This NORSOK standard is developed with broad petroleum industry participation by interested parties in the This NORSOK standard is developed with broad petroleum industry participation by interested parties in the Norwegian petroleum industry and is owned by the
Norwegian petroleum industry and is owned by the Norwegian petroleum industry represented by The NorwegianNorwegian petroleum industry represented by The Norwegian Oil Industry Association (OLF) and Federation
Oil Industry Association (OLF) and Federation of Norwegian Manufacturing Industries (TBL). Please note of Norwegian Manufacturing Industries (TBL). Please note that whilstthat whilst every effort has been made to ensure the
every effort has been made to ensure the accuracy of this standard, neither OLF nor TBL or any of accuracy of this standard, neither OLF nor TBL or any of their memberstheir members will assume liability for any use thereof. Standards Norway is responsible for the administration and publication of will assume liability for any use thereof. Standards Norway is responsible for the administration and publication of this NORSOK standard.
this NORSOK standard. Standards
Standards Norway Norway Telephone: Telephone: + + 47 47 67 67 83 83 86 86 0000 Strandveien
Strandveien 18, 18, P.O. P.O. Box Box 242 242 Fax: Fax: + + 47 47 67 67 83 83 86 86 0101 N-1326
N-1326 Lysaker Lysaker Email: Email: petroleum@[email protected]
Rev. 2, April 2005 Rev. 2, April 2005
System control diagram
System control diagram
Foreword 2 Foreword 2 Introduction 2 Introduction 2 1 1 Scope Scope 44 2
2 Normative Normative references references 44
3
3 Definitions Definitions and and abbreviationabbreviations s 44 3.1
3.1 Definitions Definitions 44
3.2
3.2 Function Function definitions definitions 55
3.3
3.3 Abbreviations Abbreviations 77
4
4 The The SCD SCD approach approach 77
4.1
4.1 Conceptual Conceptual definition definition 77
4.2
4.2 Framework Framework 77
4.3
4.3 Life Life cycle cycle concept concept 88
4.4
4.4 Basic Basic design design (informative) (informative) 99 Annex
Annex A A (Normative) (Normative) SCD SCD Function Function standard standard 1313 Annex
Annex B B (Normative) (Normative) SCD SCD Drawing Drawing standard standard 3939 Annex
Annex C C (Informative) (Informative) Project Project excution excution guidelines guidelines 5252 Annex
Annex D D (Normative) (Normative) SCD SCD Legend Legend 5757 Annex
Annex E E (Informative) (Informative) SCD SCD Application Application guidelines guidelines 6262 Annex
Annex F F (Normative) (Normative) SCD SCD Control Control function function templates templates behaviour behaviour 8686 Annex
Foreword
Foreword
The NORSOK standards are developed by the Norwegian petroleum industry to
The NORSOK standards are developed by the Norwegian petroleum industry to ensure adequate safety,ensure adequate safety, value adding and cost
value adding and cost effectiveness for petroleum industry effectiveness for petroleum industry developmendevelopments and ts and operations. Furthermore,operations. Furthermore, NORSOK standards are as far
NORSOK standards are as far as possible intended to replace oil as possible intended to replace oil company specifications and serve ascompany specifications and serve as references in the
references in the authorities’ regulations.authorities’ regulations.
The NORSOK standards are normally based on recognised international standards, adding the provisions The NORSOK standards are normally based on recognised international standards, adding the provisions deemed necessary to fill the
deemed necessary to fill the broad needs of the Norwegian petroleum industry. Where relevant, NORSOKbroad needs of the Norwegian petroleum industry. Where relevant, NORSOK standards will be used to
standards will be used to provide the Norwegian industry input to provide the Norwegian industry input to the international standardisatiothe international standardisation process.n process. Subject to development and publication of international standards, the relevant NORSOK standard will be Subject to development and publication of international standards, the relevant NORSOK standard will be withdrawn.
withdrawn.
The NORSOK standards are
The NORSOK standards are developed according to the developed according to the consensus principle generally applicable standardsconsensus principle generally applicable standards work and according to established procedures defined in NORSOK A-001.
work and according to established procedures defined in NORSOK A-001. The NORSOK standards are prepared and published with support by
The NORSOK standards are prepared and published with support by The Norwegian Oil IndustryThe Norwegian Oil Industry Association (OLF) and Federation of Norwegian Manufacturing Industries (TBL).
Association (OLF) and Federation of Norwegian Manufacturing Industries (TBL). NORSOK standards are administered and
NORSOK standards are administered and published by Standards Norway.published by Standards Norway. Annex A, B, D and F is
Annex A, B, D and F is normative. Annex C, E and G are informative.normative. Annex C, E and G are informative.
Introduction
Introduction
The success of a
The success of a plant development project depends on good and efficient means of communicationplant development project depends on good and efficient means of communication between the involved parties, during all phases of
between the involved parties, during all phases of the project.the project. Present extensive use of computerised systems and 3D
Present extensive use of computerised systems and 3D modeling provide efficient tools for specifying andmodeling provide efficient tools for specifying and handling of physical equipment in a standardised manner. However, the development of methods and tools handling of physical equipment in a standardised manner. However, the development of methods and tools to specify functional relationships has not reached a
to specify functional relationships has not reached a corresponding level.corresponding level. During the plant development the process engineers specify the process
During the plant development the process engineers specify the process through the development of thethrough the development of the P&IDs. Throughout this work
P&IDs. Throughout this work process the process engineers acquire a thorough understanding of the totalprocess the process engineers acquire a thorough understanding of the total plant behavior. However, the P&IDs provide limited facilities
plant behavior. However, the P&IDs provide limited facilities for documentation of the overall functionality asfor documentation of the overall functionality as well as operational aspects of the
well as operational aspects of the plant.plant.
It’s the control system engineer's task to design the control system so as
It’s the control system engineer's task to design the control system so as to fulfill the process functionalityto fulfill the process functionality required to achieve product specifications as well
required to achieve product specifications as well as the requirements imposed by the overall as the requirements imposed by the overall operating &operating & control philosophy and manning levels. To conserve the functional relationships implicitly specified by the control philosophy and manning levels. To conserve the functional relationships implicitly specified by the P&IDs, the control system
P&IDs, the control system engineers have to transform the process engineers imagination of plant behavior engineers have to transform the process engineers imagination of plant behavior into the control
into the control system design and implementation.system design and implementation.
The operator's evaluation of the operational efficiency of the plant
The operator's evaluation of the operational efficiency of the plant is a difficult is a difficult task without any proper task without any proper documentatio
documentation of n of the overall control the overall control and monitoring functions available. Often, operational problems withinand monitoring functions available. Often, operational problems within the different systems can not
the different systems can not be identified until the system is be identified until the system is in operation, leading to major modifications inin operation, leading to major modifications in late project phases in the worst case.
late project phases in the worst case.
