SIST EN 61069-4:1998
(Main)Industrial process measurement and control - Evaluation of system properties for the purpose of system assessment -- Part 4: Assessment of system performance
Industrial process measurement and control - Evaluation of system properties for the purpose of system assessment -- Part 4: Assessment of system performance
Covers the method to be used to systematically assess the performance of industrial-process measurement and control systems.
Leittechnik für industrielle Prozesse - Ermittlung der Systemeigenschaften zum Zweck der Eignungsbeurteilung eines Systems -- Teil 4: Eignungsbeurteilung des Systembetriebsverhaltens
Mesure et commande dans les processus industriels - Appréciation des propriétés d'un système en vue de son évaluation -- Partie 4: Evaluation des caractéristiques de fonctionnement d'un système
Couvre la méthode à utiliser pour évaluer de manière systématique les caractéristiques de fonctionnement des systèmes de mesure et commande des processus industriels.
Industrial process measurement and control - Evaluation of system properties for the purpose of system assessment - Part 4: Assessment of system performance (IEC 61069-4:1997)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61069-4:1998
01-november-1998
Industrial process measurement and control - Evaluation of system properties for
the purpose of system assessment - Part 4: Assessment of system performance
(IEC 61069-4:1997)
Industrial process measurement and control - Evaluation of system properties for the
purpose of system assessment -- Part 4: Assessment of system performance
Leittechnik für industrielle Prozesse - Ermittlung der Systemeigenschaften zum Zweck
der Eignungsbeurteilung eines Systems -- Teil 4: Eignungsbeurteilung des
Systembetriebsverhaltens
Mesure et commande dans les processus industriels - Appréciation des propriétés d'un
système en vue de son évaluation -- Partie 4: Evaluation des caractéristiques de
fonctionnement d'un système
Ta slovenski standard je istoveten z: EN 61069-4:1997
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
SIST EN 61069-4:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 61069-4:1998
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SIST EN 61069-4:1998
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SIST EN 61069-4:1998
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SIST EN 61069-4:1998
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SIST EN 61069-4:1998
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SIST EN 61069-4:1998
NORME
CEI
INTERNATIONALE
IEC
61069-4
INTERNATIONAL
Première édition
STANDARD
First edition
1997-08
Mesure et commande dans les
processus industriels –
Appréciation des propriétés d’un système
en vue de son évaluation –
Partie 4:
Evaluation des caractéristiques
de fonctionnement d’un système
Industrial process measurement and control –
Evaluation of system properties for the purpose
of system assessment –
Part 4:
Assessment of system performance
IEC 1997 Droits de reproduction réservés Copyright - all rights reserved
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procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
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Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
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PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
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SIST EN 61069-4:1998
61069-4 © IEC:1997 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION . 9
Clause
1 Scope. 13
2 Normative references . 13
3 Definitions . 15
4 Performance properties . 15
4.1 General . 15
4.2 Performance. 17
4.3 Accuracy . 19
4.4 Response time. 19
4.5 Capacity . 19
5 Review of system requirements document (SRD) . 21
6 Analysis of system specification document (SSD). 23
7 Assessment procedure . 23
7.1 General . 23
7.2 Analysis of the SRD and the SSD. 23
7.3 Designing the assessment programme. 27
7.4 Assessment programme . 29
8 Evaluation techniques. 29
8.1 General . 29
8.2 Analytical evaluation techniques. 31
8.3 Empirical evaluation techniques . 31
8.4 Testing under influencing conditions . 37
9 Execution and reporting of the assessment . 37
Annexes
A Checklist on information to be given in the SRD . 39
B Example documentation of collated information from the SRD and the SSD. 43
C Model of an evaluation. 49
D Bibliography. 69
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SIST EN 61069-4:1998
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
_________
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSE OF SYSTEM ASSESSMENT –
Part 4: Assessment of system performance
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61069-4 has been prepared by subcommittee 65A: System aspects,
of IEC technical committee 65: Industrial-process measurement and control.
The text of this standard is based on the following documents:
FDIS Report on voting
65A/231/FDIS 65A/240/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.
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SIST EN 61069-4:1998
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The relation of this part to the other parts of IEC 61069 and the relative place of this part within
this standard is shown in figure 1.
Part 1 provides the overall guidance and as such is intended as a stand-alone publication.
Part 2 details the assessment methodology.
Parts 3 to 8 provide guidance on the assessment of specific groups of properties.
The division of properties in parts 3 to 8 have been chosen so as to group together related
properties.
IEC 61069 consists of the following parts, under the general title: Industrial-process
measurement and control – Evaluation of system properties for the purpose of system
assessment.
