[GarageCNC]

Hi guys, I am a little confused with the settings on my Nord SK 550/1 VFD.

The little lathe has a 240v 3 phase motor, the plate stating 50Hz and 1370RPM. Reading the forums I have found that the motor is wound for 87 Hz to give a top spindle speed of 2000rpm.

So I have the motor params set - Nominal Frequency 50Hz (param 201), rpm 1370 (param 202)
Min Frequency 0Hz (param 104)
Max Frequency 87Hz (param 105)

Mach3 is set up fine, I have 0-10v output into the VFD with index feedback. Pulley speed set to 2000.

So when I program M03 S2000 in Mach, it tells me the speed is around 1400rpm, I have confirmed this with a tacho, even though the display on the VFD reads 87Hz. (All speeds are out BTW, not just the max speed)

The question is, what is the difference between the nominal frequency of the motor and the max frequency of the drive? How is it outputting 87Hz and yet the motor is not reaching it's max speed? I have played with the nominal frequency, it certainly does speed up the motor but I worry about burning it out if I take it up to 87Hz...please help / advise!

[Jim Dawson]

87Hz should not hurt a normal 3 phase motor. Are you reading the RPM at the spindle or the motor?

[mactec54]

Hi guys, I am a little confused with the settings on my Nord SK 550/1 VFD.

The little lathe has a 240v 3 phase motor, the plate stating 50Hz and 1370RPM. Reading the forums I have found that the motor is wound for 87 Hz to give a top spindle speed of 2000rpm.

So I have the motor params set - Nominal Frequency 50Hz (param 201), rpm 1370 (param 202)
Min Frequency 0Hz (param 104)
Max Frequency 87Hz (param 105)

Mach3 is set up fine, I have 0-10v output into the VFD with index feedback. Pulley speed set to 2000.

So when I program M03 S2000 in Mach, it tells me the speed is around 1400rpm, I have confirmed this with a tacho, even though the display on the VFD reads 87Hz. (All speeds are out BTW, not just the max speed)

The question is, what is the difference between the nominal frequency of the motor and the max frequency of the drive? How is it outputting 87Hz and yet the motor is not reaching it's max speed? I have played with the nominal frequency, it certainly does speed up the motor but I worry about burning it out if I take it up to 87Hz...please help / advise!

Check the pole setting if it has one sounds like your motor is 4 Pole or 2 pairs

The normal Frequency is that listed as Base Frequency if so what ever your max Frequency you are using should be the same as the Base Frequency

Your min Frequency can not be 0 the motor will have a minimum speed it can safely run at before it will over heat

You can normally run your motor at twice the rated frequency so that would be 100Hz in your case