[Newbie] Why Use A Switch/button Panel?

I may be confused here. I don't recall your specifying whether your mill currently has a single phase motor or a 3 phase. And is the "service power" you refer to single phase or three phase?

A VFD is used either to convert single phase input power to three phase output power (and by varying the frequency of the output, control the speed of the motor) -or- convert 3 phase 60 Hz input power to a different frequency of 3 phase output power for speed control. In either case, it's only good for driving a three phase motor (OK, there may be ways to drive a single phase motor with a VFD, but IIRC, they tend to significantly reduce motor power).

The circuitry of the VFD is designed with the assumption that the (electronically driven) outputs will be continuously connected to the motor windings. Interrupting the connection, either to start/stop the motor, or to reverse it, will likely overload/fry one or more of the output devices, releasing the magic blue smoke from the VFD. I suppose a VFD could be designed to handle such surges/overloads. But it would add a lot of cost for little or no benefit.

220v single phase service power.
Motor is 3 phase 230/460
 
The change is that you have added a very sophisticated electronic control system to the mix......... the VFD.

The VFD does a lot more than convert single phase to 3 phase, it is not a static or rotary phase converter which could be wired as you suggest.


You can not have a switch between the motor and the VFD, but the motor is going to work fine. Your existing switch reverses the motor by swapping two wires, the VFD does this electronically by inverting the phases. (OK, not exactly inverting, but close enough for this discussion)

You are either going to have to mount the VFD in a convenient location to be able to operate the motor from the keypad, or build a remote control box to run it and hang the VFD on the wall or the back of the mill.


Okay, understanding it now. I usually need to dig deeper into why something works the way it does instead of just doing it "because"

I ran into what I think is a very good price for a new Allen Bradley 800T-4TZ Pushbutton Enclosure 4 Surface Holes on Amazon for $49.99 but the price has gone up a little since then. They are $74.11 +free shipping now.

Jim I think you gave me a list of the part #'s in another thread if I am not mistaken. I have it saved in my email....

Here is the BOM for the control box I built. Automation Direct parts.

Item Code | Unit Price | Quantity

ECX2300-5K $36.50 1
SA110-40SL $13.50 1
GCX1131 $12.50 1
GCX1102 $6.50 1
GCX1300 $9.75 1
E22NS31 $4.50 1
E22NS34 $4.50 1
E22NS38 $4.50 1
ECX2640 $3.50 1

Shipping and Handling : $0.00
Order Total : $95.75
 
Yeah, that empty Allen Bradley 4 hole box seems a bit expensive, it must be die cast metal. I bought a plastic one from Automation Direct, SA110-40SL $13.50

If you use that parts list, it includes the 4 hole box. It's all real industrial hardware but not at Allen Bradley prices. The only thing you need to add is a 6 conductor cable, and a couple of cord grips from Home Depot. The cable could be a chunk of CAT5 Ethernet cable.

https://www.automationdirect.com/adc/Home/Home
 
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The change is that you have added a very sophisticated electronic control system to the mix......... the VFD.


:+1:
This is one possibility that I didn't remember to mention. The original switch could be connected to the VFD control terminals. All of the high voltage wiring would be removed from the switch, and it would be wired into the low voltage control portion of the VFD. This would eliminate the need for a new control station.

I just saw this part of your post.

So if this was done, the mill would operate as if it were just plugged into the wall or would there still need to be other modifications?

I already have the control box so I was planning to go that route, but the info is good to know.
 
Yeah, that empty Allen Bradley 4 hole box seems a bit expensive, it must be die cast metal. I bought a plastic one from Automation Direct, SA110-40SL $13.50

If you use that parts list, it includes the 4 hole box. It's all real industrial hardware but not at Allen Bradley prices. The only thing you need to add is a 6 conductor cable, and a couple of cord grips from Home Depot. The cable could be a chunk of CAT5 Ethernet cable.

https://www.automationdirect.com/adc/Home/Home


Yes it is heavy duty die cast metal. I went with it because everytime I use a plastic box for things like this they end up getting cracked or the screw hole plastic gets stripped out.
I cannot use that BOM, they are all 22mm switches. I need 30mm for my box.
 
So if this was done, the mill would operate as if it were just plugged into the wall or would there still need to be other modifications?

No other modifications would be needed.

I cannot use that BOM, they are all 22mm switches. I need 30mm for my box.

Ebay or Amazon may be the best for that, 30mm switches are generally expensive, around $60 each from the major electrical vendors,
 
Look at the Eaton Cutler Hammer 30 mm switches at AD. They are around $30-40 for 30mm non lit push buttons. You can get a lit switch and use it for a power indicator or get a small LED indicator light. On the speed pot, get a decent 2-4W, anything from 1K to 5K will work. I prefer wire wound for durability, you will need a knob, total round $10-12 on eBay. Turn a a spacer to fit it into the 30mm hole and mount the pot to it. I have done this on a number of builds.So the switches are a bit more, but the speed pot is less.
https://www.automationdirect.com/ad...ators/Eaton_Cutler-Hammer_30mm_(HT800_Series)
 
I found two 30mm C3 Controls switches on eBay, one red, one green. The guy listed them at $15 each+$5 shipping. I made an offer of $8 each+$5 shipping and he accepted. Now I just need a potentiometer, 2 position switch, and legend plates.
 
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