IEC/IEEE 62582-6:2019
(Main)Nuclear power plants - Instrumentation and control important to safety - Electrical equipment condition monitoring methods - Part 6: Insulation resistance
Nuclear power plants - Instrumentation and control important to safety - Electrical equipment condition monitoring methods - Part 6: Insulation resistance
IEC/IEEE 62582-6:2019 contains methods for condition monitoring of organic and polymeric materials in instrumentation and control cables using insulation resistance measurements in the detail necessary to produce accurate and reproducible results during simulated accident conditions. It includes the requirements for the measurement system and measurement procedure, and the reporting of the measurement results.
NOTE Measurement of insulation resistance during simulated accident conditions with the aim of determining the lowest value during the accident in order to assess cable performance involves special requirements given in this document. Methods for measurement under stable (non-accident) conditions are available in other international standards, e.g. IEC 62631-3-3.
The different parts of the IEC/IEEE 62582 series are measurement standards, primarily for use in the management of ageing in initial qualification and after installation. IEC/IEEE 62582-1 includes requirements for the application of the other parts of the IEC/IEEE 62582 series and some elements which are common to all methods. Information on the role of condition monitoring in qualification of equipment important to safety is found in IEC/IEEE 60780-323.
Centrales nucléaires de puissance - Instrumentation et contrôle-commande importants pour la sûreté - Méthodes de surveillance de l'état des matériels électriques - Partie 6: Résistance d'isolement
l'IEC/IEEE 62582-6:2019 contient les méthodes de surveillance de l'état des matériaux organiques et polymères utilisés dans les câbles d'instrumentation et de contrôle‑commande, sur la base de mesures de la résistance d'isolement et de façon suffisamment détaillée pour obtenir des résultats précis et reproductibles en conditions accidentelles simulées. Elle comprend les exigences pour le système de mesure et la procédure de mesure, ainsi que les rapports des résultats de mesure.
NOTE La mesure de la résistance d'isolement en conditions accidentelles simulées dans le but de déterminer la valeur la plus faible durant l'accident pour évaluer les performances des câbles, implique le respect des exigences particulières définies dans le présent document. Les méthodes de mesure en conditions normales (non accidentelles) sont disponibles dans d'autres Normes internationales, par exemple dans l'IEC 62631-3-3.
Les différentes parties de la série IEC/IEEE 62582 sont des normes de mesure, principalement destinées à être utilisées pour la gestion du vieillissement dans le cadre de la qualification initiale et après installation. L'IEC/IEEE 62582-1 fournit les exigences applicables à toutes les autres parties de la série IEC/IEEE 62582 et certains éléments communs à l'ensemble des méthodes. L'IEC/IEEE 60780-323 fournit des informations concernant le rôle de la surveillance de l'état dans la qualification des matériels importants pour la sûreté.
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Standards Content (Sample)
IEC/IEEE 62582-6 ®
Edition 1.0 2019-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear power plants ‒ Instrumentation and control important to safety ‒
Electrical equipment condition monitoring methods –
Part 6: Insulation resistance
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Méthodes de surveillance de l'état des matériels
électriques –
Partie 6: Résistance d'isolement
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IEC/IEEE 62582-6 ®
Edition 1.0 2019-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear power plants ‒ Instrumentation and control important to safety ‒
Electrical equipment condition monitoring methods –
Part 6: Insulation resistance
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Méthodes de surveillance de l'état des matériels
électriques –
Partie 6: Résistance d'isolement
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-7050-9
– 2 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Abbreviated terms and acronyms . 9
5 General description . 10
6 Applicability and reproducibility . 12
7 Instrumentation . 12
7.1 Measurement voltage level . 12
7.2 Uncertainty . 12
7.3 Calibration . 13
8 IR measurement procedure . 13
8.1 General . 13
8.2 Requirements on tracking of changes of IR during the simulated accident
conditions . 13
8.3 Test specimen . 13
8.4 Interference . 13
8.5 Conditioning . 13
8.6 IR measurement during the dynamic phase of the simulated accident
conditions . 14
8.6.1 Set-up for the measurement . 14
8.6.2 Connection of IR voltage and start of measurement . 14
8.6.3 Default voltage . 14
8.6.4 Determination of IR value with the specimen not energized during the
accident simulation . 14
8.6.5 Determination of the IR value with the specimen energized during the
accident simulation . 15
9 Measurement report . 16
