[qwertysimo]

Hi,

this unit has worked 4 years like a charm. Recently I have noticed that it does not hold set RPM under load even sometimes without a load. I mean, RPM set to 12k, actual speed varies from 11k to 12k (display reading), producing very nasty sound during cutting, with me praying not get any slower and breaking a router bit. Sometimes it works normal for 3 hours and then suddenly starts to behave weird for an hour and then works normaly again. Of course I did not touch the wiring neither VFD settings. RPM set by analog control.

Any idea on possible cause or what to look for? Dying capacitors?

Thank you.


Boris

[mactec54]

Hi,

this unit has worked 4 years like a charm. Recently I have noticed that it does not hold set RPM under load even sometimes without a load. I mean, RPM set to 12k, actual speed varies from 11k to 12k (display reading), producing very nasty sound during cutting, with me praying not get any slower and breaking a router bit. Sometimes it works normal for 3 hours and then suddenly starts to behave weird for an hour and then works normaly again. Of course I did not touch the wiring neither VFD settings. RPM set by analog control.

Any idea on possible cause or what to look for? Dying capacitors?

Thank you.


Boris

My first thoughts are how is your Power supply would be worth a check, 4 years is quite good for a spindle like this without replacing the Bearings, have you always run it at 12,000 RPM this to could play a toll on the VFD as if you over load the cutter at that speed you have a very good chance of stalling the spindle, you don't have much torque at that speed

So what is your spindle max Hz

Water cooled or air cooled, is it over heating

The caps could be getting tired check the Bus Voltage this will confirm this if the input voltage is correct

[qwertysimo]

Thanks mactec.

I am not getting your power supply comment. This is unit with a single phase 230 V input and three phase output, max 400 Hz. Do you mean how stable is 230 V on input? No issue here.

It is a water cooled spindle. No cutter overloading, always calculating the chipload, no stalling ever. No play so the bearings are OK. Cutting in 12k to 18k RPM range most the time. No spindle overheating, water loop shows max 35 deg Celsius (following the ambient temp). VFD itself has a internal fan and the VFD unit is placed in good ventilated electrical box.

I cannot remember a situation that the actual RPM would vary from the set value within those 4 years! RPM was always spot on no matter of (reasonable) load.
Now it jumps like crazy, unpredictable. I can cut a straight slot in MDF and RPM will vary from 11k to 12k...

The caps could be getting tired check the Bus Voltage this will confirm this if the input voltage is correct

Can you explain please? Hook voltmeter to input phase and neutral terminals to see fluctuation of input voltage? No issue here, pretty stable 230 to 235 V.

[mactec54]

Thanks mactec.

I am not getting your power supply comment. This is unit with a single phase 230 V input and three phase output, max 400 Hz. Do you mean how stable is 230 V on input? No issue here.

It is a water cooled spindle. No cutter overloading, always calculating the chipload, no stalling ever. No play so the bearings are OK. Cutting in 12k to 18k RPM range most the time. No spindle overheating, water loop shows max 35 deg Celsius (following the ambient temp). VFD itself has a internal fan and the VFD unit is placed in good ventilated electrical box.

I cannot remember a situation that the actual RPM would vary from the set value within those 4 years! RPM was always spot on no matter of (reasonable) load.
Now it jumps like crazy, unpredictable. I can cut a straight slot in MDF and RPM will vary from 11k to 12k...


Can you explain please? Hook voltmeter to input phase and neutral terminals to see fluctuation of input voltage? No issue here, pretty stable 230 to 235 V.

The Bus voltage is DC and will be around 325v Dc for your supply voltage of 230v you can measure this on the Terminals that are for the Breaking Resistor if you VFD Drive has this

It's not only about the Voltage being stable, is the wiring and supply suited for up to 25A as a 2.2Kw needs a minimum of 25A when using single phase 230v supply

Another problem is that a IGBT may be malfunctioning which is made up of 4 different Transistors in your VFD Drive there are some Zener diodes that are part of this circuit also which may be faulty

It would be hard to say without checking with a scope

Is your main power connected to Terminals R ( live ) T ( Neutral ) and Ground to the Ground Terminal