Typical TeSys™ island Structure

The illustration below shows an example of a TeSys™ island that consists of two SILSafety Integrity Level according to standard IEC 61508.* groups. The composition of the island is defined by the TeSys island digital tools according to the functional needs expressed by the user.

SIL Group 1: includes one avatar that includes two SIL starters: for instance, a “Motor Two Directions – SIL Stop, W. Cat 1/2” avatar (Avatar A1). The actual motor is wired to these SIL starters and follows the avatar logic and the operational commands coming from the PLC through the fieldbus. The SIL Stop Command comes from the emergency stop push button wired to the SIL interface module (Wiring Category 1) and causes the SIL starters to de-energize the load and enter the safe state (contactor is opened, and the motor is de-energized).

SIL Group 2: includes two avatars, for instance a “Switch – SIL Stop, W. Cat 1/2" (Avatar A3) and a “Motor One Direction – SIL Stop, W. Cat 1/2" (Avatar A4), each of them consisting of a single SIL starter. Both avatars follow the avatar logic and operational commands coming from the PLC through the fieldbus. The SIL Stop Command comes from the external Preventa™ XPS module (or equivalent) wired to the SIL interface module, and causes the SIL starters to de-energize the load and enter the safe state (Wiring Category 2).