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Author Topic: Analog servo spindle drive questions.  (Read 1658 times)

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Analog servo spindle drive questions.
« on: March 21, 2015, 10:49:50 AM »
I have purchased an AMC BE25A20AC Analog Servo Drive to replace the KB SCR speed control on my lathe.  Got decent deal on it and want to install it place of the KB to stabilize the spindle speed.  I have a week before it arrives to bone-up on the installation.

I plan to leave the existing Baldor ¾ hp PM DC motor & its belt drive system in place.  I had previously installed a Servo-Tek 7v per1000 rpm tach generator on the Baldor and plan to use it for the velocity input to the drive.  I have no plans for spindle positioning with the drive at this time, just accurate speed control.

Baldor says my motor’s armature inductance is 7.098 mH at 90V/.75HP and the AMC manual says “Minimum Load Inductance, Line to Line” is 250µH. 7.098 mH is way more than 250µH so I should be OK with that motor yes? Or do I have it backward?  I have very little understanding of inductance figures.

The drive’s speed & direction is controlled by a +/- 10V input which my CNC4PC C11 happily provides the positive direction for, but not the negative. I’ll need to reverse the C11’s 0-10V output polarity via DPDT relay for reverse spindle direction commands, yes? I already have a reverse-polarity relay wired up to reverse the tach/gen input signal to the existing KBMM drive so it should be easy to rewire it if that’s what I need to do with the servo drive.

Even though the drive is described as being brushless type, the manual says it can be used with single phase brushed motors by switching the commutation DIP switch to 60-degree phasing.  It’s unclear though, which of the 3 (A, B & C) motor output terminals to use.  Hopefully it either doesn’t matter or I’ve missed it in the manual & can find it later.

I was able to attach the drive basic manual but the one with more detail is too big?
Milton from Tennessee ya'll.

Offline Hood

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Re: Analog servo spindle drive questions.
« Reply #1 on: March 21, 2015, 06:04:52 PM »
Yes you will have to invert the signal with a DPDT relay, I did that on the CSMIO/IP-S at first, it was before they had the Step/Dir spindle option.

Do you have a link to the full manual?

Hood
Re: Analog servo spindle drive questions.
« Reply #2 on: March 21, 2015, 08:51:59 PM »
Oops, missed your post.  SWMBO went on an errand & I laid down for quick nap...4 hours ago. ;D

Here's the manual.  It covers a range of drives, mine is the brushless type with a built-in power supply.
http://www.a-m-c.com/download/manual/AMC_AnalogDrives_InstallManual.pdf
Milton from Tennessee ya'll.

Offline Hood

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Re: Analog servo spindle drive questions.
« Reply #3 on: March 22, 2015, 05:01:18 AM »
Seems A and B are used if you use the 60 degree method or if you tie one hall to Gnd then you have to look at the table to see which ones.
Hood
Re: Analog servo spindle drive questions.
« Reply #4 on: March 22, 2015, 07:36:49 AM »
Great, thanks!  Funny,  I read that part but totally missed that sentence.  Since I don't have a Halls device on the motor, I must have mentally skipped over that part.
Milton from Tennessee ya'll.