SIST EN 62501:2009

SLOVENSKI STANDARD
01-oktober-2009
(OHNWULþQRSUHVNXãDQMHHOHNWURQN]DSUHWYRUQLNHQDSHWRVWQLKYLURY96&]D
HQRVPHUQLYLVRNRQDSHWRVWQLSUHQRVHOHNWULþQHHQHUJLMH+9'&,(&
Electrical testing of voltage sourced converter (VSC) valves for high-voltage direct
voltage (HVDC) power transmission (IEC 62501:2009)
Spannungsgeführte Stromrichterventile (VSC-Ventile) für die
Hochspannungsgleichstromübertragung (HGÜ) - Elektrische Prüfung (IEC 62501:2009)
Essais électriques sur les valves à convertisseur de source de tension (VSC) pour le
transport d'énergie en courant continu à haute tension (CCHT) EEIC 62501:2009)
Ta slovenski standard je istoveten z: EN 62501:2009
ICS:
29.200 8VPHUQLNL3UHWYRUQLNL Rectifiers. Convertors.
6WDELOL]LUDQRHOHNWULþQR Stabilized power supply
QDSDMDQMH
29.240.01 2PUHåMD]DSUHQRVLQ Power transmission and
GLVWULEXFLMRHOHNWULþQHHQHUJLMH distribution networks in
QDVSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62501
NORME EUROPÉENNE
August 2009
EUROPÄISCHE NORM
ICS 29.200; 29.240
English version
Voltage sourced converter (VSC) valves
for high-voltage direct current (HVDC) power transmission -
Electrical testing
(IEC 62501:2009)
Valves à convertisseur de source  Spannungsgeführte Stromrichterventile
de tension (VSC) pour le transport (VSC-Ventile) für die
d'énergie en courant continu Hochspannungsgleichstromübertragung
à haute tension (CCHT) - (HGÜ) -
Essais électriques Elektrische Prüfung
(CEI 62501:2009) (IEC 62501:2009)

This European Standard was approved by CENELEC on 2009-07-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: Avenue Marnix 17, B - 1000 Brussels

© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62501:2009 E
Foreword
The text of document 22F/185/FDIS, future edition 1 of IEC 62501, prepared by SC 22F, Power
electronics for electrical transmission and distribution systems, of IEC TC 22, Power electronic systems
and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 62501 on 2009-07-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2010-04-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2012-07-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62501:2009 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60146-2 NOTE  Harmonized as EN 60146-2:2000 (not modified).
__________
- 3 - EN 62501:2009
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60060 Series High-voltage test techniques EN 60060 Series

IEC 60060-1 1989 High-voltage test techniques - HD 588.1 S1 1991
Part 1: General definitions and test
requirements
IEC 60071-1 2006 Insulation co-ordination - EN 60071-1 2006
Part 1: Definitions, principles and rules

IEC 60700-1 1998 Thyristor valves for high voltage direct current EN 60700-1 1998
A1 2003 (HVDC) power transmission - A1 2003
A2 2008 Part 1: Electrical testing A2 2008

1) 2)
ISO/IEC 17025 - General requirements for the competence of EN ISO/IEC 17025 2005
testing and calibration laboratories

1)
Undated reference.
2)
Valid edition at date of issue.

IEC 62501 ®
Edition 1.0 2009-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing

