3.2 Selecting the required safety type

Step 1: Perform risk assessment e.g. in accordance with EN ISO 12100-1

(Safety of machinery, risk analysis and risk assessment)

Step 2: Select type of optoelectronic protective device and protective function

Depends on:

• Specifications of regional or machine-specific regulations
  
  
• Geometric dimensions of the area to be protected
  
  
• The protective function to be performed (e.g. machine stop with hand or finger detection)
  
  
• Ergonomic factors (ease of operation, manual cyclical insertion of parts, yes/no)
  
  
• Accessibility of danger zones: process-conditional, maintenance-conditional
  
  
• Financial criteria

The suitable optoelectronic protective device must be selected on the basis of the above information (see table).

	Protective function	Application	Leuze electronic products
	Example video Machine stop with hand or finger detection Example video With control function for restarting machines	With small operator distance to the danger zone, e.g. with feeding-in work at a press	Safety Light Curtains, Safety Laser Scanners (-E model)
	Example video Machine stop with detection of person accessing the danger zone	With accessible danger zones and bigger distance to the danger zone	Single Light Beam Safety Devices, Multiple Light Beam Safety Devices, Safety Laser Scanners (-E model), Safety Switches and Safety Locking Devices (in combination with guards)
	Example video Machine stop with detection of person accessing the danger zone and prevention of the restart with constant presence detection Example video Combined detection of access and presence	Safeguarding danger zone at (accessible) feeding-in areas of machines or guarding driveways on driverless transport systems	Safety Laser Scanner Safety Light Curtains (installed at an angle or horizontal) Light curtains in host/guest configuration

Step 3: Selecting the required safety type of optoelectronic protective device

The optoelectronic protective device is a component of the safety-related part of the machine control system and a component in the effective chain of a partial safety function consisting of sensor, control unit and actuator. From the risk assessment (graph) in accordance with EN ISO 13849-1 or EN 62061, the designer determines the safety-related performance required for the risk minimization for this partial safety function (see Safety-related parts of control systems and Control Reliability). Regardless of the control system applied, the achieved level of safety-related performance (category, PL, SIL) of the entire safety function is always less than or equal to the lowest value (category, PL, SILCL) of one of its partial systems. Put simply, the chain is therefore as strong as its weakest link.

Optoelectronic protective devices have different safety-related capacities, depending on the detection principle and the internal technical setup. IEC/EN 61496 and UL 61496 "Safety of machinery – Electro-sensitive protective equipment" define 3 different types of active optoelectronic protective devices (AOPD), which differ in their effectiveness and frequency of error detection, i.e. their safety-related performance. The following table 4.2.1-1 shows the requirements of this standard. For applications in the USA it must be determined which OSHA / ANSI control reliability requirement is relevant for the respective application case (observe machine-specific and regional specifications!). The corresponding AOPD type must then be selected.

Types and functional safety (control reliability) of electro-sensitive protective equipment in accordance with IEC/EN 61496 and UL 61496.