Voltage characteristics of electricity supplied by public distribution networks

This European Standard defines, describes and specifies the main characteristics of the voltage at a network user's supply terminals in public low voltage and medium voltage electricity distribution networks under normal operating conditions. This standard describes the limits or values within which the voltage characteristics can be expected to remain over the whole of the public distribution network and does not describe the average situation usually experienced by an individual network user. NOTE 1 For the definitions of low and medium voltage see 3.7 and 3.8. The European Standard does not apply under abnormal operating conditions including the following: – a temporary supply arrangement to keep the network users supplied during condition arising as a result of a fault, maintenance and construction work or to minimize the extent and duration of a loss of supply; – in case of non-compliance of a network user's installation or equipment with the relevant standards or with the technical requirements for connection, established either by the public authorities or the distribution network operator (DNO) including the limits for the emission of conducted disturbances; NOTE 2 A network user’s installation may include load as well as generation. – in exceptional situations, in particular, – exceptional weather conditions and other natural disasters, – third party interference, – acts by public authorities, – industrial actions (subject to legal requirements), – force majeure, – power shortages resulting from external events. The voltage characteristics given in this standard are not intended to be used as electromagnetic compatibility (EMC) levels or user emission limits for conducted disturbances in public distribution networks. The voltage characteristics given in this standard are not intended to be used to specify requirements in equipment product standards and in installation standards. NOTE 3 The performance of equipment might be impaired if it is subjected to supply conditions which are not specified in the equipment product standard. This standard may be superseded in total or in part by the terms of a contract between the individual network user and the DNO.

Merkmale der Spannung in öffentlichen Elektrizitätsversorgungsnetzen

Diese Europäische Norm definiert, beschreibt und spezifiziert die wesentlichen Merkmale der Versorgungsspannung an der Übergabestelle zum Netznutzer in öffentlichen Nieder- und Mittelspannungs-Elektrizitätsversorgungsnetzen unter normalen Betriebsbedingungen. Diese Norm beschreibt die Grenzen oder Werte, innerhalb derer die Merkmale der Spannung über das gesamte öffentliche Elektrizitätsversorgungsnetz zu erwarten sind; sie beschreibt aber nicht die durchschnittliche Situation in einem öffentlichen Energieversorgungsnetz, wie sie ein einzelner Nutzer des Netzes gewöhnlich erfährt. ANMERKUNG 1 Zur Definition von Nieder- und Mittelspannung siehe 3.7 und 3.8. Diese Europäische Norm gilt nicht für von den normalen Betriebsbedingungen abweichende Betriebsbedingungen, welche die folgenden einschließen: – vorübergehende Versorgungsmaßnahmen, die angewandt werden, um Nutzer des Netzes während Bedingungen, die als Ergebnis einer Störung bzw. eines Fehlers, von Wartungs- und/oder Baumaßnahmen auftreten, weiter zu versorgen oder die angewandt werden, um das Ausmaß und die Dauer von Versorgungsausfällen zu minimieren; – Fälle, bei denen eine Anlage oder ein Gerät des Netznutzers nicht den einschlägigen Normen oder den technischen Anschlussbedingungen – aufgestellt entweder von den Behörden oder dem Netzbetreiber – entsprechen oder die Grenzwerte für die Aussendung leitungsgeführter Störgrößen überschreiten. ANMERKUNG 2 Eine Anlage des Netznutzers kann sowohl Lasten als auch Generatoren enthalten. – Ausnahmesituationen, insbesondere bei – außergewöhnlichen Wetterbedingungen und anderen Naturkatastrophen, – Störungen durch Dritte, – Maßnahmen der Behörden, – Arbeitskampfmaßnahmen (nach gesetzlichen Bestimmungen), – höherer Gewalt, – Versorgungsengpässen als Ergebnis äußerer Einflüsse. Die in dieser Norm beschriebenen Merkmale der Versorgungsspannung sind nicht dafür vorgesehen, als Werte für die Elektromagnetische Verträglichkeit (EMV) oder als Grenzwerte für die Aussendung von leitungsgeführten Störgrößen durch Anlagen oder Geräte des Netznutzers in öffentlichen Energieversorgungs-netzen verwendet zu werden. Die in dieser Norm beschriebenen Merkmale der Versorgungsspannung sind nicht dafür vorgesehen, zur Festlegung von Anforderungen in Produktnormen der angeschlossenen Geräte oder in Installationsnormen verwendet zu werden. ANMERKUNG 3 Das Betriebsverhalten eines angeschlossenen Gerätes kann beeinträchtigt werden, wenn dieses Versorgungsbedingungen ausgesetzt ist, die nicht in der Produktnorm des Gerätes berücksichtigt sind. Diese Norm kann ganz oder teilweise durch vertragliche Vereinbarungen zwischen dem einzelnen Netznutzer und dem Netzbetreiber außer Kraft gesetzt werden.

