SIST EN 50160:2008

SLOVENSKI oSIST prEN 50160:2005

PREDSTANDARD
november 2005
Značilnosti napetosti v javnih razdelilnih omrežjih
Voltage characteristics of electricity supplied by public distribution systems
ICS 29.020 Referenčna številka
oSIST prEN 50160:2005(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

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DRAFT
EUROPEAN STANDARD prEN 50160
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2005

ICS 29.020 Will supersede EN 50160:1999


English version


Voltage characteristics of electricity supplied by public distribution
systems


Caractéristiques de la tension fournie par Merkmale der Spannung in öffentlichen
les réseaux publics de distribution Elektrizitätsversorgungsnetzen


This draft European Standard is submitted to CENELEC members for CENELEC enquiry.
Deadline for CENELEC: 2006-03-17

It has been drawn up by Technical Committee CENELEC TC 8X.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CENELEC 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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

Warning : This document is not a European Standard. It is distributed for review and comments. It is
subject to change without notice and shall not be referred to as a European Standard.

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


© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Project: 17025 Ref. No. prEN 50160:2005 E
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Foreword

This European Standard was prepared by the Working Group 1, Physical characteristics of
electrical energy of CENELEC TC 8X, System aspects of electrical energy supply. It is
submitted to the CENELEC enquiry.

If ratified, this European Standard will supersede EN 50160:1999 + corrigendum
September 2004.


CS note  Before voting stage, this draft will have to be restructured according to the Internal
Regulations, Part 3, regarding the following clauses: Normative references (Clause 2) and
Definitions (Clause 3).
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Contents

1 General. 4
1.1 Scope. 4
1.2 Object. 5
1.3 Definitions.5
1.4 Normative references.9

2 Low-voltage supply-characteristics. 9
2.1 Power frequency. . 9
2.2 Magnitude of the supply voltage. 9
2.3 Supply voltage variations. . 9
2.4 Rapid voltage changes. 10
2.5 Supply voltage dips. . 10
2.6 Short interruptions of the supply voltage . 11
2.7 Long interruptions of the supply voltage . 11
2.8 Temporary power frequency overvoltages between live conductors and earth. 11
2.9 Transient overvoltages between live conductors and earth . 11
2.10 Supply voltage unbalance . 12
2.11 Harmonic voltage.12
2.12 Interharmonic voltage.13
2.13 Mains signalling voltage on the supply voltage. 13

3 Medium-voltage supply-characteristics . 13
3.1 Power frequency . 14
3.2 Magnitude of the supply voltage. 14
3.3 Supply voltage changes . 14
3.4 Rapid voltage changes. 14
3.5 Supply voltage dips. 14
3.6 Short interruptions of the supply voltage . 15
3.7 Long interruptions of the supply voltage . 15
3.8 Temporary power frequency overvoltages between live conductors and earth. 15
3.9 Transient overvoltages between live conductors and earth . 15
3.10 Supply voltage unbalance . 15
3.11 Harmonic voltage.16
3.12 Interharmonic voltage.16
3.13 Mains signalling voltage on the supply voltage. 17

Annex A (informative) Special nature of electricity . 18

Bibliography . 20

Figures
Figure 1 - Voltage levels of signal frequencies in percent of U used
n
         in public LV distribution systems. 13
Figure 2 - Voltage levels of signal frequencies in percent of U used
c
         in public MV distribution systems. 16

Tables
Table 1 - Values of individual harmonic voltages at the supply terminals for orders
        up to 25 given in percent of U . 12
n
Table 2 - Values of individual harmonic voltages at the supply terminals for orders
         up to 25 given in percent of U . 17
c
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1 General

1.1 Scope

This standard gives the main characteristics of the voltage at a network user's supply terminals
in public low voltage and medium voltage electricity distribution systems under normal operating
conditions. This standard gives the limits or values within which the voltage characteristics can
be expected to remain, and does not describe the typical situation in a public supply network.

NOTE  For the definitions of low and medium voltages see 1.3.7 and 1.3.8.

The standard does not apply under abnormal operating conditions including the following:

- conditions arising as a result of a fault or a temporary supply arrangement adopted to keep
network users supplied during 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  A network user’s installation may include load as well as generation.

- in exceptional situations outside the DNO's control, 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 systems.

The voltage characteristics given in this standard are not intended to be used to specify
requirements in equipment product standards.

NOTE  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.

