Safety, General information / 2. safety – WIKA T32.xS User Manual

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11583631.03 08/2014 GB/D/F/E

WIKA safety manual temperature transmitter T32.xS

Systematic capability

The systematic capability of an element (SC 1 to SC 4) states

that the systematic safety integrity for the corresponding SIL is

achieved.

SFF

Safe Failure Fraction

SIL

Safety Integrity Level, the international standard IEC 61508

defines four discrete safety integrity levels (SIL 1 to SIL 4).

Each level corresponds to a range of probability with which a

safety-related system performs the specified safety functions in

accordance with the requirements. The higher the safety integrity

level of the safety-related system, the greater the probability that

the safety function is executed.

or T

proof

Interval of the proof tests (in hours, typically one year (8760 h))

Following this interval, the proof test will be carried out.

Proof test

Proof testing for the detection of hidden failures to danger in a

safety-related system so that, if necessary through repair, the

system can be placed, as far as possible, in an “as-new” condition.

For further relevant abbreviations, see IEC 61508-4.

2. Safety

2.1 Intended use in safety applications

All safety functions relate exclusively to the analogue output signal (4 … 20 mA). The

instrument is certified to SIL 2 (IEC 61508). Due to the systematic capability of the

transmitter for SC 3, it is possible, depending on the safety integrity of the hardware, to

use the instrument in homogenous redundant systems up to SIL 3.

Taking into account the error detection functions of the model T32.xS temperature

transmitter, the following temperature sensors connected to the transmitter achieve a

sufficient SFF (Safe Failure Fraction) for SIL 2 of > 60 %.

■

Thermocouples with internal or external Pt100 cold junction

(Type E, J, T, U, R, S, B, K, L, N)

■

Resistance temperature sensors with 2-, 3- or 4-wire connection

(Pt100, JPt100, Ni100, Pt1000, Pt500, Pt25, Pt10)

■

Dual thermocouples or dual resistance temperature sensors

Only permitted in the operating modes “Sensor 1 and sensor 2 redundant”, “Mean

value”, “Minimum value”, “Maximum value” and if both sensors are being used

for the monitoring of the same measuring point. The operating mode “Differential

measurement” is not permitted.

1. General information / 2. Safety