Caractéristiques de la tension fournie par les réseaux publics de distribution

Cette Norme Européenne définit, décrit et spécifie, au point de livraison de l’utilisateur du réseau, les caractéristiques principales de tension fournie par un réseau public de distribution basse tension et moyenne tension dans des conditions normales d'exploitation. Cette norme décrit les limites ou les valeurs des caractéristiques de la tension qui peuvent être attendues sur l’ensemble du réseau public de distribution et ne décrit pas la situation moyenne habituellement rencontrée par un utilisateur du réseau. NOTE 1 Voir les définitions de la basse tension et de la moyenne tension en 3.7 et 3.8. Cette Norme Européenne ne s'applique pas dans les situations d'exploitation anormales, y compris dans les cas suivants: – conditions d'alimentation provisoires pour maintenir les utilisateurs du réseau alimentés dans une situation faisant suite à une avarie, pendant les travaux d'entretien ou de construction sur le réseau ou pour limiter l'étendue et la durée d'une coupure d'alimentation; – non conformité de l'installation ou des équipements de l’utilisateur du réseau aux normes applicables ou aux prescriptions techniques de raccordement de charges établies soit par l'administration, soit par le Gestionnaire de Réseau de Distribution (GRD) incluant les limites d'émission de perturbations conduites; NOTE 2 L'installation d’un utilisateur du réseau peut inclure des charges aussi bien que des productions. – dans les situations exceptionnelles, en particulier, – conditions climatiques exceptionnelles et autres catastrophes naturelles, – faits provenant de tiers, – décisions officielles, – faits de grève (soumises à des obligations légales), – force majeure, – coupures dues à des causes externes. Les caractéristiques de la tension données dans cette norme ne sont pas destinées à être utilisées comme des niveaux de compatibilité électromagnétique (CEM) ou comme des limitations d’émission de l'utilisateur pour les perturbations conduites dans les réseaux publics de distribution. Elles ne sont pas non plus destinées à être utilisées pour définir les exigences dans les normes de produit des équipements et les normes d’installation. NOTE 3 Les performances d’un équipement peuvent être dégradées si les conditions d’alimentation ne sont pas celles spécifiées dans la norme produit correspondante. Cette norme peut être en tout ou en partie remplacée par les termes d'un contrat conclu entre un utilisateur du réseau et le GRD.

Značilnosti napetosti v javnih distribucijskih omrežjih

General Information

Status
Withdrawn
Publication Date
30-Nov-2007
Withdrawal Date
31-May-2010
Current Stage
9960 - Withdrawal effective - Withdrawal
Start Date
01-Mar-2013
Completion Date
01-Mar-2013

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SLOVENSKI STANDARD
SIST EN 50160:2008
01-junij-2008
1DGRPHãþD
SIST EN 50160:2000
=QDþLOQRVWLQDSHWRVWLYMDYQLKGLVWULEXFLMVNLKRPUHåMLK
Voltage characteristics of electricity supplied by public distribution networks
Merkmale der Spannung in öffentlichen Elektrizitätsversorgungsnetzen
Caractéristiques de la tension fournie par les réseaux publics de distribution
Ta slovenski standard je istoveten z: EN 50160:2007
ICS:
29.240.01 2PUHåMD]DSUHQRVLQ Power transmission and
GLVWULEXFLMRHOHNWULþQHHQHUJLMH distribution networks in
QDVSORãQR general
SIST EN 50160:2008 en,fr

