IEC TS 62910:2020

Utility-interconnected photovoltaic inverters - Test procedure for under voltage ride-through measurements

IEC TS 62910:2020 provides a test procedure for evaluating the performance of Under Voltage Ride-Through (UVRT) functions in inverters used in utility-interconnected Photovoltaic (PV) systems. This document is most applicable to large systems where PV inverters are connected to utility high voltage (HV) distribution systems. However, the applicable procedures may also be used for low voltage (LV) installations in locations where evolving UVRT requirements include such installations, e.g. single-phase or 3-phase systems. The assessed UVRT performance is valid only for the specific configuration and operational mode of the inverter under test. Separate assessment is required for the inverter in other factory or user-settable configurations, as these may cause the inverter UVRT response to behave differently. This second edition cancels and replaces the first edition issued in 2015 and constitutes a technical revision.

General Information

• Status: Published
• Publication Date: 23-Jul-2020
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 6 - TC 82/WG 6
• Current Stage: PPUB - Publication issued
• Start Date: 24-Jul-2020
• Completion Date: 16-Jun-2020

Relations

• Revises: IEC TS 62910:2015 - Utility-interconnected photovoltaic inverters - Test procedure for low voltage ride-through measurements
• Effective Date: 05-Sep-2023

Overview

IEC TS 62910:2020 - Utility‑interconnected photovoltaic inverters - Test procedure for Under Voltage Ride‑Through (UVRT) measurements - is a Technical Specification from IEC TC 82 that defines recommended test procedures to evaluate UVRT behaviour of photovoltaic (PV) inverters. This second edition (2020) cancels and replaces the 2015 edition and provides a technical revision aimed at harmonizing UVRT testing where grid‑code requirements vary. The TS is primarily targeted at large utility‑interconnected PV systems (HV distribution) but its procedures can also be applied to LV installations where UVRT obligations exist.

Key topics and requirements

• Scope of testing: Procedures to assess inverter UVRT functions for a given factory or user‑set configuration; results are valid only for the tested configuration and require retesting for other settings.
• Test circuit and equipment: Describes required apparatus such as precision measuring instruments, DC source, short‑circuit emulator, and converter‑based grid simulator (voltage source with low internal resistance and optional broadband amplifiers).
• Test protocol: Defines test sequence components - pre‑test, no‑load test, load test, and tolerance limits - and generation of the UVRT curve (including highest point, inflection point and lowest point) used to select test points.
• Measurement accuracy and tolerances: Specifies instrument accuracy classes and tolerances for voltage drops and timing to ensure repeatable UVRT results.
• Assessment criteria: Outlines how to determine ride‑through time, reactive current response, and active power recovery for pass/fail evaluation.
• Guidance annexes: Informative annexes cover fault types, voltage drop modelling for different short‑circuit faults, and methods to determine critical UVRT performance values.

Applications

• Product testing and type‑approval of PV inverters to verify compliance with utility UVRT requirements.
• Certification and conformity assessment by test laboratories and independent bodies using consistent, repeatable UVRT procedures.
• Grid‑code validation and research for utilities and grid operators assessing inverter behaviour during voltage dips and system faults.
• System design and commissioning by integrators and manufacturers to confirm inverter settings and firmware meet required ride‑through performance.

Who should use this standard

• PV inverter manufacturers and R&D teams
• Accredited test laboratories and certification bodies
• Grid operators, utilities and regulators
• EPC contractors, system integrators and asset owners

Related guidance

• IEC TS 62910:2020 is intended to be used alongside applicable national or regional grid codes and other IEC standards for photovoltaic systems. Users should consult local requirements when selecting UVRT curves and K‑factor settings.

Keywords: IEC TS 62910:2020, UVRT, under voltage ride‑through, photovoltaic inverters, utility‑interconnected, test procedure, short‑circuit emulator, grid simulator, PV inverter testing.

Standards Content (Sample)

IEC TS 62910 ®
Edition 2.0 2020-07
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for under voltage
ride-through measurements
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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IEC TS 62910 ®
Edition 2.0 2020-07
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for under voltage

ride-through measurements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-8383-7

– 2 – IEC TS 62910:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviated terms . 7
3.1 Terms, definitions and symbols . 7
3.2 Abbreviated terms . 9
4 Test circuit and equipment . 10
4.1 General . 10
4.2 Test circuit . 10
4.3 Test equipment . 10
4.3.1 Measuring instruments. 10
4.3.2 DC source . 11
4.3.3 Short-circuit emulator . 11
4.3.4 Converter based grid simulator . 14
5 Test . 14
5.1 Test protocol . 14
5.2 Test curve . 16
5.3 Test procedure . 17
5.3.1 Pre-test . 17
5.3.2 No-load test . 17
5.3.3 Tolerance . 17
5.3.4 Load test . 17
6 Assessment criteria . 18
Annex A (informative) Circuit faults and voltage drops . 19
A.1 Fault types . 19
A.2 Voltage drops . 21
A.2.1 General . 21
A.2.2 Three-phase short-circuit fault . 22
A.2.3 Two-phase short-circuit fault with ground . 22
A.2.4 Two-phase short-circuit fault without ground . 23
A.2.5 Single-phase short-circuit fault with ground . 24
Annex B (informative) Determination of critical performance values in UVRT testing . 26
B.1 General . 26
B.2 Drop depth ratio . 26
B.3 Ride-through time . 26
B.4 Reactive current. 26
B.5 Active power . 27
Annex C (informative) Requirements of the UVRT curve . 28
C.1 General . 28
C.2 UVRT curve . 28
C.3 Test points . 28
Bibliography . 29

