functional safety and diagnostics - … integrity level sil 2 example . performace level pl d ....
TRANSCRIPT
FUNCTIONAL SAFETY AND DIAGNOSTICS Eric Ringholm
Example: Electro / hydraulic circuit diagram of a mobile machine
Hydraulics and Electronics belong together
Introduction Technology Trends
Input / Sensor
Processing / Logic
Output / Actuator
Mechanical eningeering
Electrical eningeering Software
Mecha- tronics
Functional Safety and Diagnostics
Murphy: “Whatever can go wrong will go wrong, and at the worst possible time, in the worst possible way.”
Functional Safety and Diagnostics
Correspondingly the legal and standards situation has reacted to this development
Functional Safety and Diagnostics
Hydraulic
Sensors Controllers
Visualization Software
System / Application
Increasing of functionality and productivity means for the system and the system components
higher complexity
- higher safety requirements - more diagnostics
Functional Safety and Diagnostics
IEC 61508 EN ISO 13849 ISO 26262 DO 178B / 254 ISO 25119
Relevant directives
Example Safety Integrity Level
SIL 2
Example Performace Level
PL d
Example Agricultural SIL
AgSIL 2
Example Automotive SIL
ASIL 2
Example Design Assurance Level
DAL 2
EN 15000
Functional Safety and Diagnostics
Standards, principles and implementation
The manufacturer confirms to comply with the following guidelines:
• Machinery Directive – 2006/42/EC • Noise Emission Standards – 2000/14/EC • Electromagnetic Compatibility Standards – 2004/108/EC
Machinery Directive 2006/42/EC All machinery that are put in circulation in the European Economic Union, have to satisfy the requirements of the Machinery Directive.
Some key principles: - The machinery has to be built in such a way that no
person is exposed to a hazard during Operation Mounting/Service Predictable misuse
- Principles for risk reduction Elimination or minimization of risks as far as possible Take protective measures against risks which cannot be
eliminated Information of users of remaining risks
- Controls need to be designed in such a way, that hazard situations are avoided, specifically considering: Predictable usage scenarios and external influences Defects in hardware or software Errors in logic Predictable misuse
Harmonized standards for Machinery Directive 2006/42/EC
Presumption of conformity: “Where products have been designed in accordance with suitable harmonized Standards, market surveillance authorities are obliged to assume that the essential requirements of the applicable directive(s) which are covered by these Standards have been fulfilled. The products are deemed to comply with the directives (presumption of conformity). “
EN ISO 13849 and other safety standards as a part of the machinery directive
Machinery Directive - 2006/42/EC
Extract from a technical article in ETZ (electro-technical magazine)
Risk for the manufacturer However, there is also a certain risk for the manufacturer: an accident which could have been avoided by following the EN ISO 13849-1, can turn into a problem for the manufacturer and the responsible persons involved. Essential for the clarification of liability is the state of technology which is no longer represented by EN 954-1 based on deterministic approaches or the choice of the control architecture, but by the broader defined EN 13849.
In contrast to the civil Compensation Laws, in criminal law, the injuring party is always called to account personally, a corporate liability is not possible in this case. As, in general, the managing director and the technical director are out of responsibility, the investigations are often directed against the design engineers. "In many cases, it is difficult to find the guilty party for an accident.” a prosecutor from Cologne said. “Often enough, there is sufficient suspicion of a criminal act – due to design faults or to non-conformity with the safety regulations.“ In civil right, it is very realistic that design engineers become personally liable. Still, the principle set up by the federal labour court applies that employees can only be made fully responsible in case of intentional act or gross negligence. Nevertheless, gross negligence, i.e. the ignorance of the most apparent things, is not very difficult to prove.
Extract from an article about liability in case of accidents caused by machines:
Excerpt from “Legal considerations in Product Liability”
Legal Environment and Terminology Current Standards: IEC 61508 und EN ISO 13849-1
IEC 61508 EN 954
EN 13849
Automotive Machinery Directive
2006/42/EC
IEC 62061 ISO 26262
Functional Safety of E/E/PES
Determinsim
„Safety of Machinery“
ISO 25119
Agricultural
Machinery Industry
Harmonized according to
Comparison ISO EN 13849-1 and IEC 62061
Typical Implementation of the Standards / Regulations
Standards, principles and implementation
Functional Safety and Diagnostics
Hazard and Risk analysis
H&R Analysis
Machine function
Functional Safety and Diagnostics
List of machine functions - Example -
Performance Level
Required risk minimisation and Performance Level: Severity of injury: S1 slight (usually reversible injury) S2 serious (usually irreversible injury which may include death) Frequency and / or duration of exposure to danger: F1 rarely up to not very frequently and / or the time of exposure to danger is short F2 frequently up to continuously and / or the time of exposure to danger is long Probability of avoiding the exposure [P] P1 possible under certain conditions P2 rarely possible
Basic structure of a component or a system
Input / Sensor
Processing / Logic
Output / Actuator
Designated Architectures for Categories B, 1 and 2:
Architecture of Category B and 1 Design with “basic safety level”
Architecture of Category 2 Design with “increased safety level”
Architecture of Category 3 Design with “increased safety level”
Architecture of Category 4 Design with “increased safety level”
Designated Architectures for Categories 3 and 4:
Classification of the MTTFd values according to standard:
Total period: 3 up to 100 years: 3 up to 10 years = low 10 up to 30 years = medium 30 up to 100 years = high
• MTTFd values exceeding 100 years will be considered
with max. 100 years in their safety calculation
MTTFd is a measure for the quality of the component
Typical values according to practical experience:
MTTFd HYDAC Electronic Products
Note: 1 Mio h = 114 years i. e, all MTTFd-Values are classified „high“
Characteristics Products HYDAC Electronic
Diagnostic Coverage Indicator of how many dangerous failures/ outages are detected
Out of all DCs of the single components, the DC avg for the controller is defined.