The logic and arithmetic functions available for implementing the required control system
The logic and arithmetic functions available for implementing the required control system functionality arefunctionality are accurate, but vendor specific. In-depth system k
accurate, but vendor specific. In-depth system k nowledge is required to understand both the availablenowledge is required to understand both the available functions as well as
functions as well as their interconnections. There is no intuitive link their interconnections. There is no intuitive link between the control system functionsbetween the control system functions and their interconnections, and the process flow itself.
and their interconnections, and the process flow itself. The interactions between the process and the controlThe interactions between the process and the control functions are identified through single tags only.
functions are identified through single tags only. Due to the missing
Due to the missing link between the functions implemented in the control system link between the functions implemented in the control system and the P&IDs defining theand the P&IDs defining the process flow, the process engineer’s possibility to verify that all process aspects have been properly catered process flow, the process engineer’s possibility to verify that all process aspects have been properly catered
The SCD Approach has been introduced in order
The SCD Approach has been introduced in order to eliminate this missing link. to eliminate this missing link. The SCD ApproachThe SCD Approach represents a structured methodology based on the development of the System
1
Scope
1
Scope
This standard is intended to cover functional as well as drawing related requirements for use of System This standard is intended to cover functional as well as drawing related requirements for use of System Control Diagrams.
Control Diagrams.
The standard will also establish a
The standard will also establish a general framework for implementation of the SCD Approach in general framework for implementation of the SCD Approach in terms of terms of Project Execution Guidelines and Application Guidelines. The Project
Project Execution Guidelines and Application Guidelines. The Project Execution Guidelines defines aExecution Guidelines defines a strategy for project execution and is
strategy for project execution and is intended for project responsible engineers. The Application Guidelineintended for project responsible engineers. The Application Guideliness provides a basis for
provides a basis for application design and is intended for application engineers responsible for developingapplication design and is intended for application engineers responsible for developing SCDs.
SCDs.
The Readers Manual will contain a simplified introduction for
The Readers Manual will contain a simplified introduction for engineers and operators using SCDs for engineers and operators using SCDs for verification and documentation of control functionality.
verification and documentation of control functionality. The Functional Standard as well as the
The Functional Standard as well as the Drawing Standard shall be considered normative, while the other Drawing Standard shall be considered normative, while the other documents are informative only.
documents are informative only.
2
2
Normative
Normative references
references
The following standards include provisions and guidelines which, through reference in this
The following standards include provisions and guidelines which, through reference in this text, constitutetext, constitute provisions and guidelines of this NORSOK standard. Latest issue
provisions and guidelines of this NORSOK standard. Latest issue of the references shall be of the references shall be used unlessused unless otherwise agreed. Other recognized standards may be used provided it
otherwise agreed. Other recognized standards may be used provided it can be shown that they can be shown that they meet or meet or exceed the requirements and guidelines of the standards referenced below.
exceed the requirements and guidelines of the standards referenced below. NORSOK
NORSOK I-002 I-002 Safety Safety and and Automation Automation Systems Systems (SAS)(SAS) NORSOK
NORSOK L-003 L-003 Piping Piping detailsdetails NORSOK
NORSOK Z-002 Z-002 Code Code ManualManual NORSOK
NORSOK Z-004 Z-004 CAD CAD Symbol Symbol LibrariesLibraries IEC
IEC 61131-1 61131-1 Programmable Programmable controllers controllers - - Part Part 1: 1: General General informationinformation IEC
IEC 61131-3 61131-3 Programmable Programmable controllers controllers - - Part Part 3: 3: Programming Programming languageslanguages ISO 3511 (all parts)
ISO 3511 (all parts) Process measurement control functions and instrumentation - SymbolicProcess measurement control functions and instrumentation - Symbolic representation
representation NS
NS 1710 1710 Technical Technical drawings drawings – – Drawing Drawing symbols symbols for for piping piping systemssystems NS 1438
NS 1438 Process measurement control functions and Process measurement control functions and instrumentation – Symbolicinstrumentation – Symbolic representation – Part 1: Basic
representation – Part 1: Basic requirementsrequirements
3
3
Definitions
Definitions and
and abbreviations
abbreviations
3.1
Definitions
3.1
Definitions
3.1.2 3.1.2 shall shallverbal form used to indicate requirements strictly to be followed in order to conform to the standard and from verbal form used to indicate requirements strictly to be followed in order to conform to the standard and from which no deviation is permitted, unless accepted by
which no deviation is permitted, unless accepted by all involved partiesall involved parties 3.1.3
3.1.3 should should
verbal form used to
verbal form used to indicate that among several possibilities one is recommended as particularly suitable,indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excludin
without mentioning or excluding others, or that a g others, or that a certain course of action is preferred but not necessarilycertain course of action is preferred but not necessarily required required 3.1.4 3.1.4 may may
verbal form used to indicate a course of action permissible within the limits of the
verbal form used to indicate a course of action permissible within the limits of the standardstandard 3.1.5
3.1.5 can can
verbal form used for
3.2
3.2
Function
Function definitions
definitions
All definitions are based on positive logic;
All definitions are based on positive logic; defined state is true defined state is true when logical equal to "1".when logical equal to "1". Definition
Definition ExplanationExplanation Alarm
Alarm
Alarm categories Alarm categories
Discrete change of state r
Discrete change of state resulting in an audio/visual annunciationesulting in an audio/visual annunciation requiring operator
requiring operator acknowledges.acknowledges.
The following categories are defined, not reflecting priority or The following categories are defined, not reflecting priority or criticality of the alarm:
criticality of the alarm: Action alarm:
Action alarm: Alarm feature including blocking facilities Alarm feature including blocking facilities intendedintended for automatic safeguarding actions in order to protect
for automatic safeguarding actions in order to protect equipment,equipment, environment or human beings.
environment or human beings. Warning alarm
Warning alarm: Alarm without blocking facilities intended for : Alarm without blocking facilities intended for abnormal conditions enabling operator intervention in order to abnormal conditions enabling operator intervention in order to prevent further escalation.
prevent further escalation. Fault alarm
Fault alarm: Alarm associated to fault or failure in the instrument: Alarm associated to fault or failure in the instrument and/or control device.
and/or control device. Alarm
Alarm filtering filtering Alarms determined Alarms determined by by additional additional processing processing to to be be less less important,important, irrelevant or otherwise unnecessary are not
irrelevant or otherwise unnecessary are not presented to thepresented to the operator, but can be accessed upon r
operator, but can be accessed upon r equest.equest. Alarm
Alarm hysteresis hysteresis The The degree degree of of normalization normalization required required to to reset reset an an active active alarm alarm state,state, measured from the alarm activation limit. Normally
measured from the alarm activation limit. Normally expressed inexpressed in terms of a fraction (%)
terms of a fraction (%) of the operating range.of the operating range. Alarm
Alarm suppression suppression Disable Disable alarm alarm annunciation annunciation as as well well as as any any associated associated automaticautomatic actions.
actions. Blocking
Blocking Disable Disable of of a a safeguarding safeguarding action, action, but but allowing allowing associated associated alarmalarm annunciation as well as manual / automatic control.
annunciation as well as manual / automatic control. Blocking appliesBlocking applies to both individual action alarms and input signals effecting
to both individual action alarms and input signals effecting safeguarding and disables functions.
safeguarding and disables functions. Commands
Commands Manipulation Manipulation affecting affecting the the mode mode of of the the function function template.template. The following commands are defined:
The following commands are defined: Set
Set: Memory variable set to true state on being true.: Memory variable set to true state on being true. Reset
Reset: Memory variable reset to false state on being true. Reset: Memory variable reset to false state on being true. Reset shall have priority over set.
