IEC TR 63222-100:2023

Power quality management - Part 100: Impact of power quality issues on electrical equipment and power system

IEC TR 63222-100:2023, which is a Technical Report, collects relevant information on power quality impacts from, e.g., CIGRE reports, case studies, research findings, etc., in order to uncover the mechanisms of how electrical equipment/installations/system are impacted by power quality disturbances, as well as to fully understand the guidelines for power quality management. The contents of this document aim to help network operators, network users and equipment suppliers make rational investments and actively cooperate to manage power quality and keep it consistent with relevant EMC standards.

General Information

• Status: Published
• Publication Date: 29-Aug-2023
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: TC 8 - System aspects of electrical energy supply
• Current Stage: PPUB - Publication issued
• Start Date: 30-Aug-2023
• Completion Date: 17-Jul-2023

Standards Content (Sample)

IEC TR 63222-100 ®
Edition 1.0 2023-08
TECHNICAL
REPORT
colour
inside
Power quality management –
Part 100: Impact of power quality issues on electric equipment and power
system
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IEC TR 63222-100 ®
Edition 1.0 2023-08
TECHNICAL
REPORT
colour
inside
Power quality management –
Part 100: Impact of power quality issues on electric equipment and power

system
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.020  ISBN 978-2-8322-7443-9

– 2 – IEC TR 63222-100:2023 © IEC 2023
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 General impacts of power quality issues . 12
4.1 General . 12
4.2 Harmonic distortion . 12
4.3 Voltage unbalance . 13
4.4 Voltage deviation . 13
4.5 Frequency deviation . 13
4.6 Flicker and rapid voltage change . 14
4.7 Voltage dip . 14
4.8 Transient over-voltages . 14
4.9 Voltage swell . 14
5 Continuous power quality disturbances impact. 14
5.1 The impact of voltage deviation . 14
5.1.1 General . 14
5.1.2 Impact on equipment . 16
5.1.3 Impact on power system . 17
5.2 The impact of frequency deviation . 18
5.2.1 General . 18
5.2.2 Impact on electrical equipment . 19
5.3 The impact of voltage unbalance . 21
5.3.1 General . 21
5.3.2 Impact on electrical equipment . 22
5.3.3 Impact on power system . 27
5.3.4 Impact on electrical equipment . 30
5.3.5 Impact on power system . 32
5.3.6 Impact on electrical equipment . 34
5.3.7 Impact on electrical equipment . 40
6 Discontinuous power quality disturbances impact . 41
6.1 The impact of voltage dip and short time interruptions . 41
6.1.1 General . 41
6.1.2 Impact on power system equipment . 42
6.1.3 Effects on end users' devices . 43
6.1.4 Useful impacts assessment indices . 45
6.2 The impact of voltage swell . 47
6.2.1 General . 47
6.2.2 Impact on power system . 48
6.2.3 Effects on some electrical equipment . 48
6.3 The impact of transient over-voltage . 49
6.3.1 General . 49
6.3.2 Impact on power system equipment . 49
6.3.3 Effects on some electrical equipment . 50
Annex A (informative) Case analysis: Voltage deviation impact on power loss . 52

A.1 Loss of low voltage distribution network . 52
A.1.1 Transformer iron loss . 52
A.1.2 Transformer copper loss . 52
A.2 LED Lights . 55
Annex B (informative) Case analysis: Voltage unbalance impact . 57
B.1 Three-phase unbalance leads to voltage deviation . 57
B.2 Increases the loss of power network . 58
Annex C (informative) Case analysis: flicker and rapid voltage change impact . 61
C.1 The impact of RVC on induction motor . 61
C.2 The impact of RVC on electrolytic capacitor lifetime . 63
C.3 The experiment of the impact of voltage fluctuation on induction motor life 64
C.4 Voltage fluctuation reduces the energy efficiency . 67
Annex D (informative) Case analysis: Harmonic, inter-harmonic and the high
frequency component impact . 70
D.1 Harmonic impact on tripping time of relay protection device . 70
D.2 The impact of harmonics on billable meters in Markal, Dist. Pune Steel Mill
.................................................................................................................. 71
D.3 The impact of harmonics on power cable . 72
D.3.1 Parameter aspect . 72
D.3.2 Performance aspect . 73
D.4 The impact of inter-harmonics on sub-synchronous oscillation of power
system . 74
Annex E (informative) Case: Voltage dip impact . 76
E.1 Voltage dip sensitive equipment tolerance test . 76
E.1.1 Alternating current contactor (ACC) voltage dip tolerance results . 76
E.1.2 PLC voltage dip tolerance test and test results . 78
E.1.3 Relay voltage dip tolerance test and test results . 81
E.2 Voltage dip sensitive industrial customers . 87
Annex F (informative) Case: Voltage swell impact . 88
Annex G (informative) Case: Transient over-voltage impact . 89
G.1 Test waveform . 89
G.2 Case of interaction between the power system and communications system
.................................................................................................................. 89
G.3 Case of 10kV hybrid OHL-cable system during energization . 89
Bibliography . 90