Outage rate: detected dangerous failures Outage rate: all dangerous failures
Regulations for the medium DC for the entire system by approximation formula:
Formula for DCavg in Standard according to fig. 28
Term Value range
Diagnostic Coverage
CCF - Common Cause Failures
Causes for outage
of channel 1
Causes for outage
of channel 2 CCF
CCF: breakdown of diverse parts due to common cause List of measures, table of points (maximum: 100 points in total) • dividing the signal paths 15 points • diversity 20 points • protection against over voltage/ overpressure 15 points • proven components 5 points • FMEA 5 points • Expertise/ training of developers 5 points • EMC or filtering of pressure fluid and protection against contamination 25 points • Temperature, humidity, shock, vibration, etc. 10 points Target: at least 65 points
In multi-channel controller structures starting from category 2, an observation of the CCF must be effected. This means, measures are to be taken so that both channels in a safety system can not break down due to a common cause.
For this purpose, there is a table of points in the EN 13849-1 standard.
Of 100 available points
at least 65 points shall be reached.
Safety related parts of machine controls
The achieved safety level is the result (balance) from the combination of the parameters:
Architecture Reliability of used components
Recognisability (diagnosibility) of safety relevant failures
Functional Safety and Diagnostics
Standards, principles and implementation
Summary characteristics
The achieved safety level (= PL) is the result of the combination of:
• Architecture (= category) • Quality of components (= MTTFd) • Capability to detect safety relevant failures (= DC) • For safety functions of category 2 or higher CCF need to be considered
PL column chart according to EN ISO 13849-1 illustrates the relationship between PL, MTTFd, category and DC
Example 1: Performance Level “PLr c” for a machine function is required
PL column chart according to EN ISO 13849-1 illustrates the relations between PL, MTTFd, category and DC
Example 1: Performance Level “PL c” for a machine function is required
PL column chart according to EN ISO 13849-1 illustrates the relations between PL, MTTFd, category and DC
design with
“increased safety level“
Example for an „increased safety hydraulic design“
Functional Safety and Diagnostics
Standards, principles and implementation
Sensors and Controllers for Applications with Increased
Functional Safety
Functional Safety and Diagnostics
Overview of control architectures (categories)
design for “normal safety level“
design with “increased safety level“
Achievable safety level
Costs
Functional Safety and Diagnostics
Standards, principles and implementation
Pressure transducer HDA 8000 Category 2 MTTFd: high (190 years)
DC: low (87%) Safety level: PL d, SIL 2
Pressure transducer HDA 4000 Category 3
MTTFd: high (976 years) DC: low (84%) Safety level: PL d
Position switch HLS 100 Category 2
MTTFd: high (419 years) DC: low (88%) Safety level: PL d, SIL 2
Linear position sensor HLT 1000 Category 2
MTTFd: high (83 years) DC: low (91%) Safety level: PL d, SIL 2
Valve position switch HLS 200 Category 2 MTTFD hoch / high (110 Jahre/ years) DC: medium (91%) Safety level: PL d
Sensors for pressure, position and distance
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Pressure transducer
Category 2
Category B/1
Category 3
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Category 2
Category B / 1
Standard version Standard version
Linear position sensor, magnetostrictive
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Function principle, standard version
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Functional principle of a magnetostrictive sensor - version with increased functional safety and diagnosis
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Functional principle of a magnetostrictive sensor - version with increased functional safety and diagnosis
Functional Safety and Diagnostics
Sensors with increased Functional Safety and Diagnostics
Characteristics for HY-TTC 90 with PLd, Excerpt from TUV certificate Architecture: Category 2
Category: 2 MTTFd: high
DC: low PL d
Safety & Availability
• EN ISO 13849 PL d & IEC 61508 SIL 2 TÜV certified
• ISO 25119 AgPL d certifiable • CODESYS Safety SIL 2 • CANOpen Safety • Separation of safety / non-
safety software • Output shut-off in groups
Connectivity • Up to 7 CAN interfaces • Automatic baudrate
detection • Configurable CAN
termination • Ethernet
Performance • Up to 32-bit 180MHz dual-
core lockstep • Floating-Point-Unit • Up to 2.3MB RAM / 11 MB
Flash
Robustness • Automotive style
aluminium housing for rough operating conditions
• Total current up to 60A
Flexibility and Usability
• Up to 96 I/Os with multiple configuration options • Open programming environments
i.e. C and CODESYS 3 SIL 2
Safety Controller Key Features
Usability
• Easy integration and usage • CANopen compliant • Auto-baudrate-detection • CAN termination configurable via connector pins
• Node-ID configuration via dedicated input pins
Robustness
• Automotive style aluminium housing for rough operating conditions • High maximum current
Safety
• EN ISO 13849 PL c certified • CANopen Safety
Flexibility
• Extensive I/O set with small form factor • 30 I/Os with multiple configuration options per pin
• 5 variants offer flexible building blocks
Safety I/O Module Key Features
Displays
Why Displays?
Rising demand for visualization, driven by automotive and consumer industry Used for Diagnostics User Manuals Configuration (Parameterization) Video cameras
Target Applications
Target Applications
Features: High CPU Performance Fast Boot Up Time Excellent Sunlight Readability Robust and Easy to Clean Touch Screen Flexible graphical developer interface
Displays Key Features
Pressure sensors Controller Displays
Linear position sensors Angle sensors Inclination sensors
IEC 61508 ISO 26262 ISO 25119 EN ISO 13849
Functional Safety
Summary Functional Safety and Diagnostics - Sensors, Controllers, Displays, Systems...