IEC 61514-2:2004

INTERNATIONAL IEC
STANDARD 61514-2
First edition
2004-01
Industrial process control systems –
Part 2:
Methods of evaluating the performance
of intelligent valve positioners
with pneumatic outputs
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INTERNATIONAL IEC
STANDARD 61514-2
First edition
2004-01
Industrial process control systems –
Part 2:
Methods of evaluating the performance
of intelligent valve positioners
with pneumatic outputs
 IEC 2004  Copyright - all rights reserved
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– 2 – 61514-2  IEC:2004(E)
CONTENTS
FOREWORD.4

INTRODUCTION.6

1 Scope.7

2 Normative references.8

3 Terms and definitions .9

4 Design review.10

4.1 Positioner identification.10
4.1.1 Power supply unit.11
4.1.2 Sensor/input assembly.11
4.1.3 Auxiliary sensor assembly.11
4.1.4 Human interface.11
4.1.5 Communication interface.12
4.1.6 Data processing unit .12
4.1.7 Output subsystem.12
4.1.8 External functionality.13
4.2 Aspects of functionality and capabilities to be reviewed .13
4.2.1 Checklist.13
4.2.2 Reporting.19
4.3 Documentary information.19
5 Performance testing.20
5.1 Reference conditions for performance tests .20
5.1.1 Valve characteristics.21
5.2 General testing procedures.23
5.2.1 Test set-up.23
5.2.2 Testing precautions.24
5.3 Initial observations and measurements .24
5.3.1 Mounting procedure.24
5.3.2 Configuration procedures.25
5.3.3 Stem position calibration procedure .25
5.3.4 Stem position tuning procedure.25
5.4 Performance test procedures .26

5.4.1 Tests under reference conditions .26
5.4.2 Effects of influence quantities .28
6 Other considerations.34
6.1 Safety.34
6.2 Degree of protection provided by enclosures.34
6.3 Electromagnetic emission.34
6.4 Variants.34
7 Evaluation report.34

Annex A (normative) Vibration test set-up.36

Bibliography .37

61514-2  IEC:2004(E) – 3 –
Figure 1 – Positioner model in extensive configuration.11

Figure 2 – Basic design for positioners with analogue outputs.13

Figure 3 – Basic design for positioners with pulsed output .13

Figure 4 – Basic test set-up.24

Figure 5 – Examples of step responses of positioners .28

Table 1 – Single or double acting linear .21

Table 2 – Single or double acting rotary for an angle between 60° – 90° .22

Table 3 – Matrix of instrument properties and tests.29

– 4 – 61514-2  IEC:2004(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

___________
INDUSTRIAL PROCESS CONTROL SYSTEMS –

Part 2: Methods of evaluating the performance of

intelligent valve positioners with pneumatic outputs

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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 61514-2 has been prepared by subcommittee 65B: Devices, of
IEC technical committee 65: Industrial-process measurement and control.
This standard is to be read in conjunction with IEC 61514.
The text of this standard is based on the following documents:
FDIS Report on voting
65B/515/FDIS 65B/522/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

61514-2  IEC:2004(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until
2009. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or

• amended.
A bilingual version of this publication may be issued at a later date.

– 6 – 61514-2  IEC:2004(E)
INTRODUCTION
New instruments for process control and measurement including valve positioners are mainly

equipped with microprocessors thereby utilising digital data processing and communication

methods and/or artificial intelligence, making them more complex and giving them a consider-

able added value.
Modern intelligent valve positioners are no longer only controlling the valve position, but they

are in many cases also equipped with various facilities for self-testing, actuator/valve condition

monitoring and alarming. The variety of added functionalities is large. They can no longer be

compared with the single function "cam-type" positioners. Therefore, accuracy related

performance testing although still very important is no longer sufficient to demonstrate their
flexibility, capabilities and other features with respect to engineering, installation, maintain-
ability, reliability and operability.
In this standard the evaluation considers performance testing and a design review of both
hardware and software. The layout of this document follows to some extent the framework of
IEC 62098. A number of performance tests described in IEC 61514 are still valid for intelligent
valve positioners. Further reading of IEC 61069 is recommended.

