Spindle voltages?

1. VFD setup problem or broken spindle.

Hi All.
With the aid of some students we are putting together a simple XYZ linear rail CNC using Fluidic control. We were using a hand router as our main cutting tool but decided to upgrade to a spindle. We purchased a Chinese 2.2KW 220v 400hz Spindle (GDZ80X73-2.2)from Amazon with a YL260-A VFD. Our problem is we can't get the spindle to work. I've taken voltages at the entry to the spindle and got 135Vac to earth from each phase but nothing between phases whilst the frequency was set to 400hz, however, I measured the Hz at the outgoing W,U,V, terminals to earth and got 0Hz. the continuity reading between all phases at the spindle is 3.7Ohm. I'm pretty sure I have all the correct perimeters set in the VFD but I'm wondering if I missed something noting the 0Hz at the VFD W,U,V terminals..
I'm also wondering if the spindle is broken.

Any ideas would be greatly received.

2. Re: Spindle voltages?

Hi,
measuring the output voltage of a VFD is very problematic. It is not, as you might believe, a sine wave. It is in fact a PWM modulated square wave and without at the very least an oscilloscope
you'll not get any useful info from it, and ideally you need a high voltage differential probe. Any attempt to apply an earth reference on the output will be met with a shower of sparks wrecking your scope, your
VFD and if your lucky both of them!!

Measuring the output with a multimeter is just not going to cut it.

What most people don't realise is that the VFD should have a V/F characteristic. That is to say the at low frequency the voltage must also be low and only at high frequency will the output voltage approach
the maximum (determined by the input voltage of the VFD). VFDs are programmed from the factory to be applied to a 50Hz or 60Hz motor. Such induction motors would be 220VAC output at 50-60Hz,
but your 400Hz motor will need be only 220 x 50/400=27.5VAC at 50Hz. If you hooked up this VFD to your motor you will cause a fault, which may, at worst destroy the VFD or the spindle or both Don't do it.

Most people program the max frequency to be 400Hz....fine, but what they do not do is program the V/F curve properly. I don't know how many spindles or VFDs have been blown up as a result.
Do not attempt to run the spindle until you are 100% that you have understood and correctly programmed the V/F characteristic correctly.

Craig

3. Re: Spindle voltages?

Hi,
I use Delta VFD's (Taiwanese brand made in China) and have always had good results. I do not like nor do I trust el-cheapo Chinese made VFD's.

This is from the MS300 manual (of my new VFD)

Note how there is a table that describes the voltage applied at a given frequency.
There are up to four points (a frequency and a voltage pair) for each of the four possible motors. That this drive can have up to four different motors complicates things a little.....but in your case all
you need worry about is the V/F table for your one spindle. The end point is the voltage at max frequency, I would guess your motor voltage, say 220VAC at 400Hz.
Then you may program several mid points....for example 50Hz and 27.5VAC.

It is a good idea to program a minimum frequency, usually 1/3 of max frequency, 400/3= 133Hz. This will ensure that you don't run your spindle too slow and blow it up.

With a beginning (or midpoint) and and endpoint the drive will now know what voltage to apply at any given frequency.

God knows what terminology YL use but there will be some parameters that mean the same thing. Good luck.

Craig

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