Figure 1 –The influence of under-voltage deviation on transmission loss . 18
Figure 2 – Derating factor for motors operating with phase voltage unbalance . 23
Figure 3 – Percentage changes in torques of induction motor . 24
Figure 4 – Standard drive with DC-link LC filter under 5 % grid voltage amplitude
unbalanced condition . 27
Figure 5 – Proportion of neutral line additional loss (%) . 28
Figure 6 – Neutral shift vector diagram . 29
Figure 7 – Capacitor current value under different voltage fluctuations condition . 32
Figure 8 – Current waveform and spectrum, transformer derating due to current
harmonic losses up to 2 kHz . 35
Figure 9 – Effect of harmonics on power loss . 38
Figure 10 – Effect of harmonics on temperature rise . 38

– 4 – IEC TR 63222-100:2023 © IEC 2023
Figure 11 – Effect of harmonics on expected useful life . 39
Figure 12 – ITIC (CBEMA) curve for equipment connected to 120 V 60 Hz systems . 44
Figure 13 – Region of uncertainty for sensitivity curves of equipment . 45
Figure A.1 – Equivalent circuit diagram of low voltage distribution network . 52
Figure A.2 – The relationship between the ratio of constant impedance load to
constant power load and voltage deviation in the connected system when the
additional copper loss is 0 . 54
Figure A.3 – U-I curves of four LED lamps . 56
Figure A.4 – P-U curves of four LED lamps . 56
Figure B.1 – Guowan #2 station . 57
Figure B.2 – Voltage curve of Guowan #2 station on January 27 . 57
Figure B.3 – Three – phase power curve of Guowan #2 station on January 27 . 58
Figure B.5 – Losses vs. unbalance factor . 60
Figure C.1 – Energy efficiency indexes of A phase when the frequency of am wave is
8,8 Hz . 61
Figure C.2 – Energy efficiency indexes of A phase when the amplitude modulation is
10 % (based on 50Hz system) . 62
Figure C.3 – Motor lifetime estimation with load torque gradually increase subject to
10 % voltage magnitude change and different modulation frequency . 64
Figure C.4 – Motor lifetime estimation with load torque gradually increase subject to
10 % voltage magnitude change and different modulation frequency . 64
Figure C.5 – The compassion of motor lifetime between voltage fluctuations condition
and normal condition. 65
Figure C.6 – Motor lifetime estimation with light load subject to various voltage
fluctuations . 66
Figure C.7 – Motor lifetime estimation with heavy load subject to various voltage
fluctuations . 67
Figure C.8 – Three-dimensional diagram of copper loss of A phase stator . 68
Figure C.9 – Three-dimensional diagram of copper loss of A phase rotor . 68
Figure C.10 – Three-dimensional diagram of iron loss of A phase . 68
Figure C.11 – Three-dimensional diagram of energy efficiency of A phase . 69
Figure D.1 – Test setup . 70
Figure D.2 – Tripping time with distortion current (each test for each order harmonic
with 20% distortion) . 71
Figure D.3 – Recording kWh consumption at HT consumer metering installation . 72
Figure D.4 – Effect of harmonics on resistance (R) . 72
Figure D.5 – Effect of harmonics on inductance (L) . 72
Figure D.6 – Effect of harmonics on power loss . 73
Figure D.7 – Effect of harmonics on temperature rise . 74
Figure D.8 – Effect of harmonics on expected lifetime . 74
Figure E.1 – VTC (voltage tolerance curve) under different POW . 76
Figure E.2 – VTC (voltage tolerance curve) under different PAJ . 77
Figure E.3 – Voltage tolerance curve of each PLC . 78
Figure E.4 – Voltage tolerance curves of P1 and P3 at different starting phases . 79
Figure E.5 – Voltage tolerance curve of P1 at different supply voltages . 80
Figure E.6 – The relation curve between different harmonic phases and U . 80
dc
Figure E.7 – When THD is 5 % and 10 %, the voltage tolerance curve of P3 of
different sub-harmonics is tested at 0° of harmonic phase . 81
Figure E.8 – Voltage dip sensitivity curve of R1 relay at the starting point of 0°-360° 82
Figure E.9 – The maximum normal operating duration curve of R1 relay obtained at
voltage dip starting point from 0° to 360° . 83
Figure E.10 – Sensitivity curves of 8 relays obtained at voltage dip starting point of 0°
and 90° . 84
Figure E.11 – Critical voltage difference . 85
Figure E.12 – VTC under voltage dips with/without harmonics . 85
Figure E.13 – Sensitivity curves of R1 and R4 relays influenced by operation voltage
before voltage dip occurring at voltage dip starting point 0°/90° . 86
Table E.4 – Successive dips testing information . 86