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1.2 Object

The object of this standard is to define and describe the characteristics of the supply voltage
concerning

- frequency;
- magnitude;
- wave form;
- symmetry of the three phase voltages.

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
impossible to give 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.

1.3 Definitions

For the purposes of this standard, the following definitions apply.

1.3.1
network user
party being supplied by or supplying to an electricity distribution network

1.3.2
distribution network operator (DNO)
party responsible for operating, ensuring the maintenance of and, if necessary, developing the
distribution system in a given area and, for ensuring the long term ability of the system to meet
reasonable demands for the distribution of electricity

1.3.3
supply terminal
a 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.

1.3.4
supply voltage
the r.m.s. value of the voltage at a given time at the supply terminal, measured over a given
interval

1.3.5
nominal voltage (U )
n
the voltage by which a distribution network is designated or identified and to which certain
operating characteristics are referred

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1.3.6
declared supply voltage (U )
c
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
c

1.3.7
low voltage (abbreviation: LV)
for the purpose of this standard a voltage, whose upper limit of nominal r.m.s. value is 1 kV

1.3.8
medium voltage (abbreviation: MV)
for the purpose of this standard a voltage, whose nominal r.m.s. value lies above 1 kV and
below 35 kV

1.3.9
normal operating condition
for a distribution network the 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

1.3.10
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

1.3.11
frequency of the supply voltage
repetition rate of the fundamental wave of the supply voltage measured over a given interval of
time

1.3.12
voltage variation
an increase or decrease of voltage normally due to variation of the total load of a distribution
system or a part of it

1.3.13
rapid voltage change
a single rapid variation of the r.m.s. value of a voltage between two consecutive levels which
are sustained for definite but unspecified durations

1.314
voltage fluctuation
a series of voltage changes or a cyclic variation of the voltage envelope
[IEV 161-08-05]

1.3.15
flicker
impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or
spectral distribution fluctuates with time
[IEV 161-08-13]

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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.

1.3.16
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 10 min;
st

- long term severity (P ) calculated from a sequence of 12 P -values over a two hour
lt st
interval, according to the following expression:

12
3
P
sti
3
Plt =
∑
12
i=1
1.3.17
supply voltage dip
a 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
c
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
c

1.3.18
supply interruption
a 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
c

- prearranged, when network users are informed in advance, to allow the execution of
scheduled works on the distribution system, 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 min) caused by a permanent fault,
• a short interruption (up to three min) caused by a transient fault

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.

1.3.19
temporary power frequency overvoltage
an overvoltage, at a given location, of relatively long duration

NOTE  Temporary overvoltages usually originate from switching operations or faults (e.g. sudden load reduction,
single phase faults, non-linearities).

1.3.20
transient overvoltage
a short duration oscillatory or non-oscillatory overvoltage usually highly damped and with a
duration of a few ms or less
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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 µs up to a few ms.

1.3.21
harmonic voltage
a 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
n 1
the order of the harmonic;
- globally, for example by the total harmonic distortion factor THD, calculated using the
following expression:
40
2
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 system. Harmonic currents flowing through the system impedance give rise to harmonic
voltages. Harmonic currents and system impedances and thus the harmonic voltages at the supply terminals vary in
time.

1.3.22
interharmonic voltage
a 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.

1.3.23
voltage unbalance
in a three-phase system, a condition in which the r.m.s. values of the phase voltages or the
phase angles between consecutive phases are not equal

1.3.24
mains signalling voltage
a signal superimposed on the supply voltage for the purpose of transmission of information in
the public distribution system and to network users' premises. Three types of signals in the
public distribution system 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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1.4 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 60038 1983 IEC standard voltages
+ A1 1994
+ A2 1997
IEC 60050-161 1990 International Electrotechnical Vocabulary - Chapter 161:
+ A1 1997 Electromagnetic compatibility
+ A2 1998


2 Low-voltage supply characteristics

2.1 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 . 50,5 Hz) during 99,5 % of a year,
50 Hz + 4 %/- 6 % (i.e. 47 . 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 . 51 Hz) during 95 % of a week,
50 Hz ± 15 % (i.e. 42,5 . 57,5 Hz) during 100 % of the time.

2.2 Magnitude of the supply voltage

The standard nominal voltage U for public low voltage is
n

- for four-wire three phase systems
U = 230 V between phase and neutral,
n

- for three-wire three phase systems
U = 230 V between phases.
n

NOTE  In low voltage systems declared and nominal voltage are equal.