Valves à convertisseur de source de tension (VSC) pour le transport d’énergie
en courant continu à haute tension (CCHT) – Essais électriques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 29.200; 29.240 ISBN 2-8318-1048-1
– 2 – 62501 © IEC:2009
CONTENTS
FOREWORD.0H0H0H5
1 Scope.1H1H1H7
2 Normative references .2H2H2H7
3 Terms and definitions .3H3H3H7
3.1 Insulation co-ordination terms .4H4H4H7
3.2 Power semiconductor terms .5H5H5H8
3.3 Operating states.6H6H6H8
3.3.1 Operating state of an IGBT-diode pair .7H7H7H8
3.3.2 Operating state of converter .8H8H8H9
3.4 VSC construction terms.9H9H9H9
3.5 Valve structure terms .10H10H10H10
4 General requirements .11H11H11H10
4.1 Guidelines for the performance of type tests.12H12H12H10
4.1.1 Evidence in lieu .13H13H13H10
4.1.2 Test object .14H14H14H10
4.1.3 Sequence of test .15H15H15H11
4.1.4 Test procedure .16H16H16H11
4.1.5 Ambient temperature for testing.17H17H17H11
4.1.6 Frequency for testing.18H18H18H11
4.1.7 Test reports .19H19H19H11
4.2 Atmospheric correction factor .20H20H20H11
4.3 Treatment of redundancy.21H21H21H12
4.3.1 Operational tests .22H22H22H12
4.3.2 Dielectric tests.23H23H23H12
4.4 Criteria for successful type testing.24H24H24H12
4.4.1 General .25H25H25H12
4.4.2 Criteria applicable to valve levels .26H26H26H13
4.4.3 Criteria applicable to the valve as a whole.27H27H27H14
5 List of type tests .28H28H28H14
6 Operational tests .29H29H29H14
6.1 Purpose of tests .30H30H30H14
6.2 Test object .31H31H31H15
6.3 Test circuit .32H32H32H15
6.4 Maximum continuous operating duty test .33H33H33H15
6.5 Maximum temporary over-load operating duty test.34H34H34H16
6.6 Minimum d.c. voltage test.35H35H35H16
7 Dielectric tests on valve support structure .36H36H36H17
7.1 Purpose of tests .37H37H37H17
7.2 Test object .38H38H38H17
7.3 Test requirements .39H39H39H17
7.3.1 Valve support d.c. voltage test.40H40H40H17
7.3.2 Valve support a.c. voltage test.41H41H41H18
7.3.3 Valve support switching impulse test .42H42H42H19
7.3.4 Valve support lightning impulse test .43H43H43H19
8 Dielectric tests on multiple valve unit.44H44H44H19
8.1 Purpose of tests .45H45H45H19

62501 © IEC:2009 – 3 –
8.2 Test object .46H46H46H19
8.3 Test requirements .47H47H47H20
8.3.1 MVU d.c. voltage test to earth .48H48H48H20
8.3.2 MVU a.c. voltage test .49H49H49H20
8.3.3 MVU switching impulse test .50H50H50H21
8.3.4 MVU lightning impulse test .51H51H51H22
9 Dielectric tests between valve terminals .52H52H52H22
9.1 Purpose of the test .53H53H53H22
9.2 Test object .54H54H54H23
9.3 Test requirements .55H55H55H23
9.3.1 Valve a.c. – d.c. voltage test.56H56H56H23
9.3.2 Valve impulse tests (general) .57H57H57H25
9.3.3 Valve switching impulse test.58H58H58H25
9.3.4 Valve lightning impulse test .59H59H59H26
10 IGBT overcurrent turn-off test .60H60H60H26
10.1 Purpose of test.61H61H61H26
10.2 Test object .62H62H62H27
10.3 Test requirements .63H63H63H27
11 Short-circuit current test .64H64H64H27
11.1 Purpose of tests .65H65H65H27
11.2 Test object .66H66H66H27
11.3 Test requirements .67H67H67H27
12 Tests for valve insensitivity to electromagnetic disturbance .68H68H68H28
12.1 Purpose of tests .69H69H69H28
12.2 Test object .70H70H70H28
12.3 Test requirements .71H71H71H28
12.3.1 General .72H72H72H28
12.3.2 Approach one .73H73H73H28
12.3.3 Approach two .74H74H74H29
12.3.4 Acceptance criteria.75H75H75H29
13 Production tests .76H76H76H29
13.1 Purpose of tests .77H77H77H29
13.2 Test object .78H78H78H29
13.3 Test requirements .79H79H79H30
13.4 Production test objectives .80H80H80H30
13.4.1 Visual inspection .81H81H81H30
13.4.2 Connection check .82H82H82H30
13.4.3 Voltage-grading circuit check.83H83H83H30
13.4.4 Control, protection and monitoring circuit checks.84H84H84H30
13.4.5 Voltage withstand check .85H85H85H30
13.4.6 Partial discharge tests .86H86H86H30
13.4.7 Turn-on / turn-off check .87H87H87H30
13.4.8 Pressure test .88H88H88H31
14 Presentation of type test results .89H89H89H31
Annex A (informative) Overview of VSC topology.90H90H90H32
Annex B (informative) Fault tolerance capability .91H91H91H40
Bibliography.92H92H92H41

