Induction Motor Synchronisation

You indicate each drive is run by their own VFD.

If so, can the VFD supply the higher current? The magnetizing current for the larger motor will be a little higher. Check the NP data.

Now, I am not familiar with the Siemens VFD, but the competing products can estimate the motor RPM to very close tolerances. Assuming the VFD is set to actually run RPM and not in scalar mode (HZ) there should be no problem. However the drive will need to be "tuned" for the new motor.

If you are actually running in HZ (V/HZ, scalar, etc) mode, then just tweak the frequency until the motor runs at the speed you want.

The Micromaster drive has a hardware current trip that is not accessible in the software. You shouldn’t have a problem if your breakaway torque is not too high. While fine for variable torque loads, you can need extra torque at start for constant torque loads (like your conveyor) that the drives will not provide, if sized close to the motor kW rating. Adding a little more magnetizing current could possibly send a marginal application over the edge, but worth a try.

I ended up having to replace each drive on some 1.5kW motors running progressive cavity pumps, the pump shafts never turned, drives tripped immediately on Run Command. The equipment package supplier or consultant was not used to those drives, where you as the application engineer need to account for load characteristics beyond drive nominal kW rating.

Consult manufacturer of VFD if it is OK to run a 3 kW motor using a 2.2 kW rated VFD.

The answer may be negative.

It is simpler to get a 2.2 kW motor than to replace a 2.2 kW VFD with a 3 kW rated VFD.

The nature of the <...damage...> is of interest.

It may prove attractive to order two replacement motors, and keep one as the strategic spare.

The Micromaster 440 comes in several versions each rated for different loads. The crucial point for you is that the next up from a 2Kw is the 3Kw. So if you have been running a 2.2Kw motor on you existing VFD it must be the 3Kw version and it will be compatible with the larger motor. If you run the upstream VFD using the 4-20mA input (AIN1 terminals) from an independent signal derived from the speed of the downstream conveyor speed (not the VFD) then the two conveyors will always match speeds. Don't connect the up and down stream VFDs over than the order that I have indicated or in the event of a downstream failure you will get a pile up of product at the junction.

Thanks all for sharing your experiences.

I replaced the VFD with a spare one (4kW rated, other specifications, make are same) that I had. I am running the conveyor. Motors are coupled with the gearbox by belts. So far it is working fine but sometimes under heavy load, I am observing some mechanical jamming on the larger motor side (3kW). It seems that chain conveyor is getting jammed for a moment but conveyor never stopped from running. But its very minor till now. I am coordinating with the mechanical team to assess whether it's a fault on their part or not.

You might have some bad roller bearings in the conveyor belt itself that is causing the stress on the motor...this could be the reason for the motor fail...