SIST EN 60700-1:2015

SLOVENSKI STANDARD
01-december-2015
1DGRPHãþD
SIST EN 60700-1:2001
SIST EN 60700-1:2001/A1:2004
SIST EN 60700-1:2001/A2:2009
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Thyristor valves for high voltage direct current (HVDC) power transmission - Part 1:
Electrical testing
Ta slovenski standard je istoveten z: EN 60700-1:2015
ICS:
19.080 (OHNWULþQRLQHOHNWURQVNR Electrical and electronic
SUHVNXãDQMH testing
29.200 8VPHUQLNL3UHWYRUQLNL Rectifiers. Convertors.
6WDELOL]LUDQRHOHNWULþQR Stabilized power supply
QDSDMDQMH
31.080.20 Tiristorji Thyristors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60700-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2015
ICS 29.200 Supersedes EN 60700-1:1998
English Version
Thyristor valves for high voltage direct current (HVDC) power
transmission - Part 1: Electrical testing
(IEC 60700-1:2015)
Valves à thyristors pour le transport d'énergie en courant Thyristorventile für Hochspannungsgleichstrom-
continu à haute tension (CCHT) - Partie 1: Essais Energieübertragung (HGÜ) - Teil 1: Elektrische Prüfung
électriques (IEC 60700-1:2015)
(IEC 60700-1:2015)
This European Standard was approved by CENELEC on 2015-09-01. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60700-1:2015 E
European foreword
The text of document 22F/341/CDV, future edition 2 of IEC 60700-1, 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 approved by
CENELEC as EN 60700-1:2015.
The following dates are fixed:
• latest date by which the document has to be (dop) 2016-06-01
implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2018-09-01
• latest date by which the national
standards conflicting with the
document have to be withdrawn
This document supersedes EN 60700-1:1998.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 60700-1:2015 was approved by CENELEC as a European
Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu
Publication Year Title EN/HD Year

IEC 60060 Series High-voltage test techniques EN 60060 Series
IEC 60060-1 -  High-voltage test techniques - EN 60060-1 -
Part 1: General definitions and test
requirements
IEC 60071-1 -  Insulation co-ordination - EN 60071-1 -
Part 1: Definitions, principles and rules
IEC 60099 Series Surge arresters EN 60099 Series
IEC 60270 -  High-voltage test techniques - Partial EN 60270 -
discharge measurements
IEC 61803 1999 Determination of power losses in high- EN 61803 1999
+A1 2010 voltage direct current (HVDC) converter +A1 2010
stations
1)
ISO/IEC Guide 25 -  General requirements for the competence - -
of calibration and testing laboratories

1)
Withdrawn publication.
IEC 60700-1 ®
Edition 2.0 2015-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thyristor valves for high voltage direct current (HVDC) power transmission –

Part 1: Electrical testing
Valves à thyristors pour le transport d'énergie en courant continu à haute

tension (CCHT) –
Partie 1: Essais électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.200 ISBN 978-2-8322--2805-0

– 2 – IEC 60700-1:2015 © IEC 2015
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions. 7
3.1 Insulation co-ordination terms . 8
3.2 Valve construction terms . 9
3.3 Terms related to type tests . 10
3.4 Terms related to production tests . 10
4 General requirements . 10
4.1 Guidelines for the performance of type tests . 10
4.1.1 Evidence in lieu . 10
4.1.2 Test object . 10
4.1.3 Sequence of tests . 10
4.1.4 Test procedures . 11
4.1.5 Ambient temperature for testing . 11
4.1.6 Frequency for testing . 11
4.1.7 Test reports . 11
4.2 Atmospheric correction . 11
4.3 Treatment of redundancy . 11
4.3.1 Dielectric tests . 11
4.3.2 Operational tests . 11
4.4 Criteria for successful type testing . 12
4.4.1 General . 12
4.4.2 Criteria applicable to thyristor levels . 12
4.4.3 Criteria applicable to the valve as a whole . 13
5 List of type tests . 13
6 Dielectric tests on valve support . 14
6.1 Purpose of tests . 14
6.2 Test object . 14
6.3 Test requirements . 15
6.3.1 General . 15
6.3.2 Valve support d.c. voltage test . 15
6.3.3 Valve support a.c. voltage test . 15
6.3.4 Valve support switching impulse test . 16
6.3.5 Valve support lightning impulse test . 16
7 Dielectric tests for multiple valve units (MVU) . 16
7.1 Purpose of tests . 16
7.2 Test object . 16
7.3 Test requirements . 17
7.3.1 MVU d.c. voltage test to earth . 17
7.3.2 MVU a.c. voltage test . 18
7.3.3 MVU switching impulse test . 18
7.3.4 MVU lightning impulse test . 19
8 Dielectric tests between valve terminals . 20
8.1 Purpose of tests . 20
8.2 Test object . 20