– 4 – 62501 © IEC:2009
Figure A.1 – A single VSC phase unit and its idealized output voltage .93H93H93H33
Figure A.2 – Output voltage of a VSC phase unit for a 2-level converter .94H94H94H33
Figure A.3 – Output voltage of a VSC phase unit for a 15-level converter, without PWM .95H95H95H34
Figure A.4 – Basic circuit topology of one phase unit of a 2-level converter .96H96H96H35
Figure A.5 – Basic circuit topology of one phase unit of a 3-level diode-clamped
converter .97H97H97H36
Figure A.6 – Basic circuit topology of one phase unit of a 5-level diode-clamped
converter .98H98H98H36
Figure A.7 – Basic circuit topology of one phase unit of a 3-level flying capacitor
converter .99H99H99H37
Figure A.8 – A single VSC phase unit with valves of the “controllable voltage source”
type .100H100H100H38
Figure A.9 – One possible implementation of a multi-level “voltage source” VSC valve .101H101H101H38

Table 1 – Minimum number of valve levels to be tested as a function of the number of
valve levels per valve.102H102H102H11
Table 2 – Valve level faults permitted during type tests.103H103H103H13
Table 3 – List of type tests.104H104H104H14

62501 © IEC:2009 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
______________
VOLTAGE SOURCED CONVERTER (VSC)
VALVES FOR HIGH-VOLTAGE DIRECT CURRENT (HVDC)
POWER TRANSMISSION – ELECTRICAL TESTING

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
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
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
IEC 62501 has been prepared by subcommittee 22F: Power electronics for electrical
transmission and distribution systems, of IEC technical committee 22: Power electronic
systems and equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
22F/185/FDIS 22F/193/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 6 – 62501 © IEC:2009
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
62501 © IEC:2009 – 7 –
VOLTAGE SOURCED CONVERTER (VSC)
VALVES FOR HIGH-VOLTAGE DIRECT CURRENT (HVDC)
POWER TRANSMISSION – ELECTRICAL TESTING

1 Scope
This International Standard applies to self-commutated converter valves, for use in a three-
phase bridge voltage sourced converter (VSC) for high voltage d.c. power transmission or as
part of a back-to-back link. It is restricted to electrical type and production tests.
The tests specified in this standard are based on air insulated valves. For other types of
valves, the test requirements and acceptance criteria must be agreed.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60060 (all parts), High-voltage test techniques
IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60071-1:2006, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60700-1:1998, Thyristor valves for high voltage direct current (HVDC) power transmission
)
– Part 1: Electrical testing 1F1F0F
Amendment 1(2003)
Amendment (2008)
ISO/IEC 17025, General requirements for the competence of testing and calibration
laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Insulation co-ordination terms
3.1.1
test withstand voltage
value of a test voltage of standard waveshape at which a new valve, with unimpaired integrity,
does not show any disruptive discharge and meets all other acceptance criteria specified for
the particular test, when subjected to a specified number of applications or a specified
duration of the test voltage, under specified conditions
___________
)
There exists a consolidated edition 1.2 (2008) that comprises IEC 60700-1, Amendment 1 and Amendment 2.

– 8 – 62501 © IEC:2009
3.1.2
internal insulation
air external to the components and insulating materials of the valve, but contained within the
profile of the valve or multiple valve unit
3.1.3
external insulation
air between the external surface of the valve or multiple valve unit and its surroundings.
3.2 Power semiconductor terms
There are several types of controllable semiconductor switch device which can be used in
VSC converters for HVDC. For convenience, the term IGBT is used throughout this standard
to refer to the main, controllable, semiconductor switch device. However, the standard is
equally applicable to other types of controllable semiconductor switch device.
3.2.1
insulated gate bipolar transistor
IGBT
a controllable switch with the capability to turn-on and turn-off a load current
An IGBT has three terminals: a gate terminal (G) and two load terminals emitter (E) and
collector (C).
By applying appropriate gate to emitter voltages, the load current can be controlled, i.e.
turned on and turned off.
3.2.2
free-wheeling diode
FWD
power semiconductor device with diode characteristic
A FWD has two terminals: an anode (A) and a cathode (K). The current through FWDs is in
the opposite direction to the IGBT current.
FWDs are characterized by the capability to cope with high rates of decrease of current
caused by the switching behaviour of the IGBT.
3.2.3
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.3 Operating states
3.3.1 Operating state of an IGBT-diode pair
3.3.1.1
blocking state
the condition in which an IGBT-diode pair is turned off
In that state, the load current does not flow through the IGBT. However, a load current can
flow through the diode as the diode is not controllable.
3.3.1.2
de-blocked state
the condition when the load current flows either through the IGBT or diode of an IGBT-diode
pair depending on the load current direction