Annex A (informative) Example of equivalent diagram for a cable and the measuring
device using DC . 17
Annex B (informative) Measurement of leakage current using AC voltage . 18
Annex C (informative) Dependence of IR on temperature only and combined with
steam . 19
Annex D (informative) Examples of results of measurement of IR on aged cables
during simulated accident conditions. 20
Annex E (informative) Example of a measurement loop and calculation of the time
available for stabilization for more than one conductor or group of conductors
measured with the same measurement instrument . 23
E.1 Example of one measurement loop . 23
E.2 Total time for each measurement of all combinations during the dynamic
phase of the simulated accident conditions . 23
Bibliography . 24
Figure 1 – Time to stabilization of IR measured before LOCA, after 10 min in LOCA
and after 60 min in LOCA . 11
Figure A.1 – Set-up for measurement of IR using a DC voltage source (guard is not
needed if the ground plane is close to the insulator) . 17
Figure B.1 – Set-up for measurement of IR using an AC voltage source . 18
Figure C.1 – Temperature influence on IR of an insulation between 20 °C and 150 °C . 19
Figure D.1 – Example of result of measurement of IR between conductors and
ground/shielding during a LOCA test . 20
Figure D.2 – Example of measurement of IR between conductor and ground and
between conductors . 21
Figure D.3 – Example of measurement of IR on a three-conductor cable during LOCA
simulation . 22
Figure E.1 – Example of one measurement loop . 23
– 4 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
NUCLEAR POWER PLANTS ‒
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY ‒
ELECTRICAL EQUIPMENT CONDITION MONITORING METHODS –
Part 6: Insulation resistance
FOREWORD
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International Standard IEC/IEEE 62582-6 has been prepared by subcommittee 45A:
Instrumentation, control and electrical power systems of nuclear facilities, of IEC technical
committee 45: Nuclear instrumentation, in cooperation with the Nuclear Power Engineering
Committee of the Power & Energy Society of the IEEE] , under the IEC/IEEE Dual Logo
Agreement.
It is published as an IEC/IEEE dual logo standard.
The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/1267/FDIS 45A/1277/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
A list of all parts in the IEC/IEEE 62582 series, published under the general title Nuclear
power plants – Instrumentation and control important to safety – Electrical equipment
condition monitoring methods, can be found on the IEC website.
International standards are drafted in accordance with the rules given in the ISO/IEC
Directives, Part 2.
The IEC Technical Committee and IEEE Technical Committee have decided that the contents
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– 6 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
INTRODUCTION
a) Technical background, main issues and organisation of the Standard
This IEC/IEEE standard specifically focuses on insulation resistance measurement methods
for monitoring of the dielectric condition of instrumentation and control cables during
simulation of design basis events.
This IEC/IEEE standard is the sixth part of the IEC/IEEE 62582-series. It contains detailed
descriptions of condition monitoring based on insulation resistance measurements.
The IEC/IEEE 62582-series of standards is issued with a joint logo which makes it applicable
to management of ageing of electrical equipment qualified to IEEE as well as IEC Standards.
For aged cables and accessories, the dielectric behaviour during simulated accident
conditions generally indicates the condition of the cable during the simulated accident
condition.
Significant research has been performed on condition monitoring techniques and the use of
these techniques in equipment qualification as noted in NUREG/CR-6704, vol.2
(BNL-NUREG-52610) and JNES-SS-0903, 2009.
It is intended that this Standard be used by test laboratories, operators of nuclear power
plants, systems evaluators and licensors.
b) Situation of the current Standard in the structure of the IEC SC 45A standard series
IEC/IEEE 62582-6 is the third level IEC SC 45A document tackling the specific issue of
application and performance of insulation resistance measurements during simulated accident
conditions in nuclear power plants.
IEC/IEEE 62582-6 is to be read in association with IEC/IEEE 62582-1. IEC/IEEE 62582-1
provides requirements for application of methods for condition monitoring of electrical
equipment important to safety of nuclear power plants.
For more details on the structure of the IEC SC 45A standard series, see item d) of this
introduction.
c) Recommendations and limitations regarding the application of the Standard
It is important to note that this Standard establishes no additional functional requirements for
safety systems.
d) Description of the structure of the IEC SC 45A standard series and relationships
with other IEC documents and other bodies documents (IAEA, ISO)
The top-level documents of the IEC SC 45A standard series are IEC 61513 and IEC 63046.
