Torque
Torque
(OP)
Hi,
I know this topic had been discussed previuosly in this forum.I am looking for a direct relationship between torque and power consumed above rated speed for VSD application.We know that the output torque is reduced because of reduced V/F and overfluxing of the iron core.But the power consumption is more dependent on the application and in some cases increases with increased speed.What happened to the output torque in this situation?
Regards.
Guardiano
I know this topic had been discussed previuosly in this forum.I am looking for a direct relationship between torque and power consumed above rated speed for VSD application.We know that the output torque is reduced because of reduced V/F and overfluxing of the iron core.But the power consumption is more dependent on the application and in some cases increases with increased speed.What happened to the output torque in this situation?
Regards.
Guardiano





RE: Torque
Is there any special application you are thinking about? And what are your observations or problems?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Torque
As the load on a motor is increased, the current increases. When the current exceeds rated current the motor will run hotter. Some overloading may be allowable depending on the ambient temperature as it relates to the maximum design temperature and the pattern of the overloading. (Is the overload steady or are there adequate "cool down" periods.)
As the overload becomes greater, the heating of the motor increases and shortens the life of the motor. Moderate overloading may reduce the number of years that the motor will last. Extreme overloads may reduce the expected lifetime of the motor to a few minutes.
As the torque demand or overload increases the second limit may be reached. This is the maximum torque that the motor may produce at the applied voltage and frequency. When this limit is reached the motor stalls.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Torque
Power consumption is proportional to torque x rpm + motor and VFD losses.
Reducing the V/Hz doesn't over flux the motor. You'd have to increase the V/Hz to do so.
RE: Torque
So you should consider load torque variation with speed somewhat independent of any motor torque LIMIT variation with speed, up until the point when the motor torque limit becomes limiting.
=====================================
(2B)+(2B)' ?
RE: Torque
So you should consider load torque variation with speed somewhat independent of motor torque LIMIT variation with speed, up until the point when the motor torque limit becomes limiting.
=====================================
(2B)+(2B)' ?
RE: Torque
*Other than the fact that you may have some minor additional losses in the VFD and motor.
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RE: Torque
Guardiano
RE: Torque
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Torque
Gurdiano
RE: Torque
Bill
--------------------
"Why not the best?"
Jimmy Carter