Figure 1 – Testing circuit diagram . 10
Figure 2 – Short-circuit emulator . 12

Figure 3 – Converter device example . 14
Figure 4 – UVRT curve example . 16
Figure 5 – Tolerance of voltage drop. 17
Figure A.1 – Grid fault diagram . 21
Figure A.2 – Diagram of voltage vector for three-phase short-circuit fault . 22
Figure A.3 – Diagram of voltage vector of two-phase (BC) short-circuit fault with
ground . 23
Figure A.4 – Diagram of voltage vector of two-phase (BC) short-circuit fault . 24
Figure A.5 – Diagram of voltage vector of single-phase (A) short-circuit fault with

ground . 25
Figure B.1 – Determination of reactive current output . 27
Figure B.2 – Determination of active power recovery . 27
Figure C.1 – The typical curve of UVRT . 28

Table 1 – Accuracy of measurements . 11
Table 2 – Fault type and switch status . 13
Table 3 – Test specification for UVRT (Indicative) . 15
Table A.1 – Short-circuit paths for different fault types . 19
Table A.2 – Amplitude and phase changes in three-phase short-circuit fault . 22
Table A.3 – Amplitude and phase changes in two-phase (BC) . 23
Table A.4 – Amplitude and phase changes in two-phase (BC) short-circuit fault . 24
Table A.5 – Amplitude and phase changes in single-phase (A) . 25

– 4 – IEC TS 62910:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a Technical
Specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62910, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

This second edition cancels and replaces the first edition issued in 2015, and constitutes a
technical revision.
It remains a TS because it is limited to providing recommended practices for UVRT testing in
the context of non-uniform grid-codes lacking international consensus, and the rapid
development of test technology in recent years.
The main technical changes with regard to the previous edition are as follows:
Clause Previous edition Present edition
the voltage support of EUT in accordance with the K-factor is to be supplied by the EUT
the voltage drops. The K-factor is to be manufacturer meeting additional requirements
3.1.12
specified by the EUT manufacturer imposed by national standards and/or local codes
Back to Back circuit Back to Back circuit
A A
B B
Figure 2
C C
Grid Grid
(optional) (optional)
The test circuit essentially comprises a voltage The test circuit essentially comprises a voltage
4.3.4 source with a low internal resistance combined source with a low internal resistance combined
with broadband amplifiers. optionally with broadband amplifiers.
d The test should be carried out under specified d The test should be carried out under specified
K-factor provided by manufacture meeting
K-factor provided by local manufacture.
Table 3
additional requirements imposed by national
standards and/or local codes.
1,2
1,2
1,1
1,1
LVRT curve
LVRT curve
Keep connecting to the grid
Keep connecting to the grid 1,0
1,0
highest point
0,9
0,9
inflection point
0,8 inflection point 0,8
0,7 inflection point 0,7 inflection point
0,6 0,6
0,5 0,5
May cut off from the grid May cut off from the grid
Figure 4
0,4 0,4
0,3 inflection point 0,3 inflection point
0,2
0,2
Lowest point
Lowest point
0,1
0,1
t
t0 t1 t2 t3 4 t
t t t t 4
0 1 2 3
Time (s)
Time (s)
NOTE The example shows two types of points The example shows three types of points on the
on the UVRT curve: the lowest point and the UVRT curve: the highest point, the lowest point
5.2
inflection point. Tests must be carried out at and the inflection point. Tests shall be carried out
both types of points at above types of points.
Prior to the fault simulation tests, the EUT Prior to the fault simulation tests, the EUT should
should run in normal operating mode. The run in normal operating mode. The selected
5.3.1 selected UVRT curve should be used to identify UVRT curve should be used to identify voltage
voltage drop points, including the lowest point drop points, including the highest point, the
and the inflection point, . lowest point and the inflection point, .

Voltage of PCC ( p.u. )
Voltage of PCC
( p.u. )
– 6 – IEC TS 62910:2020 © IEC 2020
The text of this Technical Specificationis based on the following documents:
Draft TS Report on voting
82/1607/DTS 82/1640A/RVDTS
Full information on the voting for the approval of this Technical Specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://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 publication 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.
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
1 Scope
This document provides a test procedure for evaluating the performance of Under Voltage
Ride-Through (UVRT) functions in inverters used in utility-interconnected Photovoltaic (PV)
systems.
This document is most applicable to large systems where PV inverters are connected to utility
high voltage (HV) distribution systems. However, the applicable procedures may also be used
for low voltage (LV) installations in locations where evolving UVRT requirements include such
installations, e.g. single-phase or 3-phase systems.
The assessed UVRT performance is valid only for the specific configuration and operational
mode of the inverter under test. Separate assessment is required for the inverter in other
factory or user-settable configurations, as these may cause the inverter UVRT response to
behave differently.
The measurement procedures are designed to be as non-site-specific as possible, so that
UVRT characteristics measured at one test site, for example, can also be considered valid at
other sites.
This document is for testing of PV inverters, though it contains information that may also be
useful for testing of a complete PV power plant consisting of multiple inverters connected at a
single point to the utility grid. It further provides a basis for utility-interconnected PV inverter
numerical simulation and model validation.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms, definitions and symbols
For the purposes of this document, the terms and definitions in IEC TS 61836 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

