Hot or Active Redundancy - Maximum failure rate

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• Satyawati Patil   -Posted on 07 Oct 15
  Redundancy deals with the generation of novel parallel paths possessing the similar nature of system to improve the mean life and reliability of an overall system. On the basis of status and switching time, redundancy is classified into an active, standby and warm redundancies.
  
  In cold standby or shared redundancy, during the failure of unit 1, only the switch is turned ON and unit 2 is started. As the switch change-over causes transient stress, unit gets shut down. Therefore, after the failure of main system, the probability that the redundant system can turn ON instantaneously is almost very less. Hence, the failure rate for unit 2 is also less.
  
  In warm redundancy, since unit 2 is idle & redundancy system is always ON, the probability of system reliability mainly depends on the switch operation. Therefore, failure rate for unit 2 is almost more.
  
  In an active redundancy, both the units are in working condition. If the unit 2 and switch are turned ON, then they result in the prevention of transient stress. Since both the units are placed under full load, the redundancy system can be immediately used after the failure of main system. This gives rise to the maximum reliability & hence the failure rate is also greater as compared to cold and warm redundancies.
  
  
  

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