shall have priority over set. Force:
Force: Action overruling any other signal while being true. TheAction overruling any other signal while being true. The mode is reset to its original state when signal is no longer true. mode is reset to its original state when signal is no longer true. Lock:
Lock: Action overruling any other signal while being true. Action overruling any other signal while being true. TheThe new mode is maintained when lock signal is
new mode is maintained when lock signal is no longer true.no longer true. Control
Control option option Pre-defined Pre-defined properties properties of of the the function function template template defined defined during during thethe configuration of the system reflecting the specific
configuration of the system reflecting the specific controlcontrol requirements.
requirements. Deviation
Deviation warning warning State State calculated calculated in in a a modulating modulating controller controller by by subtracting subtracting thethe measured value from the set point value. A warning will be measured value from the set point value. A warning will be announced if deviation is outside working area.
announced if deviation is outside working area. Disabled
Disabled mode mode Function Function not not available available for for external external control control commandscommands Dynamic
Dynamic information information Information Information displayed displayed on on the the VDUs VDUs reflecting reflecting the the state state of of the the processprocess or system. The following dynamic information elements are defined: or system. The following dynamic information elements are defined:
Alarm:
Alarm: Discrete change of data resulting in an audio / visualDiscrete change of data resulting in an audio / visual annunciation in the control room, requiring operator annunciation in the control room, requiring operator acknowledge
acknowledgement as well as ment as well as input to alarm list.input to alarm list. Event:
Event: Discrete change of state resulting in a displayed status inDiscrete change of state resulting in a displayed status in the control room as well as input to the event list.
the control room as well as input to the event list. Status:
Status: Binary state.Binary state. Indication:
Indication: Continuos display of information.Continuos display of information. Enabled
Enabled mode mode Function Function available available for for external/remote external/remote control control commands.commands. Flow
Flow element element Device Device used used to to control/ control/ shut shut down down or or manipulatemanipulates s a a flow flow of of fluid fluid or or electric energy, ex. Valve, pump. Where the flow device only has two electric energy, ex. Valve, pump. Where the flow device only has two positions, it is referred to as a
valve -
valve - Open/Close.Open/Close. High position:
High position: No flow restrictionNo flow restriction Low position:Low position: No flowNo flow Function
Function template template Function Function assembly assembly detailed detailed requirements requirements for for operation operation and and control.control. Limit
Limit switch switch Device Device connected connected to to the the actuator actuator or or valve valve providing providing a a positive positive signalsignal when the valve reaches a
when the valve reaches a pre-established position.pre-established position. MCC
MCC Motor Motor Control Control Center Center (electrical (electrical protection protection relay relay assembly)assembly) Mode
Mode State State of of operation operation selected selected by by the the operator operator or or resulting resulting from from anan external event
external event
The following operation modes are
The following operation modes are defined:defined: Auto:
Auto: Operation of process objects Operation of process objects automatically performed byautomatically performed by the control logic.
the control logic. Outside:
Outside: Flow element operated from a field device. I.e. Flow element operated from a field device. I.e. locallocal panel.
panel. Manual:
Manual: Flow element manually controlled by the operator fromFlow element manually controlled by the operator from the CCR.
the CCR.
Duty/ Standby:
Duty/ Standby: Intended for automatic supervision of flowIntended for automatic supervision of flow element operating in parallel to increase the system availability. element operating in parallel to increase the system availability. One flow element will be assigned duty (priority 1) and will thus One flow element will be assigned duty (priority 1) and will thus normally be in operation. The other is
normally be in operation. The other is assigned standby (priorityassigned standby (priority 2) and will automatically be put in operation if duty fails. All flow 2) and will automatically be put in operation if duty fails. All flow elements will have to be
elements will have to be selected auto to obtain automaticselected auto to obtain automatic duty/standby function.
duty/standby function. Blocked:
Blocked: Alarm status signals from process Alarm status signals from process variable limitvariable limit checking are blocked within
checking are blocked within the function, giving annunciation, butthe function, giving annunciation, but not allowing all r
not allowing all r elated automatic safeguarding actions.elated automatic safeguarding actions. Associated safeguarding function disabled. Related alarm Associated safeguarding function disabled. Related alarm annunciatio
annunciation not disabled (i.e. no n not disabled (i.e. no external signal outputs areexternal signal outputs are blocked).
blocked). Suppress:
Suppress: The intention of suppress is to disable the faulty stateThe intention of suppress is to disable the faulty state of an object. For input objects like MA and MB templates it of an object. For input objects like MA and MB templates it disables
fault-disables fault- and abnormaand abnormal state alarm annuncil state alarm annunciation as well asation as well as related safeguarding actions. For output objects like SBE and related safeguarding actions. For output objects like SBE and SBV templates suppress disables fault alarm annunciation and SBV templates suppress disables fault alarm annunciation and feedback conflict.
feedback conflict.
Internal set point mode:
Internal set point mode: Sub- mode to auto mode used for PIDSub- mode to auto mode used for PID controllers. The set point to
controllers. The set point to be entered by the operator.be entered by the operator. External set point mode:
External set point mode: Sub-Sub- mode to mode to auto mode auto mode used for Pused for PIDID controllers. The set point to be entered from external functions in controllers. The set point to be entered from external functions in the control logic. Typically use in
the control logic. Typically use in cascading PID controllers.cascading PID controllers. Track:
Track: To follow another signal. I.e. "set-point" tracking etc.To follow another signal. I.e. "set-point" tracking etc. Safeguarding:
Safeguarding: Flow device is in safe state. The term safe isFlow device is in safe state. The term safe is related to the protection of equipment, environment and human related to the protection of equipment, environment and human beings.