– 8 – IEC TS 62910:2020 © IEC 2020
3.1.1
drop depth
magnitude of voltage drop during a fault or simulated fault, as a percentage of the nominal
supply voltage
3.1.2
double drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of point of
common coupling (PCC), followed after a short time by a voltage recovery, which happens
twice
Note 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.
3.1.3
equipment under test
EUT
equipment on which these tests are performed and refers to the utility-interconnected PV
inverter. During test period, EUT is connected with PV simulator instead of real PV modules
on the direct current (DC) side, while alternating current (AC) side is connected with grid
3.1.4
I
q
output reactive current of EUT
3.1.5
under voltage ride through
UVRT
capability of an inverter to continue generating power to connected loads during a limited
duration loss or drop of grid voltage
3.1.6
maximum power point tracking
MPPT
control strategy of operation at maximum power point or nearby
3.1.7
N
EUT
access point of the EUT during the test
3.1.8
P
N
rated power of EUT
3.1.9
point of common coupling
PCC
point of a 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 devices, equipment or system, or distinct customer’s installations.
Note 2 to entry: In some applications, the term “point of common coupling” is restricted to public networks.
[SOURCE: IEC 60050-161:1990, 161-07-15]

3.1.10
proportionality constant K
K-factor
the K-factor is to be supplied by the EUT manufacturer meeting additional requirements
imposed by national standards and/or local codes
3.1.11
PV array simulator
simulator that has I-V characteristics equivalent to a PV array
3.1.12
S
EUT
apparent short-circuit power at N
EUT
S = I × U , I refer to short-circuit current at N during the no-load test
EUT sc N sc EUT
3.1.13
single drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of PCC, followed
after a short time by a voltage recovery, which happens once
Note 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.
3.1.14
Z
grid
grid short-circuit impedance value of the main point (MP) 1 (see Figure 1)
3.1.15
Z
i
impedance value between the fault point and PCC
3.1.16
Z
p
impedance value between the fault point and EUT
3.2 Abbreviated terms
AC alternating current
A/D analog to digital
DC direct current
EUT equipment under test
HV high voltage
LV low voltage
MV middle voltage
PV photovoltaic
RMS root mean square
UVRT under voltage ride through

– 10 – IEC TS 62910:2020 © IEC 2020
4 Test circuit and equipment
4.1 General
The circuits and equipment described in this clause are developed to allow tests that simulate
the full range of anticipated grid faults, including:
• Single phase to ground fault (any phase).
• Two phase isolated fault, between any two phases.
• Two phase grounded fault, involving any two phases.
• Three phase short-circuit fault.
A full discussion of these faults and the resulting impact on voltage magnitude and phase
angles is included in Annex A.
The short circuit emulator and grid simulator described in 4.3.3 and 4.3.4 are informative
examples and are not intended to restrict design flexibility. Other designs may be used to
achieve equivalent test functionality.
4.2 Test circuit
The UVRT test circuit includes a DC source, the EUT, a grid fault simulator and the grid. A PV
simulator (or PV array) provides input energy for the EUT. The output of the EUT is connected
to the grid via a grid fault simulator, as shown in Figure 1.

NOTE MP1 is the measurement point between the grid and the grid fault simulator; MP2 is the measurement point
at the high voltage side of the transformer; MP3 is the measurement point at the low voltage side of the
transformer.
Figure 1 – Testing circuit diagram
4.3 Test equipment
4.3.1 Measuring instruments
Waveforms shall be measured by a device with memory function, for example, a storage or
digital oscilloscope, or a high speed data acquisition device. Accuracy of the oscilloscope or
data acquisition system should be at least 0,2 % of full scale. The analogue to A/D of the
measurement device shall have at least 12 bit resolution (in order to maintain the required
measurement accuracy).
Voltage transformers and current transformers are the required sensors for measurement.
The accuracy of the transducers should be 0,5 % of full scale or better. It is necessary to
select the transducer measuring range depending on the normal value of the signal to be
measured. The selected measuring range shall not exceed 150 % of the normal value of the
measured signal. The transducer accuracy requirements are shown in Table 1.

