Got My First Machine!

Yup! ;) But you still need to deal with the 230-460 issue.
 
Ok I think I'm getting somewhere lol so would it work if I ran a roto phase to a 3phase step up transformer so then I'd have 3 phase 230 in and 3phase 460 out? Then just ran that to the L1, L2 and L3 terminals on the fuses?
 
Izzy said:
Ok I think I'm getting somewhere lol so would it work if I ran a roto phase to a 3phase step up transformer so then I'd have 3 phase 230 in and 3phase 460 out? Then just ran that to the L1, L2 and L3 terminals on the fuses?
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Yes
 
Yes.........But, by the time you buy a RCP and a 3 phase transformer you will have more $$$$$ into it than just getting the motor to run on 230, and buy a VFD.
 
Awesome! And if I went that route I wouldn't have to touch anything else just turn it on and make chips right? If I can't find the other 6 connections in the motor I'll probably go down that route as I've got a line on a rpc and transformer.
I know Ive been annoying with the simple questions and all but I appreciate y'all walkin me through this!
 
talvare said:
Izzy,

I was just looking at the schematics that you e-mailed to me. What you could do is get a VFD with 230v single phase input and 460V three phase output rated to operate your 4 HP motor. Wire the 460V three phase output from the VFD to the tops of the three fuses designated as FU-2 in your panel (you would discard the existing wiring to and from those fuses). Then disconnect the three wires (T1,T2 & T3) from the bottom heater connections on the magnetic starter and connect them to the bottom side of the FU-2 fuses. This should put your VFD power directly to the spindle motor and utilize the existing fuses to protect the motor. Then you would disconnect the existing wires from the tops of the fuses designated as FU-3 and connect a 230V single phase power source to the top side of these fuses. Then you just need to re-do the primary side wiring on the control transformer and connect it for the 230V input as shown on the transformer. I think that should work. I'll give it some more thought to make sure I'm not overlooking something.

Ted
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that sounds easy enough hopefully I can find the other 6 wires so I can go down this route it seems cheaper and quicker as far as getting it running goes if I can't find the other 6 wires then a rpc and transformer will be my next option I was quoted 600 for the rpc and transformer together
 
$600 is a pretty good price, so that is a good option.
 
Yea it's not too bad I'm still gonna try for the 230vac conversion if I can that seems like the cheapest and most reliable option but it's always good to have a back up right!?
 
Izzy said:
Ok ok I think I understand, so since the vfd doesn't put out a consistent voltage and frequency it would mess with the rest of the electrical components as they need one constant voltage to work correct? So that means that I could just run 3 phase power from a rpc to those fuses in that picture then I wouldn't have to touch anything correct?
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You probably could configure the VFD to just act as a constant voltage, constant frequency three phase source (possibly with some additional components) but it would be a waste.
 
So maybe a few thing to clarify.
  1. I am not aware of any VFDs that have 230VAC in (single or three phase) that will regenerate it to 460VAC. Above 3Hp, most VFD are 3 phase input, to use on 230VAC single phase you need to double the VFD rating. So in this case, something like a 7.5 or 10Hp VFD to run a 4Hp motor, pricey for a decent VFD. It is not recommended to use a VFD as a fixed frequency 3 phase output to a machine when there are other components systems other than a motor; i.e. transformers DC drives, etc. Most likely both will be damaged. There are fixed phase solid state converters, they are very expensive.
  2. Even if the machine was wired for 230 VAC and you did not have the motor issue (it can be rewired to 230VAC), you still could not run it off a VFD wired directly to the machine, the cost of a single phase in to 3 phase out in the 4-5 Hp, you would be looking at a similar cost of an RPC. At 3Hp and below a VFD for a single machine is more economical.
  3. If you where to use a VFD, it would be wired directly to the motor, and would be separate form the rest of the powered components. It can be done to just run the motor, but it makes a lot of the controls and load meter useless. So you are talking a lot of rewiring and new switches. Most of the machine drives and electronics operate off of 115VAC output from the large 2kVA transformer, the transformer could be wired for 230VAC and only is connected to L1 and L3 (so it is essentially single phase). So a total rewire and new controls.
  4. A VFD since it is a direct connect to the motor does not require output fusing, but should have input fusing. More wiring and costs, VFDs use high speed fuses which can be expensive, otherwise use a breaker
  5. A static converter is a band-aid, the spindle motor would lose about 1/2 of its rated Hp, the other components would not care because they essentially run off of single phase.
  6. If the machine is rewired for 230VAC running off a RPC, you still need to change the fusing and the motor thermal/current relays.
  7. A VFD in my view doesn't add anything in this picture, mostly because there are lots of subsystems, you do not need the speed control, or the other features one uses on VFD. I have built a number of VFD systems, and I am a proponent of them, but this is one situation where I do not think it is a good fit unless you redo the whole system.

So we are back to what is the easiest way to be plug and play (and probably the least expensive route unless the motor can easily be rewired). A RPC and then a step up transformer going to 460VAC, this is what I most commonly see if it is not a simple rewiring of the motor. Brain fart on the step down transformer and voltages when using it to back feed. So your voltage would drop a bit, but that is not an issue, given line voltages tend to be a bit higher these days it would be fine. These are very common on the used market. If you opt not to use a step up or back feed a step down transformer, next would be taking the motor to a shop and seeing if they can rewire it to 230VAC, this is not something obvious that you will find the wires and know how to reconfigure them. A motor shop can asses and hopefully bring the correct wires out in the proper fashion. Then change the fuses, wiring to the transformers and thermal relays. Once again, you need to be comfortable, and need to methodically trace the power in and makes sure it is rewired/fused correctly. If the fuses are on the output side (secondary) of a transformer, they would not be changed.

If you were quoted $600 for an RPC and step-up transformer for this size load, I would jump on that in a heartbeat.
 
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