beings. Disabled:
Disabled: Function not available for Function not available for external control commands.external control commands. Safeguarding commands will not be affected in disabled mode. Safeguarding commands will not be affected in disabled mode. Override
Override Override Override function function intended intended to to set set the the output output signal signal to to predefinedpredefined state, independent of changes in logic states. Normally
state, independent of changes in logic states. Normally used inused in connection with mimic/matrix panels for test
connection with mimic/matrix panels for test purpose.purpose. Position
Position Actual position:Actual position: The feedback-position of a flow element,The feedback-position of a flow element, independ
independent of the ent of the state of the control state of the control output.output. Confirmed position
Confirmed position: Compared actual position and control: Compared actual position and control output. True if no mismatch and false if there is a mismatch. output. True if no mismatch and false if there is a mismatch. Process
Process A sequence A sequence of of chemical, chemical, physical, physical, or or biological biological activities activities for for thethe conversion, transport, or storage of
conversion, transport, or storage of material or energy.material or energy. Shutdown
Shutdown Signal Signal to to set set an an element element to to safeguardisafeguarding ng mode.mode. Shutdown level
3.3
Abbreviations
3.3
Abbreviations
API
API American American Petroleum Petroleum InstituteInstitute C&E
C&E Cause Cause & & EffectEffect CCR
CCR Central Central Control Control RoomRoom ESD
ESD Emergency Emergency Shutdown Shutdown SystemSystem F&G
F&G Fire Fire & & GasGas HIPPS
HIPPS High High Integrity Integrity Pressure Pressure Protection Protection SystemSystem HMI
HMI Human Human Machine Machine InterfaceInterface HVAC
HVAC Heating, Heating, Ventilation Ventilation and and Air Air ConditionCondition MCC
MCC Motor Motor Control Control Center Center NPD
NPD Norwegian Norwegian Petroleum Petroleum DirectorateDirectorate P&ID
P&ID Piping Piping & & Instrument Instrument DiagramDiagram PCS
PCS Process Process Control Control SystemSystem PSD
PSD Process Process Shutdown Shutdown SystemSystem SAS
SAS Safety Safety and and Automation Automation SystemSystem SCD
SCD System System Control Control DiagramDiagram VDU
VDU Visual Visual Display Display UnitUnit
4
4
The
The SCD
SCD approach
approach
4.1
4.1
Conceptual
Conceptual definition
definition
The SCD concept returns to the basis of the P&ID,
The SCD concept returns to the basis of the P&ID, the process schematic. Information not required for thethe process schematic. Information not required for the design of the control system is removed. The SCD shall focus on representing systems and functional design of the control system is removed. The SCD shall focus on representing systems and functional relationships, not individual physical
relationships, not individual physical equipmenequipment.t. The SCD
The SCD combines all functional design requirements into combines all functional design requirements into a common unambiguous document anda common unambiguous document and represents a top-down approach to the
represents a top-down approach to the design of the system.design of the system. The process schematic includes a simplified representation of
The process schematic includes a simplified representation of process lines and equipment. Instrumentationprocess lines and equipment. Instrumentation & control objects are
& control objects are represented by simplified symbols only.represented by simplified symbols only. The automation functions are represented by a limited number of
The automation functions are represented by a limited number of high-level function templates. Eachhigh-level function templates. Each template represents a specific control philosophy selected for
template represents a specific control philosophy selected for a class of a class of objects. The control philosophy isobjects. The control philosophy is defined/limited by a general range of attributes made available for the
defined/limited by a general range of attributes made available for the specific application. The applicationspecific application. The application level is defined by using
level is defined by using the applicable attributes.the applicable attributes. Complex control and interlocking str
Complex control and interlocking str ategies are developed by ategies are developed by inter-connecting templateinter-connecting templates. Additional logics. Additional logic and arithmetic functions may be used.
and arithmetic functions may be used. A functional description of the process
A functional description of the process objectives should follow the SCD.objectives should follow the SCD. The SCD function templates are vendor indepen
The SCD function templates are vendor independent, thus a set of SCDs dent, thus a set of SCDs may serve as a functional SASmay serve as a functional SAS specification, even before the system vendor is
specification, even before the system vendor is selected. The vendor on his selected. The vendor on his side has an unambiguous basisside has an unambiguous basis for system bid and
for system bid and eventually implemeneventually implementation. Functional monitoring and control solutions may be reusedtation. Functional monitoring and control solutions may be reused from one plant development to the other, even if
from one plant development to the other, even if different control systems are used different control systems are used to implement theto implement the functions.
functions.
Because the SCDs can be
Because the SCDs can be developed in parallel with the P&IDs, developed in parallel with the P&IDs, introduction of the SCD approach facilitateintroduction of the SCD approach facilitate a parallel development of both
a parallel development of both the physical and functional the physical and functional relationships visualised on dedicated documents.relationships visualised on dedicated documents. The approach encourage team work between different disciplines during the process development phases The approach encourage team work between different disciplines during the process development phases and the traditional artificial split between the development of physical and
and the traditional artificial split between the development of physical and functional relationshipfunctional relationships may bes may be eliminated. Thus enhanced overall quality is
eliminated. Thus enhanced overall quality is achievable.achievable.
4.2
Framework
4.2
Framework
The SCD standard represents an open
The SCD standard represents an open standard in terms of standard in terms of operation & control philosophy. The standard isoperation & control philosophy. The standard is based on a basic core
based on a basic core made up by function elements and terminology. The function elements are further made up by function elements and terminology. The function elements are further combined into functional templates. These templates represent a level of standardisation intended for the combined into functional templates. These templates represent a level of standardisation intended for the system application design. Templates may be adapted and combined differently in order to r
system application design. Templates may be adapted and combined differently in order to r epresent variousepresent various control strategies.
The standard is neither based on nor limited to any specific control system. A reduced number of attributes The standard is neither based on nor limited to any specific control system. A reduced number of attributes may thus be implemented in order to
may thus be implemented in order to accomplish an optimised implementatioaccomplish an optimised implementation for a n for a specific control system.specific control system. However, suppliers should consider an initial effort
However, suppliers should consider an initial effort in order to implement the complete range of in order to implement the complete range of attributes for attributes for the templates defined within this standard.
the templates defined within this standard.
The SCD approach has been developed with a view
The SCD approach has been developed with a view to industrial processes controlled by to industrial processes controlled by state-of-the-artstate-of-the-art process control systems, but as it
process control systems, but as it provides a general process oriented approach for developrovides a general process oriented approach for development of thepment of the documents, no field of
documents, no field of application are explicitly excluded. However, application are explicitly excluded. However, sequencingsequencing, global safeguarding, global safeguarding functions as well as fire & gas
functions as well as fire & gas functions are less suitable for the SCD representation as such. Please refer tofunctions are less suitable for the SCD representation as such. Please refer to the figure below.
the figure below.
Function Function Elements Elements F
Fununcctitioonn
Templates Templates SCD’s SCD’s S S e e q q u u e e n n c c e e s s C
C & & E E ’ ’ s s S
S a a f f e e t t y y
and and A A u u t t o o m m a a t t i i o o n n System System Figure 1 – SCD Framework Figure 1 – SCD Framework Typical applications proven suitable for the SCD
Typical applications proven suitable for the SCD representation are the following:representation are the following: •
• Control of process and utility systemsControl of process and utility systems •
• Process Shutdown applicationsProcess Shutdown applications •
• Package ControlPackage Control •
• HVACHVAC
A cause & effect representation will typically be used for fire &
A cause & effect representation will typically be used for fire & gas and emergency shutdown systems.gas and emergency shutdown systems. Cause & effects may
Cause & effects may additionally be used for high level PSD additionally be used for high level PSD levels in order to levels in order to provide a complementaryprovide a complementary overview. However, the SCD
overview. However, the SCD should be defined master to ensure system should be defined master to ensure system consistency.consistency. Sequence logic should be specified according to IEC
Sequence logic should be specified according to IEC 61131-3. The graphical languag61131-3. The graphical language - e - Sequential FunctionSequential Function Chart (SCF) should be used.
Chart (SCF) should be used.
4.3
4.3
Life
Life cycle
cycle concept
concept
The SCD standard is intended to cover the complete life cycle of a process plant. The SCD standard is intended to cover the complete life cycle of a process plant. The System Control Diagram, where used, will
The System Control Diagram, where used, will form the single source of form the single source of documentatiodocumentation for the n for the Safety andSafety and Automation System control and shutdown strategies for all life
Automation System control and shutdown strategies for all life cycle phases.cycle phases. • • EngineeringEngineering • • ImplementationImplementation • • CommissioningCommissioning • • OperationsOperations • • ModificationsModifications
standard is only intended to provide an overview of the standard as well as an initial starting point for standard is only intended to provide an overview of the standard as well as an initial starting point for inexperienced users.
inexperienced users.
