – Test assembly for the measurement of short-time withstand current . 26
Figure 4 – Test sequence . 27
Figure 5 – Test sequence for PCB terminal blocks with contact pressure via insulating
material . 28
Figure 6 – Current cycling ageing test procedure . 30
Figure A.1 – Structure of a PCB terminal block . 32
Figure C.1 – Structure of a high current PCB . 34
Figure C.2 – PCB terminal block with soldered connection to the PCB . 35
Figure C.3 – PCB terminal block with screwed connection to the PCB . 35
Table 1 – Standard cross-sections of copper conductors . 12
Table 2 – Relationship between maximum cross-section and connecting capacity of
PCB terminal blocks. 13
Table 3 – Standards for clamping units and connecting methods . 14
Table 4 – Tightening torques for PCB terminal blocks with screw-type clamping units . 19
Table 5 – Impulse withstand test voltages . 21
Table 6 – Dielectric test voltages corresponding to the rated insulation voltage . 21
Table 7 – Length of connectable conductors and conductor loops . 24
Table 8 – Examples of cross-sectional distribution of interconnections on printed
circuit boards . 25
– 4 – IEC 60947-7-4:2019 RLV IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-4: Ancillary equipment –
PCB terminal blocks for copper conductors
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 w
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