Puzzled

[jtdesigns]

So my multiple motor single vfd set up works great except the motor I am using on my kmg clone is a 1 1/2 hp 3 ph 3650 rpm. Last night while grinding at slow speed motor got hot and shut down. Vfd ok and motor, once cooled down, appears fine. What is causing this?

Btw I used the low voltage wiring scheme on motor with 220v service coming into vfd

 

[Matt Brook]

If your 3Phase motor isnt a inverter quality motor it wont have the cooling capacity to run at slow speeds for extended periods of times. Most 3 phase motors were designed to be on or off. So when there on the fan provides just the right ammount of cooling. Running it at low speeds for an extended period will test your thermal overload, as you have found out.

Matt

 

[12345678910]

As matt said, better that it shut off instead of smoked.

You can get an invertor motor . = $$$
get a lower rpm motor = lose the high speed
use a smaller drive wheel = lose the high speed.
Point a fan at the motor and see if that helps



Check the data plate
is it Continuous "CONT" duty?

One motor I just now saw on Ebay has a "time rating 30 minutes"


It it's a KMG clone, are you running stepped pulleys too?
Put it into the low speed pulley, or change pulleys to do that.

Motors running on VFD's lose torque at low speed.
Running the motor at at higher rpm (but lower belt speed) by making those drive wheel or pulley changes
will improve torque (reduce the attempt to )boost by the vfd and run the fan faster to increase cooling.

Which VFD?
I would use the settings on the Beaumont site for the VFD
(or try to set it the same way if you use a different VFD)

 

[jtdesigns]

I have a 1750 rpm 1 1/2 HP 3PH that I think I will swap out. Am I correct by using the low voltage wiring scheme or should I be using the high voltage. I have 220 service coming into VFD? Thanks for the other answers...makes perfect sense.

Jeff

 

[12345678910]

I have a 1750 rpm 1 1/2 HP 3PH that I think I will swap out.

Am I correct by using the low voltage wiring scheme or should I be using the high voltage.
I have 220 service coming into VFD? Thanks for the other answers...makes perfect sense.

Jeff

Depends on your equipment.


on the specs of the motor and the specs of the vfd

my vfd is a kbac27d & outputs in 220 3 phase
My motors are 220/440

so yes I use the low voltage diagram on the motor.