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[ pdf ] PLC REDUNDANCY

PLC REDUNDANCY Download
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Topic under  PLC (Programmable Logic Controller)
Source: www2.schneider-electric.com 
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File type: pdf
Last download on: Tue Apr 10, 2018 08:01:04 AM
Short Desciption:
Redundancy comes in many forms and is inherent at some level in any plant design. The most basic form of redundancy requires the inclusion of a hand-off-auto switch for each component. In the automatic mode, the plant or system controller runs the process. In the hand mode this step is bypassed, resulting in continued treatment but a loss of efficiency and/or quality. For example, in an oxidation ditch scenario, the automatic operation may stage aerators based on dissolved oxygen levels. In hand mode it would be best to turn on all the aerators. This would ensure adequate levels of air without having to continuously monitor process conditions. However, it would also waste power.

Summary:
a bypass channel around the screen can be found. Using this bypass channel can ensure the plant operates, but it may allow particles to accumulate in the downstream clarifiers and basins. Another form of redundancy exists when more equipment is installed than is required. For instance, three pumps may be provided when only two are needed. This type of redundancy is quite common. Typically the third pump still has its own dedicated starter, VFD and control components. This extends some redundancy to the control and automation system as well. Redundancy is also gained with multiple process trains. Sometimes each train has its own automation system, or trains have been grouped into multiple control panels. This also represents a level of redundancy. Finally, redundancy can be designed into an automation system. Three Types of Automation Redundancy Automation redundancy can be accomplished via three methods - cold, warm and hot.
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    Posted by dwshort@bop.gov
    Tue Jan 22, 2013 06:41:52 PM

    looking for manuals on PLC wintelligent logic 5 software

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