3 phase

[rorie]

Hi folks,

I have just been offered some tools (band saw and pillar drill) for a great price, but they are 3 phase.
What is the easiest (and cheapest) way for me to get 3 phase?

I have seen the like of this. Any good? Is there a better way of getting 3 phase into a domestic set up?

https://www.machinemart.co.uk/p/pc-20-2hp-phase-converter/

 

[slim_boy_fat]

It's prob the best way, but others on here have reported success with Chinese ones off the 'Bay. A search should find their input.

 

[Mattdiy]

Seems like a good solution. Alternatively you could buy a higher capacity drive off eBay provided the motors can be wired in delta as the cheaper drives only have 220v three phase output.

 

[brightspark]

the one above will do what u want it to do without having to swap the wiring links to 240 v 3 -phase and easy to operate

 

[brightspark]

From looking at the manual for the clarke unit, it appears to be simply a switched set of capacitors with a step-up transformer...

Seems very expensive for that, especially considering how reliable the cheap import vfd converters are.

that's why its called static

 

[Seadog]

It's a bodge really. This type of converter doesn't give true 3-phase so you'll effectively be down-rating the motor. I'm assuming the machines have 415v motors since the PC20 is 230v to 415v. The equivalent VFD would be very expensive (c£1000, similar to a Transwave rotary) and is only suitable for running one machine at a time.

 

[rikrobson]

What are the motors power and voltage?
I'd expect them to be 220/415V where Delta is the lower voltage and Star the higher. If this so a VFD would do. I got a 22V 1.5KW for £80 delivered. ordered on ebay Saturday and UPS delivered from Germany on the Tuesday Morning.

I run the Boxford's 900W motor in Delta via the VFD.

There is a little bit of setting up, but they run fine, with the added benefit of speed control

 

[zzr1200]

It's prob the best way, but others on here have reported success with Chinese ones off the 'Bay. A search should find their input.

I use a 1.5 Kw Chinese inverter (240 x 3) to power my Harrison L6 Lathe, it works fine.
If the motors have suitable change over links go for it.

I also use a Transwave 2.2 Kw rotary phase converter for my 415 volt mill.

If I needed another phase inverter I would consider buying a higher capacity one and using it as a 3 phase (240 x 3) workshop power source.

 

[rikrobson]

If I needed another phase inverter I would consider buying a higher capacity one and using it as a 3 phase (240 x 3) workshop power source.

They are not really designed for that. You really need to tune them to the motor as they are motor drivers, not a Power supply. So its one per motor

 

[zzr1200]

They are not really designed for that. You really need to tune them to the motor as they are motor drivers, not a Power supply. So its one per motor

My inverter arrived "Pretuned" for a 1.5Kw motor (2hp) so it was a simple case of wire it up and use it.

I can understand it wouldn't power a 2.2Kw motor (3hp)), but a 3hp inverter will happily run a 2hp motor.

 

[daleyd]

My inverter arrived "Pretuned" for a 1.5Kw motor (2hp) so it was a simple case of wire it up and use it.

I can understand it wouldn't power a 2.2Kw motor (3hp)), but a 3hp inverter will happily run a 2hp motor.

The problem with doing this is things like full load current, max speed, number of poles etc are programmed for each motor, so without changing the parameters you "could" (unlikely I know) damage the motor. Some inverters have different parameter sets so you can easily swap between them.

 

[rorie]

Thanks very much for all the replies. Some of this is a bit over my head to be honest!

From what i understand, if i go for the one i linked, it will do the job, but as it's running at half the voltage, the machines won't run as designed? Is this then half the speed... or torque...?

I am really not interested in spending too much money (i.e. the £1k mark!). I suppose i'll need to look at the motor on the machine to see what hp i need?

Can anybody give me some links to other inverters i should consider? I had a look most of last night, but not knowing what i am looking at makes things tricky!!