Table 1 – reference information of voltage deviation impacts . 15
Table 2 – reference documents on impact of frequency deviation . 19
Table 3 – reference documents on the impact of voltage unbalance . 22
Table 4 – Effect of voltage Unbalance on motors at full load . 24
Table 5 – Line loss and additional loss increase under three-phrase current
unbalance . 28
Table 6 – Reference documents on the impact of flicker and RVC . 30
Table 7 – Reference documents on impact of harmonic and inter-harmonic . 33
Table 8 – The actual measured capacitance value change rate . 37
Table 9 – Reference documents on impact of voltage dip and short time interruption . 42
Table 10 – reference documents on impact of voltage swell . 48
Table 11 – Reference documents for impact evaluation of transient over-voltages . 49
Table A.1 – Test object parameters . 55
Table A.2 – Raw data of fluorescent lamp under AC power supply . 55
Table B.1 – Simulation results of output voltage. 58
Table B.2 – Load distribution (L1, L2 and L3) and unbalance index D (%) for the 6
KVA network . 59
Table B.3 – Load distribution (L1, L2 and L3) and unbalance index D (%) for the 18
KVA network . 59
Table B.4 – Load distribution (L1, L2 and L3) and unbalance index D (%) for the 180
KVA network . 59
Table C.1 – The variation trend of motor energy efficiency η with voltage
fluctuation (%) . 69
Table D.1 – Test 1 THD=20 % . 71
Table E.1 – Tested ACC . 76
Table E.2 – Tested PLC equipment . 78
Table E.3 – Number and type of low voltage relay . 81

– 6 – IEC TR 63222-100:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POWER QUALITY MANAGEMENT –
Part 100: Impact of power quality issues
on electrical equipment and power system

FOREWORD
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all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TR 63222-100 has been prepared by IEC technical committee 8: System aspects of
electrical energy supply. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
8/1648/DTR 8/1660/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 63222 series, published under the general title Power quality
management, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 8 – IEC TR 63222-100:2023 © IEC 2023
INTRODUCTION
The impacts of power quality issues increasingly attract much attention with modern industrial
development. The integration of nonlinear loads, such as power-electronic based equipment,
electric arc furnace, electric locomotive, etc., and faults or other events such as short-circuit
and lightning strikes directly or indirectly cause power quality issues.
If public supply system power quality is not within the reasonable range defined in IEC TS
62749, and/or the demand-side power quality is not appropriately managed (e.g. IEC TR 63191)
and/or the equipment immunity does not accommodate the expected environment, the
performance of equipment may be impacted, likely causing malfunction, maloperation, or
damage, and likewise the power system itself.
On the other hand, the quality of power is not absolute. Regarding the levels of power quality,
the situation differs. So called “poor” power quality level for one grid may be acceptable or good
for another internal application depending on the system configuration, the transfer
characteristics between the different voltage levels (attenuation or amplification), the immunity
of the equipment /installations/appliances, the actual disturbance levels on the system, etc.
In terms of power quality, the situation in micro-grid on islanding mode, off grid, mini-grid or
weak grid may differ from that in public supply system. The level of power quality may worsen
even far outside the recommended values defined by IEC TS 62749. In those forementioned
grids, appliances may need to be better designed for immunity to power quality issues.
This document, which is a Technical Report, collects relevant information on power quality
impact from, e.g., CIGRE reports, case study, research findings, etc., in order to uncover the
mechanism of how electrical equipment/installations are impacted under specific power quality
condition, as well as to fully understand the reasons of power quality management.
This document focuses on the public supply system. Notionally, the mechanisms of how
electrical equipment/installations/system are impacted by power quality disturbances are
applicable for so-called weak grids.
The contents of this document can help network users and equipment suppliers make rational
investments and actively cooperate with network operators to take specific measures to improve
power quality.
The contents of this document can also support IEC TR 63222-101, namely, power quality
management-power quality data applications.