IEC 61513 provides general requirements for I&C systems and equipment that are used to
perform functions important to safety in NPPs. IEC 63046 provides general requirements for
electrical power systems of NPPs; it covers power supply systems including the supply
systems of the I&C systems. IEC 61513 and IEC 63046 are to be considered in conjunction
and at the same level. IEC 61513 and IEC 63046 structure the IEC SC 45A standard series
and shape a complete framework establishing general requirements for instrumentation,
control and electrical systems for nuclear power plants.
IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general topics
related to categorization of functions and classification of systems, qualification, separation,
defence against common cause failure, control room design, electromagnetic compatibility,
cybersecurity, software and hardware aspects for programmable digital systems, coordination
of safety and security requirements and management of ageing. The standards referenced
directly at this second level should be considered together with IEC 61513 and IEC 63046 as
a consistent document set.
At a third level, IEC SC 45A standards not directly referenced by IEC 61513 or by IEC 63046
are standards related to specific equipment, technical methods, or specific activities. Usually
these documents, which make reference to second-level documents for general topics, can be
used on their own.
A fourth level extending the IEC SC 45 standard series, corresponds to the Technical Reports
which are not normative.
The IEC SC 45A standards series consistently implements and details the safety and security
principles and basic aspects provided in the relevant IAEA safety standards and in the
relevant documents of the IAEA nuclear security series (NSS). In particular this includes the
IAEA requirements SSR-2/1, establishing safety requirements related to the design of nuclear
power plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of
structures, systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the
design of instrumentation and control systems for NPPs, the IAEA safety guide SSG-34
dealing with the design of electrical power systems for NPPs and the implementing guide
NSS17 for computer security at nuclear facilities. The safety and security terminology and
definitions used by SC 45A standards are consistent with those used by the IAEA.
IEC 61513 and IEC 63046 have adopted a presentation format similar to the basic safety
publication IEC 61508 with an overall life-cycle framework and a system life-cycle framework.
Regarding nuclear safety, IEC 61513 and IEC 63046 provide the interpretation of the general
requirements of IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application
sector. In this framework IEC 60880, IEC 62138 and IEC 62566 correspond to IEC 61508-3
for the nuclear application sector. IEC 61513 and IEC 63046 refer to ISO as well as to IAEA
GS-R part 2 and IAEA GS-G-3.1 and IAEA GS-G-3.5 for topics related to quality assurance
(QA). At level 2, regarding nuclear security, IEC 62645 is the entry document for the
IEC/SC 45A security standards. It builds upon the valid high level principles and main
concepts of the generic security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it
adapts them and completes them to fit the nuclear context and coordinates with the
IEC 62443 series. At level 2, IEC 60964 is the entry document for the IEC/SC 45A control
rooms standards and IEC 62342 is the entry document for the ageing management standards.
NOTE 1 It is assumed that for the design of I&C systems in NPPs that implement conventional safety functions
(e.g. to address worker safety, asset protection, chemical hazards, process energy hazards) international or
national standards would be applied.
NOTE 2 IEC/SC 45A domain was extended in 2013 to cover electrical systems. In 2014 and 2015 discussions
were held in IEC/SC 45A to decide how and where general requirements for the design of electrical systems were
to be considered. IEC/SC 45A experts recommended that an independent standard be developed at the same level
as IEC 61513 to establish general requirements for electrical systems. Project IEC 63046 is now launched to cover
this objective. When IEC 63046 is published, this NOTE 2 of the introduction of IEC/SC 45A standards will be
suppressed.
– 8 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
NUCLEAR POWER PLANTS ‒
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY ‒
ELECTRICAL EQUIPMENT CONDITION MONITORING METHODS –
Part 6: Insulation resistance
1 Scope
This part of IEC/IEEE 62582 contains methods for condition monitoring of organic and
polymeric materials in instrumentation and control cables using insulation resistance
measurements in the detail necessary to produce accurate and reproducible results during
simulated accident conditions. It includes the requirements for the measurement system and
measurement procedure, and the reporting of the measurement results.
NOTE Measurement of insulation resistance during simulated accident conditions with the aim of determining the
lowest value during the accident in order to assess cable performance involves special requirements given in this
document. Methods for measurement under stable (non-accident) conditions are available in other international
standards, e.g. IEC 62631-3-3.
The different parts of the IEC/IEEE 62582 series are measurement standards, primarily for
use in the management of ageing in initial qualification and after installation. IEC/IEEE 62582-
1 includes requirements for the application of the other parts of the IEC/IEEE 62582 series
and some elements which are common to all methods. Information on the role of condition
monitoring in qualification of equipment important to safety is found in IEC/IEEE 60780-323.
