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-   -   DC or AC motor? (http://www.knifenetwork.com/forum/showthread.php?t=69002)

M&J 03-24-2020 01:43 AM

DC or AC motor?
 
The 1.5 HP DC Baldor went down. The commutator had all kinds of carbon fouling so I took the back end apart to clean and re-assembled. Nada. Thought the VS controller was bad but it tested fine. :(

Considering this DC Leeson as a replacement since I can still use the VS controller.
http://www.electricmotorwholesale.com/LEESON-109096/

Scott at Tru Grit suggested the AC over the DC motors but I'm unfamiliar with those types...school me?

R K 04-14-2020 08:14 PM

208 3ph with VFD
 
For many years, I used a 2HP DC Baldor on my knife grinder.. Now I use a 3hp, 3ph 208V AC motor with a VFD (Variable Freq Drive)
The AC motor with a VFD is light years ahead of the DC motor/controller.
The DC only has full power at full speed, as you decrease speed you decrease power because you are decreasing speed by decreasing voltage.
The AC motor speed is controlled by varying the 3 phase frequency, thus you loose very little if any power as you decrease speed.
I have two knife grinders in my shop and both use the 208V AC motors with the VFD controllers. I can't imagine ever going back to DC.
A couple years ago, I found seven Baldor DC controllers and two 2HP Baldor motors at the dump, as it turns out, a packing plant near here was retrofitting with the new 208V AC units. Now I use the DC units on my disc sanders.
IMHO, I wouldn't even consider a DC motor for a grinder now!
RK

M&J 04-18-2020 02:06 PM

The controller which I originally thought was dead still functions. I'd called Scott at Tru Grit and we discussed the set-up. Going AC would be cool yet in these times more $ than I want to spend at ~$1,200. A new Leeson 1HP DC motor was ~$450.


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