Part 1: General considerations and methodology
Part 2: Assessment methodology
Part 3: Assessment of system functionality (under consideration)
Part 4: Assessment of system performance
Part 5: Assessment of system dependability
Part 6: Assessment of system operability (under consideration)
Part 7: Assessment of system safety (under consideration)
Part 8: Assessment of non-task-related system properties (under consideration)
Annexes A, B, C and D are for information only.
The contents of the corrigendum of December 1997 have been included in this copy.
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SIST EN 61069-4:1998
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INTRODUCTION
This part of IEC 61069 deals with the method which should be used to assess the performance
of industrial process measurement and control systems.
Assessment of a system is the judgement, based on evidence, of the system's suitability for a
specific mission or class of missions.
To obtain total evidence would require complete (i.e. under all influencing conditions)
evaluation of all system properties relevant to the specific mission or class of missions.
Since this is rarely practical, the rationale on which an assessment of a system should be
based is:
– to identify the criticality of each of the relevant system properties;
– to plan for evaluation of the relevant system properties with a cost effective dedication of
effort to the various properties.
In conducting an assessment of a system it is crucial to bear in mind the need to gain a
maximum increase in confidence in the suitability of a system within practical cost and time
constraints.
An assessment can only be carried out if a mission has been stated (or given) or if any mission
can be hypothesized. In the absence of a mission, no assessment can be made; however,
evaluations (as defined in IEC 61069-1) can still be specified and be carried out for use in
assessments performed by others.
In such cases, the standard can be used as a guide for planning an evaluation and it provides
procedures for performing evaluations, since evaluations are an integral part of assessment.
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SIST EN 61069-4:1998
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Part 1:
General considerations
and methodology
Scope
Definitions
Basis of assessment
Assessment consideration
The system
Properties
Influencing conditions
Assessment procedure
Definition of the objectives
Design and layout
Part 2:
Methodology
Analysis of objectives
Analysis of system requirements
Analysis of specification
Planning Design of assessment programme
Facilities
Expertise
Time
Funds
Protocol Execution of assessment programme
Monitor and control
Part 3: Functionality
Part 4: Performance
Part 5: Dependability
Part 6: Operability
Part 7: Safety
Part 8: NTR properties
Assessment report
Figure 1 – General layout of IEC 61069
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INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSE OF SYSTEM ASSESSMENT –
Part 4: Assessment of system performance
1 Scope
This part of IEC 61069 covers the method to be used to systematically assess the performance
of industrial-process measurement and control systems.
The assessment methodology detailed in IEC 61069-2 is applied to obtain the performance
assessment programme.
The subsidiary performance properties are analyzed, and criteria to be taken into account when
assessing performance are described.
References are made to different supplementary performance evaluation techniques.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61069. At the time of publication, the editions indicated
were valid. All normative documents are subject to revision, and parties to agreements based
on IEC 61069 are encouraged to investigate the possibility of applying the most recent editions
of the normative documents indicated below. Members of IEC and ISO maintain registers of
currently valid International Standards.
IEC 60068,
Environmental testing
IEC 60721, Classification of environmental conditions
IEC 60902: 1987, Industrial-process measurement and control – Terms and definitions
IEC 61000, Electromagnetic compatibility (EMC)
IEC 61069-1: 1991, Industrial-process measurement and control – Evaluation of system
properties for the purpose of system assessment – Part 1: General considerations and
methodology
IEC 61069-2: 1993, Industrial-process measurement and control – Evaluation of system
properties for the purpose of system assessment – Part 2: Assessment methodology
IEC 61298-2: 1995, Process measurement and control devices – General methods and
procedures for evaluating performance – Part 2: Tests under reference conditions
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SIST EN 61069-4:1998
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IEC 61298-3: —, Process measurement and control devices – General methods and
1)
procedures for evaluating performance – Part 3: Tests for the effects of influence quantities
IEC 61298-4: 1995, Process measurement and control devices – General methods and
procedures for evaluating performance – Part 4: Evaluation report content
IEC 61326-1: — Electrical equipment for measurement, control and laboratory use – EMC
1)
requirements – Part 1: General requirements
3 Definitions
For the purpose of this part of IEC 61069, the following definitions apply:
3.1 performance: The precision and speed with which the system executes its tasks under
defined conditions.
3.2 accuracy: The closeness of agreement between the specified and the realized
information translation executed by the system under defined conditions.
3.3 response time: The time interval between the initiation of an information translation and
the instant when the associated response is made available under defined conditions.
3.4 capacity: The maximum number of given information translations the system is able to
execute within a defined period of time, without influencing any of the system properties.
3.5 information translation: A conversion or conveyance of information entering the system
at its boundary into derived information exiting the system at its boundary.
