Operating instructions

Functional safety

8.2 Device-specific safety instructions

SIPART PS2 with and without HART communications

Operating Instructions, A5E00074631-09

107

HFT SFF

0 1 (0)

2 (1)

< 60 % Not permitted SIL 1 SIL 2

60 to 90 % SIL 1 SIL 2 SIL 3

90 to 99 % SIL 2 SIL 3 SIL 4

> 99 % SIL 3 SIL 4 SIL 4

As per IEC 61511-1, Section 11.4.4

According to IEC 61511-1, Section 11.4.4, the hardware fault tolerance (HFT) can be

reduced by one (values in brackets) for sensors and final controlling elements with complex

components if the following conditions are applicable for the device:

● The device is proven-in-use.

● The user can configure only the process-related parameters, e.g. control range, signal

direction in case of a fault, limiting values, etc.

● The configuration level of the firmware is blocked against unauthorized operation.

● The function requires SIL of less than 4.

The device fulfills these conditions.

8.2 Device-specific safety instructions

8.2.1 Range of applications for functional safety

The positioner is also suitable for controlling valves that satisfy the special requirements in

terms of functional safety up to SIL 2 in accordance with IEC 61508 or IEC 61511-1. The

6DR501*, 6DR511*, 6DR521* and 6DR531* variations are available for this purpose.

These are single-acting, depressurizing positioners with an input from 4 to 20 mA for

installation on pneumatic actuators with spring reset.

The positioner automatically depressurizes the valve actuator on demand or in case of faults,

which thus switches the valve to the specified safety position.

These positioners meet the following requirements:

● Functional safety to SIL 2 under IEC 61508 or IEC 61511-1, from firmware version C4

● Explosion protection on 6DR5***-*E*** variations

● Electromagnetic compatibility in accordance with EN 61326/A1, Appendix A.1