Vfd setting to prevent damage-new motor too big

I have a 10" Sheldon lathe. It came with a 3/4hp motor which has disappeared since I changed to a single glue phase years ago. I now have a VFD rated for 3hp. It is an automation direct g2 series. I initially had a 3/4 3-ph motor on it but I've been able to stall the motor very easily. This is something I have not experienced with the 1hp single phase motor. I have the pulley set up using smallest motor and largest spindle which should give the most power from the motor. I can see the current go past the nameplate spec of 3.5 amps so the motor is definitely getting over powered by the turning.

I had another 2hp motor lined up for purchase but the guy backed out so I am going to put a 3hp on the lathe. It will barely fit under the lathe in the cabinet but it will work. I've had to remove the motor mount and drill new holes for the foot. I am wondering if I should set the maximum amps to a lower number than the nameplate as protection from putting such a large motor on it?

Thanks

challenger said:

I have a 10" Sheldon lathe. It came with a 3/4hp motor which has disappeared since I changed to a single glue phase years ago. I now have a VFD rated for 3hp. It is an automation direct g2 series. I initially had a 3/4 3-ph motor on it but I've been able to stall the motor very easily. This is something I have not experienced with the 1hp single phase motor. I have the pulley set up using smallest motor and largest spindle which should give the most power from the motor. I can see the current go past the nameplate spec of 3.5 amps so the motor is definitely getting over powered by the turning.

I had another 2hp motor lined up for purchase but the guy backed out so I am going to put a 3hp on the lathe. It will barely fit under the lathe in the cabinet but it will work. I've had to remove the motor mount and drill new holes for the foot. I am wondering if I should set the maximum amps to a lower number than the nameplate as protection from putting such a large motor on it?

Thanks

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OK, you have the VFD and motor matched. I assume you are trying to protect the machine from the much larger than original motor.

You might not have to, really, but you could set the motor rated current lower, so long as you are using V/F control. Might take some experimentation, because a larger motor has a larger no-load current, and that can make it hard to set anything accurately as far as "power related current".

Might not have to, because it is not unknown for a 10" to have a 2 HP motor, and Sheldons are often pretty stout machines. Not all of them, though. Much of the power limit may be more between your ears than in the VFD, however. Just don't push the thing.

Thanks. I just put the 3 hp motor in and set the vfd as per the name plate.

Of course the guy that I was going to buy the 2hp motor from the called the evening of the day I did this. It would have saved me 3/4 of a day if I had this one from the start because I had to fiddle with the mount in the machine.

He dropped the price so I bought it anyway. It was $50.00 for a Baldor 3-ph 2hp motor. List is over $350.00. It isn't new but I'm sure there isn't much time on it.
Thanks