change 3 phase to single phase via a rotary converter

[svengali]

Gents: I own an old style hardinge dv 59 lathe...It has a old 3phase motor...I need to know the method to use a static or rotary converter to be able to use the 3 phase motor to single phase......The motor is a 3/4 hp and if need be I can send you a pic of the electrical box on the lathe so you can show me how to connect the converter so to make the 3rd leg join....The motor is a two speed job so it makes it a little more complicated...Thank you

 

[jbartos]

Suggestion: Nowadays, the AC-DC-AC converters change the single phase power supply to three phase power supply.
Visit

http://www.phaseconverter.com/static-converter.html

etc. for more info

 

[OperaHouse]

Agree that these $200 variable speed drives is a good way to go. Still, I sense that you are a good ole boy that wants to go cheap. You can use the motor on the lathe to be its own 3 phase converter. Just connect two legs of the three phase to the line. If the lathe has a control transformer, choose the two that the transformer connects to. Connect the third leg to a 100 uf capacitor and the other side of the capacitor to one of the legs connected to power. Reversing to the other leg changes direction. Find a motor capacitor from an old air onditioner etc (one or more in parallel) that has a metal case. You will destroy the ones in a plastic case. Your 3/4 hp motor will now only be able to produce about 1/2 max but you should be fine for most projects. Never start motor with a load ie not suitable for things like compressors.

 

[jraef]

As a wood turner I can attest to the unsuitability of the above post for your application. Lathes are torque-hogs in that the motor needs to maintain a minimum torque in order to avoid slowing down and affecting tool cut. This is true for both wood and metal lathes. Dropping your motor torque output by 50% will render it relatively useless in that application unless you are making pen barrels or brass chess pieces, in which case you bought too much lathe!

3/4 HP is a typical size for this and is very suitable for applying a VFD (inverter drive) to it. Almost all small ones now will take a 1 phase input and give you a 3 phase output. you may never need the variable speed feature but it will alwways be there if you do. My only suggestion here is to oversize the VFD a little, i.e. buy at least a 1HP drive for that motor, maybe even 1 1/2. You won't regret it.



Quando Omni Flunkus Moritati

 

[skills]

Both suggestions are good and will work. The cap. might even work down to 15uf but the 100uf is fine for 1 hp. Hitachi does make a small drive that will do this that is about $175.

http://www.automationdirect.com

has these. The L100 or the SJ100 are both suitable for apps like this.

 

[OperaHouse]

Gee, my wood lathe is only 1/3hp. It is a good point as to what to do if you have a need for the full motor rating. With a spare 1 hp 3 phase motor, you can use the same method to generate three phase. The combination of these two motors would give you full power on the lathe. You could hang this setup on the wall to get it out of the way. These setups are not usually recommended for "transformer operated" 3 phase devices. Some replace the capacitor with a single phase motor coupled to the three phase. Just make sure the motors are the same speed or the motor is only used to spin it up. I've even just used a rope to first get the motor spinning. I have a 3/4 hp dust collector that I think only has a 30-40 uf cap on it. Been years since I opened it up.

 

[jbartos]

Suggestion: If nature of work being performed by the lathe is such that there are frequent starts stops and speed reversals, e.g. the lathe has turret, then the proper motor control is needed as well as heavy service duty motor.

 

[svengali]

Ok all yoiu nice people who answered my question on how to change 3 phase on my dv 59 hardinge lathe...I discussed this with another engineer who has had experience in this field....Being as the metal lathe has a 3/4 hp two speed motor, I would have to use a VFD to run this lathe...Of course my motor is 220 single phase.....I contacted a company that makes a controller,, The drive is mfg by ABB their series #140 rated at 1 hp....However they are asking $375 for their VFD....My friend (who i lost contact with) got a 4hp unit for the same price......Any one know of another make that isn't so high priced????Svengali

 

[jbartos]

Suggestion: Check with

http://www.actechdrives.com

 

[ScottyUK]

Hi Svengali,

You probably have sorted this while I have been on vacation, but if your question still stands, Telemecanique in Europe (Schneider Group - maybe Square D in the US?) make a low-cost range of drives under the name 'Altivar'. These aren't especially sophisticated drives but I have used them for running a woodworking planer-thicknesser with a 2.2kW main spindle motor and .75kW feed motor with no issue. The user was very happy with the results and the cost of the drives.


Scotty.