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50160:2008
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SIST EN 50160:2008
EUROPEAN STANDARD
EN 50160
NORME EUROPÉENNE
September 2007
EUROPÄISCHE NORM
ICS 29.020 Supersedes EN 50160:1999
English version
Voltage characteristics of electricity
supplied by public distribution networks
Caractéristiques de la tension Merkmale der Spannung
fournie par les réseaux publics in öffentlichen
de distribution Elektrizitätsversorgungsnetzen

This European Standard was approved by CENELEC on 2007-06-01. CENELEC members are bound to comply

with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on

application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CENELEC member into its own language and notified

to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 50160:2007 E
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SIST EN 50160:2008
EN 50160:2007 – 2 –
Foreword

This European Standard was prepared by the Working Group 1, Physical characteristics of

electrical energy, of the Technical Committee CENELEC TC 8X, System aspects for electrical

energy supply.

The text of the draft was submitted to the formal vote and was approved by CENELEC as

EN 50160 on 2007-06-01.
This European Standard supersedes EN 50160:1999 + corrigendum September 2004.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-06-01
__________
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SIST EN 50160:2008
– 3 – EN 50160:2007
Contents

1 Scope and object.................................................................................................................... 4

1.1 Scope............................................................................................................................ 4

1.2 Object............................................................................................................................ 4

2 Normative references............................................................................................................. 5

3 Definitions............................................................................................................................... 5

4 Low-voltage supply characteristics ........................................................................................ 9

4.1 Power frequency ........................................................................................................... 9

4.2 Magnitude of the supply voltage ................................................................................... 9

4.3 Supply voltage variations.............................................................................................. 9

4.3.1 Requirements ...................................................................................................... 9

4.3.2 Test method....................................................................................................... 10

4.4 Rapid voltage changes ............................................................................................... 10

4.4.1 Single rapid voltage change .............................................................................. 10

4.4.2 Flicker severity................................................................................................... 10

4.5 Supply voltage dips..................................................................................................... 10

4.6 Short interruptions of the supply voltage .................................................................... 10

4.7 Long interruptions of the supply voltage ..................................................................... 11

4.8 Temporary power frequency overvoltages between live conductors and earth ......... 11

4.9 Transient overvoltages between live conductors and earth ....................................... 11

4.10 Supply voltage unbalance........................................................................................... 11

4.11 Harmonic voltage........................................................................................................ 12

4.12 Interharmonic voltage ................................................................................................. 12

4.13 Mains signalling voltage on the supply voltage .......................................................... 12

5 Medium-voltage supply characteristics ................................................................................ 13

5.1 Power frequency ......................................................................................................... 13

5.2 Magnitude of the supply voltage ................................................................................. 13

5.3 Supply voltage variations............................................................................................ 14

5.4 Rapid voltage changes ............................................................................................... 14

5.4.1 Magnitude of rapid voltage changes.................................................................. 14

5.4.2 Flicker severity................................................................................................... 14

5.5 Supply voltage dips..................................................................................................... 14

5.6 Short interruptions of the supply voltage .................................................................... 14

5.7 Long interruptions of the supply voltage ..................................................................... 14

5.8 Temporary power frequency overvoltages between live conductors and earth ......... 15

5.9 Transient overvoltage between live conductors and earth ......................................... 15

5.10 Supply voltage unbalance........................................................................................... 15

5.11 Harmonic voltage........................................................................................................ 15

5.12 Interharmonic voltage ................................................................................................. 16

5.13 Mains signalling voltage on the supply voltage .......................................................... 16

Annex A (informative) Special nature of electricity ................................................................... 18

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

Figure 1 - Voltage levels of signal frequencies in percent of U used in public LV distribution

networks...................................................................................................................... 13

Figure 2 - Voltage levels of signal frequencies in percent of U used in public MV

distribution networks ................................................................................................... 17

Table 1 - Values of individual harmonic voltages at the supply terminals for orders up to 25

given in percent of the fundamental voltage U .......................................................... 12

