ABB TZIDC Digital Positioner Safety operation constraints

The following constraints need to be considered when using the

positioner for SIL safety applications:

• Only the 4 to 20 mA setpoint signal is used for the safety

function, all other inputs or not part of the safety function.

• The proof-test specified within this safety manual (or an

equivalent test as specified for the final SIS safety

function) shall be performed before activating the safety

operation and in periodical cycles as demanded by the

final PFDAVG demands.

• The device is installed per manufacturer’s instructions

• The safety-related system (safety logic solver) must be

able to force the 0 mA signal direct or by using a safety

capable switch on the 4 to 20 mA signal.

• Materials are compatible with the final process conditions.

• The environmental, measurement and application limits

stated within the referenced documentations must be

considered accordingly for the SIL safety application.

The positioner does not meet safety requirements under the

following conditions:

• during installation, configuration, repair and simulation

• during an inspection or proof-test

Before commissioning the positioner in a safety loop

application, the end user must check whether the installation

setup confirms to the system's safety function.

The end user must verify also that the correct positioner has

been installed at the correct positioning point.

Whenever the positioners operating conditions are changed (for

instance, if the mounting position is changed or the setup is

modified), the safety function must be checked again.