Table 1 – Accuracy of measurements
Measurement device Accuracy
Data acquisition device 0,2 % full scale
Voltage transformer 0,5 % full scale
Current transformer 0,5 % full scale

4.3.2 DC source
A PV array, PV array simulator or controlled DC source with PV characteristics may be used
as the DC power source to supply input energy for the UVRT test. As the EUT input source,
the DC power source shall be capable of supplying the EUT maximum input power and other
power levels during the test, at minimum and maximum input operating voltages of the EUT.
The PV simulator should emulate the current/voltage characteristic of the PV module or PV
array for which the EUT is designed. The response time of a PV simulator should not be
longer than the MPP tracking response time of EUT.
For a EUT under test without galvanic isolation between the DC side and AC side, the output
of the PV simulator shall not be earthed.
The equivalent capacitance between the output of the PV simulator and earth should be as
low as possible in order to minimize the impact on the EUT.
A PV array used as the EUT input source shall be capable of matching the EUT input power
levels specified by the test conditions. It is necessary to select a period of time in which the
solar irradiance is stable and does not vary more than 5 % during the test.
4.3.3 Short-circuit emulator
As part of the grid simulator device, the short-circuit emulator is used to create the voltag
...

IEC TS 62910 ®
Edition 2.0 2020-07
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for low under
voltage ride-through measurements

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
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If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

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IEC TS 62910 ®
Edition 2.0 2020-07
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for low under

voltage ride-through measurements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-8736-1

– 2 – IEC TS 62910:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviated terms . 7
3.1 Terms, definitions and symbols . 7
3.2 Abbreviated terms . 10
4 Test circuit and equipment . 10
4.1 General . 10
4.2 Test circuit . 10
4.3 Test equipment . 11
4.3.1 Measuring instruments. 11
4.3.2 DC source . 11
4.3.3 Short-circuit emulator . 11
4.3.4 Converter based grid simulator . 14
5 Test . 14
5.1 Test protocol . 14
5.2 Test curve . 16
5.3 Test procedure . 17
5.3.1 Pre-test . 17
5.3.2 No-load test . 17
5.3.3 Tolerance . 17
5.3.4 Load test . 17
6 Assessment criteria . 18
Annex A (informative) Circuit faults and voltage drops . 19
A.1 Fault types . 19
A.2 Voltage drops . 21
A.2.1 General . 21
A.2.2 Three-phase short-circuit fault . 22
A.2.3 Two-phase short-circuit fault with ground . 22
A.2.4 Two-phase short-circuit fault without ground . 23
A.2.5 Single-phase short-circuit fault with ground . 24
Annex B (informative) Determination of critical performance values in LVRT UVRT
testing . 26
B.1 General . 26
B.2 Drop depth ratio . 26
B.3 Ride-through time . 26
B.4 Reactive current. 26
B.5 Active power . 27
Annex C (informative) Requirements of the UVRT curve . 28
C.1 General . 28
C.2 UVRT curve . 28
C.3 Test points . 28
Bibliography . 29

Figure 1 – Testing circuit diagram . 10

Figure 2 – Short-circuit emulator . 12
Figure 3 – Converter device example . 14
Figure 4 – LVRT UVRT curve example . 16
Figure 5 – Tolerance of voltage drop. 17
Figure A.1 – Grid fault diagram . 21
Figure A.2 – Diagram of voltage vector for three-phase short-circuit fault . 22
Figure A.3 – Diagram of voltage vector of two-phase (BC) short-circuit fault with
ground . 23
Figure A.4 – Diagram of voltage vector of two-phase (BC) short-circuit fault . 24
Figure A.5 – Diagram of voltage vector of single-phase (A) short-circuit fault with
ground . 25
Figure B.1 – Determination of reactive current output . 27
Figure B.2 – Determination of active power recovery . 27
Figure C.1 – The typical curve of UVRT . 28

Table 1 – Accuracy of measurements . 11
Table 2 – Fault type and switch status . 13
Table 3 – Test specification for LVRT UVRT (Indicative) . 15
Table A.1 – Short-circuit paths for different fault types . 19
Table A.2 – Amplitude and phase changes in three-phase short-circuit fault . 22
Table A.3 – Amplitude and phase changes in two-phase (BC)
short-circuit fault with ground . 23
Table A.4 – Amplitude and phase changes in two-phase (BC) short-circuit fault . 24
Table A.5 – Amplitude and phase changes in single-phase (A) short-circuit fault with
ground . 25

