The speed and standstill monitors of the DS series are SIL3/PLe and SIL2/PLd certified.

SIL is the abbreviation for Safety Integrity Level. The term comes from the field of functional safety and is used in the international standard IEC 61508. The sector-specific standard for the realization of safety-relevant electrical control systems is defined in the IEC or EN 62061.

Classified into four different Safety Integrity Levels, the reliability of safety functions of electrical systems is described. The classification is from SIL1 to SIL4. SIL1 stands for the lowest reliability and SIL4 for the highest. Depending on the sensors used, the speed monitors of the DS series can achieve a SIL3 safety integrity level.

The abbreviation PL stands for Performance Level and is used, like the safety integrity level, for the classification into safety classes. The performance level falls under the standard ISO 13849. This classification takes place from PLa to PLe. PLa stands for the lowest risk reduction, PLe for the highest. DS-series safety relays are certified up to PLe.

The picture illustrates the risk analysis, which helps to calculate the required performance level. The first analysis step S determines the severity of the injuries that can happen in an accident. The analysis F deals with the frequency, at which an error can occur or the duration of the user’s stay under the risk. Finally, there is a decision about the possibility of avoiding the threat or even limiting the damage. Consequently, high-risk applications require components with the highest performance level PLe, such as the DS-series speed monitors. But also for applications that require “non-safe” speed monitoring, Motrona has the appropriate speed monitors in the range.

The table in the picture compares the performance level to the corresponding safety integrity level. As a result, the combinations SIL3/PLe and SIL2/PLd can be derived.

Besides SIL and PL, there are a few other classification standards. For example, according to categories in the EN954-1 standard, or according to the Design Assurance Level (DAL) according to the DO-178B. (image source: Baumüller Nürnberg GmbH)