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Operating Above Nominal Frequency


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#1 ABBdrives

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Posted 13 November 2010 - 08:33 PM

Typically using a VFD to run a motor above the nominal frequency will result in lost of torque as the maximum frequency is exceeded. I just want to know if its ok to run the motor above the rated frequency using direct torque control or is scalar a better option?
How does this impact on motors with rating of up to 120 hz also on the nameplate?

#2 jOmega

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Posted 16 November 2010 - 09:56 PM

QUOTE (ABBdrives @ Nov 13 2010, 02:33 PM) <{POST_SNAPBACK}>
Typically using a VFD to run a motor above the nominal frequency will result in lost of torque as the maximum frequency is exceeded. I just want to know if its ok to run the motor above the rated frequency using direct torque control or is scalar a better option?
How does this impact on motors with rating of up to 120 hz also on the nameplate?



It would be helpful if you were to provide specific information so that a reply could be constructed that applies to your application and issues.

To that end ... please provide:
  • COMPLETE motor nameplate (rating plate) data
  • Describe application
  • Manufacturer of VFD
  • Model Number of VFD


#3 ABBdrives

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Posted 19 November 2010 - 12:27 AM

QUOTE (jOmega @ Nov 16 2010, 05:56 PM) <{POST_SNAPBACK}>
It would be helpful if you were to provide specific information so that a reply could be constructed that applies to your application and issues.

To that end ... please provide:
  • COMPLETE motor nameplate (rating plate) data
  • Describe application
  • Manufacturer of VFD
  • Model Number of VFD



Ok its an ABB ACS800 drive used to operate a 20 hp 460V motor for a gas compressor(VRU). The motor current is 22.7 A, for the frequency the nominal value is 60 hz but there are other frequency rating on the nameplate. That is 3-60hz, 6-60hz and 60-120hz.

#4 jOmega

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Posted 19 November 2010 - 02:46 PM

QUOTE (ABBdrives @ Nov 18 2010, 06:27 PM) <{POST_SNAPBACK}>
Ok its an ABB ACS800 drive used to operate a 20 hp 460V motor for a gas compressor(VRU). The motor current is 22.7 A, for the frequency the nominal value is 60 hz but there are other frequency rating on the nameplate. That is 3-60hz, 6-60hz and 60-120hz.




  • COMPLETE motor nameplate (rating plate) data



Is compressor of the Positive Displacement type, or the Centrifugal type ?

#5 ABBdrives

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Posted 19 November 2010 - 08:00 PM

It's positive displacement



#6 jOmega

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Posted 22 November 2010 - 02:31 PM

QUOTE (ABBdrives @ Nov 19 2010, 02:00 PM) <{POST_SNAPBACK}>
It's positive displacement



Thank you for reply.


Further evaluation/analysis of your Constant Torque application required to answer your questions originally stated.

Please supply ..... C o m p l e t e ...... motor nameplate data as previously requested.


Thank you.


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