4.4
4.4
Basic
Basic design
design (informative)
(informative)
The Basic System Design is closely related to the overall engineering strategy for the SAS System focusing The Basic System Design is closely related to the overall engineering strategy for the SAS System focusing on the following main design activities:
on the following main design activities: •
• Basic System DesignBasic System Design •
• Basic Function DesignBasic Function Design •
• Basic Application DesignBasic Application Design
Please refer to the figure below for an introductory overview. Please refer to the figure below for an introductory overview.
Regulations (NPD, API, PES)
Regulations (NPD, API, PES)
OP. & Contr. Philosophy
OP. & Contr. Philosophy
(Funct. Distr. Diagram, SAS Topology)
(Funct. Distr. Diagram, SAS Topology)
(SCD Legend)
(SCD Legend)
(SCD Typicals)
(SCD Typicals)
(SCD’s)
(SCD’s)
(C&E’s)
(C&E’s)
BASIC
BASIC
SYSTEM
SYSTEM
DESIGN
DESIGN
SCD Standard
SCD Standard
Vendor Standard
Vendor Standard
BASIC
BASIC
FUNCTION
FUNCTION
DESIGN
DESIGN
Instr., El., HVAC typicals
Instr., El., HVAC typicals
BASIC
BASIC
APPLICATION
APPLICATION
DESIGN
DESIGN
APPLICATION
APPLICATION
DESIGN
DESIGN
P&ID’s, D&ID’s etc
P&ID’s, D&ID’s etc
Figure 2 – Basic design Figure 2 – Basic design 4.4.1
4.4.1 Basic Basic system system designdesign
The Basic System Design is a general control system design activity, but is closely allied to t
The Basic System Design is a general control system design activity, but is closely allied to t he SCDhe SCD functional template developmen
functional template development. Based on t. Based on authority regulations as well authority regulations as well as company operational & controlas company operational & control philosophies the actual system distribution is developed. The system distribution defines the interface philosophies the actual system distribution is developed. The system distribution defines the interface between the different types of field
AREA AREA DISTRIBUTION DISTRIBUTION FUNCTIONAL FUNCTIONAL DISTRIBUTION DISTRIBUTION PLANT LAYOUT PLANT LAYOUT FUNCT. DISTR. FUNCT. DISTR. DIAGRAM DIAGRAM NPD SAFETY NPD SAFETY REGULATIONS REGULATIONS SAS TOPOLOGY SAS TOPOLOGY OP. & CONTROL
OP. & CONTROL PHILOSOPHIES PHILOSOPHIES
Figure 3 – Basic system design Figure 3 – Basic system design 4.4.2
4.4.2 Basic Basic function function designdesign
The Basic Function Design should be based on
The Basic Function Design should be based on a joint effort a joint effort between the involved parties in order to between the involved parties in order to achieveachieve an optimized use of the
an optimized use of the supplier standard functionality. Each functional element should be referred to thesupplier standard functionality. Each functional element should be referred to the corresponding supplier standard functions and combined into an optimal set of templates. It
corresponding supplier standard functions and combined into an optimal set of templates. It is important thatis important that the resulting templates are consistent with
the resulting templates are consistent with the general standard.the general standard.
FUNCTION FUNCTION TEMPLATES TEMPLATES (Level 2) (Level 2) FUNCTION ELEMENTS FUNCTION ELEMENTS (Level 1) (Level 1)
SUPPLIER SOFTWARE TYPICALS SUPPLIER SOFTWARE TYPICALS
SUPPLIER SUPPLIER STANDARDS STANDARDS
OP. & CONTROL OP. & CONTROL PHILOSOPHIES PHILOSOPHIES SCD STANDARD SCD STANDARD COMPANY/ SUPPLIER COMPANY/ SUPPLIER SCD MANUAL SCD MANUAL COMPANY/ SUPPLIER COMPANY/ SUPPLIER SCD MANUAL SCD MANUAL
Figure 4 – Basic function design Figure 4 – Basic function design
•
• Object typicalObject typical • • SCD applicationsSCD applications SCD SCD APPLICATIONS APPLICATIONS (Level 2) (Level 2) OBJECT TYPICALS OBJECT TYPICALS (Level 1) (Level 1)
P&ID, MCC, HVAC TYPICALS P&ID, MCC, HVAC TYPICALS
FUNCT. DISTR. FUNCT. DISTR. DIAGRAM DIAGRAM SCD SCD LEGEND LEGEND INSTRUMENT INSTRUMENT TYPICALS TYPICALS SCD TYPICALS SCD TYPICALS SCD TYPICALS SCD TYPICALS Figure 5 –
Figure 5 – Basic application design, application typicalBasic application design, application typical The purpose of the object typical is to reflect a typical
The purpose of the object typical is to reflect a typical signal interface for a specific control object as well assignal interface for a specific control object as well as the functional operator interface. The main objectives are listed
the functional operator interface. The main objectives are listed below.below. •
• Verify the completeness of the function templatesVerify the completeness of the function templates •
• Reduce the number of typical solutionsReduce the number of typical solutions •
• Improve the quality of the Improve the quality of the SCD DevelopmentSCD Development •
• Standardised solutionsStandardised solutions
OPERATOR OPERATOR CONTROL OPTIONS CONTROL OPTIONS (FUNCTION INTERFACE) (FUNCTION INTERFACE) OBJECT TYPICALS OBJECT TYPICALS (SIGNAL INTERFACE) (SIGNAL INTERFACE)
CONTROL OBJECT CATEGORY CONTROL OBJECT CATEGORY
Figure 6 – Object typical Figure 6 – Object typical
The purpose of the application typical is
The purpose of the application typical is to reflect comprehensive application in order to to reflect comprehensive application in order to reduce the number reduce the number of different solutions as well as verify the completeness of the object typical.
of different solutions as well as verify the completeness of the object typical. 4.4.4
4.4.4 Application Application designdesign
The SCDs should be jointly developed by the
The SCDs should be jointly developed by the System Disciplines, driven by user System Disciplines, driven by user requirements, not byrequirements, not by technology/discip
technology/discipline line organisation.organisation.
The SCDs should as far as possible be developed in parallel with the P&IDs. The application design may be The SCDs should as far as possible be developed in parallel with the P&IDs. The application design may be represented by means of a traditional water-fall model.
represented by means of a traditional water-fall model.
