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We have an important booster compressor installed at our plant site. The control system to run the machine is an Allen Bradley based PLC-5/40C. We want to implement Triple Modular Redundancy (TMR)on our machine. This means that we need to install two more transmitters alongside each already existing single transmitter.
We are not willing to modify anything in the existing PLC logic. Our plan is to install another Allen Bradley based control Logix PLC with TMR. The three signals for each point on the compressor will come to this new Control Logix PLC. The median value will then be sent to the existing PLC-5/40C. In this way, we'll be able to increase reliability of our system. Of course, signals related to anti surge will be directly routed to the existing PLC and will not be changed.
I would welcome comments/suggestions to improve this proposal. Please do also mention if you know of any standard that supports or opposes such a topology. I do know that this will increase the scan time for each signal because of the addition of a new PLC. Suggestions to improve/modify the proposal are urgently needed.
We are not willing to modify anything in the existing PLC logic. Our plan is to install another Allen Bradley based control Logix PLC with TMR. The three signals for each point on the compressor will come to this new Control Logix PLC. The median value will then be sent to the existing PLC-5/40C. In this way, we'll be able to increase reliability of our system. Of course, signals related to anti surge will be directly routed to the existing PLC and will not be changed.
I would welcome comments/suggestions to improve this proposal. Please do also mention if you know of any standard that supports or opposes such a topology. I do know that this will increase the scan time for each signal because of the addition of a new PLC. Suggestions to improve/modify the proposal are urgently needed.