Spindel overload protector trips.

Hi,

We have 3 Fadal VMC's, two of them has a Toshiba inverter for the spindle and one has a baldor spindle. When we use the machines with Toshibas below 300 RPM's the overload protector trips, we noticed that in the 2 machines with Toshiba we have this:

RPM VOLTS AMPS
100 15 43
500 138 28
1000 241 23
3000 198 25

And in the machine with Baldor:

RPM VOLTS AMPS
100 32 18
500 138 18
1000 196 13
3000 192 18

As I explained the overload protector trips when we work under 300 RPM's in the machines with Toshiba, since are protectors are of the same capacity in all machines we think that the power must be te same, any ideas????

Thank you.

Greg.