POWER QUALITY MANAGEMENT –
Part 100: Impact of power quality issues
on electrical equipment and power system

1 Scope
This part of IEC 63222, which is a Technical Report, collects relevant information on power
quality impacts from, e.g., CIGRE reports, case studies, research findings, etc., in order to
uncover the mechanisms of how electrical equipment/installations/system are impacted by
power quality disturbances, as well as to fully understand the guidelines for power quality
management.
The contents of this document aim to help network operators, network users and equipment
suppliers make rational investments and actively cooperate to manage power quality and keep
it consistent with relevant EMC standards.
NOTE 1 The boundaries between the various voltage levels may be different for different countries/regions. In the
context of this document, the following terms for system voltage are used:
• low voltage (LV) refers to U ≤ 1 kV
N
• medium voltage (MV) refers to 1 kV < U ≤ 35 kV
N
• high voltage (HV) refers to 35 kV < U ≤ 230 kV
N
NOTE 2 Because of existing network structures, in some countries/regions, the boundary between medium and
high voltage can be different.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
electricity
set of phenomena associated with electric charges and electric currents
Note 1 to entry: In the context of electric power systems, electricity is often described as a product with particular
characteristics.
[SOURCE: IEC 60050-121:1998, 121-11-76]
3.2
flicker
impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or
spectral distribution fluctuates with time

– 10 – IEC TR 63222-100:2023 © IEC 2023
[SOURCE: IEC 60050-161:1990, 161-08-13]
3.3
frequency deviation
difference between power supply frequency (f ) and nominal frequency (f )
h,1 n
[SOURCE: IEC 60050-614:1990, 614-01-10, modified]
3.4
harmonic frequency
f (abbreviation)
H,h
the frequency which is an integer multiple of the power supply (fundamental) frequency
[SOURCE: IEC 61000-4-7:2009, 3.2.1, modified (removal of formula and Note to entry)]
3.5
Harmonic order
h (abbreviation)
(Integer) the ratio of a harmonic frequency (f ) to the power supply frequency (f )
H,h H,1
[SOURCE: IEC 60050-161:1990, 161-02-19, modified]
3.6
System operator
network operator
the party responsible for safe and reliable operation of a part of the electric power system in a
certain area and for connection to other parts of the electric power system
[SOURCE: IEC 60050-617:2009, 617-02-09]
3.7
nominal frequency
f (abbreviation)
N
value of frequency used to designate or identify a system
3.8
nominal voltage (of a system)
U (abbreviation)
N
value of voltage used to designate or identify a system
[SOURCE: IEC 60050-601:1985, 601-01-21, modified (addition of abbreviation, removal of
"suitable approximate" from the beginning of definition)]
3.9
point of common coupling
PCC (abbreviation)
point in a public power supply network, electrically nearest to a particular load, at which other
loads are or may be connected
Note 1 to entry: These loads can be either device, equipment or systems, or distinct network user’s installations.
[SOURCE: IEC 60050-161:1990, 161-07-15, modified ("consumer's installation" replaced by
"load")]
3.10
supply terminals
point of supply
point in a distribution network designated as such and contractually fixed, at which electric
energy is exchanged between contractual partners
Note 1 to entry: Supply terminals may be different from the boundary between the electricity supply system and the
user’s own installation or from the metering point.
[SOURCE: IEC 60050-617:2009, 617-04-02, modified Note 1 to entry]
3.11
(power) network user
party supplying electric power and energy to, or being supplied with electric power and energy
from, a transmission system or a distribution system
[SOURCE: IEC 60050-617:2009, 617-02-07]
3.12
power quality
characteristics of the electricity at a given point on an electrical system, evaluated against a
set of reference technical parameters
Note 1 to entry: These parameters might, in some cases, relate to the compatibility between electricity supplied on
a network and the loads connected to that network.
Note 2 to entry: In the context of this Technical Specification, power quality refers to supply terminals and focuses
on defining the characteristics of the voltage and frequency.
[SOURCE: IEC 60050-617:2009, 617-01-05, modified ("electric current, voltage and
frequencies" replaced by "electricity" and Note 2 to entry added)]
3.13
rapid voltage change
RVC (abbreviation)
quick transition (that may last more than several cycles) in RMS voltage between two steady-
state conditions while the voltage stays in-between the thresholds defined for voltage swells
and dips (otherwise, it would be considered as a swell or a dip)
Note 1 to entry: For more information, see IEC 61000-4-30.
3.14
transient over-voltage
voltage surge
transient voltage wave propagating along a line or a circuit and characterized by a rapid
increase followed by a slighter decrease of the voltage
[SOURCE: IEC 60050-161:1990, 161-08-11]
3.15
voltage deviation
difference between supply voltage (U) and nominal voltage (U ), often expressed by relative
N
value
Note 1 to entry: In some circumstance, U may be replaced by U by contract or agreement.
N C
3.16
voltage dip
sudden reduction of the voltage at a point in an electrical system followed by voltage recovery
after a short period of time, usually from a few cycles to a few seconds

