AC drive won't spin its 300hz spindle.....

[tom.jelly]

I have a giordano columbo 300hz 18000 rpm 220v 3.7kw 5hp spindle motor that came on a router with a hitachi j100 inverter drive and were working until put into storage a few years ago. I'm retrofitting the control.
I returned all F settings and A parameters back to factory supplied values as in the vfd manual, but poles set to 2. (reset because the spindle motor would not start when trying to test it manually with the drive key pad after the original PLC was removed and I could not raise the frequency past 60hz, which I thought was why the 300hz motor would not run. I figured the drive parameters were lost or scrambled)
I attached a conventional 3 phase 3450 rpm 60hz 2hp motor and the drive worked fine, varying the speed no problem. With the 300hz 18krpm 3.7kv 5hp spindle motor it will only turn at an eyeball estimate speed of 40-60 rpm no matter what frequency or how many poles I set the drive to (tried 60-300hz range as indicated by the drive readout, rpm stays the same 60 or so rpm) I even tried it with another, identical spindle motor with the same result (both spindle motors test with same resistance pole to pole and no continuity from any pole to ground).
As this unit was used with this specific spindle motor before being put into storage I'm baffled. 18000 rpm=((120x300hz)/2 poles) so I have the poles right I think. The only other issue is "err" which shows in the display between f14 and f1, error 7: "when the converter voltage exceeds a certain level due to regenerative energy from the motor this protection function engages and the output of inverter is cut off" I don't see how to reset the error, but the unit functioned fine even with the "err" showing when testing the conventional motor, and does rotate the spindle motor (although slowly). The j100 is rated for 200-230v input, and I am running this a little higher on a rotary phase converter with phase voltage ranges of 240 to 256, but that doesn't seem like the issue for this error, and again the error seems to have no effect on the unit running the 60hz motor.

Any suggestions?

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[joeavaerage]

Hi,
when you returned the drive ti factory defaults you caused the V-F curve hit its peak at 60Hz.

With a motor that is rated for peak voltage but at 300Hz then the drive will fault 'over current' every time yoiu start.
You risk destroying the spindle and/or the VFD. Stop what you are doing and reprogramm the drive such that the
V-F curve peaks at 300 Hz.

Craig

[tom.jelly]

These tests were never more than a few seconds. In any case I just got the unit to work what seems like normally by changing the "base frequency" parameter from its default of 50 to 300. (when I first started it after bringing it out of storage that parameter was set to 60) You definitely know more about these settings than I do, - is the base frequency supposed to be set to the frequency on the motor data plate as I have done?

[joeavaerage]

Hi,
I can program my own drives but can't say I'm familiar with them all. Matec54, a regular on the forum, seems to have manuals for just
about every VFD ever made.

Having said that most VFDs are pretty similar, biologists call it 'convergent evolution'.

The main idea is that the voltage applied to a motor must be matched to its rated frequency.

Your spindle is rated at 300Hz, so its permissable to apply full voltage, say 230VAC at 300 Hz. At half that
frequency you can only apply half the voltage (approximately) otherwise you risk an over-current fault.
The amount of AC voltage applied to the motor at any given frequency is called the V-F curve.

Its common to give a minimum frequency, it might be a 1/3 or a 1/4 of rated frquency if the spindle is aircooled,
at which the applied voltage is zero. That is effectively stopped. Its common to have the voltage range from
0VAC at min frequency to full voltage (230VAC) at max frequency. You can program the drive to deviate somewhat
from linear but I'm not familiar with any particular reason to do so.

Most factory resets apply parameters that suit 60Hz motors (50Hz in other countries). Thus if you hook a 300Hz motor
to such a drive it will apply full 230VAC at 60Hz when it should apply ( 60 / 300) x 230VAC=46VAC and blow the spindle.
Many a spindle user has blown his new spindle up by hooking it to a VFD that has not had the V-F curve programmed
into it before being run. DON'T DO IT.

Craig

[tom.jelly]

I've got a manual, but the drive is relatively old and the manual is for a few generations newer than the one I have and a lot of it is written like it was poorly translated from Japanese- AND it was the closest thing the manufacturer had. Is it safe to assume that if I enter 300hz as the base frequency that the drive will limit the voltage and/or current to the appropriate amount over the RPM range? I could set a starting and minimum frequency of 4500 or 6000 RPM to be on the safe side if that is advisable.

[joeavaerage]

Hi,
its my understanding the the term 'Base Frequency' is used to set the basic V-F character of the drive.
If the spindle is aircooled the setting a safe minimum frequency is advised.

Craig

[tom.jelly]

It is air cooled. I'll monitor the spindle temp & set 4500 minimums. I guess rigid tapping is out...
thanks!

[joeavaerage]

Hi,
Torque=Power / Speed

Torque= 3700 / (18000 * 2 * PI / 60)
=1.96 Nm

So your spindle has about 2Nm of torque, you'll not be able to do much rigid tapping with that torque anyway, maybe 6mm in steel
or 10mm in aluminum.

Craig

[tom.jelly]

that's actually pretty good, but I guess with this thread milling would be the way to go as I think rigid tapping is an extra cost option on this control anyway..
thanks
tom