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.
JCGM 100:2008, Evaluation of measurement data – Guide to the expression of uncertainty in
measurement. First edition 2008. Corrected version 2010
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
For definitions not specifically called out in this standard, the following references could be
useful:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEEE Standards Online Dictionary: available at http://dictionary.ieee.org
3.1
capacitive charging current
current that charges the capacitor formed by the tested insulation between the conducting
parts connected to the measuring instrument inputs
Note 1 to entry: At the beginning the capacitor is not charged and high current is flowing. The current drops as
the capacitor is being charged.
3.2
conductor
material that allows the flow of an electric current
Note 1 to entry: The term conductor used in this document is synonymous with the term wire.
3.3
insulation leakage current
current that flows through insulation
3.4
insulation resistance
resistance between two conducting parts separated by electric insulation
Note 1 to entry: The value of the measured insulation resistance shall be reported as Ωm.
3.5
polarization absorption current
component of a dielectric current that is proportional to the rate of accumulation of electric
charges within the dielectric
3.6
surface leakage current
current that flows on the surface of insulation between connection points of applied voltage
Note 1 to entry: The surface leakage current is constant with time.
4 Abbreviated terms and acronyms
AC Alternating current
DAQ Data acquisition
DC Direct current
DMM Digital multimeter
GUM Guide to the expression of uncertainty in measurement
JCGM Joint committee for guides in metrology
IR Insulation resistance
l Surface leakage current
s
l Insulation leakage current
i
l Polarization absorption current
p
l Capacitive charging current
c
LOCA Loss of coolant accident
R Resistance of the resistor intended for measuring the total leakage current
meas
U Voltage across the resistor R
meas meas
U Supply voltage
source
– 10 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
5 General description
Insulation resistance measurement is one commonly applied method for indication of the
condition of insulating components, primarily cable insulation, during simulated accident
conditions. A minimum value of the insulation resistance of a cable may be prescribed to be
exceeded throughout the simulated accident conditions. The minimum insulation resistance
value may be prescribed to ensure a margin to dielectric conditions at which the safety
function of the circuit will not be affected. This is generally for instrumentation cables. The
insulation value prescribed is related to the length of the cable and should be given in Ωm, i.e.
in Ω for one m of cable length.
For measurement of IR as a measure of the condition of a cable, DC voltage is recommended.
AC voltage is primarily used for measurement of the functionality of the cable in its intended
application. An example of a set up for measurement of IR using DC voltage is shown in
Annex A. Some guidelines for leakage current measurement using AC voltage are given in
Annex B. The set up in Annex B is recommended for functional testing only, and not as a
substitute for IR measurement using DC voltage.
The total current measured after a DC voltage is applied is composed of I , I , I , and I . The
s i p c
I causes an error in insulation resistance measurement if the ground plane is not in contact
s
with the surface of the isolation and can be eliminated by use of a guard terminal. For values
of IR which can be expected during simulated accident conditions, the influence of I is
p
small.I is significant for most common insulation materials during a short time after the
c
application of voltage and the stabilization of the total current value has to be awaited. For all
common insulation materials, I may be considered as insignificant after less than 3 s when
c
the IR is measured under simulated accident conditions. Figure 1 shows an example of the
time to stabilization from measurement of IR before and during LOCA.
Figure 1 – Time to stabilization of IR measured before LOCA, after 10 min
in LOCA and after 60 min in LOCA
The diagrams show that stabilization of the measurements during LOCA is reached well within
3 s also in a case where the IR value is well above 100 MΩ.
– 12 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
6 Applicability and reproducibility
This document is limited to the use of insulation resistance measurement for monitoring the
condition of cables during simulated accident conditions. The temperature of the insulator has
a very significant influence on the values measured – an approximation that is used
sometimes is that of the IR decrease by a factor of two for each increase of temperature of
10 K. In addition, the high humidity and pressure involved in the simulated accident conditions,
resulting in moisture condensed on the insulator and penetration of moisture into the insulator,
affect the measured values. The dependence of IR on temperature and steam is discussed in
Annex C. In the simulation of accident conditions, temperature, moisture condensed and
penetration of moisture into the insulator vary with time. The result of an insulation resistance
measurement during simulated accident conditions varies significantly depending on the initial
condition of the cable and at what time during the simulated accident conditions the
measurement is taken. Annex D shows some results of IR measurement on aged cables
during a simulated LOCA.