– 12 – IEC TR 63222-100:2023 © IEC 2023
Note 1 to entry: The starting threshold of voltage dip generally is 90 % of the reference voltage.
[SOURCE: IEC 60050-161:1990, 161-08-10, modified (addition of Note 1 to entry)]
3.17
voltage fluctuation
series of voltage changes or a cyclic variation of the supply voltage envelope
Note 1 to entry: For the purpose of this document, the reference voltage is the nominal or declared voltage of the
supply system.
[SOURCE: IEC 60050-161:1990, 161-08-05, modified (addition of "supply voltage" and Note 1
to entry)]
3.18
voltage swell
sudden increase of the voltage at a point in an electrical system followed by voltage recovery
after a short period of time, usually from a few cycles to a few seconds
Note 1 to entry: The starting threshold of voltage swell generally is 110 % of reference voltage.
3.19
voltage unbalance
in a poly-phase system, a condition in which the magnitudes of the phase voltages or the phase
angles between consecutive phases are not all equal (fundamental component)
[SOURCE: IEC 60050-161:1990, 161-08-09, modified ("RMS values" replaced by
"magnitudes")]
3.20
voltage unbalance factor
in a three-phase system, the degree of unbalance is expressed by the ratio (in per cent)
between the RMS values of the negative sequence (or, rarely, of the zero-sequence) component
and the positive sequence component of voltage
[SOURCE: IEC 60050-604:1987, 604-01-30, modified (addition of "voltage" to term)]
4 General impacts of power quality issues
4.1 General
Generally, for electrical equipment exposing under continuous power quality phenomenon
disturbances, the impacts of long-time accumulated effects may be the key aspect, while
immediate impact may arise in case of events of discontinuous power quality phenomenon, e.g.,
voltage dip/swell/short time interruption.
IEC TS 62749:2020, Annex C describes the general impacts of power quality issues. This
clause refers to IEC TS 62749:2020, Annex C.
4.2 Harmonic distortion
Generally, harmonic impacts due to long-time accumulated effects are often of concern , but
harmonic resonance will lead to harmonic over-voltage which will lead to harmonic over-voltage
which produces dielectric stress of electrical equipment, and even causes dielectric breakdown.
• Capacitors for power factor correction often act as sinks for a particular order of harmonic
currents. In this case, it can lead to capacitor over current if no forethought is given at the
designing stage.
• Non-sinusoidal power supplies result in the reduction of torque of induction motors.

