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DC converters SIMOREG

Analogue log reference

Thread Starter: PISCEAN 2010   Started: 5/11/2012 8:39 AM   Replies: 6

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  5/11/2012, 8:39 AM
PISCEAN 2010
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Hello Experts,
In one of the application in 6RA70 Simoreg drive, analogue +/- 10V refernce is fed by 5K pot with 270 degree scale range. Application demand is, upto 75 % of pot scale range motor speed should vary upto 40 % of rated motor RPM & above 75% to 100 % balance 60% of rated speed should vary i.e. log pot. (Please see the attached graph)
Now a days in market linear pots are available & log pots are not available. So how can linear reference be converted to log value. 
Can any one help in this matter?
Thanks in advance.


DEEP. 

Attachment: ref pot skd.pdf  (9 Downloads)
Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  5/11/2012, 9:25 AM
KSN
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For this use S00 and characteristic block on diagram B160.
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  5/11/2012, 10:25 AM
PISCEAN 2010
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Hello,
But with this option only 10 points can be configured & shall not fulfill the application demand, precisely.
Can PLC module help for this application. If yes, how linear analogue can convert to logarithmic out-put? Does anyone has come across such application?


Regards,
DEEP.
Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  5/11/2012, 11:02 AM
KSN
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If you have S00, you may build logic so, that all 9 characteristic blocks will be used for reference speed from potentiometer, and you will have more points.
What PLC module do you mean?
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  5/11/2012, 11:33 AM
PISCEAN 2010
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KSN wrote:
If you have S00, you may build logic so, that all 9 characteristic blocks will be used for reference speed from potentiometer, and you will have more points.
What PLC module do you mean?


No I don’t have any S00 option. We are first checking the application workability. The reply I received from Siemens RSC is, “With S00 option, the same characteristic cannot be guaranteed.” Regarding PLC module, I don’t have any specific module consideration. This is my thought, whether using analogue PLC module, is it possible to convert linear analogue value into logarithmic as per graph?
Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  5/11/2012, 12:22 PM
KSN
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You can temporary enable S00 option by entering in U977=1500 and test how characteristis block will work for your application.
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  5/11/2012, 12:27 PM
PISCEAN 2010
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I am informed that its an option & need to purchase. Apart from this, no one is sure about its functioning & suitability from application point of view.
Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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