61514-2  IEC:2004(E) – 7 –
INDUSTRIAL PROCESS CONTROL SYSTEMS –

Part 2: Methods of evaluating the performance of

intelligent valve positioners with pneumatic outputs

1 Scope
This part of IEC 61514 specifies design reviews and tests intended to measure and determine
the static and dynamic performance, the degree of intelligence and the communication
capabilities of single-acting or double-acting intelligent valve positioners. The tests may be
applied to positioners which receive standard analogue electrical input signals (as specified in
IEC 60381) and/or digital signals via a data communication link and have a pneumatic output.
An intelligent valve positioner as defined in Clause 3 is an instrument that uses for performing
its functions digital techniques for data processing, decision-making and bi-directional
communication. It may be equipped with additional sensors and additional functionality
supporting the main function.
The performance testing of an intelligent valve positioner needs to be conducted with the
positioner mounted on and connected to one or preferably more actuator/valve assemblies in
turn. The specific characteristic parameters of these combinations such as size, stroke, friction
(hysteresis), type of packing, spring package and supply pressure for the pneumatic part, are
to be carefully chosen and reported. It should be noted that the performance of a positioner in
such combinations is actuator dependent. Tests on different sizes of actuators are required in
particular for the determination of the operational range (dynamic response and stability) of a
positioner.
The methods of evaluation given in this standard are intended for use by manufacturers to
determine the performance of their products and by users or testing laboratories to verify
equipment performance specifications. The manufacturers of intelligent positioners are urged
to apply this standard at an early stage of development.
This standard is intended to provide guidance for designing evaluations of intelligent valve
positioners by providing:
– a checklist for reviewing their hardware and software design in a structured way;
– test methods for measuring and qualifying their performance under various environmental
and operational conditions;
– methods for reporting the data obtained.

When a full evaluation, in accordance with this standard, is not required or possible, the tests
which are required should be performed and the results reported in accordance with the
relevant parts of this standard. In such cases, the test report should state that it does not cover
the full number of tests specified herein. Furthermore, the items omitted should be mentioned,
to give the reader of the report a clear overview.
The standard is also applicable for non-intelligent microprocessor-based valve positioners
without means for bi-directional communication. In that case an evaluation should be reduced
to a limited programme of performance testing and a short review of the construction.

– 8 – 61514-2  IEC:2004(E)
2 Normative references
The following referenced documents are indispensable for the application of this document. For

dated references, only the edition cited applies. For undated references, the latest edition of

the referenced document (including any amendments) applies.

IEC 60050-351:1998, International Electrotechnical Vocabulary (IEV) – Part 351: Automatic

control
IEC 60068-2-1: 1990, Environmental testing – Part 2: Tests. Tests A: Cold

IEC 60068-2-2: 1974, Environmental testing – Part 2: Tests. Tests B: Dry heat
IEC 60068-2-6: 1995, Environmental testing – Part 2: Tests. Test Fc: Vibration (sinusoidal)
IEC 60068-2-31: 1969, Environmental testing – Part 2: Tests. Test Ec: Drop and topple,
primarily for equipment-type specimens
IEC 60068-2-78: 2001, Environmental testing – Part 2-78: Tests. Test Cab: Damp heat, steady
state
IEC 60079 (all parts), Electrical apparatus for explosive gas atmospheres
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60534-1, Industrial-process control valves – Part 1: Control valve terminology and general
considerations
IEC 60654 (all parts), Operating conditions for industrial-process measurement and control
equipment
IEC 60721-3, Classification of environmental conditions – Part 3 Classification of groups of
environmental parameters and their severities
IEC 61000-4-11, Electromagnetic compatibility (EMC) – Part 4-11: Testing and measurement
techniques – Voltage dips, short interruptions and voltage variations immunity tests
IEC 61010-1:2001, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 1: General requirements