Table 2 - Values of individual harmonic voltages at the supply terminals for orders up to 25

given in percent of the fundamental voltage U .......................................................... 16

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SIST EN 50160:2008
EN 50160:2007 – 4 –
1 Scope and object
1.1 Scope

This European Standard defines, describes and specifies the main characteristics of the voltage

at a network user's supply terminals in public low voltage and medium voltage electricity

distribution networks under normal operating conditions. This standard describes the limits or

values within which the voltage characteristics can be expected to remain over the whole of the

public distribution network and does not describe the average situation usually experienced by

an individual network user.
NOTE 1 For the definitions of low and medium voltage see 3.7 and 3.8.

The European Standard does not apply under abnormal operating conditions including the

following:

– a temporary supply arrangement to keep the network users supplied during condition arising

as a result of a fault, maintenance and construction work or to minimize the extent and

duration of a loss of supply;

– in case of non-compliance of a network user's installation or equipment with the relevant

standards or with the technical requirements for connection, established either by the public

authorities or the distribution network operator (DNO) including the limits for the emission of

conducted disturbances;
NOTE 2 A network user’s installation may include load as well as generation.
– in exceptional situations, in particular,
– exceptional weather conditions and other natural disasters,
– third party interference,
– acts by public authorities,
– industrial actions (subject to legal requirements),
– force majeure,
– power shortages resulting from external events.

The voltage characteristics given in this standard are not intended to be used as

electromagnetic compatibility (EMC) levels or user emission limits for conducted disturbances in

public distribution networks.

The voltage characteristics given in this standard are not intended to be used to specify

requirements in equipment product standards and in installation standards.

NOTE 3 The performance of equipment might be impaired if it is subjected to supply conditions which are not

specified in the equipment product standard.

This standard may be superseded in total or in part by the terms of a contract between the

individual network user and the DNO.
1.2 Object

The object of this European Standard is to define and describe the characteristics of the supply

voltage concerning
– frequency,
– magnitude,
– wave form,
– symmetry of the line voltages.
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SIST EN 50160:2008
– 5 – EN 50160:2007

These characteristics are subject to variations during the normal operation of a supply system

due to changes of load, disturbances generated by certain equipment and the occurrence of

faults which are mainly caused by external events.

The characteristics vary in a manner which is random in time, with reference to any specific

supply terminal, and random in location, with reference to any given instant of time. Because of

these variations, the levels of the characteristics can be expected to be exceeded on a small

number of occasions.

Some of the phenomena affecting the voltage are particularly unpredictable, which make it very

difficult to give useful definite values for the corresponding characteristics. The values given in

this standard for such phenomena, e.g. voltage dips and voltage interruptions, shall be

interpreted accordingly.
2 Normative references

The following referenced documents are indispensable for the application of this document. For

dated references, only the edition cited applies. For undated references, the latest edition of the

referenced document (including any amendments) applies.
IEC 60050-161 International Electrotechnical Vocabulary -
Chapter 161: Electromagnetic compatibility
3 Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
network user
party being supplied by or supplying to an electricity distribution network
3.2
distribution network operator (DNO)

party responsible for operating, ensuring the maintenance of and, if necessary, developing the

distribution network in a given area and, for ensuring the long term ability of the network to meet

reasonable demands for the distribution of electricity
3.3
supply terminal

point in a distribution network designated as such and contractually fixed, at which electrical

energy is exchanged between contractual partners

NOTE This point can differ from, for example, the electricity metering point or the point of common coupling.

3.4
supply voltage

r.m.s. value of the voltage at a given time at the supply terminal, measured over a given interval

3.5
nominal voltage (U )

voltage by which a distribution network is designated or identified and to which certain operating

characteristics are referred
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SIST EN 50160:2008
EN 50160:2007 – 6 –
3.6
declared supply voltage (U )

the declared supply voltage U is normally the nominal voltage U of the distribution network. If

c n

by agreement between the DNO and the network user a voltage different from the nominal

voltage is applied to the terminal, then this voltage is the declared supply voltage U

3.7
low voltage (LV)

for the purpose of this European Standard, voltage whose upper limit of nominal r.m.s. value is