4 Performance properties
4.1 General
A system should be able to execute industrial-process measurement and control tasks with
accuracy and within a specified time (response time). If several tasks are to be executed the
system should handle these without obstructing the execution of the other tasks, and hence the
number of tasks which can be executed within a time frame (throughput) is important and
depends on the capacity of the system.
To assess the performance of a system it is therefore necessary to identify and assess the
subsidiary properties that determine performance.
Figure 2 shows the performance hierarchy.
__________
1)
To be published.
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Performance
Accuracy Response time Capacity
Figure 2 – Performance hierarchy
4.2 Performance
Performance cannot be assessed directly, but can only be determined by analysis and testing
of its subsidiary properties.
To be able to determine the subsidiary properties it is necessary to analyze the system in terms
of information translations.
It is necessary to examine the subsidiary properties for each of the information flows through
the system.
The performance of a system is mainly determined by the design of the system, and to a lesser
extent by factors which can be introduced (through both hardware and software) during the
manufacturing and integration stages of the system.
It should be noted that the subsidiary performance properties are mutually dependent.
A system may not have a single performance measure because various tasks can utilize a
different amount of information translations. Moreover, these information translations can be
mutually dependent when they share common facilities.
When a system accomplishes several tasks, their performance can vary, and for each of these
tasks a separate analysis is required.
Performance cannot be described by a single number, as long as there does not exist a
suitable synthesis model. The subproperties can be quantified; they are deterministic with
probabilistic elements, due to interdependencies, etc.
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4.3 Accuracy
The accuracy of an information translation comprises the following elements:
*
– conformity ;
– hysteresis;
– dead band;
– repeatability error;
– reproducibility error;
– resolution.
The terms and definitions relating to these elements are given in IEC 60902.
Accuracy is expressed in quantitative terms as an absolute or relative value.
4.4
Response time
The response time of an information translation comprises the following consecutive elements:
– information collection, which depends on the time constant of input filters (hard and/or
software) and input cycle times;
– information processing, which depends on the processing cycle time;
– output actuation, which depends on the times of output filters (hard and/or software) and
output cycle times.
Each of the above elements of the information translation can be executed in a synchronous or
asynchronous way.
Attention should be paid to the fact that the overall response time of an information translation
is not simply the sum of the constituent elements, due to interdependencies. For example, new
information can coincide in time with a running information translation resulting in an increase
in response time.
The response time differs with respect to each information translation, and depends on priority
settings of concurrent tasks, cycle time settings, activated credibility mechanisms, etc.
The response time can be quantified for individual tasks. Its value can contain probabilistic
elements depending on the exactness to which evaluation and or test conditions can be
controlled, the use of shared resources, etc.
4.5
Capacity
The capacity of a system depends on the number of system elements, the way in which these
are shared between the functions within the information translations and the element cycle
time(s).
The capacity of a given system is fixed and can only be changed through a system
modification.
__________
*
"Conformity" as used in this standard is not restricted to static conditions only, but should include dynamic
considerations, which can be affected by factors that may be embedded in the design of a system.
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The capacity of a system cannot be measured directly, but can be evaluated by measuring the
spare capacity which the system has for each of the information translations.
The spare capacity of a system for a particular information translation is the difference between
the maximum number of that particular information translation (100 % load) and the reference
number of the same information translation as defined in the system requirements document
(SRD) (base load), which the system is able to execute within a defined period of time and
under defined reference conditions. None of the system properties shall degrade in value,
when the spare capacity for a particular information translation is being measured.
For systems capable of performing a number of different information translations the spare
capacity cannot be expressed as a single value.
In such a case, the spare capacity could be expressed as an array of values, calculated from
the maximum amount of each of the information translations, which can be executed by the
system within a defined period of time, when the other information translations are kept at the
constant values required in the SRD, and none of the system properties are degraded in value.
An indication of the spare capacity of the system can be obtained by calculating for each of the
information translations a load factor:
number of information translations as given in SRD/unit of time
________________________________________________________
load factor =
maximum number of information translations as measured/unit of time
For each value, precise and detailed information should be given of the conditions under which
they are measured.
The above model can be operated in a computer as a simulation of system performance and
can be valuable for complex systems.
For the evaluation of systems, capable of executing different information translations, the
reference conditions in terms of number of translations per unit of time shall be defined for
each of the information translations before an evaluation of the capacity can be executed.
5 Review of system requirements document (SRD)
The system requirements document should be reviewed to check that the performance
requirements have been addressed and are listed in the manner as described in IEC 61069-2.
The effectiveness of the performance assessment is strongly dependent upon the comprehen-
siveness of the statement of requirements.
Particular attention should be given to check that for each of the system tasks the performance
requirements for accuracy, response time and capacity are stated under specific operating
conditions, for example, steady state, bursts of input information, etc.
