Allen-Bradley 1794-IE8H Specifications download pdf (Page 8)

Publication 1794-RM001F-EN-P - September 2011

SIL Policy 1-3

Proof Tests

IEC 61508 requires the user to perform various proof tests of the equipment

used in the system. Proof tests are performed at user-defined times (for

example, proof test intervals can be once a year, once every two years or

whatever timeframe is appropriate) and include some of the following tests:

• Testing of all fault routines to verify that process parameters are

monitored properly and the system reacts properly when a fault

condition arises.

• Testing of digital input or output channels to verify that they are not

stuck in the ON or OFF state.

IMPORTANT

Important Note related to published PFDs.

• The user must choose the appropriate PFD depending

on combinations and the appropriate 1oo1 or 1oo2

configuration.

• Descrete and analog inputs must be used in a 1oo2

configuration for SIL 2.

• Adapters must be used in a 1oo2.

• Outputs may be 1oo2 in series or 1oo1 monitored by

an input with an external relay as a secondary device to

remove power.

• Some specialized inputs can only be wired to a single

sensor such as thermocuples and two 1oo1 PFDs must

be used for each.

• The total PFD for two 1oo1s is the sum of both.

IMPORTANT

The system user is responsible for:

• the set-up, SIL rating and validation of any sensors or

actuators connected to the ControlLogix/FLEX I/O

control system.

• project management and functional testing.

programming the application software and the module

configuration according to the description in the

following chapters.

The SIL2 portion of the certified system excludes the

development tools and display/human machine interface

(HMI) devices; these tools and devices are not part of the

run time control loop.

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Allen-Bradley 1794-IE8H Specifications Page 8