– 4 – IEC TS 62910:2020 RLV © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR LOW UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a Technical
Specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62910, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.
This second edition cancels and replaces the first edition issued in 2015, and constitutes a
technical revision.
It remains a TS because it is limited to providing recommended practices for UVRT testing in
the context of non-uniform grid-codes lacking international consensus, and the rapid
development of test technology in recent years.
The main technical changes with regard to the previous edition are as follows:
Clause Previous edition Present edition
the voltage support of EUT in accordance with the K-factor is to be supplied by the EUT
3.1.12 the voltage drops. The K-factor is to be manufacturer meeting additional requirements
specified by the EUT manufacturer imposed by national standards and/or local codes
Back to Back circuit Back to Back circuit
A A
B B
Figure 2
C
C
Grid Grid
(optional) (optional)
The test circuit essentially comprises a voltage The test circuit essentially comprises a voltage
4.3.4 source with a low internal resistance combined source with a low internal resistance combined
with broadband amplifiers. optionally with broadband amplifiers.
d The test should be carried out under specified d The test should be carried out under specified
K-factor provided by local manufacture. K-factor provided by manufacture meeting
Table 3
additional requirements imposed by national
standards and/or local codes.
1,2
1,2
1,1
1,1
LVRT curve
LVRT curve
Keep connecting to the grid
Keep connecting to the grid 1,0
1,0
highest point
0,9
0,9
0,8 inflection point
0,8 inflection point
inflection point
0,7 inflection point 0,7
0,6
0,6
0,5 0,5
May cut off from the grid May cut off from the grid
Figure 4
0,4
0,4
0,3 inflection point
0,3 inflection point
0,2
0,2
Lowest point Lowest point
0,1
0,1
t t t t t4
0 1 2 3 t
t t1 t2 t3 4
Time (s)
Time (s)
Voltage of PCC ( p.u. )
Voltage of PCC ( p.u. )
– 6 – IEC TS 62910:2020 RLV © IEC 2020
NOTE The example shows two types of points The example shows three types of points on the
on the UVRT curve: the lowest point and the UVRT curve: the highest point, the lowest point
5.2
inflection point. Tests must be carried out at and the inflection point. Tests shall be carried out
both types of points at above types of points.
Prior to the fault simulation tests, the EUT Prior to the fault simulation tests, the EUT should
should run in normal operating mode. The run in normal operating mode. The selected
5.3.1 selected UVRT curve should be used to identify UVRT curve should be used to identify voltage
voltage drop points, including the lowest point drop points, including the highest point, the
and the inflection point, . lowest point and the inflection point, .

The text of this Technical Specificationis based on the following documents:
Draft TS Report on voting
82/1607/DTS 82/1640A/RVDTS
Full information on the voting for the approval of this Technical Specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://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 publication 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.
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR LOW UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
1 Scope
This document provides a test procedure for evaluating the performance of Low Under
Voltage Ride-Through (LVRT UVRT) functions in inverters used in utility-interconnected
Photovoltaic (PV) systems.
This document is most applicable to large systems where PV inverters are connected to utility
high voltage (HV) distribution systems. However, the applicable procedures may also be used
for low voltage (LV) installations in locations where evolving LVRT UVRT requirements
include such installations, e.g. single-phase or 3-phase systems.
The assessed LVRT UVRT performance is valid only for the specific configuration and
operational mode of the inverter under test. Separate assessment is required for the inverter
in other factory or user-settable configurations, as these may cause the inverter LVRT UVRT
response to behave differently.
The measurement procedures are designed to be as non-site-specific as possible, so that
LVRT UVRT characteristics measured at one test site, for example, can also be considered
valid at other sites.
This document is for testing of PV inverters, though it contains information that may also be
useful for testing of a complete PV power plant consisting of multiple inverters connected at a
single point to the utility grid. It further provides a basis for utility-interconnected PV inverter
numerical simulation and model validation.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 61400-21:2008, Wind turbines – Part 21: Measurement and assessment of power quality
characteristics of grid connected wind turbines
IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms, definitions and symbols
For the purposes of this document, the terms and definitions in IEC TS 61836 and symbols
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/

– 8 – IEC TS 62910:2020 RLV © IEC 2020
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
drop depth
magnitude of voltage drop during a fault or simulated fault, as a percentage of the nominal
supply voltage
3.1.2
double drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of point of
common coupling (PCC), followed after a short time by a voltage recovery, which happened
happens twice
Note 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.
3.1.3
equipment under test
EUT
equipment on which these tests are performed and refers to the utility-interconnected PV
inverter. During test period, EUT is connected with PV simulator instead of real PV modules
on the direct current (DC) side, while alternating current (AC) side is connected with grid
3.1.4
IT system
IT power system has all live parts isolated from earth or one point connected to earth through
an impedance. The exposed-conductive-parts of the electrical installation are earthed
independently or collectively or to the earthing of the system
[SOURCE: IEC 60364-1:2005, 312.2.3]
3.1.4
I
q
output reactive current of EUT
3.1.5
low under voltage ride through
LVRT UVRT
capability of an inverter to continue generating power to connected loads during a limited
duration loss or drop of grid voltage
3.1.7
maximum MPP voltage
maximum voltage at which the EUT can convert its rated power under MPPT conditions
[SOURCE: EN 50530:2010]
3.1.6
maximum power point tracking
MPPT
control strategy of operation at maximum power point or nearby
3.1.9
minimum MPP voltage
minimum voltage at which the EUT can convert its rated power under MPPT conditions
[SOURCE: EN 50530:2010]
3.1.7
N
EUT
access point of the EUT during the test
3.1.8
P
N
rated power of EUT
3.1.9
point of common coupling
PCC
point of a 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 devices, equipment or system, or distinct customer’s installations.
Note 2 to entry: In some applications, the term “point of common coupling” is restricted to public networks.
[SOURCE: IEC 60050-161:1990, 161-07-15]
3.1.10
proportionality constant K
K-factor
voltage support of EUT in accordance with the voltage drops. the K-factor is to be specified by
the EUT manufacturer.
the K-factor is to be supplied by the EUT manufacturer meeting additional requirements
imposed by national standards and/or local codes
3.1.11
PV array simulator
simulator that has I-V characteristics equivalent to a PV array
3.1.15
PV simulator MPP voltage
U
MPP, PVS
MPP voltage of the setting PV curve that is provided by the PV simulator
3.1.12
S
EUT
apparent short-circuit power at N
EUT
S = I × U , I refer to short-circuit current at N during the no-load test
EUT sc N sc EUT
3.1.13
single drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of PCC, followed
after a short time by a voltage recovery, which happened happens once
Note 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.
3.1.14
Z
grid
grid short-circuit impedance value of the MP1 main point (MP) 1 (see Figure 1)
3.1.15
Z
i
impedance value between the fault point and PCC

