45kW DC motor change with AC - advice?

Hi,
I have to retrofit one plant, intended for cream production. There is DC motor 45kW (up to 3000RPM, 440V)which is driving emulsifier and I would like to change it with 55kW VFD driven 400V AC motor. Are there some specific precautions?

Thank you.

Ensure the AC motor is rated for the speed.

What is the base speed of the DC motor? Is it like 1500rpm and field-weakened to 3000rpm? Or os 300rpm the base speed.

What is the base and maximum speed of the AC motor?

The torque rating of the motors will be based on the base speed.

I assume from your post that the supply in 440 VAC 3 Phase 50 HZ
The original motor full speed is 3000 rpm that would be a 2 pole ac motor.
At 3000 rpm you are real close to the max speed for a dc motor, above 3200 rpm they tend to flash over on the commutater and burn up.
Keep in mind that when going from a DC motor to an AC motor the motor frames are not the same and you will need to make a new motor mount.
I assume that you are planning on using a VFD on the motor
As for the KW of the motor, the original motor is 45KW. Many of the older motors had a service factor of 1.5 so if I were doing this I would select a motor of at least (45 X 1.5 ) or 67.5 KW. Or the next standard size up.
Then select the correct VFD for the motor and line voltage
I know that that seems like a much larger motor, but the most new AC motors only have a service factor of 1.0 if the original motor has a service factor of 1.5 and is loaded to the max and you don’t allow for the load then you will overload both the VFD and motor and you will have to upgrade later it will cost you a lot more having to remount and rewire everything plus you are stuck with a motor and VFD you can’ t use.
Also select a good quality VFD the has local service in case you need it.

If on the odd chance that your original motor was connect to 500VDC source then we can still upgrade to an AC Motor and VFD powered from the 500VDC source it’s just a matter of selecting the correct hardware.
I would recommend you do the upgrade from DC to AC you will see a huge benefit in the end.