As illustrated by Annex D, Figures D.1 through D.3, limited time is available for each
measurement to allow detection of the lowest IR value during a simulated accident condition
when a multiconductor cable is measured. Figure D.1 also illustrates the importance of
measuring IR on each conductor in order to find the conductor with the lowest value.
The elimination of voltage stress may yield a better condition, or lesser level of degradation
than if it is applied during the test. Some cable qualification standards, such as IEEE Std 383,
require that the cable is loaded with rated voltage and current during the test. The
measurement technique then needs to combine measurement and load. If there is a non-
continuous measurement the interval between measurements needs to be defined to find the
lowest value with a required uncertainty.
The purpose of the IR measurement according to this document is to detect values in the
range up to 100 MΩm, i.e. IR values above which no significant effects during simulated
accident conditions will be expected on functionality of typical low voltage cables.
NOTE The acceptable level of IR depends on the application. For most applications, the required insulation is well
below 100 MΩm.
Per IEEE Std 383-2015 the qualification type tests for coaxial, triaxial, twinaxial and
data/communication cables should include sufficient testing of cables critical electrical
performance characteristics to permit an adequate analysis of the compatibility of the cables
for the specific application, as appropriate. This may include insulation resistance testing for
some applications but the IR may need to be higher than 100 MΩm.
7 Instrumentation
7.1 Measurement voltage level
Measurement equipment shall be capable to supply enough voltage to be able to keep the
specified measurement voltage level constant over the whole measurement range, including
the lowest acceptable IR value.
7.2 Uncertainty
The measuring device shall be calibrated to an overall uncertainty within ±10 %.
NOTE This can be achieved in a standard set up with a 10 kΩ shunt resistor when a 6 ½ digit digital multi-meter
is used. The uncertainty limit occurs at 100 MΩ and IR in the 10 kΩ range can still be traced.
The uncertainty shall be calculated according to JCGM 100:2008 (GUM methodology).
7.3 Calibration
The IR measurement device shall be calibrated in the range of the quantities measured to
ensure accuracy. These quantities can be either voltage and the current or the resistance.
8 IR measurement procedure
8.1 General
The measurement procedure described allows determination of the lowest IR of individual
conductors of a multiconductor cable. In the case only one conductor or group of connected
conductors per measurement instrument is measured, the measuring period can be equal to
the test time in case of measurement on non-energized specimens. If this is not the case and
one instrument is used for measurement of more than one conductor or group of conductors,
the measurement procedure has to include switching. For the case of measurement on
energized specimens, see 8.6.5.
8.2 Requirements on tracking of changes of IR during the simulated accident
conditions
To catch the maximum influence on the resistance of the rapidly varying
temperature/moisture/pressure at the initial part of the accident condition simulation the
switching time, the stabilizing time and the measuring time shall be limited to enable tracking
of the changes in insulation resistance. The procedure shall allow consecutive readings of the
IR value at least every 7,5 min during the accident condition simulation. The lowest value
detected during the accident condition simulation shall be reported. In addition to reporting
the lowest IR value, a diagram shall be included, showing the IR time history during the
accident condition simulation.
8.3 Test specimen
The test specimen (complete cable or single conductor under test) shall have a minimum
length of 3 m. The conductors shall be sealed at the ends. When a complete cable, including
jacket, is tested, there shall be no sealing between the conductors and the jacket, unless the
test is intended purely for a certain application where it is sealed.
The ground plane shall be in contact with all parts of the surface of the isolator of the test
specimen. No guard is then needed. This is achieved by using a metallic braid around the
specimen as ground plane. The metallic braid shall be of a construction that does not
influence absorption of moisture into the insulation material or penetration of moisture through
cracks in the insulation material.
NOTE 1 The position of the ground plane in contact with the isolator results in a conservative (low) value of IR,
similar to what can be expected in the field if the cable is installed in a metallic conduit or at the bottom of a solid
metallic cable tray. If the cable in the field is installed on a cable ladder the connection to ground is point-wise,
resulting in higher values of IR.
NOTE 2 In case of testing of specimen submerged in water, the water may be used as ground plane.
8.4 Interference
Other specimens in the chamber that are AC loaded or energized shall be shut off during the
IR measurement in order to avoid cross-talk.
8.5 Conditioning
Before start of the accident simulation, the specimen shall be stabilized to a condition
corresponding to normal operation in the field.
– 14 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
8.6 IR measurement during the dynamic phase of the simulated accident conditions
8.6.1 Set-up for the measurement
Annex A illustrates a typical set-up for measurement of IR using DC voltage.