– 10 – IEC TS 62910:2020 RLV © IEC 2020
3.1.16
Z
p
impedance value between the fault point and EUT
3.2 Abbreviated terms
AC alternating current
A/D analog to digital
DC direct current
EUT equipment under test
HV high voltage
LV low voltage
MV middle voltage
PV photovoltaic
RMS root mean square
UVRT under voltage ride through
4 Test circuit and equipment
4.1 General
The circuits and equipment described in this clause are developed to allow tests that simulate
the full range of anticipated grid faults, including:
• Single phase to ground fault (any phase).
• Two phase isolated fault, between any two phases.
• Two phase grounded fault, involving any two phases.
• Three phase short-circuit fault.
A full discussion of these faults and the resulting impact on voltage magnitude and phase
angles is included in Annex A.
The short circuit emulator and grid simulator described in 4.3.3 and 4.3.4 are informative
examples and are not intended to restrict design flexibility. Other designs may be used to
achieve equivalent test functionality.
4.2 Test circuit
The LVRT UVRT test circuit includes a DC source, the EUT, a grid fault simulator and the grid.
A PV simulator (or PV array) provides input energy for the EUT. The output of the EUT is
connected to the grid via a grid fault simulator, as shown in Figure 1.

NOTE MP1 is the measurement point between the grid and the grid fault simulator; MP2 is the measurement point
at the high voltage side of the transformer; MP3 is the measurement point at the low voltage side of the
transformer.
Figure 1 – Testing circuit diagram

4.3 Test equipment
4.3.1 Measuring instruments
Waveforms shall be measured by a device with memory function, for example, a storage or
digital oscilloscope, or a high speed data acquisition device. Accuracy of the oscilloscope or
data acquisition system should be at least 0,2 % of full scale. The analogue to A/D of the
measurement device shall have at least 12 bit resolution (in order to maintain the required
measurement accuracy).
Voltage transducers (or Voltage transformers) and current transducers (or current
transformers) are the required sensors for measurement. The accuracy of the transducers
should be 0,5 % of full scale or better. It is necessary to select the transducer measuring
range depending on the normal value of the signal to be measured. The selected measuring
range shall not exceed 150 % of the normal value of the measured signal. The transducer
accuracy requirements are shown in Table 1.
Table 1 – Accuracy of measurements
Measurement device Accuracy
Data acquisition device 0,2 % full scale
Voltage transducer transformer 0,5 % full scale
Current transducer transformer 0,5 % full scale

4.3.2 DC source
A PV array, PV array simulator or controlled DC source with PV characteristics may be used
as the DC power source to supply input energy for the LVRT UVRT test. As the EUT input
source, the DC power source shall be capable of supplying the EUT maximum input power
and other power levels during the test, at minimum and maximum input operating voltages of
the EUT.
The PV simulator should emulate the current/voltage characteristic of the PV module or PV
array for which the EUT is designed. The response time of a PV simulator should not be
longer than the MPP tracking response time of EUT.
For a EUT under test without galvanic isolation between the DC side and AC side, the output
of the PV simulator shall not be earthed.
The equivalent capacitance between the output of the PV simulator and earth should be as
low as possible in order to minimize the impact on the EUT.
A PV array used as the EUT input source shall be capable of matching the EUT input power
levels specified by the test conditions. It is necessary to select a period of time in which the
solar irradiance is stable and does not vary more than 5 % during the test.
4.3.3 Short-circuit emulator
As part of the grid simulator device, the short-circuit emulator is used to create the voltage
drops due to short-circuits between the two or three phases, or between one or two phases to
ground, via the impedance network Z and Z as shown in the test device layout in Figure 2.
1 2
– 12 – IEC TS 62910:2020 RLV © IEC 2020