IEC 61032:1997, Protection of persons and equipment by enclosures – Probes for verification
IEC 61069 (all parts), Industrial-process measurement and control – Evaluation of system
properties for the purpose of system assessment
IEC 61158 (all parts), Digital data communications for measurement and control – Fieldbus for
use in industrial control systems
IEC 61298 (all parts), Process measurement and control devices – General methods and
procedures for evaluating performance
IEC 61326:2002, Electrical equipment for measurement, control and laboratory use – EMC
requirements
61514-2  IEC:2004(E) – 9 –
IEC/PAS 61499 (all parts), Function blocks for industrial-process measurement and control

systems
IEC 61514:2000, Industrial-process control systems – Methods of evaluating the performance

of valve positioners with pneumatic outputs

IEC 62098:2000, Evaluation methods for microprocessor-based instruments

CISPR 22, Information technology equipment – Radio disturbance characteristics – Limits and

methods of measurement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61514 and
IEC 60050(351), in addition to the following apply.
3.1
intelligent valve positioner
position controller as defined in 3.1 of IEC 61514 based on microprocessor technology, and
utilising digital techniques for data processing, decision-making and bi-directional communi-
cation; it may be equipped with additional sensors and additional functionality supporting the
main function.
NOTE 1 In this standard, only positioners with pneumatic output signals are considered. The input signal may be
an electric current or voltage, or a digital signal via a fieldbus.
NOTE 2 For non-intelligent microprocessor-based position controllers without bi-directional communication an
evaluation is reduced to a limited amount of performance testing and an abridged design review of the construction.
3.2
configuring
process of implementing the functionality required for a certain application
3.3
configurability
extent to which an intelligent positioner can be provided with functions to control various
applications
3.4
calibration
process of adjusting the range of travel to the required value for acquiring a defined input-to-
travel characteristic. The adjusted travel can either be from stop to stop or to a value in
between as defined by the valve manufacturer
NOTE Instruments may exist that are provided with an automatic procedure for travel range adjustment, which
may then be addressed with the term auto-calibration.
3.5
tuning
process of adjusting the various control parameters for a certain application
NOTE The stem tuning procedure can range from "trial and error" to an automatic proprietary procedure provided
by the manufacturer and often addressed as auto-tuning.
3.6
set-up
process of configuring, calibrating and tuning a positioner for optimal controlling of a specific
actuator/valve assembly
– 10 – 61514-2  IEC:2004(E)
3.7
travel cut-off
point close to the extreme end (low or high) of the characteristic curve at which the positioner

forces the valve to the corresponding mechanical stop (fully closed or fully open)

3.8
stroke time
time required to travel between two different positions under a defined set of conditions

3.9
dead band
finite range of values within which reversal of the input variable does not produce any
noticeable change in the output variable
3.10
operating mode
selected method of operation of the positioner
3.11
setpoint
input variable, which sets the desired value of the controlled variable (travel)
NOTE The input variable may originate from an analogue source (mA or voltage) or from a digital source (fieldbus)
or local keyboard).
3.12
balance pressure
average of the pressures on the opposite chambers of a double acting actuator in steady state
condition
NOTE The balance pressure must be expressed as a percentage of the positioner supply pressure to evaluate the
stiffness of the double acting system.
4 Design review
The observations of this clause shall be based on open literature (manuals, instruction leaflets,
etc.) provided to a user on delivery of the instruments and whatever the manufacturer is willing
to disclose. They shall not contain confidential information.
The design review is meant to identify and make explicit the functionality and capabilities of the
intelligent valve positioner under consideration in a structured way. As intelligent positioners
appear in a great variety of designs a review has to show in a structured way the details of
– their physical structure;
– their functional structure.
Subclause 4.1 guides the evaluator in the process of describing the physical structure of
intelligent positioners through identifying the hardware modules and the I/O's to the operational
and environmental domains.
Thereafter the functional structure is described using the checklist of 4.2. The checklist gives a
structured framework of the relevant issues, which have to be addressed by the evaluator
through adequate qualitative and quantitative experiments.
4.1 Positioner identification
The structured identification process, based on the following considerations, leads to a
blockscheme and a concise description of the positioner under test, which shall be included in
the evaluation report. It may be enhanced with photographs or drawings of important details.