1 kV
3.8
medium voltage (MV)

for the purpose of this European Standard, voltage whose nominal r.m.s. value lies above 1 kV

and below 35 kV
3.9
normal operating condition

for a distribution network, condition of meeting load and generation demands, system switching

and clearing faults by automatic system protection in the absence of exceptional conditions due

to external influences or major events
3.10
conducted disturbance

electromagnetic phenomenon propagated along the line conductors of a distribution network. In

some cases an electromagnetic phenomenon is propagated across transformer windings and

hence between networks of different voltage levels. These disturbances may degrade the

performance of a device, equipment or system or they may cause damage
3.11
frequency of the supply voltage

repetition rate of the fundamental wave of the supply voltage measured over a given interval of

time
3.12
voltage variation
increase or decrease of voltage normally due to load variations
3.13
rapid voltage change

single rapid variation of the r.m.s. value of a voltage between two consecutive levels which are

sustained for definite but unspecified durations (for more information see EN 61000-3-3)

3.14
voltage fluctuation
series of voltage changes or a cyclic variation of the voltage envelope
[IEV 161-08-05]
3.15
flicker

impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or

spectral distribution fluctuates with time
[IEV 161-08-13]

NOTE Voltage fluctuation causes changes of the luminance of lamps which can create the visual phenomenon

called flicker. Above a certain threshold flicker becomes annoying. The annoyance grows very rapidly with the

amplitude of the fluctuation. At certain repetition rates even very small amplitudes can be annoying.

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SIST EN 50160:2008
– 7 – EN 50160:2007
3.16
flicker severity

intensity of flicker annoyance defined by the UIE-IEC flicker measuring method and evaluated

by the following quantities:
– short term severity (P ) measured over a period of ten minutes;

– long term severity (P ) calculated from a sequence of 12 P values over a two hour interval,

lt st
according to the following expression:
sti
Plt =
∑ 12
i=1
3.17
supply voltage dip

sudden reduction of the supply voltage to a value between 90 % and 1 % of the declared

voltage U followed by a voltage recovery after a short period of time. Conventionally the

duration of a voltage dip is between 10 ms and 1 min. The depth of a voltage dip is defined as

the difference between the minimum r.m.s. voltage during the voltage dip and the declared

voltage. Voltage changes which do not reduce the supply voltage to less than 90 % of the

declared voltage U are not considered to be dips
3.18
supply interruption

condition in which the voltage at the supply terminals is lower than 1 % of the declared voltage,

U . A supply interruption can be classified as

– prearranged, when network users are informed in advance, to allow the execution of

scheduled works on the distribution network, or

– accidental, caused by permanent or transient faults, mostly related to external events,

equipment failures or interference. An accidental interruption is classified as:
– a long interruption (longer than three minutes);
– a short interruption (up to three minutes).

NOTE 1 The effect of a prearranged interruption can be minimized by the network users by taking appropriate

measures.

NOTE 2 Accidental supply interruptions are unpredictable, largely random events.

3.19
temporary power frequency overvoltage

overvoltage, at a given location, of relatively long duration (see CLC/TR 50422, Clause 3 for

more information)

NOTE Temporary overvoltages usually originate from switching operations or faults (e.g. sudden load reduction,

single phase faults, non-linearities).
3.20
transient overvoltage

short duration oscillatory or non-oscillatory overvoltage usually highly damped and with a

duration of a few milliseconds or less
[IEV 604-03-13 modified]

NOTE Transient overvoltages are usually caused by lightning, switching or operation of fuses. The rise time of a

transient overvoltage can vary from less than a microsecond up to a few milliseconds.

