Voting logic

Secondly small quantities of airborne pollutants may poison the catalyst in the detector. This severely reduces its sensitivity. The detector becomes less reliable and often makes duplication, voting logic and frequent maintenance necessary. 

The fundamental idea is to utilize additional relevant process information for assessing the correctness of information generated by a sensor. This approach is known as the functional redundancy and it is more attractive than physical redundancy by duplicating sensors and using a voting logic to select the correct information. Several techniques based on statistics and system theory have been developed for validation of sensor information by functional redundancy. In most of these techniques, it is assumed that detailed process information is available a priori. Often, this knowledge is in the form of an accurate state-space model [39, 230]. In many cases, this type of accurate representation of a chemical process based on first principles is not available. 

Each division of the DRPS is divided in two sets. Both sets control the ESFAS actuators of the division. Each set of a DRPS division controls respectively a set of TRIP breakers performing a 2oo3 voting logic from the three divisions. This structure provides a diverse protection system. 

Plant Implem. year Primary System Voting logic Diverse System... 

Application of required redundancy and voting logic to improve availability... 

To reduce the chance of cross-link failures of redundant equipment, the redundant subsystems should be separated electrically and physically. The correct overall result may be obtained by voting the results obtained by each subsystem even when a component has failed or a subsystem is taken out of service for maintenance of the failed component. Because the voting logic itself necessitates common usage by all the subsystems, adequate and sufficient buffering should be used to ensure that the separation of the redundant equipment in the subsystems is maintained. Also, redundant subsystems should ran asynchronously. 

Determine if a fault-tolerant control system is necessary. This is one in which a single fault can not cause the system to fail. T)rpically such a system uses triplicate redundancy with two-out-of-three voting logic and redimdant functions. 

The DAS is not claimed as a safety measure by the fault schedule. However, it does provide defence in depth, and as such it possesses two out of two voting logic to prevent spurious actuation, and it is designed to higher quality standards than normal duty systems. 

Redundancy in addition to the typical four redundant channel sets configuration and 2/4 voting logic the IPS provides extensive redundancy within each channel set that allows to maintain complete operability and integrity of the system even in presence of maintenance or failures. 

By-passes a sophisticated logic is provided that allow to by-pass each channel or each channel set in case of test or maintenance, and to convert the voting logic in the remaining operating channels from 2/4 to 2/3 ... 

The occurrence of this hazardous event is based on the voting logic of the APU ... 

Avionics systems using redundant subsystems to perform the same computation with voting logic to determine the safe result when one subsystem fails. 

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