Safety Considerations Guide for Trident v2 Systems - TUV ...

Emergency Shutdown Systems
The safe state of the plant should be a de-energized or low (0) state.
All power supplies should be monitored for proper operation.
Burner Management Systems
The safe state of the plant is a de-energized or low (0) state.
General Guidelines 21
When a safety system is required to conform to the EN 50156 standard for electrical equipment
for furnaces, PES throughput time should ensure that a safe shutdown can be performed within
one second after a problem in the process is detected.
Fire and Gas Systems
Fire and gas applications should operate continuously to provide protection. The following
industry guidelines apply:
• If inputs and outputs are energized to mitigate a problem, a PES system should detect
and alarm open and short circuits in the wiring between the PES and the field devices.
• An entire PES system should have redundant power supplies. Also, the power supplies
that are required to activate critical outputs and read safety-critical inputs should be
redundant. All power supplies should be monitored for proper operation.
• De-energized outputs may be used for normal operation. To initiate action to mitigate a
problem, the outputs are energized. This type of system shall monitor the critical
output circuits to ensure that they are properly connected to the end devices.
Safety Considerations Guide for Trident v2 Systems