Figure 2 – Short-circuit emulator
The impedance Z is used to limit the effect of the short circuit on the utility service that
powers the test circuit. The sizing of Z shall therefore account for all test sequences to be
performed and limit the short-circuit current taken from the grid to values that do not cause an
excessive reduction of the grid voltage. Considering an acceptable voltage reduction of at
most 5 % when performing the test, the minimum value of Z shall be at least 20 × Z ,
1 Grid
where Z is the grid short-circuit impedance measured at the test circuit connection point.
Grid
To ensure that the test is realistic, however, the apparent short-circuit power (S ) available
EUT
at the EUT connection node N should be at least equal to 3×Pn, where Pn is the rated
EUT
power of the EUT (minimum value S > 3 × Pn, recommended S = 5 to 6 × Pn
EUT EUT
5 × Pn < S < 6 × Pn). This means during the short-circuit tests, the contribution of current
EUT
through Z and Z from the grid remains dominant compared to the current contributed by the
1 2
EUT. In this way, the inverter current does not create a significant voltage rise for the duration
of the test relative to the no-load drop.
The two conditions described above define the minimum and maximum limits of Z . The two
conditions combined also define the limit criteria for the choice of a grid infrastructure suitable
for performing the test with the impedance circuit. If the grid infrastructure cannot meet above
requirements, an alternative test circuit utilizing a back-to-back converter is allowed, as
shown in Figure 2 may be added to reduce the grid short-circuit impedance Z .
Grid
Generally, the X/R value of inductor Z and Z for the short-circuit emulator may close to the
1 2
transmission line impedance values for different countries and regions. It is also appropriate
that the inductive impedances Z and Z should be characterised by an X/R ratio equal to at
1 2
least 3, in order to reproduce the typical minimum values of X/R found in HV as well as MV
power lines.
NOTE 1 X: Equivalent impedance of inductor.
NOTE 2 R: Equivalent resistance of inductor.
A bypass connection (Switch S ) of Z is usually used to prevent overheating of the
1 1
impedance Z before and after the execution of each test sequence.
The voltage drop is created by connecting the impedance Z by the switch S . If the voltage
2 2
drop is required to be created twice in a short period (for double drop tests), a parallel switch
S ′ is normally used. The value of Z /(Z + Z + Z ) shall be adjusted to the required voltage
2 2 1 2 Grid
magnitudes. For example, when the required voltage magnitude is 50 % of the rated voltage,
the value of Z /(Z + Z + Z ) should be about 0,5.
2 1 2 Grid
The switch S shall be able to accurately control the time between connection and
disconnection of Z for single phase, two-phase or three-phase tests. If the phase of switch S
2 2
cannot be independently controlled, the serial switch B may be used to choose the fault
phase. B is used to select whether the fault is to earth or not. All switches may be either
mechanical circuit breakers or power electronic devices.
The status of switch B and B should be set before performing the test. The status of
1 2
switches corresponding to fault types is shown in Table 2.
The test report shall specify the values of impedances Z and Z , the related X/R ratio, and a
1 2
description of the circuit used. In addition, the grid short-circuit power available at the voltage
level at which the test is performed shall be documented.
The status of switches and fault types are shown in Table 2.
Table 2 – Fault type and switch status
Fault type Switch status
Phase A of B Phase B of B Phase C of B B
1 1 1 2
Phase A to ground Closed Open Open Closed
Phase B to ground Open Closed Open Closed
Phase C to ground Open Open Closed Closed
Phase A and B to ground Closed Closed Open Closed
Phase B and C to ground Open Closed Closed Closed
Phase C and A to ground Closed Open Closed Closed
Phase A and B Closed Closed Open Open
Phase B and C Open Closed Closed Open
Phase C and A Closed Open Closed Open
Phase A, B and C Closed Closed Closed ---
NOTE 1 During the period of voltage drop, S should be opened first. S should be closed after S is opened.
1 2 1
The time interval between the above two actions shall be very short.
NOTE 2 During the period of voltage recovery, S should be opened first. S should be closed after S is
2 1 2
opened. The time interval between the above two actions shall be very short.

– 14 – IEC TS 62910:2020 RLV © IEC 2020
4.3.4 Converter based grid simulator
The test circuit mentioned in 4.3.3 is recommended for simulation of grid faults. However, if
the test conditions cannot be met, an alternative test circuit utilizing a back-to-back converter
is allowed, as shown in Figure 3.
The test circuit essentially comprises a voltage source with a low internal resistance
combined optionally with broadband amplifiers (linear or forced switching type) capable of
faithfully reproducing three sinusoidal voltages with controlled harmonic content, and
adjustable amplitude, fundamental frequency and phase relationship within broad margins.
When the converter is used, it shall meet the following requirements:
a) It shall be capable of independently controlling the three phases in terms of amplitude and
phase angle.
b) It shall incorporate impedances Z , Z and Z , that can be adjusted in order to reproduce
A B C
the ohmic and inductive components of short-circuit impedances that are typical of the grid.
c) It shall be capable of reproducing the phase voltages and relative phase angles that occur
on the LV side of transformers in the event of each of the various fault types.
(See Annex A for the vector representations for each fault).