APPLICATION APPLICATION DESIGN DESIGN DETAIL DESIGN DETAIL DESIGN FUNCTIONAL FUNCTIONAL REQUIREMENTS REQUIREMENTS IMPLEMENTATION IMPLEMENTATION SCD’S SCD’S P&ID’S P&ID’S C&E’S C&E’S etc. etc. TYPICALS TYPICALS STRUCTURES STRUCTURES CONVENTIONS CONVENTIONS etc. etc. PROGRAMMING PROGRAMMING
Figure 7 – Object typical Figure 7 – Object typical Development of SCDs are made up of
Development of SCDs are made up of the following main steps:the following main steps: •
• Establish process schematic and identify all Establish process schematic and identify all control objects.control objects. •
• Describe the Process and Control Describe the Process and Control Objectives.Objectives. •
• Define applicable function templates.Define applicable function templates. •
• Develop basic interlocking strategies Develop basic interlocking strategies based on an based on an overall interlocking hierarchy/philosophy.overall interlocking hierarchy/philosophy. •
• Develop automatic control strategies. (e.g. Develop automatic control strategies. (e.g. package start/stop, duty/standby, sequencing)package start/stop, duty/standby, sequencing) •
Annex A
Annex A
(Normative)
(Normative)
SCD Function standard
SCD Function standard
A.1
Introduction
A.1
Introduction
This annex contains a collection of
This annex contains a collection of definitions, explanationdefinitions, explanations and descriptions of s and descriptions of function templates, the mainfunction templates, the main bricks for the
bricks for the SCD approach. It holds the SCD approach. It holds the legend of functional templates and their terminal names. Templateslegend of functional templates and their terminal names. Templates are normally implemented in the various control systems,
are normally implemented in the various control systems, employing special developeemploying special developed "Function Blocks" or d "Function Blocks" or by combining other properties built in the
by combining other properties built in the control system. This annex shall control system. This annex shall be considered to be normative.be considered to be normative. It is
It is permitted to reject terminals or permitted to reject terminals or introduce additional terminals on the templates to meet specialintroduce additional terminals on the templates to meet special requirements. However, the terminals that are included shall have
requirements. However, the terminals that are included shall have the same functionality as described in thisthe same functionality as described in this annex.
annex.
A.2
A.2
Terminal
Terminal codes
codes
A.2.1
Syntax
A.2.1
Syntax
A.2.1.1 Standard A.2.1.1 Standard
The general syntax for standard terminals is: The general syntax for standard terminals is: ( ) = Has to be used ( ) = Has to be used [ ] = [ ] = OptionalOptional
A.2.2
Overview
A.2.2
Overview
Each function has defined input and output signals. Input denoted with X
Each function has defined input and output signals. Input denoted with X is acting on the is acting on the output Y and/or onoutput Y and/or on operator presentation as described by the main function tag.
operator presentation as described by the main function tag. The template contains necessary monitoringThe template contains necessary monitoring functions to ensure that the most
functions to ensure that the most frequent faults regarding to the field frequent faults regarding to the field object are detected and reported.object are detected and reported. Each signal interconnecting two functions uses terminal codes for
Each signal interconnecting two functions uses terminal codes for identification.identification.
The codes are established from the following table. If numbers are used in the code, it shall always be The codes are established from the following table. If numbers are used in the code, it shall always be considered to be a modifier to the proceeding letter (letter + number = one code).
considered to be a modifier to the proceeding letter (letter + number = one code). Letter
Letter 1.Character 1.Character Succeeding charactersSucceeding characters A
A Action Action Alarm Alarm Auto Auto modemode B
B Binary Binary status status Blocked Blocked modemode
C Confirmed
C Confirmed
D
D Disabled Disabled transition transition modemode E
E Enabled Enabled statusstatus F
F Force Force command command Fault Fault / / FailedFailed
G Position
Letter
Letter 1.Character 1.Character Succeeding charactersSucceeding characters
H High
H High
I
I Internal Internal set set point point modemode J
J Not Not usedused
K
K Not Not usedused
L
L Lock Lock command command LowLow M
M Manual modeManual mode N
N Not Not usedused
O
O Outside modeOutside mode P
P Priority Priority allocationallocation
Q Quantity
Q Quantity
R
R Reset Reset command command Reference signalReference signal S
S Set Set command command Safeguarding Safeguarding modemode T
T Track Track modemode
U
U suppressed suppressed modemode V
V Variance Variance / / DeviationDeviation W
W Warning Warning alarm alarm Warning Warning alarmalarm X
X External External input input External set-point External set-point mode.mode.
Note: Together with B as 1.st character - X= external Note: Together with B as 1.st character - X= external
Y
Y Normal Normal functionfunction output
output
Not used Not used Z
Z Not Not usedused
# Number
# Number
%
% User User defined defined (to (to be be shown shown on on SCDs)SCDs)
Only positive logic shall be used. This implies that a defined state of terminal is true when it is
Only positive logic shall be used. This implies that a defined state of terminal is true when it is logical equallogical equal to ' 1 '.
to ' 1 '.
A.2.3
A.2.3
Signal
Signal types
types (1.Character
(1.Character))
A.2.3.1 Inputs A.2.3.1 Inputs X = External f
X = External function Inputunction Input A.2.3.2 Commands A.2.3.2 Commands S = Set S = Set R = Reset R = Reset F = Force F = Force L = Lock L = Lock A.2.3.3 Outputs A.2.3.3 Outputs Y = Normal
Y = Normal function output (Related to main function of element)function output (Related to main function of element) A = Action Alarm A = Action Alarm W = Warning alarm W = Warning alarm B = Binary status B = Binary status A.2.3.4
A.2.3.4 Special Special characterscharacters
% = User defined (To be shown on SCDs).
% = User defined (To be shown on SCDs). Could be used as 1.letter on a pin not in accordance with thisCould be used as 1.letter on a pin not in accordance with this standard. Note! Some SAS systems may
A.2.4
A.2.4
Explanatory
Explanatory code
code (Succeeding
(Succeeding characters
characters))
A.2.4.1 Modes A.2.4.1 Modes A = Auto mode A = Auto mode B = Blocked mode B = Blocked mode
D = Disabled transition mode D = Disabled transition mode I = Internal Set point mode I = Internal Set point mode M = Manual mode
M = Manual mode
O = Outside mode (Locally - Field - operated) O = Outside mode (Locally - Field - operated) S = Safeguarding mode S = Safeguarding mode T = Track mode T = Track mode U = Suppressed mode U = Suppressed mode X = External Set point mode X = External Set point mode A.2.4.2
A.2.4.2 Signal Signal identifiersidentifiers C = Confirmed C = Confirmed E = Enabled status E = Enabled status F = Fault/Failed F = Fault/Failed G = Position G = Position Q = Quantity Q = Quantity R = Reference R = Reference W = Warning W = Warning X = External X = External A.2.4.3
A.2.4.3 Sub Sub functionsfunctions H = High H = High HH = High High HH = High High L = Low L = Low LL = Low Low LL = Low Low V = Variance / deviation V = Variance / deviation
A.2.5
A.2.5
Terminal
Terminal description
description for
for function
function templates
templates
Index of normative terminal codes used in
Terminal Terminal Code Code
Signal Type
Signal Type Terminal NameTerminal Name Supplementary descriptionSupplementary description AHH
AHH binary binary output output Action Action alarm alarm High-High High-High True, True, when when X-value X-value >AHH >AHH limitlimit ALL
ALL binary binary output output Action Action alarm alarm Low-Low Low-Low True, True, when when X-value X-value <ALL <ALL limitlimit BA
BA binary binary output output Status Status auto/man. auto/man. mode mode True: True: auto auto , , false: false: manualmanual BB
BB binary binary output output Status Status blocked blocked mode mode The The function function is is in in blocked blocked mode mode (no (no actionaction output). I.e. all safeguarding signals are blocked output). I.e. all safeguarding signals are blocked BBHH
BBHH binary binary output output Action Action alarm alarm High-High High-High isis blocked
blocked BBLL
BBLL binary binary output output Action Action alarm alarm Low-Low Low-Low isis blocked
blocked BCH
BCH binary binary output output Output Output position position highhigh confirmed
confirmed
Output Y compared to feedback position high Output Y compared to feedback position high from MCC or limit switch and validated as true from MCC or limit switch and validated as true BCL
BCL binary binary output output Output Output position position lowlow confirmed
confirmed
Output Y compared to feedback position Low Output Y compared to feedback position Low from MCC or limit switch and validated as true from MCC or limit switch and validated as true BG analogue
BG analogue output output
Output
Output of of valve valve position position Position Position of of the the valve-for valve-for use use in in downstream downstream logiclogic BHH
BHH binary binary output output Status Status alarm alarm High-High High-High Status Status alarm alarm annunciation annunciation (HH) (HH) without without blockingblocking logic
logic BLL
BLL binary binary output output Status Status alarm alarm Low-Low Low-Low Status Status alarm alarm annunciation annunciation (LL) (LL) without without blockingblocking logic
logic BO
BO binary binary output output Status Status outside outside mode mode The The control control function function is is in in outside outside modemode BP1
BP1 integer integer output output Status Status priority priority 11 BP1F
BP1F binary binary output output Priority Priority 1 1 faulty faulty Start Start Priority Priority 2 2 (For (For Standby Standby logic)logic) BP2
BP2 integer integer output output Status Status priority priority 22 BP2F
BP2F binary binary output output Priority Priority 2 2 faulty faulty Start Start Priority Priority 3 3 (For (For Standby Standby logic)logic) BS
BS binary binary output output Status Status safeguardinsafeguarding g mode mode A A shutdown shutdown signal signal of of the the process process function function is is truetrue BT
BT binary binary output output Status Status tracking tracking mode mode In tracking In tracking mode mode as as long long as as signal signal is is true. true. Ex.Ex. Set point tracking.
