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Octogon develops and manufactures sensors specifically designed for use in systems with high functional safety requirements according to EN IEC 61508 (SIL) and EN ISO 13849-1 (PL). Our load pins, force transducers, and load cells achieve SIL 3 and/or PL e ratings.
SIL and PL compliant sensor technology
In industrial plants and machinery, the protection of people, machines, and the environment is the top priority. For safety-critical applications, reliable proof of the total system's failure safety is required. Sensors such as load pins, load cells and force transducers, as well as torque transducers are often the first and most important link in the safety chain.
The safety standards: An overview of SIL and PL
Depending on the industry and risk assessment, different standards apply that pursue the same goal: reducing the risk of a dangerous machine failure to an acceptable level.
- SIL (Safety Integrity Level), defined according to EN IEC 61508. Relevant for the process industry and complex electronic systems, categorized into levels SIL 1 to SIL 4.
- PL (Performance Level), defined according to EN ISO 13849-1. The standard in classic mechanical and plant engineering, categorized into levels PL a to PL e.
For demanding applications in lifting or stage technology, specifications like SIL 3 or PL e are now the industry standard. To meet these system requirements, the sensors used must possess corresponding architectures and reliability parameters. An overview of available designs can be found under load cells with SIL and PL classification and in the measuring electronics for safety-related applications.
Technical implementation: Redundancy and CCF prevention
A single-channel sensor cannot meet the highest safety levels by design. For safety-related applications, we therefore rely on consistent dual-channel 1oo2 architecture and measures to prevent Common Cause Failures (CCF).
True mechanical and electrical redundancy
The sensor's deformation body is equipped with two independent full-bridge strain gauges. Both measuring circuits record the same physical force but operate galvanically isolated. If one measuring circuit fails or provides implausible values, the higher-level safety system detects the discrepancy and initiates the safe state. The application of the strain gauges takes place in-house, as does the manufacturing of the measuring bodies.
Separate signal paths and connections
To prevent crosstalk and common failure causes, such as a single cable break that cuts off both signals, the internal wiring is routed physically separately. Connection is made via separate cable outlets or isolated multi-pin connectors.
Diagnostic capability and signal diversity
The safety of a control system depends on its ability to detect sensor errors. We support this diagnostic coverage through various signal configurations:
- Inverted analog signals. Channel A, for example, provides 4…20 mA, while channel B provides the inverse 20…4 mA. The sum of both values in the controller must always result in 24 mA; any deviation immediately indicates an error.
- Digital safety protocols. Fully integrated electronics with CANopen Safety or PROFIsafe, which cyclically monitor latency, data integrity, and message loss.
Documentation is part of the product
A redundant sensor is unusable for system certification without the appropriate statistical evidence. Functional safety requires seamless documentation.
We therefore support mechanical engineers and system integrators not only with hardware but also by providing the data for SISTEMA calculations or similar tools:
| Parameter | Significance for system certification |
|---|---|
| MTTF<sub>D</sub> | Mean Time To dangerous Failure, the average time until a dangerous failure of the sensor technology |
| B10<sub>D</sub> | For electromechanical components: Number of switching cycles until 10% of components fail dangerously |
| DC | Diagnostic Coverage, the diagnostic coverage of our integrated electronic components |
| FMEA | Failure Mode and Effects Analysis to evaluate potential design weaknesses |
Important for planning: These parameters describe the component. The safety level achieved by your safety function depends on your overall architecture, diagnostic measures, and downstream evaluation.
Typical areas of application
Safety-related sensors from Octogon are used wherever mechanical failure could endanger people or cause significant property damage:
- Lifting technology and crane construction: Overload protection and load moment limitation on mobile, tower, and overhead cranes
- Stage technology: Rope force monitoring over audience and performer areas
- Automated guided vehicles (AGVs) and robotics: Safe force and torque monitoring in human-robot collaboration
- Presses and forming technology: Securing clamping forces in heavy machinery
When no standard sensor fits
Safety-related applications often involve installation situations for which no catalog sensor exists. We design and manufacture custom force transducers with redundant architecture, develop the appropriate measuring electronics if required, and calibrate the measuring chain according to ISO 17025 in our own laboratory. If the task includes a complete test setup, we also handle test stand construction.
Safe machines begin with safe sensor technology.
Are you planning a system according to EN ISO 13849 or EN IEC 61508? Describe your safety function to us, and we will support you from sensor design to the provision of certification-relevant reliability data.