2.3 Supply voltage variations

2.3.1 Requirements

Under normal operating conditions the voltage variation should not exceed ± 10 %.

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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 2.3.2. Therefore, in accordance with relevant product standards and
application of IEC 60038 end users’ appliances are usually designed to tolerate supply terminal
voltages of ± 10 % around the nominal system voltage, which is sufficient to cover an
overwhelming majority of supply conditions. It is hence neither technically nor economically
viable to generally give appliances the ability to handle supply terminal 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 are to be
taken in cooperation with the local network operator. The same applies in cases, where specific
appliances have an increased sensitivity with respect to voltage variations.

Situations like those arising from faults or voltage interruptions, the circumstances of which are
beyond the reasonable control of the parties, are excluded.

2.3.2 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
n
• all 10 min mean r.m.s. values of the supply voltage shall be within the range of
U + 10 % / - 15 %.
n

NOTE 1  In cases of electricity supplies in remote areas with long lines the voltage could be outside the range of
U + 10 % / - 15 %. Network users should be informed of the conditions.
n

2.4 Rapid voltage changes

2.4.1 Magnitude of rapid voltage changes

Rapid voltage changes of the supply voltage are 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
n
but a change of up to 10 % U with a short duration might occur some times per day in some
n
circumstances.

NOTE  A voltage change resulting in a voltage less than 90 % U is considered a supply voltage dip (see 2.5).
n

2.4.2 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.
lt

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 Plt = 1 gives rise to annoyance, whereas in other cases higher levels of Plt are
found without annoyance.

2.5 Supply voltage dips

Voltage dips are generally caused by faults occurring in the network users' installations or in the
public distribution system. 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.

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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 depth less than 60 %. However, voltage dips with greater depth and duration can
occur infrequently. In some areas voltage dips with depths between 10 % and 15 % of U can
n
occur very frequently as a result of the switching of loads in network users' installations.

2.6 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 1 s.

NOTE  In some documents short interruptions are considered as having durations not exceeding 1 min. But
sometimes control schemes are applied which need operating times of up to 3 min in order to avoid long voltage
interruptions.

2.7 Long interruptions of the supply voltage

Accidental interruptions are usually caused by external events or actions which cannot be
prevented by the supplier. 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
3 min 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.

2.8 Temporary power frequency overvoltages between live conductors and earth

A temporary power frequency overvoltage generally appears during a fault in the public
distribution system 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 V/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.

Indicative values:
Under certain circumstances, a fault occurring upstream of a transformer may produce
temporary overvoltages on the Iv side for the time during which the fault current flows. Such
overvoltages will generally not exceed 1,5 kV r.m.s.

2.9 Transient overvoltages between live conductors and earth

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

NOTE 1  The rise time can cover a wide range from ms down to much less than a µs. However, for physical reasons
transients of longer durations usually have much lower amplitudes. Therefore, the coincidence of high amplitudes
and a long rise time is extremely unlikely

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NOTE 2  The energy content of a transient overvoltage varies considerably according to the origin. An induced
overvoltage due to lightning generally has a higher amplitude but lower energy content than an overvoltage caused
by switching, because of the generally longer duration of such switching overvoltages.

NOTE 3  End users’ appliances are designed to withstand transient overvoltages, in accordance with standard
EN 60664-1, which is sufficient to withstand an overwhelming majority of transient overvoltages. If necessary
additional surge protective devices in a network user's installation should be selected according to IEC 60364-4-44 to
take account of the more severe over-voltages. This will cover the induced over-voltage s due both to lightning and to
system switching (IEC 60364-5-53).

2.10 Supply voltage unbalance

Under normal operating conditions, during each period of one week, 95 % of the 10 min mean
r.m.s. values of the negative phase sequence component of the supply voltage shall be within
the range 0 % to 2 % of the positive phase sequence component. In some areas with partly
single phase or two phase connected network users' installations, unbalances up to about 3 %
at three-phase supply terminals occur.

NOTE  In this standard only values for the negative sequence component are given because this component is the
relevant one for the possible interference of appliances connected to the system.

2.11 Harmonic voltage

Under normal operating conditions, during each period of one week, 95 % of the 10 min mean
r.m.s. values of each individual harmonic voltage shall be less than or equal to the value given
in Table 1. Resonances may cause higher voltages for an individual harmonic.

Moreover, the THD of the supply voltage (including all harmonics up to the order 40) shall be
less than or equal to 8 %.

NOTE  The limitation to order 40 is conventional.


Table 1 - Values of individual ha
...