61514-2  IEC:2004(E) – 11 –
The instrument, schematically shown in Figure 1, can have the following main physical

modules and provisions for connection to the external world:

To external system
Supply voltage
Power supply Communication
Supply pressure
interface
unit
Current input
Data
Sensor/input Output
E
processing
Feedback from actuator
assembly subsystem
Output pressure
P
unit
to actuator
Pos. output pressure
Aux. sensor
pos. internal temp.
assembly
Human
Upstream line pressure mA position output
interface
Diff. pressure
Stuffing box
over valve
leakage
detector
To human operator
IEC  002/04
Figure 1 – Positioner model in extensive configuration
4.1.1 Power supply unit
Instruments that require a separate connection to an a.c. or d.c. supply voltage may exist.
However, the majority of instruments are "loop powered" which means that they receive power
either through the current input for instruments that need an analogue (mA) setpoint, or
through the fieldbus when the setpoint is a digital signal.
4.1.2 Sensor/input assembly
The main sensor/input assembly is that part of the positioner to which the analogue setpoint is
connected and which also receives the feedback signal from the actuator/valve assembly (stem
movement). It supports the primary function of the positioner. Parts of the assembly may be
distributed at physically different locations in the positioner. In instruments that receive a digital
setpoint the current input as shown in Figure 4 does not exist. The feedback signal is
generated by a mechanical interface (linkage) between the positioner and the valve stem.
4.1.3 Auxiliary sensor assembly
The auxiliary sensor assembly is for the electronics part integrated with the main sensor input

assembly. Many positioners are equipped with a pressure sensor in the pneumatic output
circuit and a temperature sensor inside the electronics housing. Their signals may be used in
the stem position control algorithm. For safeguarding and condition monitoring of the valve a
positioner may be equipped with additional sensors. It may also be equipped with circuits for
digital inputs from switches.
4.1.4 Human interface
A positioner can be classified as intelligent only when data produced by the positioner can be
communicated to the external world. The human interface is an important tool for
communication. It consists of integral means at the instrument for reading out data (local
display) and provisions for entering and requesting data (local pushbuttons). It may appear that
some instruments are not equipped with a human interface. In these cases access is provided
via the data communication interface and an external device (handheld terminal or PC).

– 12 – 61514-2  IEC:2004(E)
4.1.5 Communication interface
Positioner intelligence is further supported by the communication interface, which connects the

positioner to external systems. Through the interface and a fieldbus, data transfer (setpoint,

configuration and process data) takes place between the positioner and the external system.

There are also hybrid instruments, which require an analogue input for control data where the
data communication interface is integrated in the input circuit and has no separate point of

connection for the fieldbus. The digital information is superimposed on the analogue input

current. There may be instruments which do not have a communication interface. Then

configuration and read-out of data take place via the human interface.

4.1.6 Data processing unit
The data processing unit provides the instrument with a number of functions that may vary
considerably from make to make. The functions that can be implemented include:
– control function;
– configuration;
– calibration;
– tuning;
– valve condition monitoring (valve diagnostics);
– external process control function;
– self-testing;
– trending and data storage;
– part of the functionality may be located in external devices that are temporarily or
continuously connected to the data communication interface (e.g. configuration, trending).
4.1.7 Output subsystem
In the single acting version the output subsystem converts the digital information via an electro-
pneumatic converter (E/P) into the pneumatic signal for controlling the actuator.
In the double acting version the output subsystem is equipped with two oppositely operating
E/P-converters. In balanced (steady) position the converters provide pressures that, apart from
the friction force to the valve stem, are equal. The relation between the balance pressure and
the supply pressure determines the stiffness of a double acting system.
With respect to the pneumatic unit, the following two designs can be identified:
– using analogue techniques of conventional E/P-converters as shown in Figure 2;