Set point tracking. BU
BU binary binary output output Status Status suppressed suppressed mode mode Any Any process process output output function function is is suppressed. suppressed. NoNo action output and no
action output and no alarm annunciation.alarm annunciation. BX
BX binary binary outputoutput Status external modeStatus external mode or or function input
function input
True: extern and false: intern or
True: extern and false: intern or image of input.image of input. BXH
BXH binary binary output output Binary Binary status status High High True, True, when when X-value X-value > > High High limit.limit.
No Alarm annunciation, event only No Alarm annunciation, event only BXHH
BXHH binary binary output output Binary Binary status status High-High High-High True, True, when when X-value X-value > > High-High High-High limitlimit No Alarm annunciation, event only No Alarm annunciation, event only BXL
BXL binary binary output output Binary Binary status status Low Low True, True, when when X-value X-value < < Low Low limitlimit
No Alarm annunciation, event only No Alarm annunciation, event only BXLL
BXLL binary binary output output Binary Binary status status Low-Low Low-Low True, True, when when X-value X-value < < Low-Low Low-Low limitlimit No Alarm annunciation, event only No Alarm annunciation, event only FB
FB binary binary input input Force Force blocked blocked mode mode Logic input: Logic input: alarm alarm action action is is blocked blocked as as long long asas input signal is true.
input signal is true. FBHH
FBHH binary binary input input Force Force blocked blocked mode mode for for alarm High-High
alarm High-High
Logic input: alarm HH action is blocked as long Logic input: alarm HH action is blocked as long as input signal is true.
as input signal is true. FBLL
FBLL binary binary input input Force Force blocked blocked mode mode for for alarm Low-Low.
alarm Low-Low.
Logic input: alarm LL action is blocked as long as Logic input: alarm LL action is blocked as long as input signal is true
input signal is true FDH
FDH binary binary input input Force Force disable disable transitiontransition high.
high.
Permissive to start when f
Permissive to start when false and preventsalse and prevents element to be started when true.
element to be started when true. FDL
Terminal Terminal Code Code
Signal Type
Signal Type Terminal NameTerminal Name Supplementary descriptionSupplementary description FSH
FSH binary binary input input Force Force safeguarding safeguarding highhigh ShutdownShutdown – Signal overrules operator inputs– Signal overrules operator inputs (forcing the template Y-output high). After signal (forcing the template Y-output high). After signal returns to normal, template will react to actual returns to normal, template will react to actual terminal status again. Signal is subject to terminal status again. Signal is subject to blocking .
blocking . FSL
FSL binary binary input input Force Force safeguarding safeguarding lowlow ShutdownShutdown – Signal overrules operator inputs– Signal overrules operator inputs (forcing the template Y-output low). After
(forcing the template Y-output low). After signalsignal returns to normal, template will react to actual returns to normal, template will react to actual terminal status again. Signal is subject to terminal status again. Signal is subject to blocking.
blocking. FT
FT binary binary input input Force Force track track mode mode Track Track signal: signal: XT-valueXT-value FU
FU binary binary input input Force Force suppression suppression mode. mode. Logic Logic input: input: alarm alarm action action and and alarm alarm annunciationannunciation is suppressed as long as input signal is true. is suppressed as long as input signal is true. FUHH
FUHH binary binary input input Force Force suppression suppression mode mode for for alarm High-High.
alarm High-High.
Logic input: alarm HH action
Logic input: alarm HH action and annunciation isand annunciation is suppressed as long as input true.
suppressed as long as input true. FULL
FULL binary binary input input Force Force suppression suppression mode mode for for alarm Low-Low.
alarm Low-Low.
Logic input: alarm LL action and
Logic input: alarm LL action and annunciatioannunciation isn is suppressed as long as input tr
suppressed as long as input true.ue. FUWH
FUWH binary binary input input Force Force suppression suppression mode mode for for alarm WH
alarm WH
Logic input: alarm WH annunciation is Logic input: alarm WH annunciation is suppressed as long as input true.
suppressed as long as input true. This outputThis output should normally not be used for
should normally not be used for downstreamdownstream logic.
logic. FUWL
FUWL binary binary input input Force Force suppression suppression mode mode for for alarm WL
alarm WL
Logic input: alarm WL annunciation is Logic input: alarm WL annunciation is suppressed as long as input true.
suppressed as long as input true. This outputThis output should normally not be used for
should normally not be used for downstreamdownstream logic.
logic. LA
LA binary binary input input Lock Lock auto auto mode. mode. Locks Locks the the control control function function to to auto auto mode,mode,
overruling the operator. After signal disappears, overruling the operator. After signal disappears, template keeps in auto mode.
template keeps in auto mode. LI
LI binary binary input input Lock Lock internal internal set set pointpoint mode.
mode.
Locks the logic to
Locks the logic to internal mode, overruling theinternal mode, overruling the operator. After signal disappears the logic
operator. After signal disappears the logic keepskeeps in internal set point operation mode.
in internal set point operation mode. LM
LM binary binary input input Lock Lock manual manual mode. mode. Locks Locks the the logic logic to to manual manual mode, mode, overruling overruling thethe operator. After signal disappears the logic
operator. After signal disappears the logic keepskeeps in manual mode.
in manual mode. LO
LO binary binary input input Lock Lock outside outside operationoperation mode.
mode.