• Harmonics will increase interference with telephone, communicating and analogue circuits.
• Excessive levels of harmonics can cause errors in the reading of induction type energy
meters which are calibrated for pure sinusoidal AC power.
• High-order harmonics cause voltage stresses.
• Harmonic currents flowing through power system networks can cause additional losses.
It is reported that the level of inter-harmonics in power supply systems is increasing due to the
development of frequency converters and similar electronically controlled equipment. Harmonic
voltages and inter-harmonic voltages, if not controlled, might lead (among other effects) to
overloading or disturbance of equipment on the supply networks and in electricity users
'installations.
In some cases, inter-harmonic voltages, even at low levels, can give rise to flicker or cause
interference in ripple control systems.
4.3 Voltage unbalance
Voltage unbalance is always a concern as it affects the transformers, electrical motors,
electrical generators, transmission losses and relay protection.
• Voltage unbalance degrades the performance and shortens the life of a three-phase motor.
• Current unbalance caused by voltage unbalance essentially creates counter-torque
(resisting torque). That is, it tries to make the motor turn in the opposite direction. This may
create heating.
• Voltage unbalance may also reduce the capacity of equipment such as motors or generators
if not properly taken into consideration at the design stage (equipment is normally designed
and rated to account for some degree of voltage unbalance normally present in any power
system).
• Voltage unbalance causes distance protection and negative-sequence protection to
malfunction, which may result in abnormal starting or even tripping of relay protection.
• Current unbalance caused by voltage unbalance may cause additional losses of distribution
lines and cable lines. It may also lead to the shift of neutral point of high voltage side of the
transformer.
• Voltage unbalance may increase non-characteristics harmonics produced by converters.
• Voltage unbalance may transfer triple harmonic currents in the transmission system,
normally blocked by delta-connected transformer windings.
4.4 Voltage deviation
Large voltage deviations from the nominal values may shorten the life of electrical equipment,
lower the stable limit of the power system, increase the cost of network operation and reduce
the output of reactive power compensation. Electrical equipment operating under this condition
may malfunction, break down or be damaged.
4.5 Frequency deviation
Frequency deviation will endanger the reliability and stability of power system operation and
production efficiency of end-users. The rapid change of frequency will bring great harm to the
normal operation of the equipment of units, such as induction motor or feed water pump. The
accuracy of the energy meter may be impacted by the frequency deviation. Frequency
disturbances in the main network causing local electrical resonance may lead to a large-scale
off-grid accident of renewable energy, e.g. sub-synchronous resonance.
If frequency deviation exceeds the limit, motors are usually protected by means of stopping
their operation. Sustained operation will alter the speed of motors and potentially create unsafe
conditions for the processes in which they function.

– 14 – IEC TR 63222-100:2023 © IEC 2023
Where frequency deviations occur frequently, such as islanded power systems, users may
notice time drift with their analogue clocks.
4.6 Flicker and rapid voltage change
Flicker is considered to be an annoying problem for network users. Most of the time, it does not
have a high financial impact. However, at high levels it can cause inconvenience and adverse
health effects to people when frequent flickering of lights (different technology of lamps may
have different sensitivity to voltage fluctuation) occurs at their work-places or homes.
Flicker can cause photosensitive epileptic seizures, asthenopia (i.e. eyestrain) and
stroboscopic effects (noting that stroboscopic effects pose a danger in industrial settings due
to the possibility that rotating machinery can appear stationary).
Voltage fluctuations and rapid voltage change can cause a number of harmful technical effects
such as data errors, memory loss, equipment shutdown, flicker, motors stalling and reduced
motor life, resulting in disruption to production processes and substantial costs. In addition,
large voltage fluctuations damage electrical equipment such as LED lamps.
4.7 Voltage dip
Motor drives, including variable speed drives, are particularly susceptible because the load still
requires energy that is no longer available except the inertia of the drive. In processes where
several drives are involved, individual motor control units may sense the loss of voltage and
shut down the drive at a different voltage level from its peers and at a different rate of
deceleration, resulting in a complete loss of process control. Data processing and control
equipment is also very sensitive to voltage dips and can suffer from data loss and extended
downtime.
4.8 Transient over-voltages
Transient over-voltage can cause large dV/dt values that can damage or reduce the lifetime of
variable speed drives, motors, transformers, and cables. It also causes the abnormal operation
of wind farms, HVDC systems and energy systems along with flash-over and partial discharge
phenomena and damage their key equipment after events.
4.9 Voltage swell
Voltage swell can affect the operation of wind turbines and may lead it off the grid. When the
grid voltage is disturbed by a temporary rise, the stator flux will generate positive (forced)
component, negative (asymmetric temporary rise) component and DC (free) component, which
will generate over-voltage at wind turbine.
Besides, the surge arresters can be exposed to swells during their lifetime. If the voltage is high
enough, a swell is li
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