3 phase

[rorie]

Morning folks,

I must be honest, I have been somewhat confused by a lot of the comments so far with terms such as star and delta, VFD, transwave rotary etc. But I have done a lot of reading, so lets see if I have this right. I also have some outstanding questions.

Pillar drill:

As the plate states both 240 and 440v, I can run this using single phase. I change the arrangement from Star to Delta. I need to get a hold of a capacitor, but then I can use a normal 3 pin plug and away I go.

1) Rikrobson – you noted that for this arrangement a VFD would be good. Why? Can the motor not run as noted above without the need to buy anything but a capacitor? Is it only there to allow you to change the speed of your motor?

2) Will the motor run as designed? I have read places that I can be down rating the motor if I am not supplying with 440v…. or is that only the case for motors that do not have a 240 option?

3) How do I work out what size of capacitor I need, and where can I buy one?

Bandsaw:

My band saw is 440v only. This is where I get lost as to my options.


As I will not be using both tools at the same time, what is the best solution?

 

[Wendelspanswick]

Whip the terminal cover off the bandsaw motor connections and take a picture, my mill motor stated 415v but it was actually 240/415v.
The 240v/415v motors are the same power on either voltage, they just draw more current per phase when setup for 240v.

 

[daleyd]

You can't just put a capacitor on the drill motor and make it run, you still need 3 phase but you can either use 440v 3 phase or 240v 3 phase (cheaper).

The bandsaw needs 440 v 3 phase (assuming it can't be connected for 240v operation - as wendelspanswick says above it might be worth digging deeper into whether it can or can't ) , so to my mind the easiest method would be to get hold of a 240 - 440 3 phase inverter, or some means of providing 440v be that a rotary converter or something else.

Or get hold of a 240v 3 phase inverter and swap the bandsaw motor for a 240v compatible one.

 

[Wendelspanswick]

Morning folks,

I must be honest, I have been somewhat confused by a lot of the comments so far with terms such as star and delta, VFD, transwave rotary etc. But I have done a lot of reading, so lets see if I have this right. I also have some outstanding questions.

Pillar drill:

As the plate states both 240 and 440v, I can run this using single phase. I change the arrangement from Star to Delta. I need to get a hold of a capacitor, but then I can use a normal 3 pin plug and away I go.

1) Rikrobson – you noted that for this arrangement a VFD would be good. Why? Can the motor not run as noted above without the need to buy anything but a capacitor? Is it only there to allow you to change the speed of your motor?

2) Will the motor run as designed? I have read places that I can be down rating the motor if I am not supplying with 440v…. or is that only the case for motors that do not have a 240 option?

3) How do I work out what size of capacitor I need, and where can I buy one?

Bandsaw:

My band saw is 440v only. This is where I get lost as to my options.


As I will not be using both tools at the same time, what is the best solution?

Motors are either single phase or 3 phase.
Single phase motors are powered by one phase and the neutral but are not self starting. There are various methods to get them to self start including start windings/capacitors etc but they need a switch to click out the start method.
3 phase motors are powered by 3 phases and are self starting. They come in 240v or 415v versions and also 240v and 415v versions. One of the reasons is that as motors draw more current on starting with large motors it's easier to start them on 415v (less current) and once they are up to speed switch it over to 240v (more current but now upto speed so not drawing as much current as when starting).

It sounds like your pillar drill motor is a 3 phase dual voltage motor. It is not a single phase motor!
You can get a 3 phase motor to run on single phase by sticking a capacitor on it but it will be underpowered, it will sound very rough, it will run hot and the biggest problem is that it won't self start under any sort of load. For that you need another capacitor which you switch in on starting and out when up to speed.

If I was in your position I would check your bandsaw motor to see if it will run on 240v 3 phase, if it does buy a cheap Chinese VFD and power both machines with it with the added benefit of varying the pillar drill speeds with the VFD.
Next option if the bandsaw is 415v only is a static converter which is a 240v to 415v transformer with banks of capacitors to run both machines with.
Or change the motor on the bandsaw to either a single phase or 3 phase 240v motor and use a VFD with it and the pillar drill.

The other option is to modify the 415v motor from star to delta by opening up the casing and seeing if you can find where the 3 windings are joined together and seperate them but it's not for the faint hearted.

 

[Seadog]

If I was in your position I would check your bandsaw motor to see if it will run on 240v 3 phase, if it does buy a cheap Chinese VFD and power both machines with it

I'll just add to this point - You cannot run both motors from a VFD at the same time. They are not designed to do this. You will need a method of connecting one or the other. A plug and socket is the usual way.

 

[rorie]

Ok, i think i am slowly starting to understand.

Here are the plates and insides. First off is the pillar drill

And now the band saw

 

[WorkshopChris]

With either a static or rotary converter you can more or less just plug in your machine and your done, it will operate with all its original controlgear and switching.

With a VFD you need to rewire the machine with the motor direct to the VFD then use the front panel of the VDF to control your machine, maybe configuring it to operate with any guarding and interlocks on the bandsaw.

In theory a VFD should be re programmed when switching between machines. To allow for different motor FLC and start up ramping.

 

[daleyd]

The bandsaw motor doesn't look like it's easily configurable for 240v operation I'm afraid. As said it could be done with some poking around inside but if your not confident in doing this then I wouldn't try. (The drill motor has extra terminals which you connect links to enable either 240 or 440 operation).