62501 © IEC:2009 – 9 –
3.3.2 Operating state of converter
3.3.2.1
blocking state
a condition of the converter, in which a turn-off signal is applied to all IGBTs of the converter
Typically, the converter is in the blocking state condition after energization.
3.3.2.2
de-blocked state
a condition of the converter, in which turn-on signals are applied to IGBTs of the converter
3.3.2.3
valve protective blocking
means of protecting the valve or converter from excessive electrical stress by the emergency
turn-off of all IGBTs in one or more valves
3.4 VSC construction terms
3.4.1
VSC phase unit
the equipment used to connect the two d.c. busbars to one a.c. terminal
3.4.2
VSC valve
complete controllable device assembly, which represents a functional unit as part of a VSC
phase unit and characterized by switching actions of the power electronic devices upon
control signals of the converter base electronics
NOTE Dependent on the converter topology, a valve can either have the function to act like a controllable switch
or to act like a controllable voltage source.
3.4.3
diode valve
a semiconductor valve containing only diodes as the main semiconductor devices, which
might be used in some VSC topologies
3.4.4
valve
VSC valve or diode valve according to the context
3.4.5
VSC valve level
part of a VSC valve comprising a controllable switch and an associated diode, or controllable
switches and diodes connected in parallel, or controllable switches and diodes connected to a
half bridge arrangement, together with their immediate auxiliaries, storage capacitor, if any
3.4.6
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.7
redundant levels
the maximum number of VSC valve levels or diode valve levels in a valve that may be short-
circuited externally or internally during service without affecting the safe operation of the
valve as demonstrated by type tests, and which if and when exceeded, would require
shutdown of the valve to replace the failed levels or acceptance of increased risk of failures

– 10 – 62501 © IEC:2009
3.5 Valve structure terms
3.5.1
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.5.2
valve support
that part of the valve which mechanically supports and electrically insulates the active part of
the valve from earth
NOTE A part of a valve which is clearly identifiable in a discrete form to be a valve support may not exist in all
designs of valves.
3.5.3
multiple valve unit
MVU
mechanical arrangement of 2 or more valves or 1 or more VSC phase units sharing a common
valve support
NOTE A MVU might not exist in all topologies and physical arrangement of converters.
3.5.4
valve section
electrical assembly defined for test purposes, comprising a number of VSC or diode valve
levels and other components, which exhibits pro-rated electrical properties of a complete
valve
The minimum number of VSC or diode valve levels allowed in a valve section is defined along
with the requirements of each test.
3.5.5
valve base electronics
electronic unit, at earth potential, which is the interface between the converter control system
and the VSC valves
4 General requirements
4.1 Guidelines for the performance of type tests
4.1.1 Evidence in lieu
Each design of valve shall be subjected to the type tests specified in this standard. If the
valve is demonstrably similar to one previously tested, the supplier may, in lieu of performing
a type test, submit a test report of a previous type test for consideration by the purchaser.
This should be accompanied by a separate report detailing the differences in the design and
demonstrating how the referenced type test satisfies the test objectives for the proposed
design.
4.1.2 Test object
This subclause does not apply to tests on the valve supporting structure and multiple valve
unit. The test object for those tests is defined in 7.2 and 8.2.
a) Type tests may be performed either on a complete valve or, in certain circumstances, on
valve sections, as indicated in Table 3.
b) The minimum number of valve levels to be tested, depending on the valve levels in a
single valve, is as shown in Table 1.

