User guide

Trusted

Module T8442

Issue 8 Apr 10 PD-T8442 18

1.3.6. Speed Monitor Module Safety Features

The T8442 system is able to provide uninterrupted functionality, speed monitoring and output control

functions under the following circumstances:

• Complete failure of Trusted

system processors.

• Complete failure of any or all communication links between the T8442 and the Trusted

system processors.

• The following safety strategies are also observed:

• T8442 operating parameters are downloaded from the Trusted

system processors on

system or module initialisation (start-up).

• It is not possible to change the safety parameters for a speed input group while any input in

that group is above zero speed.

• Over-speed and over-acceleration shutdown parameters are downloaded from the Trusted

system processors on module initialisation.

• It is not possible to increase the over-speed or over-acceleration thresholds beyond the safety

limits passed at initialisation. These parameters may be moved in a safe direction via the

IEC1131 TOOLSET.

• A standby T8442 module is educated with operating parameters from the active T8442 module

prior to on-line replacement using the Trusted

system companion slot method. The

Trusted(TM) Smart Slot method of on-line replacement is not supported by this module.

• Over-speed test mode is limited by a configurable timer.

• Every group-specific configuration parameter can be changed when the group is at zero

speed.

• The safety case for the module is maintained within the module while the turbine is running

and cannot be affected by the Trusted

system processor in any way.