The other option i found was at the link below. Would this be a better option (although pushing it price wise)

http://www.drivesdirect.co.uk/Products/Digital_Inverters240_415.htm

 

[daleyd]

If you can take a look on the motors and see if they have 230v option on the nameplate, then you can get a cheap vfd off eBay as you won't need the 415v. Once you get to supplying true 415v that's where it gets expensive.

 

[piman]

Hello Rorie,

the first thing to check is the nameplate of your motors to see if they will run at 220v three phase (It will just say 415 if they are not), if so there is the choice of changing the motors for single phase or as said a VFD 240 to 415, which from Drives DIrect will be in the order of £300 to £400 depending on size, a bit over twice the price of a new single phase motor. However as it is unlikely that you will be running both together, you could use one VFD for both machines via a plug and socket and have the benefit of variable speed if you want.
If the motors are dual voltage then a cheaper 240 to 220 3 phase VFD is the best answer.

Alec

 

[zzr1200]

The problem with doing this is things like full load current, max speed, number of poles etc are programmed for each motor, so without changing the parameters you "could" (unlikely I know) damage the motor. Some inverters have different parameter sets so you can easily swap between them.

Most workshop machine tools are 1440 rpm (lathes and drills). My Harrison was converted to run on 240 x 3 and is connected with a 4 pin 3 phase plug/socket. If I purchased another 240 x 3 machine I'd just fit the right plug to connect to the inverter (provided the motor doesn't excess the inverters capacity)

My 415 volt supply is from a Transwave Rotary fitted with a 5 pin socket, which will run both 2 pole (2800 rpm) and 4 pole (1400 rpm) motors.

My mill has a two speed motor and the 8 inch bench grinder is a 415, 2800 rpm motor, so are fitted with 5 pin plugs..

So with a bit of planning all all types of motor can be used.

 

[daleyd]

Most workshop machine tools are 1440 rpm (lathes and drills). My Harrison was converted to run on 240 x 3 and is connected with a 4 pin 3 phase plug/socket. If I purchased another 240 x 3 machine I'd just fit the right plug to connect to the inverter (provided the motor doesn't excess the inverters capacity)

My 415 volt supply is from a Transwave Rotary fitted with a 5 pin socket, which will run both 2 pole (2800 rpm) and 4 pole (1400 rpm) motors.

My mill has a two speed motor and the 8 inch bench grinder is a 415, 2800 rpm motor, so are fitted with 5 pin plugs..

So with a bit of planning all all types of motor can be used.

Yeah I wasn't having a go at your method!! if it works then all well and good but there is the possibility it could be an issue, though as I said it would be very unlikely for normal workshop stuff.

 

[Henrik]

I have to just add here that a rotary converter can be built for next to nothing (definitely less than 50 quid all in).

It may not generate "perfect" 3 phase, but it's close enough to power 3 phase motors (assuming the motors can be wired for 240v delta).

 

[Wendelspanswick]

Before I got my VFD I used to power up my spindle moulder (5.5Kw 415v motor) using the Transwave static converter and leave it running, effectively turning it into a rotary converter, I then could then run my lathe, pillar drill, ironworker etc without having to flip switches on the static converter each time I turned them on.

 

[rorie]

great, thank you for all the replies!! I am picking up the tools tomorrow evening, so i'll report back with the spec of the motors and then look to buy the right kit.

Cheers

 

[rorie]

Ok folks, so i have picked up the kit and here is what i have

Pillar drill:
1/2 hp
220/250v
380/440v

Band saw:
440/440V
Speed: 1420
Rating: Cont

So, can anybody suggest what i am best doing? I am highly unlikely to get any further kit that is 3 phase (but who knows!).
If i run the pillar drill as it is, what am i best getting? Will these converters downrate the tool if the motor already states the lower voltage range?
If i am best (i.e. cheapest) replacing the motor on the band saw, any suggestions of where to start looking? Also, will the bandsaw have a poor performance, or will it make no odds?

I see no time when i would be working both tools at the same time...if that makes a difference.

Any suggestions appreciated!