Got My First Machine!

A few things that you might consider. There is no difference in electricity costs if you use 230 vs step up to 460VAC, the efficiency of transformers is on the order of 90-95%. The machine has a 4Hp motor which is more than adequate, most of us get by with 1-3Hp machines with no issues. A 5Hp would be overkill, let alone the added weight, and then there is the fitment and the cost. If you are looking at a replacement motor, heaters, fuses and maybe someone to check it when you are done, it will get pricey. Not saying it isn't the correct route, but if one is not familiar/comfortable with converting to the low voltage setup, I would recommend a 230 to 460VAC 3 phase transformer.

If you want to pursue the 230VAC conversion, I would first bring the motor to a motor shop and see what would be involved in converting to 230V. Most of the control systems/drives, run off of 120VAC secondary, so in these cases the fusing if on the output side would not be changed. The transformers have taps and would need different jumpers for 230V operation. Since this is an integrated machine with a number of control systems and drives, there is a little more to think about in switching voltages. I would price out the options, a 3 phase step up transformer in the 5-7.5KVA range in the used market would be around 300-$500, shipping could also be costly. You also have the cost of an RPC. So I would think the first step is having the motor looked at.
 
It seems to me like either route is going to be pricey I'll just have to price out some parts and compare the 2.
So if I understand correctly it won't make a difference in how it runs physically and cost wise whether I run it 230 or 460 only difference will be the start up cost? I'll call some motor shops around town and some use transformer dealers and see what I come up with
@JimDawson thanks for the link! Mississauga is only an hour or 2 from where I live!
 
Izzy said:
So if I understand correctly it won't make a difference in how it runs physically and cost wise whether I run it 230 or 460 only difference will be the start up cost
Click to expand...
Correct. It really comes down to the ability to convert the motor to 230V and cost of the conversion to 230V vs. the cost of a step-up transformer. There should be used step up/step down transformers at reasonable prices, but it may take some time and any shipping costs. Some people will use a step down transformer and back feed the 230VAC secondary to get 460/480VAC out of the primary, there can be some issues with this approach. Typically the wingdings are designed to account for a 5-6% voltage drop in the conversion, so they are not an exact 2:1 ratio for something like a 460 to 230VAC transformer. By back feeding the secondary, you might see something like 480VAC instead of 460VAC. Most machines can operate in a +/-5% voltage window, and there should be some voltage drop in the wiring, etc. The larger the transformer, the larger the inrush current when it becomes initially energized, this can trip breakers, so I would not significantly oversize the transformer (something in the 5-12kVA range). Others may have more detailed comments and experience in this area.
 

Attachments

  • Back Feeding Transformers.pdf
    33.2 KB · Views: 6
Well I was just quoted $650 for the re-wind.... I'm gonna be 600 deep atleast if I get a used step up transformer and an RPC... Another option would be to sell this motor to offset the cost of buying a 230 volt moto hmmmm....
 
Your motor might not need a full rewind. I suspect that it has been rewound before and maybe they just didn't bring out all of the leads. It might be worth a trip over to the motor shop and let them take a look at it. It may just be simple as bringing the leads out which should not cost anywhere near $650
 
mksj said:
Typically the wingdings are designed to account for a 5-6% voltage drop in the conversion, so they are not an exact 2:1 ratio for something like a 460 to 230VAC transformer. By back feeding the secondary, you might see something like 480VAC instead of 460VAC.
Click to expand...
Other way around. In order to get 240 out with 480 in while accounting for full load voltage drop the turns ratio is slightly less than 2:1. This means that when you turn it around the no load output voltage will be slightly less than twice the input voltage. Integral horsepower motors are generally pretty tolerant of voltage variations, though, especially when never started under load and rarely (if ever) run at anything like full load.

You might consider a single-phase transformer and a "static converter" (which is really a way to turn a three-phase motor into a capacitor-start capacitor-run single phase motor).
 
The guy I got it from was saying to run it on static converters but I never looked into those as much as I have RPCs and such, ive contacted a few local guys and ive found transformer and vfd combos for about 600 I'll have to continue my tear down of the motor to see if the leads are tucked away or not. Thanks for the help so far guys!
 
Izzy said:
The guy I got it from was saying to run it on static converters but I never looked into those as much as I have RPCs and such, ive contacted a few local guys and ive found transformer and vfd combos for about 600 I'll have to continue my tear down of the motor to see if the leads are tucked away or not. Thanks for the help so far guys!
Click to expand...
Unless you can find the other leads and reconnect for 240 I'd suggest going with the VFD.
 
I'm gonna dig into the motor a little more and see what I can find, I'm just having trouble getting the bottom half of the pulley out...
 
You must log in or register to reply here.
Back
Top