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SIST EN 50160:2008
EN 50160:2007 – 8 –
3.21 harmonic voltage

sinusoidal voltage with a frequency equal to an integer multiple of the fundamental frequency of

the supply voltage. Harmonic voltages can be evaluated

– individually by their relative amplitude (U ) related to the fundamental voltage U , where h is

h 1
the order of the harmonic,

– globally, for example by the total harmonic distortion factor THD, calculated using the

following expression:
THD = (u )
∑ h
h=2

NOTE Harmonics of the supply voltage are caused mainly by network users' non-linear loads connected to all

voltage levels of the supply network. Harmonic currents flowing through the network impedance give rise to harmonic

voltages. Harmonic currents and network impedances and thus the harmonic voltages at the supply terminals vary in

time.
3.22
interharmonic voltage

sinusoidal voltage with a frequency between the harmonics, i.e. the frequency is not an integer

multiple of the fundamental

NOTE Interharmonic voltages at closely adjacent frequencies can appear at the same time forming a wide band

spectrum.
3.23
voltage unbalance

condition in a polyphase system in which the r.m.s. values of the line-to-line voltages

(fundamental component), or the phase angles between consecutive line voltages, are not all

equal. The degree of the inequality is usually expressed as the ratios of the negative and zero

sequence components to the positive sequence component
[IEV 161-08-09 modified]

NOTE 1 In this European Standard, voltage unbalance is considered in relation to three-phase systems and

negative phase sequence only.

NOTE 2 Several approximations give reasonably accurate results for the levels of unbalance normally encountered

(ratio of negative to positive sequence components), e.g.:
where U , U and U are the three line-to-line voltages.
12 23 31
3.24
mains signalling voltage

signal superimposed on the supply voltage for the purpose of transmission of information in the

public distribution network and to network users' premises. Three types of signals in the public

distribution network can be classified:

– ripple control signals: superimposed sinusoidal voltage signals in the range of 110 Hz to

3 000 Hz;

– power-line-carrier signals: superimposed sinusoidal voltage signals in the range between

3 kHz to 148,5 kHz;

– mains marking signals: superimposed short time alterations (transients) at selected points

of the voltage waveform.
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SIST EN 50160:2008
– 9 – EN 50160:2007
4 Low-voltage supply characteristics
4.1 Power frequency

The nominal frequency of the supply voltage shall be 50 Hz. Under normal operating conditions

the mean value of the fundamental frequency measured over 10 s shall be within a range of:

– for systems with synchronous connection to an interconnected system:
50 Hz ± 1 % (i.e. 49,5 Hz... 50,5 Hz) during 99,5 % of a year;
50 Hz + 4 % / - 6 % (i.e. 47 Hz... 52 Hz) during 100 % of the time;
– for systems with no synchronous connection to an interconnected system
(e.g. supply systems on certain islands):
50 Hz ± 2 % (i.e. 49 Hz... 51 Hz) during 95 % of a week;
50 Hz ± 15 % (i.e. 42,5 Hz... 57,5 Hz) during 100 % of the time.
4.2 Magnitude of the supply voltage

The standard nominal voltage U for public low voltage is U = 230 V, either between phase and

n n
neutral, or between phases
– for four-wire three phase systems:
U = 230 V between phase and neutral;
– for three-wire three phase systems:
U = 230 V between phases.
NOTE In low voltage systems declared and nominal voltage are equal.
4.3 Supply voltage variations
4.3.1 Requirements
The voltage variation should not exceed ± 10 %.

Situations like those arising from faults or voltage interruptions, the circumstances of which are

beyond the reasonable control of the parties, are excluded.

NOTE 1 Overall experience has shown, that sustained voltage deviations of more than ± 10 % over a longer period

of time are extremely unlikely, although they could theoretically be within the given statistical limits of 4.3.2.

Therefore, in accordance with relevant product and installation standards and application of IEC 60038 end users’

appliances are usually designed to tolerate supply voltages of ± 10 % around the nominal system voltage, which is

sufficient to cover an overwhelming majority of supply conditions. It is expected to be neither technically nor

economically viable to generally give appliances the ability to handle supply voltage tolerances broader than ± 10 %.

If, in single cases, evidence is given, that the magnitude of the supply voltage could depart beyond this limit for a

longer period of time, additional measures should be taken in cooperation with the local network operator, depending

on a risk assessment. The same applies in cases, where specific appliances have an increased sensitivity with

respect to voltage variations.