IEC 60700-1:2015 © IEC 2015 – 3 –
8.3 Test requirements . 20
8.3.1 Valve d.c. voltage test . 20
8.3.2 Valve a.c. voltage test . 21
8.3.3 Valve impulse tests (general) . 22
8.3.4 Valve switching impulse test . 23
8.3.5 Valve lightning impulse test . 23
8.3.6 Valve steep front impulse test . 23
8.4 Valve non-periodic firing test . 24
8.4.1 Purpose of test . 24
8.4.2 Test object . 24
8.4.3 Test requirements . 24
9 Periodic firing and extinction tests . 25
9.1 Purpose of tests . 25
9.2 Test object . 26
9.3 Test requirements . 26
9.3.1 General . 26
9.3.2 Maximum continuous operating duty tests . 27
9.3.3 Maximum temporary operating duty test (α = 90°) . 28
9.3.4 Minimum a.c. voltage tests . 29
9.3.5 Temporary undervoltage test . 30
9.3.6 Intermittent direct current tests . 31
10 Tests with transient forward voltage during the recovery period . 31
10.1 Purpose of tests . 31
10.2 Test object . 31
10.3 Test requirements . 31
11 Valve fault current tests . 33
11.1 Purpose of tests . 33
11.2 Test object . 33
11.3 Test requirements . 33
11.3.1 General . 33
11.3.2 One-loop fault current test with re-applied forward voltage . 34
11.3.3 Multiple-loop fault current test without re-applied forward voltage . 35
12 Tests for valve insensitivity to electromagnetic disturbance . 35
12.1 Purpose of tests . 35
12.2 Test object . 36
12.3 Test requirements . 36
12.3.1 General . 36
12.3.2 Approach one . 36
12.3.3 Approach two . 36
12.3.4 Acceptance criteria . 37
13 Testing of special features and fault tolerance . 37
13.1 Purpose of tests . 37
13.1.1 General . 37
13.1.2 Circuits to facilitate the proper control, protection and monitoring of the
valve . 37
13.1.3 Features included in the valve to provide fault tolerance . 37
13.2 Test object . 37
13.3 Test requirements . 38
14 Production tests . 38

– 4 – IEC 60700-1:2015 © IEC 2015
14.1 General . 38
14.2 Purpose of tests . 38
14.3 Test object . 38
14.4 Test requirements . 38
14.5 Routine test – minimum requirements . 38
14.5.1 Visual inspection . 38
14.5.2 Connection check . 39
14.5.3 Voltage-grading circuit check . 39
14.5.4 Voltage withstand check . 39
14.5.5 Partial discharge tests . 39
14.5.6 Check of auxiliaries . 39
14.5.7 Firing check . 39
14.5.8 Pressure test . 39
15 Method for loss determination . 39
16 Presentation of type test results . 39
Annex A (normative) Test safety factors . 40
A.1 General . 40
A.2 Test safety factors for dielectric tests . 40
A.2.1 Impulse tests . 40
A.2.2 AC and d.c. temporary and long-term voltage tests . 43
A.3 Test safety factors for operational tests . 43
Annex B (normative) Partial discharge measurements . 44
B.1 Measurement of partial discharge . 44
B.2 Partial discharge during a.c. tests . 44
B.3 Partial discharge during d.c. tests . 44
B.4 Composite a.c. plus d.c. voltage stress . 45

Figure 1 – Steep front impulse test voltage . 8

Table 1 – Thyristor level faults permitted during type tests . 13
Table 2 – List of type tests . 14

IEC 60700-1:2015 © IEC 2015 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THYRISTOR VALVES FOR HIGH VOLTAGE DIRECT
CURRENT (HVDC) POWER TRANSMISSION –

Part 1: 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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
International Standard IEC 60700-1 has been prepared by subcommittee 22F: Power
electronics for electrical transmission and distribution systems, of IEC technical committee 22:
Power electronic systems and equipment.
This second edition cancels and replaces the first edition published in 1998, its Amendment
1:2003 and its Amendment 2: 2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition.
a) Definitions of terms “redundant thyristor levels”, “thyristor level”, “valve section” have been
changed for clarification.
b) The notes were added to test requirements of dielectric d.c. voltage tests for valve support,
MVU, valve, specifying that before repeating the test with opposite polarity, the tested

