ISO 13849-1 is the most important standard for regulating the basic principles and performance required of a safety control system for machines and devices. This standard was greatly revised almost 10 years ago in November 2006. The 2006 revision highlighted changes to the fundamentals of system design in manufacturing safety. A major update overhauled the use of Performance Levels when performing risk assessments of machine design and use.
Performance Levels (PL) are not just extra boxes to check off on the paperwork, but make a difference in real-world safety when operators and designers work together.
Benefits of Using Performance Levels
How to Determine Required Performance Level (PLr)
Method to Evaluate Performance Level (PL)
Four parameters are used to evaluate a control system’s performance level in manufacturing safety.
1. Category
The Categories refer to the architecture of a safety related control system, and are classified into five categories as defined in EN954-1 and earlier version of ISO13849-1 : 1999. (see below)
2. MTTFd (Mean Time To Dangerous Failure)
MTTFd refers to an average life before the dangerous failure of a component occurs.
3. DCavg (Average Diagnostic Coverage)
DC refers to the certainty of detecting failures in the entire system (including software).
4. CCF (Common Cause Failure)
CCF refers to the protection of the entire system from failing due to a common cause.
As parameters for reliability, MTTFd and DCavg are determined by formulas, and CCF is determined with a checklist method. Each of the parameters is classified into levels using standard values: three levels for MTTFd, three levels for DC and two levels for CCF. Performance Levels are evaluated comprehensively in terms of these four parameters.
In future articles we will focus on each of these parameters in more detail… STAY TUNED!
In the meantime, the knowledgeable staff here at ACD can answer any questions you may have about Performance Levels or manufacturing safety products & procedures, or assist you with industrial electrical supplies. Find out how ACD earned its reputation for unbeatable customer service with engineering support.
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