Three Phase to Single Phase Power Transformer?

Why?

Because I have aquired a cheap 3 phase diesel generator and my house runs on single phase.

How big is the generator and how big is your house load?

Also is your generator the type that can have the windings reconfigured for other voltages and what not? Many can.

Most 3 phase generators are designed to handle at least half of their rated load capacity on any one phase and many smaller one are built for 100% rated capacity on one phase depending on the winding configuration.

Yes its called a 'Z' connection.

You're right on the money there mate.

That's how I do it.

OP will still need a transfer switch. A couple of links on the 1 phase side and no need to faff around.

The main distribution board will need a 3P breaker to replace the single pole he has and a buscomb or links would take care of the distribution with some semblence of balancing.

Pretty difficult to do it inexpensively. You are getting presented with the correct engineering solution by others: a transfer switch and 3 phase panel.

But I am guessing that you would like to try to do it for least cost and sacrifice some of the niceties of a proper (and costly) solution.

You might consider another way--find a used inverter of the power rating you need and convert your three phase AC to DC, then use the power inverter to convert back to single phase AC. The power inverters I'm referring to are often used to convert DC produced by solar panels to single phase AC.

But there is a second way. Possibly the least cost inverter would be to find an old variable frequency drive (VFD) with an output rating at least 1.73 times the rating of your diesel generator. VFD's have been around for years and are available pretty inexpensively on eBay. You then put your 3 phase AC into the VFD and happily pull the single phase you need from one phase of the VFD output. Not forgetting, of course, to set the VFD to the line frequency you want! The 1.73 uprating is because you want to pull all of the power out of the VFD on only one phase. The total power your generator puts out on all three phases is equal to 1.73 x the power per phase. (volts x amps).

I use a VFD in my home shop the other way around: to convert single phase AC to 3 phase to run machines that have come from industry with 3 phase motors.

For electrical safety and to meet code in many jurisdictions you would need to install a transfer switch so when you switch to generator power you positively shut off the utility power. This is important because during a power outage you don't want to be accidentally backfeeding power to the utility lines and maybe kill someone who is working on the lines miles away. ---That happened to a my high school buddy's dad years ago. He was a lineman, fixing a rural power line that a tree had dropped onto. It was late in the day, he got hasty and shortcut a few safety procedures. A telephone backup generator automatically started up, on the same line, miles away, without a transfer switch. Killed him immediately.

Jon.

But I am guessing that you would like to try to do it for least cost

How can anything else be less costly than a couple of links and a new 3P breaker?

Using a normal, off the shelf VFD 3phase output type: You will be leaving one output phase not connected! That is not advisable for such VFDs that are made to drive a balanced 3 phase output (Electric motors, 3ph). Your VFD will not last long!!

Just take one phase with neutral & earth. Once again we don't know where in the world you are but here in the mother country this would work.

Bazzer