Running 3 phase motors on Single phase

[kempy]

I ended up with this air pump from the shed tour.

 

It's a Siemens 3 phase industrial pump and it caught my eye for the purpose of an extraction fan for my bead blaster.

Initially I had thoughts of swapping the motor for a single phase 230v or even a DC motor with a controller so I can adjust the speed,  I need the flow rate high enough to keep the cabinet free  of dust but not too high so it starts sucking out all the media.

Was just about to dismantle it for a clean up when wiped the dust off the top cap which showed the connection options and this is when it got a little more interesting, this motor can be wired in 3 Phase Star or 3 Phase Delta. (Obligatory warning, Dont ever try this unless you are qualified to do this as there's a chance of electrocution, explosion, fire, pestilence, flood and other nastiness)

 

As you can see, in delta the windings are configured in a 240v config, but however if you did hook up a 230v source to say L1 and L2 the motor wont start, it'll just sit there and him and get hot! as there's no air moving to cool it down, you can get the motor running by spinning the shaft and eventually it will start but at a lesser power output and of course wont restart.

Remembering a bit of my NZCE done years ago I know that adding a capacitor can have the effect of a phase shift or delay which is similar to adding another phase, there's a few calculations you need to do which I wont go into here in the interest of safety as things can go horribly wrong if you mess it up

 

End result is a very use able 3 phase air pump on single phase, I have a Variac that can make this variable speed, win!

 

 

 

 

[hmmmnz]

and as a bonus when you burn out a phase you have 2 more spare

[xsspeed]

iirc theres a way to wire a capacitor or two to lag to get more power/smoother running from motor. i started looking at it for potential hoist

Bat signal to @UTERUS

[Mr Burns]

And if anyone needs an identical motor/pump to try this on, there may still be one or 3 left.

[UTERUS]

3 hours ago, xsspeed said:

iirc theres a way to wire a capacitor or two to lag to get more power/smoother running from motor. i started looking at it for potential hoist

Bat signal to @UTERUS

That's exactly what he did bruh

[xsspeed]

Oh lols skim read fail

[anglia4]

One of my mates built a single to three phase converter to run his lathe and mill in his car shed.

It runs on mostly black magic with a bit of your run of the mill wizardry thrown in for good measure.

I'll try and remember how it works... its mind blowing.

[ProZac]

Most 3 phase VSD/VFD's out there will run with only a single phase input (however, you need to de-rate them to about half their stated power) and output a happy three phase for your motorvation needs.

[taiparacer]

makes that 3 phase lathe look interesting 

[SOHC]

I have a 15HP 3 phase motor running on single phase with capacitor start to get it going and it generates the missing phase to run another smaller 3 phase motor witch needs to start under load and then work hard.