Figure 3 – Converter device example
If the programmable voltage source is a bi-directional, controlled output voltage type and is
capable of replicating the influence of short-circuit impedances typical of the grid, the
impedances Z , Z , Z may be omitted.
A B C
5 Test
5.1 Test protocol
The LVRT UVRT test protocol is designed to verify that the EUT responds appropriately to
voltage drops (due to grid faults). During the test, the EUT shall demonstrate that it can:
• Appropriately detect the simulated fault.
• Ride through the event and continue operation as specified in the applicable curves.
• Not suffer any damage from the event.
NOTE The required levels of active power and reactive power output during the voltage drop
period may differ depending on the country local codes. The response to the voltage drop
specified in Table 3 shall be recorded over the EUT operating period with two output power
ranges:
a) between 0,1 P and 0,3 P ;
n n
b) above 0,9 P ;
n
and with two fault conditions:
c) three-phase drop;
d) two-phase drop or single-phase drop.
The tests should be carried out at least twice at each test point listed in Table 3.
Table 3 – Test specification for LVRT UVRT (Indicative)
b c d
Drop times Drop depth Drop phase EUT output conditions
Full load (above 0,9 P )
n
three-phase
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
two-phase
Part load (0,1 P and 0,3 P )
n n
A
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
three-phase
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
two-phase
Part load (0,1 P and 0,3 P )
n n
Single drop …
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
three-phase
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
two-phase
Part load (0,1 P and 0,3 P )
n n
A
n
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
three-phase
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
two-phase
Part load (0,1 P and 0,3 P )
n n
A
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
three-phase
a
Double drop Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
two-phase
Part load (0,1 P and 0,3 P )
n n
…
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
three-phase
A Part load (0,1 P and 0,3 P )
n n n
Full load (above 0,9 P )
two-phase
n
– 16 – IEC TS 62910:2020 RLV © IEC 2020
b c d
Drop times Drop depth Drop phase EUT output conditions
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Two-phase to ground
Part load (0,1 P and 0,3 P )
n n
Full load (above 0,9 P )
n
Single-phase to ground
Part load (0,1 P and 0,3 P )
n n
a
Double drop test may be required in some countries or regions. For devices under test not being required for
double drop test, above testing points can be omitted.
b
Drop depth is the residual voltage during the LVRT UVRT testing period which can be decided according to
the requirement specified by different countries or regions (See Annex B, Clause B.2 for drop depth ratio
calculation).
c
Drop phase can be decided according to the requirement specified by different countries or regions; the
value of two-phase voltage should be line voltage.
d
The test should be carried out under specified K-factor provided by local manufacture manufacturer meeting
additional requirements imposed by national standards and/or local codes.

5.2 Test curve
The LVRT UVRT response characteristic shall meet the requirements of the LVRT UVRT
curve specified by different countries and regions as needed (see also Annex C). An example
LVRT UVRT curve is shown in Figure 4.

Figure 4 – LVRT UVRT curve example
The example curve shows that the EUT should keep operating during operating conditions
indicated in the area above the LVRT UVRT curve. Specifically, the EUT should keep
operating for (t -t ) seconds without disconnecting from the grid when the interconnection
1 0
voltage drops to 0 % of rated voltage; for (t -t ) seconds when the voltage drops to 30 % of
2 0
rated voltage; and for (t -t ) seconds when the voltage drops to 70 % of rated voltage. The
3 0
EUT should disconnect from the grid during operating conditions indicated within the shaded
areas.
The example shows two three types of points on the LVRT UVRT curve: the highest point, the
lowest point and the inflection point. Tests shall be carried out at both above types of points.

5.3 Test procedure
5.3.1 Pre-test
Prior to the fault simulation tests, the EUT should run in normal operating mode. The selected
LVRT UVRT curve should be used to identify voltage drop points, including the highest point,
the lowest point and the inflection point, as well as other random points in the curve. Selection
of the drop time should follow the requirement of the applicable country or region.
5.3.2 No-load test
Prior to the load test, adjust the fault emulator to simulate symmetrical and asymmetrical
voltage drops without EUT connection, and validate that the measured results are as intended.
This step ensures that the amplitude of voltage and drop duration can match the requirements
in Figure 5.
5.3.3 Tolerance
The tolerances for drop depth and duration during the no-load test shall reference meet the
requirement of Figure 6 in IEC 61400-21:2008, and not exceed the values shown in Figure 5.
The tolerance for voltage magnitude is ±5 % of rated voltage for the period before and during
the voltage drop. The tolerance for voltage magnitude is ±10 % of rated voltage during the
period after voltage is recovered. The tolerances shall must be measured between 0 and
+5 % of rated voltage for the lowest point and the inflection point under no-load conditions,
and the tolerances shall be measured between −5 % and 0 of rated voltage for the highest
point under no-load conditions.
The duration of each voltage drop is determined according to the requirements of the
applicable LVRT UVRT curve. The tolerance range for both drop duration and rise time
prefers 40 ms.
Figure 5 – Tolerance of voltage drop
5.3.4 Load test
Tests under load shall be carried out after the no-load test results successfully meet the
performance requirements. The parameters of the grid fault simulator should be consistent
with the no-load test.
– 18 – IEC TS 62910:2020 RLV © IEC 2020
With the EUT connected to the grid fault simulator device and the PV simulator (or PV array),
the output power should be set to (0,1 ~ 0,3)P and above 0,9P separately. Additional load
n n
tests at other power levels should be performed as determined by the specific country or
regional requirements.
During the LVRT UVRT test, MP1, MP2, and MP3 (shown in Figure 1) shall be selected as the
test points for measuring and recording the values of voltage and current.
The waveform and data of the measured voltage and current at the measuring points shall be
recorded by the data acquisition device from time A prior to the voltage drop to time B after
the subsequent voltage rise.
For A and B, specific data should be determined by
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