What is SIL3/PLe and SIL2/PLd

The DS range of speed and standstill monitors are all SIL3/PLe and SIL2/PLd certified.

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

The reliability of safety functions of electrical systems is classified into four different safety integrity levels. These classifications are SIL1 to SIL4. SIL1 is the lowest reliability classification, and SIL4 is the highest. The DS range of safety speed monitors can achieve a SIL3 safety integrity level.

PL (Performance Level) is used similarly to the safety integrity level when classifying safety classes. The performance level falls under the standard ISO 13849. This classification takes place from PLa to PLe. PLa has the lowest risk reduction, and PLe has the highest. The DS range of safety relays is certified up to PLe.

The picture below depicts the risk analysis, which assists in the calculation of the performance level. The first analysis step, S determines the severity of the injuries that can be sustained due to an accident. The analysis F deals with the frequency of a possible accident or the duration of the user’s stay under the risk. There is also a section regarding the possibility of avoiding the threat and the limitation of the damage that might occur. Consequently, high-risk applications require components with the highest performance level PLe, such as the DS Range of speed monitors.

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.