[davidg4]

I have just purchased a hurco sm-1 cnc that had been in storage for years, and has 9000 hrs on the meter., I am using a Vfd to operate it since i do not have 3 phase. i have managed to get the axis to all function and the spindle to opererate, when i had the spindle motor running @ high speed and slowed it down rapidly there are three electrocube suppressors on the motor circuit breaker assembly that started cooking/melting and smoking. i can still operate the spindle but now the suppressors strt to get hot very quickly. Can they be removed without harm? what could have caused them to burn out, To rapid of slow down of the motor?, . please help, tia

[Jim Dawson]

Your post is a bit confusing. Are you running the whole machine on the VFD or just the spindle?

The VFD should be wired directly to the spindle motor, nothing in between.

[davidg4]

the machine has a vari speed head, i am using the vfd strictly as a phase converter as i do not have 3 phase

[Jim Dawson]

the machine has a vari speed head, i am using the vfd strictly as a phase converter as i do not have 3 phase

I'm surprised that it works at all. I will be really surprised if running that way doesn't blow your entire control system. A VFD is not a phase converter (except to run a 3 phase motor). There are CNC rated inverter phase converters available. I'm guessing that only the spindle motor and maybe the coolant pump are 3 phase, the rest of the control system is probably single phase and could be operated from a separate single phase feed. This is pretty common, but without seeing the electrical documentation for the machine I couldn't say for sure.

I would highly recommend a rotary phase converter or an inverter phase converter rated for CNC use.

To answer you original question, yes you can probably remove the suppressors, but not safely, because they were damaged by overvoltage while the motor was spinning down. The good news is the suppressors probably saved the rest of the system by shorting out.

[davidg4]

Thanks for the advice, i will wire the vfd strictly to the motor,and have determined everything else can be ran on single phase 220v

[Smarttowers]

I'm surprised that it works at all. I will be really surprised if running that way doesn't blow your entire control system. A VFD is not a phase converter (except to run a 3 phase motor). There are CNC rated inverter phase converters available. I'm guessing that only the spindle motor and maybe the coolant pump are 3 phase, the rest of the control system is probably single phase and could be operated from a separate single phase feed. This is pretty common, but without seeing the electrical documentation for the machine I couldn't say for sure.

I would highly recommend a rotary phase converter or an inverter phase converter rated for CNC use.

To answer you original question, yes you can probably remove the suppressors, but not safely, because they were damaged by overvoltage while the motor was spinning down. The good news is the suppressors probably saved the rest of the system by shorting out.

I am adding a vfd to a eztrak dx bridgeport and as i was adding it i came across similar issues with 3 electrocubes on the output side of a relay. I'm trying to understand their function better in the original setup so i know if i need them using a vfd. I am not certain but think the problem i had was from the frequency ramp up of the vfd. I took them out of circuit and it runs now but really want to better understand them so i can know if the filter effect isnt needed with a vfd. Any help is appreciated and sorry for bumping an old thread but it was the only place online ive found any reference to this problem.

Oh also the vfd is only used to run the spindle none of the other components.

[machinehop5]

Any help is appreciated and sorry for bumping an old thread but it was the only place online ive found any reference to this problem.

...Welcome to the last outpost of information.
What Brand and Model number VFD will help or photos

DJ

[Jim Dawson]

I am adding a vfd to a eztrak dx bridgeport and as i was adding it i came across similar issues with 3 electrocubes on the output side of a relay. I'm trying to understand their function better in the original setup so i know if i need them using a vfd. I am not certain but think the problem i had was from the frequency ramp up of the vfd. I took them out of circuit and it runs now but really want to better understand them so i can know if the filter effect isnt needed with a vfd. Any help is appreciated and sorry for bumping an old thread but it was the only place online ive found any reference to this problem.

Oh also the vfd is only used to run the spindle none of the other components.

You would not need snubbers with a VFD, and they might be detrimental to a VFD.