– 6 – IEC 60700-1:2015 © IEC 2015
object may be short-circuited and earthed for several hours. The same procedure may be
followed at the end of the d.c. voltage test.
c) Table 1 on thyristor level faults permitted during type tests was supplemented.
d) The alternative MVU dielectric test method was added.
e) It was specified that production tests may include routine tests as well as sample tests.
f) It was added into test requirements for periodic firing and extinction tests that a scaling
factor for tests shall be applied when testing with valve sections.
The text of this standard is based on the following documents:
CDV Report on voting
22F/341/CDV 22F/351A/RVC
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.
A list of all parts in the IEC 60700 series, published under the general title Thyristor valves for
high voltage direct current (HVDC) power transmission, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC website 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.
IEC 60700-1:2015 © IEC 2015 – 7 –
THYRISTOR VALVES FOR HIGH VOLTAGE DIRECT
CURRENT (HVDC) POWER TRANSMISSION –

Part 1: Electrical testing
1 Scope
This part of IEC 60700 applies to thyristor valves with metal oxide surge arresters directly
connected between the valve terminals, for use in a line commutated converter 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 can be agreed.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
IEC 60060, High-voltage test techniques
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60099 (all parts), Surge arresters
IEC 60270, High-voltage test techniques – Partial discharge measurements
IEC 61803:1999, Determination of power losses in high-voltage direct current (HVDC)
converter stations
IEC 61803:1999/AMD 1:2010
ISO/IEC Guide 25, General requirements for the technical competence of testing laboratories
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
___________
There exists a consolidated edition 1.1 (2011) that comprises IEC 61803:1999 and its Amendment 1:2010.
Withdrawn.
– 8 – IEC 60700-1:2015 © IEC 2015
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
3.1.2
steep front impulse
fast-front voltage impulse whose time to peak is less than that of a standard lightning impulse
but not less than that of a very-fast-front voltage as defined in IEC 60071-1
Note 1 to entry: For this standard, the steep front impulse voltage for test purposes is as shown in Figure 1.
Steepness S
Peak value U
0,2 T
0,5 U
T
Time
T
IEC
Key
U specified peak value of steep front impulse test voltage (kV)
S specified steepness of steep front impulse test voltage (kV/µs)
U
T virtual front time = (µs)
S
The following conditions shall be satisfied:
a) The peak value of the recorded test voltage shall be U ± 3 %. This tolerance is the same as that in IEC 60060
for standard lightning impulse.
b) Over a voltage excursion of not less than 0,6 U, the rising portion of the recorded test voltage shall be entirely
contained between two parallel lines of steepness S and separation 0,2 T
1.
c) The value of the test voltage at T shall not be lower than 0,5 U. T is defined as the time interval between the
2 2
origin and the instant when the voltage has decreased to half the peak value of the waveform which is obtained
from system study. However, it shall be assured that an unintentional du/dt switching of the thyristors can be
adequately detected.
Figure 1 – Steep front impulse test voltage
0,6 U
Voltage
IEC 60700-1:2015 © IEC 2015 – 9 –
3.1.3
internal and external insulation
air external to the components and insulating materials of the valve, but contained within the
profile of the valve or multiple valve unit is considered as part of the internal insulation system
of the valve
Note 1 to entry: The external insulation is the air between the external surface of the valve or multiple valve unit and
its surroundings.
3.1.4
valve protective firing
means of protecting the thyristors from excessive voltage by firing them at a predetermined
voltage
3.2 Valve construction terms
3.2.1
valve support
that part of the valve which mechanically supports and electrically insulates from earth the
active part of the valve which houses the valve sections
Note 1 to entry: 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.
3.2.2
valve structure
physical structure holding the thyristor levels of a valve which is insulated to the appropriate
voltage above earth potential
3.2.3
redundant thyristor levels
maximum number of thyristor levels in a thyristor valve that may be short-circuited externally or
internally during service without affecting the safe operation of the thyristor valve as
demonstrated by type tests, and which if and when exceeded, would require shutdown of the
converter to replace the failed thyristors or acceptance of increased risk of failures
3.2.4
valve base electronics
electronic unit, at earth potential, which is the interface between the control system for the
converter and the thyristor valves
3.2.5
thyristor level
part of a thyristor valve comprising a thyristor, or thyristors connected in parallel, together with
their immediate auxiliaries, and reactor, if any
3.2.6
valve section
electrical assembly, comprising a number of thyristors and other components, which exhibits
pro-rated electrical properties of a complete valve
3.2.7
multiple valve unit
MVU
single physical structure comprising more than one valve with a common mechanical support
structure
– 10 – IEC 60700-1:2015 © IEC 2015
3.3 Terms related to type tests
NOTE Those tests which are carried out to verify that the valve design will meet the requirements specified. In this
standard, type tests are classified under two major categories: dielectric tests and operational tests.
3.3.1
dielectric tests
tests which are carried out to verify the high voltage characteristics of the valve
3.3.2
operational tests
tests which are carried out to verify the turn-on, turn-off and current related characteristics of
the valve
3.4 Terms related to production tests
NOTE Those tests which are carried out to verify proper manufacture, so that the properties of a valve correspond
to those specified.
3.4.1
routine tests
production tests which are carried out on all valves, valve sections or components
3.4.2
sample tests
production tests which are carried out on a small number of valves, valve sections or
components taken at random from a batch
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
Test object should meet the following requirements:
a) Certain type tests may be performed either on a complete valve or on valve sections, as
indicated in Table 2. For those type tests on valve sections, the total number of valve
sections tested shall be at least as many as the number in a complete valve.
b) The same valve sections shall be used for all type tests unless otherwise stated.
c) 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 tests
The type tests specified can be carried out in any order.
NOTE Tests involving partial discharge measurement can provide added confidence if performed at the end of the
dielectric type test programme.