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These requirements should have been provided both in relation to individual tasks as well as in
relation to the total mission.
Annex A gives guidance on the type of information the system requirements document should
give to enable the performance properties to be assessed.
6 Analysis of system specification document (SSD)
The system specification document should be reviewed to check that all performance data are
listed as described in clause 6 of IEC 61069-2.
Particular attention should be paid to check that information is given on:
– the information translations to support the required task(s);
– the system functions, modules and elements, both hardware and software, supporting the
information translations;
– for each of the information translations the location of the end points;
– quantified performance data for each of the information translations provided by the
system;
– facilities provided by the system which, in the assembled operational system, support
analysis of performance properties, such as calculation of spare capacity on memory
devices, statistical analysis of system resource utilization, etc.;
– notes made in the specification of any side-effects which can occur, when changes are
made to any of the other system properties.
7 Assessment procedure
7.1
General
The assessment should follow the procedure as laid down in clause 7 of IEC 61069-2.
The objective of the assessment shall be clearly stated. Guidance is given in 4.1 of IEC 61069-1.
The information given in the SRD and the SSD should be complete and precise to enable the
assessment of the performance.
If at any phase of the assessment, information is missing or incomplete, the originators of the
SRD and SSD should be consulted with specific questions to obtain the required further
information.
7.2 Analysis of the SRD and the SSD
7.2.1 Collation of documented information
For the purpose of the assessment of performance, information related to performance shall be
extracted from the SRD and the SSD as described in 7.2 of IEC 61069-2.
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The requirements as stated in the SRD and the performance data of the system as given in the
SSD should be drawn together and cross-related, to compile precise and concise statements,
in quantitative terms and their range of values of the following:
– the required task(s) as defined in the SRD, and the information translations provided by
the system to support these;
– the performance properties required for each of the tasks and performance data for each
of the information translations provided by the system;
– for each of the information translations the location of the end points;
– items in which the system does not comply with the requirements;
– the stated pre-knowledge available and extent to which the accuracy, response time and
capacity properties should be assessed.
7.2.2 Conditions influencing performance
The performance of a system can be affected by the influencing conditions listed in 4.4 of
IEC 61069-1.
For each of the performance subproperties the main influencing conditions are as follows:
a) Accuracy is affected by influencing conditions originating from the:
– environment, the influence of ambient temperature, although partly predictable, should
be tested over at least the total range to which the system will be subjected. The effects
of the time that the system will be exposed to temperature and heat radiation are
significant, as well as the system's exposure to humidity and vibration;
– utilities, such as voltage variations and surges expected from the main power supply;
– process, electrical noise pick-up by the in-coming and out-going lines from and to
field-mounted equipment, due to earthing problems, and conducted and/or radiated
electro-magnetic interferences.
b) Response time is mainly affected by conditions originating in the task-domain, such as:
– increase in activities (e.g. an alarm burst);
– externally generated interruptions, for example from the main power supply, and/or
from electrical noise as under accuracy above, generating the need for error correction
processing.
c) Capacity can only be affected by enhancing the system, however the effective spare
capacity available in the system is affected by:
– increase in activities (e.g. an alarm burst);
– externally generated interruptions, for example from the main power supply, and/or
from electrical noise as under accuracy above, generating the need for error correction
processing.
In general, any deviations from the reference conditions in which the system is supposed to
operate can affect the correct working of the system.
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When specifying tests to evaluate the effects of influencing conditions, the following IEC
standards shall be consulted:
– IEC 60068;
– IEC 60721;
– IEC 61000;
– IEC 61326-1.
7.2.3 Documenting collated information
The information collated as stated above should be documented in a form that can be
manipulated for the process of designing the assessment programme.
The lay-out shown in annex B is an example of the way the information can be documented.
7.3
Designing the assessment programme
7.3.1 Comparison of the SRD and the SSD
The first step in designing the assessment programme is to analyze the information collected
from the SRD and the SSD as per 7.2.
By comparing the SSD and the SRD as described in 7.2, a task-by-task list can be constructed
of all the proposed information translations supporting the tasks, their functions, modules,
elements and other means provided in support of the information flows to achieve the
performance requirements.
Each entry in this list is a potential assessment item.
Each potential assessment item shall be examined to decide the extent to which it should be
evaluated to obtain the required increase in the level of confidence.
7.3.2 Assessment items
The complete list of assessment items is reduced by considering the following filters:
– importance of the task(s) to the mission;
– existing level of confidence based upon prior knowledge, which may be based on
preceding success of the system in similar or identical missions, experience with the
manufacturer, the experience of users with the same system type or comparable systems;
– the level of interdependency of different functions
...
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