Replacing guts with VFD

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CoDef911

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Hopefully I've researched enough to have the proper answer, but I'm hesitant enough so I'll ask to be sure.
ENCO 110-1351- WAS working, until I decided to "fix" it. By fix it, I mean removed nearly everything inside the electrical panel chasing down an issue.
End result- bad contactor. It was stuck pulled in (melted contacts). Found the offending item on Amazon for $18. So, as always, ordered 3. If one goes bad, the others aren't far behind. On a 25 year old machine, I'd rather be safe than sorry, especially for $60.
Now. As I patiently await the mailman, I had a thought.
Why not ditch the switching gear with a VFD? The one I installed yesterday was so easy, and it appears there's nearly infinite control, wouldn't it make sense to wire direct to the motor with a new VFD? Hypothetically, removing all the contactors, relays, heating relay, and transformer simplifies the electrical. The VFD could control forward and reverse, the speeds are controlled by voltage/hertz.
Just wondering if others have done the same just to simplify the system. As I'm still VERY new to this, I don't want to be the new guy who rushes headfirst into the fray, only to discover that others have made the same decisions, and failed.
Read multiple threads where guys have done this same thing, (albeit different machines), but in my small mind, having a VFD mounted after the plug, and before the motor would negate all the other controls.
VFD should control forward/reverse. Simple E-Stop could stop power. Don't know if I could low voltage control with the apron switch or not, but maybe....
Yes? No? Leave it alone, and just reinstall the contactor that'll be here today?
I'm just thinking that a $90 VFD could alleviate any future wiring issues.
 
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If that's the case, then I'm way off base. The reason I was contemplating the VFD, is highlighted below.
Am I reading too much into it?
My motor data plate is also below.
1.5hp 110/220
If my assumptions are incorrect, then I'm all ears. Again, this is all new to me, so it won't be the first time I'm wrong
 

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Single phase motors which have a start winding have a problem with a VFD because when the motor is slowed below a certain point, the centrifugal switch kicks in and runs current through the start winding. Start windings are designed to deliver high torque over a brief period of time and cannot sustain that current for very long without overheating.

One fix is to remove the start capacitor and centrifugal switch from the circuit and treat the start winding as another leg of a three phase motor. The VFD settings are adjusted to limit the current through that winding preventing overheating and hopefully to correct the phase error.

From what I have seen, it seems that the single phase out VFD are fairly popular with controlling large ventilation fans. A fan has a very low torque requirement at low speeds, unlike a lathe or mill and I don;'t know the what the impact would be on a lathe or mill.
 
CoDef911 said:
Hopefully I've researched enough to have the proper answer, but I'm hesitant enough so I'll ask to be sure.
ENCO 110-1351- WAS working, until I decided to "fix" it. By fix it, I mean removed nearly everything inside the electrical panel chasing down an issue.
End result- bad contactor. It was stuck pulled in (melted contacts). Found the offending item on Amazon for $18. So, as always, ordered 3. If one goes bad, the others aren't far behind. On a 25 year old machine, I'd rather be safe than sorry, especially for $60.
Now. As I patiently await the mailman, I had a thought.
Why not ditch the switching gear with a VFD? The one I installed yesterday was so easy, and it appears there's nearly infinite control, wouldn't it make sense to wire direct to the motor with a new VFD? Hypothetically, removing all the contactors, relays, heating relay, and transformer simplifies the electrical. The VFD could control forward and reverse, the speeds are controlled by voltage/hertz.
Just wondering if others have done the same just to simplify the system. As I'm still VERY new to this, I don't want to be the new guy who rushes headfirst into the fray, only to discover that others have made the same decisions, and failed.
Read multiple threads where guys have done this same thing, (albeit different machines), but in my small mind, having a VFD mounted after the plug, and before the motor would negate all the other controls.
VFD should control forward/reverse. Simple E-Stop could stop power. Don't know if I could low voltage control with the apron switch or not, but maybe....
Yes? No? Leave it alone, and just reinstall the contactor that'll be here today?
I'm just thinking that a $90 VFD could alleviate any future wiring issues.
Click to expand...
this may help

www.hobby-machinist.com

VFD Retrofit - Shenwai SW900B 1236 Lathe

I finally got around to doing the retrofit on my Shenwai SW900B 1236 lathe it came with a 1.5 hp(ish) 115v/220v single phase motor, as the OEM powerplant. i had to change that :grin: i surfed the site that sounds a lot like E-PAY, and found an inverter rated 2 hp motor by Marathon, very...
www.hobby-machinist.com www.hobby-machinist.com
 
That looks very similar to my setup. So, after reading some prior comments, (and the contactors are MIA) I got a super bad case of ADD today. Went full throttle on a different project, but it required me to do some organizing.
In that cleanup, I managed to find 3, yes 3 other motors in my pile. And they are all 3 phase!!
Now. None of them have the proper pulley, but I might be able to fab something up to work.
I shall update tomorrow with what I’ve found.
In the process of all this stuff, I'm fighting the city over a sign violation. They busted me for a sign I’ve had on my building since 2018. It’s only an issue now because I refused to allow the city code enforcement “official” to extort my gun store. So now she writes us up for everything. I’ll be dealing with the building department for most of the day I’m sure.
Thank you for the guidance thus far. I really do appreciate it.
 
As long as the part is on the way, you might as well install it. That will give you lots of time to think it over.
The VFD, while nice, can have problems too.
 
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