– using pulsed digital techniques basically as shown in Figure 3, with electronically controlled
two-position pilot valves.
Moreover, the output subsystem can also be provided with isolated analogue signal outputs
proportional to one (or more) of the measured or calculated data and/or one or more
configurable output relays for alarm purposes. Such outputs usually require a separate power
supply.
61514-2  IEC:2004(E) – 13 –
Control signal Stem position
Data processing
unit
feedback
Supply pressure
E/P
converter
Pneumatic
amplifier
Valve and actuator
IEC  003/04
Figure 2 – Basic design for positioners with analogue outputs

Control signal Control signal
open close
Pilot Pilot
valve 1 valve 2
Supply
Venting
pressure
output
Actuator
Stem travel
IEC  004/04
Figure 3 – Basic design for positioners with pulsed output
4.1.8 External functionality
Through the data communication interface and the fieldbus the instrument communicates with
PCs, handheld devices and DCS systems. In many cases a part of the functionality of the
positioner may reside in these devices. This may include the following functions:
– (Remote) configuration tool.
– Data storage (configuration, position trend, valve condition).

– Parts of the calibration and stem tuning procedure.
– Automated valve condition monitoring and alarming.
In an evaluation the external functionality (if present) shall be considered as well.
4.2 Aspects of functionality and capabilities to be reviewed
4.2.1 Checklist
The following tables shall serve as a checklist for the determination of the functions and
capabilities implemented in the positioner under consideration. An example of the reporting
format can be found in 4.3.
– 14 – 61514-2  IEC:2004(E)
4.2.1.1 Functionality
Function/capability Aspects to be considered during evaluation

Suitable for rotary valve If so, also indicate the stroke range and describe the accessories required for

mechanical linkage
Suitable for linear stroke valve If so, also indicate the stroke range and describe the accessories required for

mechanical linkage
Direct/reverse action Check whether choice of direct/reverse action is possible and describe how the

mechanism operates
Double acting version Mention availability

Stem position control algorithm For each control parameter give:

parameters
• Name
• Adjustment range if user-adjustable
• Default values if applicable
• Check whether invalid values are recognised and rejected
• Check whether negative values are accepted, if so observe behaviour on
instability after step change
• Check if outputs of internal sensors are used in the stem position control
algorithm and check whether and how backup is provided in case of
sensor failure
• Some designs have a double set of control parameters for upscale or
downscale movement, verify
• What value defines indefinite (‘99999’ or ‘0’)?
Other parameters affecting For a number of parameters (supply pressure, valve and actuator data, etc.)
control values may be requested to be entered during configuration. They might be
used in the stem position control algorithm. Check whether they are indeed
used in the stem position control algorithm or are informative only.
Operating modes Describe the available operating modes, their hierarchy, span of control,
switching order (also check availability of bumpless transfer), degree of
authorised access to positioner database (configuration, control parameters,
secondary parameters).
Operating modes could be:
• Out of service or standby
• Automatic control
• Manual control (local or remote)
Split range application Is split range operation possible?
If so, check whether it is a fixed setting or a user-adjustable range
Stroke time Check whether the stroke time is user-adjustable. When set to zero,
parameters such as actuator volume, valve friction, spring package, supply
pressure and restrictions determine stroke time. When set to values exceeding
the actuator characteristic, speed is constant.
Travel cut-off Cut-off is usually possible at the lower end of the characteristic (also known as

tight shut-off), but also cut-off at the upper end can be present. Indicate which
option is available and whether cut-off values are user-configurable.
Check whether a dead band is implemented and operational between activation
and release. Indicate whether it is related to the input signal or to the feedback
position signal.
Filters If filters are provided, are they analogue or digital?
External (process) control Can function blocks (according to IEC 61499) for an external control loop be
implemented?
Special functions Indicate if special functions are available (e.g. pressure sensor in actuator,
leak detection, flow measurement)

