Process Minimizing Risks Associated with the Machine

General

The goal of designing machines safely is to protect people. The risk associated with machines with electrically controlled drives comes chiefly from moving machine parts and electricity itself.

Only you, the user, machine builder, or system integrator can be aware of all the conditions and factors realized in the design of your application for the machine. Therefore, only you can determine the automation equipment and the related safeties and interlocks which can be properly used, and validate such usage.

Hazard and Risk Analysis

Based on the system configuration and utilization, a hazard and risk analysis must be carried out for the system (for example, according to ISO 12100 or ISO 13849-1). The results of this analysis must be considered when designing the machine, and subsequently applying safety-related equipment and safety-related functions. The results of your analysis may deviate from any application examples contained in the present or related documentation. For example, additional safety components may be required. In principle, the results from the hazard and risk analysis have priority.

WARNING
	NON-CONFORMANCE TO SAFETY FUNCTION REQUIREMENTS Specify the requirements and/or measures to be implemented in the risk analysis you perform. Verify that your safety-related application complies to applicable safety regulations and standards. Make certain that appropriate procedures and measures (according to applicable sector standards) have been established to help avoid hazardous situations when operating the machine. Use appropriate safety interlocks where personnel and/or equipment hazards exist. Validate the overall safety-related function and thoroughly test the application. Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

NON-CONFORMANCE TO SAFETY FUNCTION REQUIREMENTS

Specify the requirements and/or measures to be implemented in the risk analysis you perform.
Verify that your safety-related application complies to applicable safety regulations and standards.
Make certain that appropriate procedures and measures (according to applicable sector standards) have been established to help avoid hazardous situations when operating the machine.
Use appropriate safety interlocks where personnel and/or equipment hazards exist.
Validate the overall safety-related function and thoroughly test the application.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

The ISO 13849-1 Safety of machinery - Safety-related parts of control systems - Part 1: General principle for design describes an iterative process for the selection and design of safety-related parts of controllers to reduce the risk to the machine to a reasonable degree:

To perform risk assessment and risk minimization according to ISO 12100, proceed as follows:

Defining the boundary of the machine.
Identifying risks associated with the machine.
Assessing risks.
Evaluating risks.
Minimizing risks by:
- Intrinsically safe design
- Protective devices
- User information (see ISO 12100)
Designing safety-related controller parts (SRP/CS, Safety-Related Parts of the Control System) in an interactive process.

To design the safety-related controller parts in an interactive process, proceed as follows:

Step	Action
1	Identify necessary safety functions that are executed via SRP/CS (Safety-Related Parts of the Control System).
2	Determine required properties for each safety function.
3	Determine the required performance level PL_r.
4	Identify safety-related parts executing the safety function.
5	Determine the performance level PL of the afore-mentioned safety-related parts.
6	Verify the performance level PL for the safety function (PL ≥ PL_r).
7	Verify if all requirements have been met (validation).

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