3/28/2020 4:30 AM | |
Joined: 9/9/2015 Last visit: 9/25/2024 Posts: 727 Rating: (278) |
Let me share my view. By using failsafe DO, it provide you the capabilities of dark test and various diagnostic function, so you can choose energise to trip or de-energise to trip. For these concepts, the norm for a safety system is always de-energise to trip. But for process system that need more availability instead of safety, it would be energise to trip. It depends on the safe state you define. If the safe state is the pump running, then when you de-energise, it should go to a safe state (pump running) which is de-energise to a safe state. |
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