IEC 60700-1:2015 © IEC 2015 – 11 –
4.1.4 Test procedures
The tests shall be performed in accordance with IEC 60060, where applicable. The
competence of testing and calibration laboratories should correspond to the
ISO/IEC Guide 17025.
4.1.5 Ambient temperature for testing
The tests shall be performed at the prevailing ambient temperature of the test facility, unless
otherwise specified.
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 16.
4.2 Atmospheric correction
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:
a) If the insulation coordination of the tested part of the thyristor 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
s
equipment 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
0 s
standard procedure according to IEC 60060-1 is used except that the reference
atmospheric pressure b is replaced by the atmospheric pressure corresponding to an
altitude of 1 000 m (b );
1 000 m
b) If the insulation coordination of the tested part of the thyristor 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 Dielectric tests
For all dielectric tests between valve terminals, the redundant thyristor levels shall be short
circuited, with the possible exception of the valve non-periodic firing test (see 8.4). The location
of thyristor levels to be short circuited shall be agreed by the purchaser and supplier.
NOTE Depending on the design, limitations can be imposed upon the distribution of short-circuited thyristor levels.
For example, there may be an upper limit to the number of short-circuited thyristor levels in one valve section.
4.3.2 Operational tests
For operational tests, redundant thyristor levels shall not be short circuited. The test voltages
used shall be adjusted by means of a scaling factor k :
n
– 12 – IEC 60700-1:2015 © IEC 2015
N
tut
k =
n
N − N
t r
where
N is the number of series thyristor levels in the test object;

tut
N is the total number of series thyristor levels in the valve;

t
N is the total number of redundant series thyristor levels in the valve.
r
4.4 Criteria for successful type testing
4.4.1 General
Experience in industry shows that, even with the most careful design of valves, it is not
possible to avoid occasional random failures of thyristor 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 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 thyristor 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 thyristor levels
The following criteria are applicable to thyristor levels:
a) If, following a type test as listed in Clause 5, more than one thyristor level (alternatively
more than 1 % of the series-connected thyristor levels in a complete valve, 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 thyristor 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 thyristor levels during all type tests is more than
3 % of the series-connected thyristor levels in a complete valve, then the valve shall be
deemed to have failed the type test programme.
d) When type tests are performed on valve sections, the criteria for acceptance above also
apply since the number of valve sections tested shall be not less than the number of
sections in a complete valve (see 4.1.2 a)).
e) The valve or valve sections shall be checked after each type test to determine whether or
not any thyristor levels have become short-circuited. Failed thyristors or auxiliary
components found during or at the end of a type test may be replaced before further testing.
f) 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 thyristor levels in both forward and reverse direction;
– check of the gating circuits where applicable;
– check of the monitoring circuits;
– check of the thyristor level protection circuits by application of transient voltages above
and below the protection setting(s) where applicable;
– check of the voltage grading circuits.
g) Thyristor level 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 thyristor levels exhibiting faults which do not result in thyristor level short circuit, which
are discovered during the type test programme and the subsequent check tests, shall not
exceed 3 % of the series-connected thyristor levels in a complete valve. If the total number

IEC 60700-1:2015 © IEC 2015 – 13 –
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.
h) When applying the percentage criteria to determine the permitted maximum number of
short-circuited thyristor levels and the permitted maximum number of levels with faults
which have not resulted in a thyristor level becoming short-circuited, it is usual practice to
round off all fractions to the next highest integer, as illustrated in Table 1.
Table 1 – Thyristor level faults permitted during type tests
Number of thyristor levels Number of thyristor levels Total number of thyristor Additional number of
in a complete valve minus permitted to become levels permitted to thyristor levels, in all type
the number of redundant short-circuited in any one circuited in tests, which have
become short-
levels type test all type tests experienced a fault but
(N – N ) have not become short-

t r
circuited
Up to 33 1 1 1
34 to 67 1 2 2
68 to 100 1 3 3
101 to 133 2 4 4
etc.
The distribution of short-circuited levels and of other thyristor 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 thyristor 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 adja
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