So it looks like either:

static or rotary converter to give you a 440 supply and run both machines as they are
change the bandsaw motor for a 240v compatible one and a cheap inverter

 

[arther dailey]

I by trade was an armature winder, niether of those motors will change to single phase. the best and cheapest option is just to buy two replacement single phase motors. I would suggest bandsaw would be better with a capacitor start motor, basically more umph on start up.
although saying that for the past twenty years I have run two three phase motors on a vibrating table (now dont get excited fellas concrete table) with a inverter, I bought this from VIBTEC , if I remember correctly in sussex, it also has the benefit of variable speed. it wasnt cheap but niether was it imported with no long term back up.
try and find some cheap second hand motors if not in a hurry ,it would be cheaper. good luck.

 

[rorie]

You lot are being really helpful - thank you!

Ok, so i think i like the idea of the converter so i can run the tools as they are. A few more questions then;

1) whats the difference between a "240 - 440 3 phase inverter" and a rotary or static converter? Or are they the same thing?
2) Any suggestions as to what ones to get or where to start looking?
3) If i am to explore changing the motors for single phase, where would be a good place to start looking for a new motor?
4) Would there be much resale value in the motors i currently have?

 

[eSCHEn]

I can't help with the first two Rorie but three phase motors unfortunately don't command the same price as singles. It's because people want to do exactly what you're doing and convert to single phase, usually 240V.

Have you tried a "Motors Wanted" advert in the Equipment Wanted sub-section? Lots of exposure there and I remember a few people getting motors when they've asked for them.

 

[Henrik]

Oh, one problem with changing the motors is that the pulleys might not fit. There's a whole load of different pulley centre diameters in use.

Do you have a lathe or similar to modify the pulleys (or make a bushing) if required?

If not, I'm sure someone on here could be coerced into making one, but it's something to keep in mind.

 

[rikrobson]

The two motors are in Star or 400V mode. They are set to use supplied 3 phase from the mains. I'm going to use 200V and 400V instead of the slight differences in voltages that are often quoted due to differing systems
3 phase comes in different voltatges just to make things easy
220V is when the motor is in Delta formation. each of the 3 coils is a side of a trangle and the 3 suplys are conneected to the corners. Therefore the supply voltage is over 1 coil
400 is when the motor is in star. the coils are all joined in the middle to form a Y. (the middle in effect becomes a hidden neutral) the spare ends are connected to the supply. this has the supply voltage going over 2 coils.

the VFDs dont change the voltage, just the frequency. therefore a 200v one will supply 3 phase at 200v from 200v single phase. its 200V phase to phase. therefore the motors need to run at the lower voltage in delta.

the thing to remember is that there is phase to phase and phase to neutral voltages. A single coil can take 200v which is at 200V phase to phase and at 400V phase to neutral, because there are two coils. Each phase is 120 degrees out of sync so if measure the relative AC voltages they will be 400V between each one. if you connect each one to one side of a load then connect all the other ends together that will become your neutral and the voltage over the loads will be 200V. your mains at home is phase to neutral 200V.

The pillar drill can be converted. thats why multiple brass strips and posts. Unfortunately the Bandsaw is not unless you take the motor appart and reconfigure the coils.

A rotary converter will generate 400V 3 phase and will run both machines thay are only 1/2 HP motors. A static converter will do the same.

So your options are:

1. replace both motors with single phase motors
2. run a static converter to power both
3. run a rotory converter to power both
4. change the motor on the bandsaw to a 200/400V motor and run both of separate VFDs

 

[slim_boy_fat]

That Hoover motor - built in Scotland from girders.

 

[rorie]

great! So i am all sorted now.... i think!

I am going to keep the motors as they are, because i think this is the cheapest (and easies) way given the motors are so small and i can get a really small converter.

I will read up tonight on the differences between Static and Rotory converters and then explore my various options for buying.

Thank you very much to everybody for their input. I may be back later with some further questions, but for now, i know what i need to look for.

 

[rorie]

Oh, sorry, another question!

Is it worth considering one of the phase converters from Drives Direct, or is that a bit overkill for my needs? I gave him a call as i thought they did static and rotary phase converters, but they no longer do. He said they used to sell the clark converters in my first post, but they are a heap of rubbish. His recommendation was to get one of their D2 units at a cost of around 350.... nearer 400 with postage....

 

[arther dailey]

Rick r is correct, that will teach me to look at pics properly ! so thankyou Rick, yes the pillar drill can be run on 240 volt single phase , just reset links on connection board to suit, you will probably find diagram inside cover you have taken off.
So the simplest route now would be to google vibtec and get a price from them for inverter, and see how cost effective that would be,rotary coverters take up more space and generally are used where a lot of power is needed, so I would say inverter is best option, or try and get replacement single phase motor for b.saw.
Yes I got it wrong and am big enough to say and thankyou again Rick,good catch. good luck either way. Arther

 

[Wendelspanswick]

Rick r is correct, that will teach me to look at pics properly ! so thankyou Rick, yes the pillar drill can be run on 240 volt single phase , just reset links on connection board to suit, you will probably find diagram inside cover you have taken off.
So the simplest route now would be to google vibtec and get a price from them for inverter, and see how cost effective that would be,rotary coverters take up more space and generally are used where a lot of power is needed, so I would say inverter is best option, or try and get replacement single phase motor for b.saw.
Yes I got it wrong and am big enough to say and thankyou again Rick,good catch. good luck either way. Arther

You still got it wrong, by changing the links on the pillar drill motor you are changing the voltage from 415 to 230 but it will still need 3 phases!

 

[arther dailey]

I knew that I should have stayed in the pit today.....

 

[arther dailey]

Now I have stopped laughing (at myself) yes even more reason to get an inverter . must go to specsavers.....