Yokogawa EJA440E User Manual download pdf (Page 38)

A1-1

IM 01C25T03-01E

Appendix 1. Safety Instrumented Systems

Installation

WARNING

The contents of this appendix are cited from

exida.com safety manual on the transmitters

specically observed for the safety transmitter

purpose. When using the transmitter for Safety

Instrumented Systems (SIS) application, the

instructions and procedures in this section must

be strictly followed in order to preserve the

transmitter for that safety level.

A1.1 Scope and Purpose

This section provides an overview of the user

responsibilities for installation and operation of the

transmitter in order to maintain the designed

safety level for Safety Instrumented Systems (SIS)

applications. Items that will be addressed are proof

testing, repair and replacement of the transmitter,

reliability data, lifetime, environmental and

application limits, and parameter settings.

A1.2 Using the Transmitter for

an SIS Application

A1.2.1 Safety Accuracy

The transmitter has a specied safety accuracy

of 2%. This means that the internal component

failures are listed in the device failure rate if they will

cause an error of 2% or greater.

A1.2.2 Diagnostic Response Time

The transmitter will report an internal failure within 5

seconds of the fault occurrence.

A1.2.3 Setup

During installation the transmitter must be setup

with engineering units parameters. This is typically

done with a handheld terminal. These parameters

must be veried during the installation to insure

that the correct parameters are in the transmitter.

Engineering range parameters can be veried by

reading these parameters from the optional local

display or by checking actual calibration of the

transmitter.

The calibration of the transmitter must be performed

after parameters are set.

A1.2.4 Required Parameter Settings

The following parameters need to be set in order to

maintain the designed safety integrity.

Table A1.1 Required Parameter Settings

Item Description

Burnout

direction switch

To specify if the output should go 21.6

mA or higher or 3.6 mA or lower upon

detection of an internal failure.

Write protection

switch

The write function should be

disabled.

A1.2.5 Proof Testing

The objective of proof testing is to detect failures

within the transmitter that are not detected by the

diagnostics of the transmitter. Of main concern

are undetected failures that prevent the safety

instrumented function from performing its intended

function. See table A1.2 for proof testing method.

The frequency of the proof tests (or the proof

test interval) is to be determined in the reliability

calculations for the safety instrumented functions

for which the transmitter is applied. The actual

proof tests must be performed more frequently or

as frequently as specied in the calculation in order

to maintain required safety integrity of the safety

instrumented function.

The following tests need to be specically executed

when a proof test is performed. The results of

the proof test need to be documented and this

documentation should be part of a plant safety

management system. Failures that are detected

should be reported to Yokogawa.

The personnel performing the proof test of the

transmitter should be trained in SIS operations

including bypass procedures, transmitter

maintenance, and company management of

change procedures.

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