61514-2  IEC:2004(E) – 15 –
4.2.1.2 Configurability
Function/capability Aspects to be considered during evaluation

Fieldbus compatibility Check whether the instrument under test is suited for either:

• connection to one of the fieldbusses in accordance with IEC 61158

• or stand-alone application in combination with a temporary connection to a

proprietary fieldbus
• or stand-alone application
A concise listing may be added of instrument versions versus link compatibility

Configuration tools Check if the instrument can be configured:

• From local controls (human interface) on instrument
• Remotely from PC or a host computer
• Via handheld communication unit to be connected temporarily
On-line (re)configuration Check whether parameters can be changed in control mode, if so whether the
position of the valve stem is unacceptably affected.
Check whether there is a security mechanism that prohibits on-line access to
all or some parameters.
Off-line configuration Check whether it is possible to set up and store configurations for a number of
positioners on a separate (off-line) PC, which is not connected to a positioner.
Up/download to/from PC Check if configuration upload is possible. Check if download of off-line
prepared configurations is possible.
Configurable travel Mention user-selectable characteristics that reside in the instrument, such as:
characteristics
• Linear
• Equal percentage (IEC 60534-1) 1:50; 1:30; 1:25, etc.
• Equal percentage proprietary
• Quick opening
• Segmental (user defined travel characteristic), mention number of
segments
NOTE The equal percentage characteristic is sometimes realised by
segmental approach. It is important to state the number of segments and their
size and to evaluate the maximum errors with respect to the theoretical equal
percentage characteristic.
Configurable “fail-safe” position Check the availability of a configurable fail-safe position:
• What is reaction on failures (closed or open)?
• On what failures is fail-safe activated?
Balance pressure Check whether the balance pressure for the double acting version is user-
adjustable
Conditions on start-up after loss After a power down the user may want the positioner to return to a defined
of power or an instrument reset position. Positioners may be provided with:
• Return to last value
• Go to fail-safe
• Go to a user-defined value
• Return to control in manual mode

– 16 – 61514-2  IEC:2004(E)
4.2.1.3 Hardware configuration

Function/capability Aspects to be considered during evaluation

Hinged covers
Comment for these items on:
Valve position feedback
• Complexity and soundness of construction and protection against damage
mechanism
• Separate termination compartment
Internal modules
• Availability of material of construction for severe service application (e.g.
Support to valve offshore, food)

• Availability of integrated pneumatic connections

Protruding parts
• Availability of quick connect provisions for electrical and pneumatic

Local controls
connections
Electrical connections
• Isolation of pneumatic and electronic compartments
Pneumatic connections
Remote position sensor Check the availability of a remote position sensor that provides mechanical
separation of the electronics and comment on soundness and ease of
installation and calibration
4.2.1.4 Operability
Function/capability Aspects to be considered during evaluation
Local controls (tools) for access Give a concise description of:
• Available controls (pushbuttons, etc.)
• Accessibility
• Ergonomic layout and use of the controls
• Can controls be used in hazardous locations?
Local displays Give concise description of data that can be shown on the local displays:
• Number of lines and characters per line
• Control parameters given
• Error messages, etc.
Is display readable without removing covers?
Human interface at external Give a concise description of the organisation and hierarchy of the various user
system access groups and related displays in the PC based software.
Give for a handheld communicator a picture with layout of display and
keyboard.
Other points for human List other hardware tools (switches, potmeters, etc.) and the related
interaction parameters they control
Valve diagnostics Check whether implemented Valve Diagnostics cover the following aspects:
• Change in performance of control valve (dead band, resolution, etc.)
• Change of friction
• Wear of plug
• Wear of stem
• Packing leakage
• Seat leakage
• Break of stem
• Cavitation
• Broken actuator spring
• Air leakage at actuator
• Valve stuck
• Torn diaphragm at actuator
• Detection of reduction of performance by plugging of pneumatic
• Other aspects
Robustness
61514-2  IEC:2004(E) – 17 –
Function/capability Aspects to be considered during evaluation

Checks on extent of and tools for Check how the aspects mentioned above are diagnosed, tested, stored,

Valve Diagnostics reported and presented by the positioner or the host system.

