Hello.

I have a 3.7 KW 220V 1 phase input VFD and a 3Kw Spindle. Both are from China and are very cheap.
They were running fine even if sometimes I had to unplug and plug again the energy to make the spindle start for some reason. I usually turn off the energy supply of my garage at the end of the day. While I was doing a full slot in aluminium the spindle stalled, before that it started to lose speed (RPM). With no load I was still able to run it.

Days later I tried to make a simple operation and the spindle was cutting well for the first few minutes but then it stalled again with current draw that was no over 6A; max current draw should be 12A. After that it started to run alone at around 25Hz (maybe is related to the fact that is the home line frequency/number of poles of the motor) form the VFD and with a 5A current draw even with no load. Even if I switch the control mode to potentiometer instead of 0 10v nothing change and regardless of the potentiometer command the frequency remains 25Hz.

Also, the spindle usually make a strange buzzing sound when powered but not rotating. The motor cable is shielded and the shielding is grounded. I also bought an input EMI filter and I will install it soon. I was also thinking to buy a DC or AC reactor even if maybe it is useless with this kind of load.
I checked the cable with multimeter and the wires are well connected.
I tried to run the spindle with the motor unplugged and the VFD had the exact same output. I also tried a full reset and obtained nothing.

I also had some random strange noise coming from the motor for few seconds.

Is there a way to tell for sure if the spindle or the VFD are broken and which one of them?

The chineese customer service guy was very kind in the past but for some reason now he is not answering to my question.


Thanks.