I am a fresh engineer and I took part in a project of a toolmachine retrofit. The Spindle motor used to work with Dahlander junction and it is 30 kW at high speed. Now by using flux vector control it reach at a maximum torque of 1600Nm at 5 Hz. Is the machine going to face overheating problems at this frenquency under load condition due to high overcurrents ?
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motor retrofit
- Thread starter kolonos
- Start date
- Replies 2
- Views 1,351
jeffserv
Plastic
- Joined
- Aug 5, 2014
- Location
- Rome, GA USA
OK,
I have been doing Machine Design and CNC systems for many years... and your question to me is kind of funny!
Freq. Drives usually will provide good and high torque, even at slow speeds. As well, to protect themselve from overload... then they have settings therein, which will allow you to create a fault condition, if they do draw beyond a set ampere load... or over-current.
My reason for thinking this is a funny question... "...due to high ovrecurrents?", it is not desired, to run a motor at slow speed, except when under light loads. In other words... if you know the motor will be under hight torque loads, and there is a probabillity of high over-currents as a result. Then you need to modify, or design the system to avoid this at all cost.
Better gearing, or belt reduction, and set the machine, to run the motor, when under load, to be operating in the area of it best performance.
As a rule of thumb, I try to build my system, to where the motor will be running on average, approx. 75% of its speed and torque max. Motors today are only rated to allow approx. 5% over the top of there spec's... where as older motor used to allow up to 25%. Not the new ones... they will burn up.
So build the system, to use the power of the motor, at a reasonable speed. (like 75%) If the motor has to be run at such low speeds, to do the work... then the machine is most likely the wrong machine for the job, or designed wrong.
___________________________________________
I run my motors at low speed often, but never do I overload motors. Motors being overloaded, are why motors burn up. They will get hotter and hotter... till eventually, the insulation on the windings melt... then you are in for replacement, or rewinding.
My 2 cents worth...
I have been doing Machine Design and CNC systems for many years... and your question to me is kind of funny!
Freq. Drives usually will provide good and high torque, even at slow speeds. As well, to protect themselve from overload... then they have settings therein, which will allow you to create a fault condition, if they do draw beyond a set ampere load... or over-current.
My reason for thinking this is a funny question... "...due to high ovrecurrents?", it is not desired, to run a motor at slow speed, except when under light loads. In other words... if you know the motor will be under hight torque loads, and there is a probabillity of high over-currents as a result. Then you need to modify, or design the system to avoid this at all cost.
Better gearing, or belt reduction, and set the machine, to run the motor, when under load, to be operating in the area of it best performance.
As a rule of thumb, I try to build my system, to where the motor will be running on average, approx. 75% of its speed and torque max. Motors today are only rated to allow approx. 5% over the top of there spec's... where as older motor used to allow up to 25%. Not the new ones... they will burn up.
So build the system, to use the power of the motor, at a reasonable speed. (like 75%) If the motor has to be run at such low speeds, to do the work... then the machine is most likely the wrong machine for the job, or designed wrong.
___________________________________________
I run my motors at low speed often, but never do I overload motors. Motors being overloaded, are why motors burn up. They will get hotter and hotter... till eventually, the insulation on the windings melt... then you are in for replacement, or rewinding.
My 2 cents worth...
