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Author Topic: VFD recommendation  (Read 8034 times)

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Offline Graham Waterworth

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VFD recommendation
« on: August 05, 2006, 07:09:11 PM »
Hi All,

I am looking for A VFD unit to drive a .75HP DC motor. Any recommendations for use with Mach3.

Graham.
Without engineers the world stops

Offline chad

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Re: VFD recommendation
« Reply #1 on: August 05, 2006, 10:38:28 PM »
I have a baldor 5 hp H2 on my knee mill, It has been totally rock solid, it also has a nice open loop vector mode that keeps a pretty constant torque or speed.

Chad

Hood

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Re: VFD recommendation
« Reply #2 on: August 06, 2006, 02:01:03 AM »
I am probably showing my ignorance here, but I have plenty of it to give away ;) , are VFD's not just  for AC motors.
Hood

Offline Graham Waterworth

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Re: VFD recommendation
« Reply #3 on: August 06, 2006, 05:27:49 AM »
Hi Hood,

not according to the drives warehouse web site, they list VFD's for both AC and DC motors.

driveswarehouse.com/index.php?prop_3=1&osCsid=957229ca83b9a9a30bc0d6706ec3cd49&cPath=149&filter=1

Graham.
« Last Edit: February 19, 2013, 12:44:54 PM by Chaoticone »
Without engineers the world stops

Hood

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Re: VFD recommendation
« Reply #4 on: August 06, 2006, 05:32:49 AM »
told you i would show my ignorance ;) always thought DC speed controllers were called variators or something along these lines.  Always thought frequency was an AC thing.
 As they say every day is a school day and I think I need to attend more frequently.

Hood

Offline Graham Waterworth

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Re: VFD recommendation
« Reply #5 on: August 06, 2006, 05:36:56 AM »
Is that attend more frequently or with more varied frequency  ;)

Graham.
Without engineers the world stops

Hood

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Re: VFD recommendation
« Reply #6 on: August 06, 2006, 05:40:43 AM »
lol
probably with more frequency rather than just varying it ;) Actually just had a look at your link and I think I may be correct. VFD are for AC and vary the frequency to achieve speed control, think DC varies the voltage but will do some more reading so I dont make a total plonker out of myself the next time.

Hood

Offline Graham Waterworth

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Re: VFD recommendation
« Reply #7 on: August 06, 2006, 06:03:37 AM »
You may be correct, I think they are just listing the two types under one heading, I just clicked the VFD link and thats the page it gave me.

The range is so vast that I don't know what I want or need to give me the best results.

All I want is to drive the unit from mach3 with as little extra gubbins as possible.

The motor I have is 180 VDC, 850 watt, 5000 rpm, 5.2 adc

Any ideas on what I need.

Graham.
Without engineers the world stops

Hood

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Re: VFD recommendation
« Reply #8 on: August 06, 2006, 06:58:58 AM »
Sorry dont have any experience with DC motors :(
 Finding a speed controller that will  power your motor per your specs should be easy enough but finding the most suitable is beyond me.
 There is a good section for VFD, Phase converters etc on http://www.practicalmachinist.com/ubb/ultimatebb.php/forum/3.html lots of knowledeable guys there.
Hood

Offline chad

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Re: VFD recommendation
« Reply #9 on: August 06, 2006, 02:16:14 PM »
HI Graham,

I didn't read your post very well ( it was late), VFD is usually associated with AC motors. My baldor vfd won't do anything for you. I think it is going to be hard to find what you want. I did a little digging and most of the DC drives i can find in that voltage and hp rating are intended to run motors with field coils. I haven't personally dealt with these but from what i have been reading it looks like the filed coils are basically replacing the magnets in a permanent magnet brush motor. I don't think these will work for your motor.

Can i ask what you are using these on? My guess is is a lathe. So based on that guess i am going assume you want to do some CSS , perhaps some ridgid tapping, or maybe just get better results with thread cutting.  Again just guessing.

If you are primarily going after CSS then i would suggest you find a VFD with pwm input,  open loop vector control and single to three phase converter built in and replace your dc motor with a different 3 phase AC motor.

Tell me a little more about what this motor is on.  How many wires coming off this motor , is there a variable speed control on it now?

Is it an Asian mini mill or lathe with a speed control?  if so this might work for you ..
http://www.homanndesigns.com/DigiSpeedXLDeal.html

Chad