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Simocode Pro V Motor Thermal Model

3/23/2009 6:02 PM	Rate (0)
Cherryg2000 Posts: 6 Rating: (0)	Hello..We have installed and tested a number of Simocodes for all our MCCs. One issue about the Simocode is not clear. How does the Simocode develop the Motor Thermal Model? Is it purely by the current feed through the Current Measuring module, or one has to connect the Thermistors too? Secondly, once the Thermal model is developed (does the relay alogorithmrequire a number of operations of the motor?), does the developed motor model give protection against frequent starts? In our case, the pause time is 0 seconds. The manual says that in that event, the thermal memory will not reset and frequent restarts may be blocked if the thermal damage limit is reached. Please note that in Permissible number of starts, we have not specified any restriction.
Cherryg2000 Posts: 6 Rating: (0)
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3/24/2009 11:37 PM	Rate (0)
Cherryg2000 Posts: 6 Rating: (0)	I was expecting a reply on this!! The feedback I have received from my field guy is that even if we operate the load at 100%, the relay looks at it as 87% load since we have a service factor of 1.15. Hence, we are able to start & stop the motor and again restart the motor, countless number of times, without the thermal model tripping\block closing !!! Is this a correct behaviour of the relay?
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3/31/2009 9:54 AM	Rate (0)
LesPaul Posts: 467 Rating: (59)	hello, the motor thermal model works on internal know-how. (according to 60947-4-1) Independent from each other the 3UF7 tripps when thermal motor model or thermistor tripps (depends on the parametrization) The relay algorithm does not require a number of operations of the motor. Yes, the motor model gives protection against frequent starts. Depending on: preloading, current and time
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3/31/2009 9:55 AM	Rate (0)
LesPaul Posts: 467 Rating: (59)	yes the behaviour of the relay is correct. See 3UF7 System Manual, chapter 3.2, page 3 - 10 regards
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4/1/2009 4:11 PM	Rate (0)
Cherryg2000 Posts: 6 Rating: (0)	Hi Paul Thanks for the reply. Even though we have not out any restriction on no of starts in an hour, we still have the Thermal model to protect the motor from getting damaged due to succesive starts.Please let me know the rationale of specifying the no. of successive starts per hour, especially since the Motor thermal model takes care of the Heating & Cooling cycles of the motor anyways. Is there any Siemens Literature on the thermal model development? I am attachingone article on this topic which may be useful to other readers. Attachment 6164.pdf (836 Downloads)
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