NOTE 2 In cases of electricity supplies in remote areas with long lines or not connected to a large interconnected

network, the voltage could be outside the range of U + 10 % / - 15 %. Network users should be informed of the

conditions.
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SIST EN 50160:2008
EN 50160:2007 – 10 –
4.3.2 Test method
Under normal operating conditions,

• during each period of one week 95 % of the 10 min mean r.m.s. values of the supply voltage

shall be within the range of U ± 10 %, and

• all 10 min mean r.m.s. values of the supply voltage shall be within the range of U + 10 % / - 15 %.

4.4 Rapid voltage changes
4.4.1 Single rapid voltage change

A rapid voltage change of the supply voltage is mainly caused either by load changes in

network users' installations or by switching in the system.

Under normal operating conditions a rapid voltage change generally does not exceed 5 % U

but a change of up to 10 % U with a short duration might occur some times per day in some

circumstances.

NOTE A negative voltage change resulting in a voltage less than 90 % U is considered a supply voltage dip

(see 4.5).
4.4.2 Flicker severity

Under normal operating conditions, in any period of one week the long term flicker severity

caused by voltage fluctuation should be P ≤ 1 for 95 % of the time.

NOTE Reaction to flicker is subjective and can vary depending on the perceived cause of the flicker and the period

over which it persists. In some cases P = 1 gives rise to annoyance, whereas in other cases higher levels of P are

lt lt
found without annoyance.
4.5 Supply voltage dips

Voltage dips are generally caused by faults occurring in the network users' installations or in the

public distribution network. They are unpredictable, largely random events. The annual

frequency varies greatly depending on the type of supply system and on the point of

observation. Moreover, the distribution over the year can be very irregular.
Indicative values:

Under normal operating conditions the expected number of voltage dips in a year may be from

up to a few tens to up to one thousand. The majority of voltage dips have a duration less than

1 s and a retained voltage greater than 40 %. However, voltage dips with greater depth and

duration can occur infrequently. In some areas voltage dips with a retained voltage between

85 % and 90 % of U can occur very frequently as a result of the switching of loads in network

users' installations.
4.6 Short interruptions of the supply voltage
Indicative values:

Under normal operating conditions the annual occurrence of short interruptions of the supply

voltage ranges from up to a few tens to up to several hundreds. The duration of approximately

70 % of the short interruptions may be less than one second.

NOTE In some documents short interruptions are considered as having durations not exceeding one minute. But

sometimes control schemes are applied which need operating times of up to three minutes in order to avoid long

voltage interruptions.
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SIST EN 50160:2008
– 11 – EN 50160:2007
4.7 Long interruptions of the supply voltage

Accidental interruptions are usually caused by external events or actions which cannot be

prevented by the DNO. It is not possible to indicate typical values for the annual frequency and

durations of long interruptions. This is due to wide differences in system configurations and

structure in various countries and also because of the unpredictable effects of the actions of

third parties and of the weather.
Indicative values:

Under normal operating conditions the annual frequency of voltage interruptions longer than

three minutes may be less than 10 or up to 50 depending on the area.

Indicative values are not given for prearranged interruptions, because they are announced in

advance.
4.8 Temporary power frequency overvoltages between live conductors and earth

A temporary power frequency overvoltage generally appears during a fault in the public

distribution network or in a network user's installation, and disappears when the fault is cleared.

Under these conditions, the overvoltage may reach the value of the phase-to-phase voltage (up

to max. 440 V in 230/400 V networks) due to a shift of the neutral point of the three-phase

voltage system, the actual value depending upon the degree of load unbalance, and the

remaining impedance between the faulty conductor and earth.

The duration is limited by the time taken for the MV protection and circuit breaker to clear the

fault, typically no more than 5 s.

Under certain circumstances, a fault occurring upstream of a transformer may produce

temporary overvoltages on the LV side for the time during which the fault current flows. Such

overvoltages do not generally exceed 1,5 kV r.m.s.
4.9 Transient overvoltages between live conductors and earth

Transient overvoltages at the supply terminals generally do not exceed 6 kV peak.

NOTE 1 The rise time can cover a wide range from milliseconds down to much less than a microsecond. However,

for physical reasons transients of longer durations usually have much lower amplitudes. Therefore, the coincidence of

high ampli
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