IEC TR 61000-2-14:2006

TECHNICAL IEC
REPORT TR 61000-2-14
First edition
2006-12
Electromagnetic compatibility (EMC) –
Part 2-14:
Environment – Overvoltages on public electricity
distribution networks
Reference number
IEC/TR 61000-2-14:2006(E)
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TECHNICAL IEC
REPORT TR 61000-2-14
First edition
2006-12
Electromagnetic compatibility (EMC) –
Part 2-14:
Environment – Overvoltages on public electricity
distribution networks
© IEC 2006 ⎯ 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.
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– 2 – TR 61000-2-14 © IEC:2006(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Description of overvoltages .10
4.1 General .10
4.2 External overvoltages.11
4.3 Internal overvoltages.11
4.4 Overvoltage waveshape .11
5 Long duration overvoltages .12
5.1 Sustained earth faults.12
5.2 Broken neutral on LV network.12
5.3 Maloperation of voltage regulating equipment.13
5.4 Overvoltages due to voltage unbalances .13
5.5 Dispersed generation .14
6 Short duration overvoltages.15
6.1 Earth faults.15
6.2 Load rejection (sudden load loss) .16
6.3 Self-excitation .16
6.4 Resonance and ferroresonance.16
7 Very short duration overvoltages (transients).18
7.1 General description .18
7.2 Lightning .19
7.3 Switching .20
7.4 Summary of surge duration and cause.26
8 Effects of overvoltages on equipment .27
8.1 General considerations.27
8.2 Reduction in life of filament lamps .28
8.3 Effect of overvoltages on IT equipment.28
9 Case studies .29
9.1 General .29
9.2 Switching of LV power factor correction capacitor.29
9.3 Metal fusion furnace .30
9.4 Switching of MV power factor correction capacitor.31
9.5 DC traction system .32
9.6 Load switching .34
10 Protection against the effects of overvoltages.36
10.1 General considerations.36
10.2 Point on wave switching .36
10.3 Arcing horns and spark gaps .37
10.4 Overvoltage protection relays .38
10.5 Snubbers (high frequency RC filter).38
10.6 Uninterruptible power supply (UPS) systems .39

TR 61000-2-14 © IEC:2006(E) – 3 –
10.7 Surge protection device (SPD) .39
11 Conclusions.41
12 Recommendations.42

Bibliography.43

Figure 1 – Lightning impulse test voltage characteristic .11
Figure 2 – Broken neutral on LV network .13
Figure 3 – The effect of distributed generation on network voltage.14
Figure 4 – Line – Neutral temporary overvoltage on healthy phase for single phase line
– earth fault .15
Figure 5 – Typical transient overvoltage when energizing a capacitor bank.22
Figure 6 – Notching caused by power electronics switching .24
Figure 7 – ITI (CBEMA) curve for equipment connected to 120 V 60 Hz systems .29
Figure 8 – Voltage waveform distorted by the energization of a PFC capacitor .30
Figure 9 – Phase to ground overvoltage in case of a single (a) or multiple (b) faults .30
Figure 10 – Equivalent circuit.31
Figure 11 – Extruder connection – single line diagram .32
Figure 12 – Current waveforms (phases A and C) taken at the main LV circuit breaker.32
Figure 13 – Single line diagram of public transportation system .33
Figure 14 – Voltage waveforms associated with overvoltages on public transportation
system .34
Figure 15 – 20 kV line-to-earth voltages during breaking transformer current.35
Figure 16 – Spark gap .37
Figure 17 – Two-stage surge protection scheme .40

Table 1 – Surges on the low voltage network .26
Table 2 – Surges on the medium voltage network .27
Table 3 – Reduction of filament lamp life .28
Table 4 – Protective levels for typical MV surge arresters (effectively earthed neutral
systems) .41

– 4 – TR 61000-2-14 © IEC:2006(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 2-14: Environment – Overvoltages on public electricity
distribution networks
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