62501 © IEC:2009 – 11 –
Table 1 – Minimum number of valve levels to be tested as a function
of the number of valve levels per valve
Number of valve levels per valve Total number of valve levels to be tested
1 – 50 Number of valve levels in one valve
51 – 250 50
20 %
≥ 251
c) Generally, the same valve sections are recommended to be used for all type tests.
However, with the agreement of the purchaser and supplier, different tests may be
performed on different valve sections in parallel, in order to speed up the programme for
executing the tests.
d) Prior to commencement of type tests, the valve, valve sections and/or the components of
them should be demonstrated to have withstood the production tests to ensure proper
manufacture.
4.1.3 Sequence of test
In order to confirm that the valve terminal-terminal insulation has not been degraded by the
fast repetitive switching stresses experienced by the converter in operation, the valve a.c. –
d.c. voltage test between terminals with partial discharge measurement should be performed
after the operational tests. Other type tests specified can be carried out in any order.
NOTE For valves of the “controllable voltage source” type (Clause A.5), the test sequence, where the a.c. – d.c.
voltage test is performed before the operational test, may be acceptable by mutual agreement between the
purchaser and supplier.
4.1.4 Test procedure
The tests shall be performed in accordance with IEC 60060, where applicable.
4.1.5 Ambient temperature for testing
The tests shall be performed in accordance with IEC 60060, where applicable.
4.1.6 Frequency for testing
AC dielectric tests can be performed at either 50 Hz or 60 Hz. For operational tests, specific
requirements regarding the frequency for testing are given in the relevant clauses.
4.1.7 Test reports
At the completion of the type tests, the supplier shall provide type test reports in accordance
with Clause 105H105H105H14.
4.2 Atmospheric correction factor
When specified in the relevant clause, atmospheric correction shall be applied to the test
voltages in accordance with IEC 60060-1. The reference conditions to which correction shall
be made are the following:
– pressure:
• If the insulation coordination of the tested part of the valve is based on standard rated
withstand voltages according to IEC 60071-1, correction factors are only applied for
altitudes exceeding 1 000 m. Hence if the altitude of the site a at which the equipment
s
will be installed is ≤1 000 m, then the standard atmospheric air pressure (b =
101,3 kPa) shall be used with no correction for altitude. If a >1 000 m, then the
s
standard procedure according to IEC 60060-1 is used except that the reference

– 12 – 62501 © IEC:2009
atmospheric pressure b is replaced by the atmospheric pressure corresponding to an
altitude of 1 000 m (b ).
1000m
• If the insulation coordination of the tested part of the valve is not based on standard
rated withstand voltages according to IEC 60071-1, then the standard procedure
according to IEC 60060-1 is used with the reference atmospheric pressure b
(b =101,3 kPa).
– temperature: design maximum valve hall air temperature (°C);
– humidity: design minimum valve hall absolute humidity (g/m ).
The values to be used shall be specified by the supplier.
4.3 Treatment of redundancy
4.3.1 Operational tests
For operational tests, redundant valve levels shall not be short-circuited. The test voltages
used shall be adjusted by means of a scaling factor k :
n
N
tut
k =
n
N − N
t r
where
N is the number of series valve levels in the test object;
tut
N  is the total number of series valve levels in the valve;
t
N  is the total number of redundant series valve levels in the valve.
r
4.3.2 Dielectric tests
For all dielectric tests between valve terminals, the redundant valve levels shall be short-
circuited. The location of valve levels to be short-circuited shall be agreed by the purchaser
and supplier.
NOTE Depending on the design, limitations may be imposed upon the distribution of short-circuited valve levels.
For example, there may be an upper limit to the number of short-circuited valve levels in one valve section.
For all dielectric tests on valve section, the test voltages used shall be adjusted by means of a
scaling factor k :
o
N
tu
k =
o
N − N
t r
where
N is the number of series valve levels not short circuit connected in the test object;
tu
N  is the total number of series valve levels in the valve;
t
N  is the total number of redundant series valve levels in the valve.
r
4.4 Criteria for successful type testing
4.4.1 General
Experience in semiconductor application shows that, even with the most careful design of
valves, it is not possible to avoid occasional random failures of valve level components during
service operation. Even though these failures may be stress-related, they are considered
random to the extent that the cause of failure or the relationship between failure rate and
stress cannot be predicted or is not amenable to precise quantitative definition. Type tests