8.6.2 Connection of IR voltage and start of measurement
Connect the specimen to the IR measurement DC voltage source.
NOTE The capacitive charging current has a great influence on the initial IR reading. The total IR will quickly drop
several decades compared to the initial value.
8.6.3 Default voltage
The default voltage shall be DC voltage and be 500 V. The reference voltage shall be
scanned and logged with the same scanning device used for the IR measurement.
Insulation materials used in nuclear power plants will normally be suitable for use with 500 V
DC test voltage without damage. For some data/communication cables where 500 V DC may
overstress the cable insulation, a value of 100 V DC may be used for the IR test value.
Accuracy will be decreased in this case.
A source of very steady direct voltage is required. This can be provided either by batteries or
by rectified and stabilized power supply. The degree of stability required is such that the
change in current due to any change in voltage is negligible compared with the current to be
measured.
8.6.4 Determination of IR value with the specimen not energized during the accident
simulation
8.6.4.1 One conductor or group of connected conductors per measurement
instrument
The insulation resistance value is measured continuously during the whole accident
simulation. The most conservative way is to measure the IR between each separate conductor
and ground.
8.6.4.2 More than one conductor or group of conductors measured with the same
measurement instrument
8.6.4.2.1 Sequence
The IR measurement sequence starts with depolarizing/de-energizing the specimen,
connection of the IR measurement voltage source followed by stabilization, and sampling of
the value indicated by the measurement instrument over a well-defined measurement interval.
8.6.4.2.2 Depolarizing/de-energizing
The specimen shall be de-energized before start of the measurement sequence. If the
specimen is energized with AC before the IR measurements, the energizing shall be broken at
zero crossing. Short circuit the specimen for 4,5 s to 5 s and leave open for 0,5 s to 1 s.
8.6.4.2.3 First measurement loop
The measurement of IR shall start within t s after connection of the IR measurement voltage
source. The average IR value shall be determined from sampling for at least 1 s. The t shall
be longer than 3 s.
8.6.4.2.4 Preparation for the next measurement loop
After the measurement, the voltage source shall be disconnected. The next conductor or
group of conductors shall be switched in and connected.
8.6.4.2.5 Summary for one loop
The test steps for one loop are summarized as follows:
Short circuit for 4,5 s to 5 s and leave open for 0,5 s to 1 s
Disconnect circuit
Connect the DC voltage source
Stabilize for t s
Measure during ≥1 s
Disconnect
Switch and connect
One loop is completed.
An example of a measurement loop and calculation of the time available for stabilization is
given in Annex E.
8.6.4.2.6 IR measurement during the stable phases of the simulated accident
conditions
At the stable phases of the simulated accident conditions test, i.e. at post LOCA, a sleeping
time can be added between the sequence bursts. Time for completing one measurement shall
always be the same.
8.6.5 Determination of the IR value with the specimen energized during the accident
simulation
The description in 8.6.4 assumes that the specimen is not energized during the simulated
accident condition. If the specimen is at rated voltage, or rated voltage and rated current, (AC
or DC depending on its application) during the simulated accident condition, it is still
recommended to perform the measurement of IR as DC measurement. In this case a break in
the energizing of the specimen is made at least once per 7,5 min and the procedure in 8.6.4 is
performed. The breaks shall be made as short as possible in order to allow maximum time
with the specimen energized but still fulfill a t of at least 3 s.
It is recommended to use automatic switching in order to minimize the length of the breaks.
At the stable phases of the simulated accident conditions test, i.e. at post LOCA, the time
between IR measurements can be extended above 7,5 min.
In the case of measurement of IR of an energized single conductor or of a single conductor
cable the switching is not relevant but the breaks for the DC measurements shall still be made
at least once per 7,5 min. This is also the case for a multiconductor cable if all conductors are
connected and measured against the ground plane for information on the general behaviour of
the cable.
During the periods where the specimen is energized the leakage current shall be continuously
measured in order to detect short term changes between the IR measurement periods. It shall
be reported as a diagram showing the time history.
– 16 – IEC/IEEE 62582-6:2019 © IEC/IEEE 2019
The periodic interruptions in the energisation may have to be considered and compensated
for in order to comply with the requirements in IEEE Std 383. The condition of the specimen
may be limited to voltage levels lower than the cable’s design and intended application.
Duplicate LOCA tests may have to be performed where cables are energized with rated
voltage and/or current to meet the requirements of IEEE Std 383.
9 Measurement report
The measurement report shall as a minimum inc
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