Locks the logic to
Locks the logic to outside system operationoutside system operation mode, overruling the operator. After signal mode, overruling the operator. After signal disappears the logic keeps in outside system disappears the logic keeps in outside system operation mode.
operation mode. LSH
LSH binary binary input input Lock Lock safeguarding safeguarding high.high. ShutdownShutdown - signal overrules operator inputs- signal overrules operator inputs (locking the template to manual mode with (locking the template to manual mode with Y-output to high -open valve-). Input is subject to output to high -open valve-). Input is subject to blocking .After signals disappear the template blocking .After signals disappear the template remains in manual mode and the output high. remains in manual mode and the output high. LSL
LSL binary binary input input Lock Lock safeguarding safeguarding low low .. ShutdownShutdown - signal overrules operator inputs- signal overrules operator inputs (locking the template to manual mode with (locking the template to manual mode with Y-output to low -stop motor-). Input is subject to output to low -stop motor-). Input is subject to blocking. After signals disappear the template blocking. After signals disappear the template remains in manual mode and the output low. remains in manual mode and the output low. LX
LX binary binary input input Lock external Lock external set set pointpoint mode.
mode.
Locks the logic function to
Locks the logic function to external mode,external mode, overruling the operator. After signal disappears overruling the operator. After signal disappears template keeps in external set point operation template keeps in external set point operation mode.
mode. PFCT
PFCT Float Float pointpoint value value
Factor used for calculation Factor used for calculation of flow
of flow
Factor compensating for design
Factor compensating for design temperature andtemperature and design pressure of the orifice.
Terminal Terminal Code Code
Signal Type
Signal Type Terminal NameTerminal Name Supplementary descriptionSupplementary description PKF
PKF Float Float pointpoint value value
K-factor used for K-factor used for calculations of flow. calculations of flow.
Measuring constant given by the pressure drop Measuring constant given by the pressure drop across the orifice plates.
across the orifice plates. PMOD
PMOD Integer Integer value value Define Define formula formula to to be be usedused for flow calculation.
for flow calculation. RX
RX binary binary input input Reset Reset latched latched outputoutput RXQ
RXQ binary binary input input Reset Reset external external totalizer totalizer Logic Logic signal signal to to resetreset SP1
SP1 binary binary input input Set Set priority priority 1 1 Set Set duty duty (prio.1) (prio.1) modemode SP2
SP2 binary binary input input Set Set priority priority 2 2 Set Set standby standby (prio.2) (prio.2) modemode WH
WH binary binary output output Warning Warning alarm alarm – – High. High. True, True, when when X-value X-value >WH >WH limitlimit WL
WL binary binary output output Warning Warning alarm alarm – – Low Low True, True, when when X-value X-value <WL <WL limitlimit WV
WV binary binary output output Warning Warning deviationdeviation X
X DI DI / / AI AI External External function function input input Binary Binary or or analogue analogue input input signal signal from from processprocess X1-X4
X1-X4 DI DI / / AI AI External External function function input input 1 1 to to 44 Binary Binary or or analogue analogue input input signal signal from from processprocess XE
XE binary binary inputinput Function eFunction exxternally enabledternally enabled ..
Electrical available used for electr. Equipm. only Electrical available used for electr. Equipm. only XEQ
XEQ binary binary input input External External enable enable totalizing totalizing Input to Input to logic logic enable/disaenable/disable ble totalizingtotalizing XF
XF binary binary input input External External fault fault Loop Loop failure-i.e. failure-i.e. input input card card broken.broken. XG
XG analogue analogue input input Position Position read read as as measuredmeasured value
value
Position read as measured value Position read as measured value
Logical deviations. Logical deviations. XGH
XGH binary input binary input Position Position high high feedback feedback Signal from Signal from MCC MCC (running) (running) or or limit limit switch switch high.high. XGL
XGL binary binary input input Position Position low low feedback feedback Signal Signal from from MCC MCC (stopped) (stopped) or or limit limit switch switch low.low. XOH
XOH binary binary inputinput (pulsed) (pulsed)
External
External outside outside set set high high From From process process to to control control element. element. I.e. I.e. valve/valve/ damper- in outside mode. Set high signal damper- in outside mode. Set high signal (positive edge) to open valve.
(positive edge) to open valve. XOL
XOL binary binary inputinput (pulsed) (pulsed)
External
External outside outside set set low low From From process process to to control control element. element. I.e. I.e. valve/valve/ damper in outside mode. Set low signal
damper in outside mode. Set low signal (positive(positive edge) to close valve.
edge) to close valve. XH
XH binary binary input input External External set set high high From From process process to to control control element. element. I.e. I.e. valve/valve/ damper- in auto mode. Set high signal ( damper- in auto mode. Set high signal ( openopen valve) only
valve) only XL
XL binary binary input input External External set set low low From From process process to to control control element. element. I.e. I.e. valve/valve/ damper in auto mode. Set low
damper in auto mode. Set low signal (closesignal (close valve) only
valve) only XP1H
XP1H binary binary inputinput (pulsed) (pulsed)
External p
External priority 1 riority 1 set highset high. . From logFrom logic or ic or process to process to control econtrol element. lement. I.e.I.e. motor- first priority in auto mode.
motor- first priority in auto mode. Set high signal (start motor) only Set high signal (start motor) only XP1L
XP1L binary binary inputinput (pulsed) (pulsed)
External
External priority priority 1 1 set set low low From From logic logic or or process process to to control control element. element. I.e.I.e. motor- first priority in auto mode.
motor- first priority in auto mode. Set low signal (stop motor) only Set low signal (stop motor) only XP2H
XP2H binary binary inputinput (pulsed) (pulsed)
External p
External priority 2 riority 2 set highset high. . From logFrom logic or ic or process to process to control econtrol element. lement. I.e.I.e. motor-second priority in auto
motor-second priority in auto mode.mode. Set high signal (start motor) only Set high signal (start motor) only XP2L
XP2L binary binary inputinput (pulsed) (pulsed)
External
External priority priority set set 1 1 low low From From logic logic or or process process to to control control element. element. I.e.I.e. motor- second priority in auto
motor- second priority in auto mode.mode. Set low signal (stop motor) only Set low signal (stop motor) only XR
XR analogue analogue input input External External set set point point value value Used in Used in external external – – auto auto – – modemode XT
XT analogue analogue input input Tracking Tracking value value Used in Used in tracking tracking modemode Y
Y (Y1, (Y1, Y2) Y2) binary binary output output Normal Normal function function output output Output Output status, status, which which can can be be used used inin downstream logic
downstream logic YF
(pulsed)
(pulsed) output output low. low. operated operated with with pulsed pulsed start/stop start/stop signalssignals
Terminal Terminal Code Code
Signal Type
Signal Type Terminal NameTerminal Name Supplementary descriptionSupplementary description YR analogue
YR analogue output output
Reference
Reference set set point point value. value. Set Set point point to to slave slave controller controller YX analogue
YX analogue output output
Measured value output Measured value output
A.3
A.3
Block
Block schematic
schematic representation
representation of
of functions
functions
For a precise
For a precise specification and better visualization of the control function behavior please refer specification and better visualization of the control function behavior please refer to Annex F.to Annex F. This Annex have been developed within a project performed by
This Annex have been developed within a project performed by Sintef electronics and Cybernetics onSintef electronics and Cybernetics on behave of the Norsok SCD
behave of the Norsok SCD committee where the objective have been to define the committee where the objective have been to define the behavior of the Norsokbehavior of the Norsok control functions in