Thread: Single to three phase converters

Avondale

32amps should allow a motor or combination of motors up to 7Kw.

Are you looking at building your own phase converter or buying a commercial unit? You should also compare the alternative of VFDs too.

Regards
Paul

I built my own Rotary Phase Converter, I used a old welder (basically a step up transformer) it give me one phase and used starting capacitors to start a 3 phase 10hp motor (these start capacitors only stay in the circuit while the 10hp motor fires up) then I balance L2 & L3 with further capacitors that stay within the circuit while the 3ph converter is running. I do this with 32 amp supply and can start multiple motors up to 6/7hp.

The set up cost me less than $1k and over the years I have only had to replace a few capacitors and momentary switches.

Avondale

If you are looking at building your own phase converter, this series of videos may be of interest:

(16) Rotary phase converter - UK - Part 1, Intro. - YouTube

Rotary phase converter - UK - Part 2. - YouTube

Rotary Phase Converter - UK - Part 3 - YouTube

(16) Rotary Phase Converter - UK - Part 4 - YouTube

Regards
Paul

Thanks for replies

Originally Posted by Bushmiller

Avondale
32amps should allow a motor or combination of motors up to 7Kw.

Are you looking at building your own phase converter or buying a commercial unit? You should also compare the alternative of VFDs too.

Regards
Paul

Purchase. My skills don't extend to doings this from scratch.
I've had a couple of conversations with Phase Change Converters, and one in Sydney
MODELS | Phase Change Converters

Originally Posted by Camelot

I built my own Rotary Phase Converter, I used a old welder (basically a step up transformer) it give me one phase and used starting capacitors to start a 3 phase 10hp motor (these start capacitors only stay in the circuit while the 10hp motor fires up) then I balance L2 & L3 with further capacitors that stay within the circuit while the 3ph converter is running. I do this with 32 amp supply and can start multiple motors up to 6/7hp.

The set up cost me less than $1k and over the years I have only had to replace a few capacitors and momentary switches.

That's certainly low cost.

At the start of my rebuild I had a new connection from the pole (with 3 phase) about 8 metres from house. Was told then 3 phase was prohibitive but now find that not true!
Now all wiring and extensions complete its a costly exercise.

I gather they aren't something to be concerned about in regards to clean and reliable power, motors don't react (overheat) providing I get the right set-up.
Hence me coming here. I can appreciate the manufacturers would recommend but it's nice, better to hear from real world users

Thanks for links to videos Paul.
Electricians I've spoken to are sceptical or say they have no idea.
My dad would have whipped one up for me but that's history

I have a PC8 phase change converter I bought second hand and it has worked great for me. No way I could have bought it new, but found a really good deal. They can also service their machines if you ever need it and a suitably experienced electrician can’t be found locally.
I was considering vfd’s but had a shed full of machines to convert. Also can’t beat buying a new machine and just plugging it straight in.

A single VFD could work assuming that all the motors are the same, and all can be connected for 240v three phase. You might even be able to use the machine's electrical switching to select the desired motor.
If different motors you would need separate VFDs.

Otherwise you will have to find a way to provide the 415v three phase. I believe the old Transarc Tradesman welders had a beefy 240v-415v transformer which you could use in a rotary phase converter design.

Before you decide to get a VFD for your setup have a really good read of this and the attached document
VFDs for Newbies

If you want to keep all your switches and wiring etc intact on your machine then a phase converted is easier and safer.

Thanks again.
I can't use VFD on my Lurem from my understanding.
The thicknesser is 2 speed as is the spindlemoulder. I recently had the feed motor rewired. $1600! So I'm somewhat nervous about any electronics that change the power, but from your input and making other discoveries I'm happy to go with a phase converter and will look at the Sydney & Melbourne options.
I'd be quite at ease if I could get a single phase combination with similar specifications to my current but haven't found one that comes near.
1650mm table, 2 speed, rock solid fence on cast iron mounts.

It's not that expensive to get 3 ph run into the home (and on to a shed). You may even have a 3 ph drop coming into the house but it's only using 1 phase currently. This was the case for me when I needed it for a 10KW solar inverter.

Not that expensive, things must be a lot different in Canberra!

Originally Posted by Uncle Bob

It's not that expensive to get 3 ph run into the home (and on to a shed). ...

Can be a bit variable.

I got a quote of about $1,000, but for a variety of reasoins I did not proceed.

Later, when I was ready to proceed, I asked for a second quote and got "an estimate around $50,000". Apparently, at that stage, there was no spare capacity in our street and the supplier wanted muggins to pay for rewiring the entire street.

Originally Posted by Avondale

At the start of my rebuild I had a new connection from the pole (with 3 phase) about 8 metres from house. Was told then 3 phase was prohibitive but now find that not true!
Now all wiring and extensions complete its a costly exercise.

We built 160m from the power lines four years ago. Mains feeder in single phase was quoted as $8.3K or $17K for three phase, in conduit in a common trench with the water supply and stormwater lines. We have 3 phase to the house and barn, basically just two extra cables in the feeder and some extra expense in the breaker box and metering. Based on that, your 8m and a slightly larger breaker box shouldn't have set you back more than about $2.5K above what single phase cost, if done while trenches were open etc. Now things are at a finished stage the sky's the limit really depending on what needs to be disturbed and reinstated.

Sky is proverbial limit!
I'd have to lift a lot of tin off the roof, only 6⁰ pitch, cathedral ceilings (can't run cables in space or anywhere near metal plaster hangers) and it only gets worse
I priced two converters yesterday. $4000 delivered or $5300 plus delivery.
Different manufacturers. Tortech was the cheaper.
Bit concerning the price difference.

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