Motor Overloading Problem
Dear All.
Hope you are in good health, I am coming across an issue on one of my systems, need your insight on this.
We were running 90KW, 1480rpm, 380 Volts motor but due to increased flow requirements, we increased its rpm to 1800, but as a results it temperature increased and motor started to fail.
Therefore we installed, 90KW, 2900rpm, 380 Volts motor on the same location, but now we are unable to increase rpm beyond 850, as its load is 100% at this point.
Please share what could be the possible cause, as per Andritz (pump supplier) same pump should run on 2900.
I have ACS800-04-0120-3+J400+L503 drive installed on it.
I look forward to your expert opinion.
Regards,
Hussain Mohsen
Asked 10 months ago
Answers
1
Hi
I think I misunderstood .... I would like to understand why you switched from a 1480 rpm engine - 90 kW to a 2900 rpm engine - 90 kW.
The calculation of the torque required for the pump as has been done?
A 90 kW electrical motor at 1480 rpm develops a nominal torque of about 578 Nm. A electrical motor at 2900 rpm - 90 kW - develops a nominal torque of 288 Nm.
These data can be obtained from any catalog of electric motors.
It is clear that the pump will not be able to turn, if the torque required at the axis - at least in the design phase - was around 578 Nm!
Try to explain better, but I think you put an inadequate electrical motor ... who gave you this advice?
IMHO if you need the same torque to turn the pump at the nominal load but at upper speed, for example 1800 - 2000 RPM you need minimum one 200 kW - 2900 rpm electrical motor ( around 640 Nm)
Or one 132 kw - 1480 rpm ( around 846 Nm, bearing in mind the derating for a 1800 rpm operation, the residual torque is still the amount required to turn the pump).
But it would be better to be able to consult the load curve of the pump, to understand how much torque / power it requires at the speed at which you have to operate your system.
You will of course have to take into account that you change the size - axis height - of the electrical motor.
The inverter, incidentally, has nothing to do with it ..... first you need to sort out the issue of the load, then we analyze what type of drive you need to control the motor.
Of course, with one increase of the size of the motor, you need to increase the size of the drive...
Hope this help you
BR
Flavio
I think I misunderstood .... I would like to understand why you switched from a 1480 rpm engine - 90 kW to a 2900 rpm engine - 90 kW.
The calculation of the torque required for the pump as has been done?
A 90 kW electrical motor at 1480 rpm develops a nominal torque of about 578 Nm. A electrical motor at 2900 rpm - 90 kW - develops a nominal torque of 288 Nm.
These data can be obtained from any catalog of electric motors.
It is clear that the pump will not be able to turn, if the torque required at the axis - at least in the design phase - was around 578 Nm!
Try to explain better, but I think you put an inadequate electrical motor ... who gave you this advice?
IMHO if you need the same torque to turn the pump at the nominal load but at upper speed, for example 1800 - 2000 RPM you need minimum one 200 kW - 2900 rpm electrical motor ( around 640 Nm)
Or one 132 kw - 1480 rpm ( around 846 Nm, bearing in mind the derating for a 1800 rpm operation, the residual torque is still the amount required to turn the pump).
But it would be better to be able to consult the load curve of the pump, to understand how much torque / power it requires at the speed at which you have to operate your system.
You will of course have to take into account that you change the size - axis height - of the electrical motor.
The inverter, incidentally, has nothing to do with it ..... first you need to sort out the issue of the load, then we analyze what type of drive you need to control the motor.
Of course, with one increase of the size of the motor, you need to increase the size of the drive...
Hope this help you
BR
Flavio
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