Does the diagnostic tool provide direct automatic interpretation by the

instrument or does it require a specific level of human expertise. For each

aspect check which of the tools (tests) mentioned below are used, check per
tool the following points:
• Whether the diagnostic tests can be performed in-service

• Whether it is an on-line automatic test or an operator-initiated

• Check intervals between automatic tests

• Check user-adaptability of test parameters
• Check whether test affects the stem position.
• Indicate whether data can be stored and where (local or in PC)
• Check whether there is a related direct alert/alarm message or whether it
has to be deduced by the user from other information given by the
positioner. (Example: Many positioners are equipped with a user-
adjustable alarm indicating that the valve is not reaching its position in a
certain time. Break of stem, and broken spring will most probably trigger
this alarm.)
• Check the action of the positioner on appearance of diagnostic alarms
Tools (tests) that can be present are amongst other things:
• High/low position alarms
• Rate of change alarm
• Cycle counter/accumulator
• Travel accumulator
• Valve signature test
• Step response test
• Time to settle exceeds the set limit
• Accumulator for time close to zero
4.2.1.5 Dependability
Function/capability Aspects to be considered during evaluation
Positioner diagnostics Describe in short the extent of the system for diagnosing internal positioner
failures and securing safe operation in case of failures. Mechanisms may be
implemented for detecting:
• Flash ROM Failure
• No Free Time
• Reference Voltage Failure
• Drive Current Failure
• Critical NVM Failure
• Temperature Sensor Failure
• Pressure Sensor Failure
• Travel Feedback Sensor Failure
Fieldbus devices may provide specific messages such as:
• I/O Processor Fault
• Output not Running
• Static Parameters Lost
• Calibration Data Read Error
Check which diagnostics are performed:
• On-line (in service) automatically, continuously or intermittently
On-line (in service) user-initiated
Offline (out of service)
Does the manufacturer provide a coverage factor with respect to detection of
internal failures?
– 18 – 61514-2  IEC:2004(E)
Function/capability Aspects to be considered during evaluation

Detection of incorrect use Does the instrument detect errors and failures due to incorrect and unintended

operation and maintenance actions such as:

• Incorrect address settings via jumpers or dip switches;

• Reverse connection of power wiring, connectors, printed circuit boards (if

possible)
• Putting connectors at incorrect positions (if length of wiring permits this)

• Leaving an open circuit by not connecting a connector

• Performing incomplete or incorrect start-up procedure

• Leaving the instrument at an incorrect security level

• Multiple use of same address in a multi-drop digital communication system
• Causing short circuit by touching adjacent parts when performing
mechanical adjustments
Alarms Basically two groups of alarm types can be distinguished:
• Process alarms (related to the above mentioned valve diagnostic aspects
and the valve/actuator condition). Alarm settings may be user-adjustable.
• Selftest alarms (related to above mentioned positioner diagnostics on
internal electrical failures). These alarms are in general not user-
accessible.
• Which alarms in both groups are provided?
• How do they communicate?
Hard wired via relay outputs
On local display
Via fieldbus
• Do alarms appear automatically or only on user request?
Security against unauthorised Describe method of implementation of security:
access
• Hardware (write protect switch)
• Software (passwords, number of access levels and the degrees of access
and configurability at these levels)
• Access to local controls
Maintainability What level of repair does the manufacturer specify? (exchange of parts,
exchange of complete instrument)
Determine time to repair comprising of replacement in workshop
...