Overview of Safety Technology
What Is Industrial Safety Technology?
Safety technology in industry comprises technical systems, measures and procedures for the protection of persons, machines, systems and data. It is divided into industrial safety, i.e. the protection of employees against hazards caused by machines, and industrial security, which covers the protection of assets and data against attacks. The aim is to minimize risks and ensure the safe operation of the plants.
What Tasks Does Safety-Oriented Sensor Technology Perform?
Personal Protection and Hazard Zone Monitoring
Electro-sensitive protective equipment monitors working ranges and detects unauthorized intervention or entry of persons into hazardous machine movements. Intelligent diagnostic tools also detect and transmit faults at an early stage. Downtime can be avoided and system availability maximized.
Highly Efficient Logistics Solutions in Optimized Space
Safety light curtains in combination with pre-assembled muting sets enable safe material transport to protected plant areas without interrupting the material flow. This allows goods to be fed in and out at the same time, while ensuring personal protection at all times. The space-saving integration supports efficient use of space and increases material throughput.
Downtime Optimization
Automatic restart combines reliable personal protection with high system availability. As soon as the danger zone is cleared again, the safety light curtain automatically switches to safety operating mode and allows the machine to restart. This reduces downtime and supports efficient workflows. However, this function is only permitted under certain conditions.
Process Safety Through Position Monitoring and Locking of Movable Protective Devices
Guard locking devices allow the electromagnetic or electromechanical locking of security doors. They provide a door locking mechanism to protect workers from potential hazards from machine movements or hidden hazards. At the same time, unintentional intervention in the process can be avoided. Higher process safety therefore ensures that there is less downtime.
Secure Communication Between Man and Machine
Command devices, in combination with suitable safety relays, enable the safe control of machines and automated processes. This means that applications can be reliably set up, started, stopped or terminated with maximum personal protection.
What Makes Safety Sensors Different from Standard Sensors?
Safety sensors must be designed and used in such a way that no danger arises even in the event of a failure. The applicable standards and safety requirements must be taken into account. The safety outputs carry 24 V DC in normal operation. The safe state is the OFF state (0 V). Wire breaks or voltage failures therefore also automatically lead to a safe state.
This level meets the industry standard to ensure high immunity to interference, reliable signal security over long distances, and protection against faulty circuits and against people and equipment. This standard also enables easy interoperability of components from different manufacturers. For maximum safety, the safety functions are retained even in the event of a fault. Permanent comparison and read-back detects errors as early as possible.
Legal Basis
| Responsible | Central task | Legal basis | That is extremely important |
|---|---|---|---|
| Machine manufacturer | The machine must be designed and constructed in such a way that it can be operated, set up and maintained safely. Both the intended use and reasonably foreseeable misuse must be taken into account in this process. | Machinery directive/Machinery ordinance |
|
| Machine operators | Work equipment may only be used after hazards have been assessed, suitable state of the art protective measures have been implemented and safe use has been established. | Ordinance on industrial safety |
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How Is the Required Performance Level Determined?
Performance Levels (PLr)
The required performance level – PLr (Performance Level required) for short – is determined as part of the risk assessment. It defines the necessary reliability of the safety function and thus forms an essential basis for the selection and design of suitable protective devices.
The following risk parameters are taken into account in the assessment:
Severity of possible injury
Frequency and duration of exposure to danger
Possibility to avoid the hazard or limit the damage
Determination of the PLr for Machine Manufacturers
Safety Integrity Level (SIL)
The safety integrity level (SIL) describes the reliability of electrical, electronic and programmable safety-related systems. It indicates to what extent a safety function reduces the existing risk or how likely a dangerous failure is.
Classification takes place according to IEC 61508 or IEC 61511 in four stages – from SIL 1 to SIL 4. SIL 1 stands for the lowest and SIL 4 for the highest required risk reduction.
SIL is used in particular in the process industry as well as in complex process and process engineering systems. In some international markets, functional safety requirements are also often specified using SIL instead of the performance level (PL) or required performance level (PLr) commonly used in the machine industry.
How Does wenglor Determine the PL?
The PL of a sensor is determined based on its safety-relevant architecture and reliability parameters. The following factors are taken into account:
Mean time to dangerous failure of the component used.
Secure Communication and Signal Processing
Why Is Secure Communication in Machine Safety Necessary?
A safety light curtain detects when a person enters a hazard zone. However, the safety function only becomes effective when the signal is reliably transmitted to the safe machine control system, correctly evaluated there and the intended protective reaction – for example the safe stop of the machine – is triggered.
Secure communication does not always prevent every error, but ensures that communication and system errors are detected and controlled in good time. This includes line interruptions, short circuits, corrupted or lost data telegrams, device failures and impermissible delays in signal transmission. If such a fault is detected, the safety system must bring the machine to a safe state within the specified response time.
Qu’est-ce qu’une sortie OSSD et comment fonctionne-t-elle ?
Les sorties OSSD, également appelées sorties de sécurité, sont les sorties d’un équipement de protection agissant sans contact qui sont connectées à la commande de la machine. Ils transmettent l’état actuel de la protection à un contrôleur de sécurité ou à un relais de sécurité.
Si le champ de protection est libre, les sorties OSSD sont à l’état MARCHE. Si le champ de protection est interrompu ou si une erreur liée à la sécurité est détectée, ils passent à l’état ARRÊT. La commande raccordée déclenche alors la réaction de protection prévue et arrête la machine en toute sécurité, par exemple.
