TMR (Triple Modular Redundancy) in Safety Systems
When a single controller failure cannot be tolerated, industries use TMR architecture to keep systems safe and reliable.
Here’s the idea in simple terms 
What is TMR?
TMR = Triple Modular Redundancy
The system uses three identical controllers running the same logic simultaneously.
The final output is determined using majority voting (2 out of 3).
How TMR works
Three controllers process the same input signals.
Controller A
Controller B
Controller C
The system compares the outputs.
If two outputs match, that becomes the final action.
Example
Controller A → Trip
Controller B → Trip
Controller C → No Trip
Majority decision = Trip
The faulty controller is ignored.
Why TMR is powerful
Tolerates one controller failure
Eliminates single point of failure
Maintains system operation
Increases system reliability and availability
Where TMR is used
Safety Instrumented Systems (SIS)
Emergency Shutdown Systems (ESD)
Turbine control systems
Critical process protection systems
Key idea
Three controllers run the same logic
Majority voting decides the output
System continues even if one module fails
Simple way to remember
TMR = 3 systems working together so that one failure does not stop the protection system.
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