Rockwell Automation T8442 Trusted TMR Speed Monitor - Manual (Page 18)

Trusted
TM
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 TM system processors.
• Complete failure of any or all communication links between the T8442 and the Trusted TM
system processors.
• The following safety strategies are also observed:
• T8442 operating parameters are downloaded from the Trusted TM 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 TM
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
TM 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
TM system processor in any way.