Pour une transmission fiable du signal, les capteurs de sécurité disposent de deux canaux OSSD surveillés séparément. Le contrôle de l’état du signal ainsi que de la concordance est effectué par l’unité de traitement. De courtes impulsions de test permettent en outre de diagnostiquer les chemins de signaux raccordés.
Ceci permet notamment de détecter les défauts suivants :
- Courts-circuits
- Court-circuits transversaux entre les canaux
- Coupures de câble
- États de commutation erronés ou contradictoires
双通道接线
在双通道接线中，安全信号以冗余方式传输至安全控制器。通过持续比较两个通道，可确保可靠识别偏差和单个故障，从而实现更高的性能等级。
反馈回路监控（EDM）
EDM 全称 External Device Monitoring，即外部设备监控，指对外部开关元件的监控。发出关断指令后，安全功能会检查所连接的接触器是否确实已释放。
由此可识别触点粘连或故障。若某个接触器未达到预期状态，系统将阻止机器重新启动。
级联有哪些优势？
级联是指将多个保护装置串联，以监控不同的防护区。由此，所有保护装置可共用一个安全输出端。级联后的保护装置对外表现为单个保护装置。这样便能以更少的接线工作量实现全面的保护方案，并灵活扩展。
优点
减少接线工作量
降低安装成本
减少安全控制器所需的输入端
灵活扩展安全系统
解决方案和重要术语
手指防护、手部防护和人体防护有何区别？
| 手指防护 |
|---|
| 分辨率最高可达 14 mm |
| 识别手指 |
| 安全距离非常短 |
| 应用场景例如：压力机、冲床、折弯自动化设备、半自动化手工工位 |
| 特点：安装得离危险点较近；得益于高分辨率，无需额外安全附加距离 |
| 手部防护 |
|---|
| 分辨率最高可达 30 mm |
| 识别手部 / 手臂 |
| 安全距离中等 |
| 应用场景例如：焊接机器人、托盘上料装置、开卷站 |
| 特点：相比手指防护，所需的最小安全距离更大 |
| 人体防护 |
|---|
| 分辨率为 300 至 500 mm |
| 识别人体 / 人员 |
| 安全距离大 |
| 应用场景例如：通道入口与危险区域，如机器人工作单元 |
| 特点：通常仅需少量光束 |
安全距离如何计算？
安全距离由以下公式得出：S = (K × T) + C
S = 安全距离
K = 接近速度
T = 系统总响应时间
C = 附加安全余量
垂直接近防护区的安全距离
安全光幕与多光束安全光栅的扩展功能
静默安全功能
静默期间，保护功能被有针对性地旁路。配套辅助功能可确保不会有人在未被察觉的情况下进入危险区域。
- 静默持续时间功能
- 输送带停止信号功能
- 静默启用功能
- 方向预设功能
- 部分静默
- 空隙抑制
- 超控功能
抑制功能
抑制功能可将防护区特定区域内的光束遮蔽。与静默不同，抑制功能下的旁路是持续性的。
- 固定抑制
- 带边缘容差的固定抑制
- 浮动抑制
安全光幕的“降低分辨率”功能是指什么？
安全光栅的降低分辨率功能，是指将物体识别的响应阈值调大。此时，光栅不再对每一束光的遮挡都进行评估，而是当规定数量的相邻光束同时被遮挡时，才触发安全功能。
由此，有效检测尺寸会增大，例如从 14 mm 增至 50 mm 或 90 mm。薄片类材料（如板材）可不受干扰地通过防护区，而较大的物体或人体部位仍能被可靠识别。
应用场景：
该功能适用于物料或工件需要穿过防护区、且不能中断生产流程的工况。只要在风险评估和计算所需安全距离时，将改变后的检测尺寸考虑在内，人员保护依然有效。
Dispositifs de protection séparateurs
Quelle est la différence entre la protection des processus et la protection des personnes dans les dispositifs de verrouillage de sécurité ?
Processus et protection des personnes
- Le dispositif de verrouillage est surveillé
- La porte reste verrouillée jusqu’à ce qu’il n’y ait plus de danger
- Convient aux machines présentant un risque d’inertie
Protection du process
- L’actionneur est surveillé
- Le verrouillage protège contre une ouverture involontaire
- Convient lorsqu’il n’y a pas de danger immédiat après l’arrêt
Codage des interrupteurs de sécurité et des dispositifs de verrouillage de sécurité
Un codage permet une affectation entre le capteur et l’actionneur correspondant. Un système codé constitue une protection simple contre les manipulations et le contournement.
| Type de codage | Affectation | Fonctionnement |
|---|---|---|
| Codage bas | Standard |
|
Codage haut | Individuel, reprogrammable |
|
Codage haut | Individuel |
|
Quelle est la différence entre le principe du courant de travail et le principe du courant de repos ?
Principe du courant de travail : verrouillage par l’énergie
Avec le principe du courant de travail, le verrouillage est activé par l’alimentation en courant de l’aimant de verrouillage. En l’absence de tension, la porte de protection est déverrouillée et peut être ouverte.
Commande magnétique 0 V : porte de protection déverrouillée
Commande magnétique 24 V : porte de protection fermée
Principe du courant de repos : Déverrouillage par énergie
Avec le principe du courant de repos, le dispositif de verrouillage est activé mécaniquement par la force du ressort. La porte de protection reste ainsi fermée même sans tension. Elle n’est déverrouillée que par l’alimentation en courant de l’aimant.
Commande magnétique 0 V : porte de protection fermée
Commande magnétique 24 V : porte de protection déverrouillée
N.B. : Pour la protection des personnes, des exigences normatives particulières doivent être respectées, voir DIN EN ISO 14119.