62501 © IEC:2009 – 13 –
subject valves or valve sections, within a short time, to multiple stresses that generally
correspond to the worst stresses that can be experienced by the equipment not more than a
few times during the life of the valve. Considering the above, the criteria for successful type
testing set out below therefore permit a small number of valve levels to fail during type
testing, providing that the failures are rare and do not show any pattern that is indicative of
inadequate design.
4.4.2 Criteria applicable to valve levels
Criteria applicable to valve levels are as follows.
a) If, following a type test as listed in Clause 5, more than one valve level (alternatively more
than 1 % of the tested valve levels, if greater) has become short-circuited, then the valve
shall be deemed to have failed the type tests.
b) If, following a type test, one valve level (or more if still within the 1 % limit) has become
short-circuited, then the failed level(s) shall be restored and this type test repeated.
c) If the cumulative number of short-circuited valve levels during all type tests is more than 3
% of the tested valve levels, then the valve shall be deemed to have failed the type test.
d) The valve or valve sections shall be checked after each type test to determine whether or
not any valve levels have become short-circuited. Failed IGBT/diode or auxiliary
components found during or at the end of a type test may be replaced before further
testing.
e) At the completion of the test programme, the valve or valve sections shall undergo a
series of check tests, which shall include as a minimum:
– check for voltage withstand of valve levels;
– check of the gating circuits;
– check of the monitoring circuits;
– check of any protection circuits forming an integral part of the valve;
– check of the voltage grading circuits.
f) Valve levels short circuits occurring during the check tests shall be counted as part of the
criteria for acceptance defined above. In addition to short-circuited levels, the total number
of valve levels exhibiting faults which do not result in valve level short circuit, which are
discovered during the type test programme and the subsequent check test, shall not
exceed 3 % of the number of tested valve levels in dielectric and operational type tests,
whichever is lower. If the total number of such levels exceeds 3 %, then the nature of the
faults and their cause shall be reviewed and additional action, if any, agreed between
purchaser and supplier.
g) When applying the percentage criteria to determine the permitted maximum number of
short-circuited valve levels and the permitted maximum number of levels with faults which
have not resulted in a valve level becoming short-circuited, it is usual practice to round off
all fractions to the next highest integer, as illustrated in Table 2.
Table 2 – Valve level faults permitted during type tests
Number of valve levels Number of valve levels Total number of valve Additional number of
tested permitted to become levels permitted to valve levels, in all type
short-circuited in any become short-circuited tests, which have

one type test in all type tests experienced a fault but
have not become short-
circuited
Up to 33 1 1 1
34 to 67 1 2 2
68 to 100 1 3 3
etc.
– 14 – 62501 © IEC:2009
The distribution of short-circuited levels and of other valve level faults at the end of all type
tests shall be essentially random and not show any pattern that may be indicative of
inadequate design.
4.4.3 Criteria applicable to the valve as a whole
Breakdown of or external flashover across common electrical equipment associated with more
than one valve level of the valve, or disruptive discharge in dielectric material forming part of
the valve structure, cooling ducts, light guides or other insulating parts of the pulse
transmission and distribution system shall not be permitted.
Component and conductor surface temperatures, together with associated current-carrying
joints and connections, and the temperature of adjacent mounting surfaces shall at all times
remain within limits permitted by the design.
5 List of type tests
Table 3 lists the type tests given in Clauses 6 to 12.
Table 3 – List of type tests
Type test Clause or Test object
subclause
Maximum continuous operating duty test 6.4 Valve or valve section
Maximum temporary over-load operating duty test 6.5 Valve or valve section
Minimum d.c. voltage test 6.6 Valve or valve section
Valve support d.c. voltage test 7.3.1 Valve support
Valve support a.c. voltage test 7.3.2 Valve support
Valve support switching impulse test 7.3.3 Valve support
Valve support lightning impulse test 7.3.4 Valve support
MVU d.c. voltage test to earth 8.3.1 MVU
MVU a.c. voltage test 8.3.2 MVU
MVU switching impulse test 8.3.3 MVU
MVU lightning impulse test 8.3.4 MVU
Valve a.c. – d.c. voltage test 9.3.1
Valve (or valve section if agreed
Valve switching impulse test 9.3.3
between supplier and purchaser)
Valve lightning impulse test 9.3.4
IGBT overcurrent turn-off test 10 Valve or valve section
Short-circuit current test 11 Valve or valve section
Test for valve insensitivity to electromagnetic disturbance 12 Valve (or valve section if agreed
between supplier and purchaser)

6 Operational tests
6.1 Purpose of tests
The principal objectives of the operational tests are:
a) to check the adequacy of the VSC/diode level and associated electrical circuits in a valve
with regard to current, voltage and temperature stresses in the conducting state, at turn-on
and turn-off under the worst
...