3 Phase Generator

[Jester129]

Having been told by my electrician that there is no 3 phase in the village, I was just wondering about a 3 phase generator.
Would it be feasible to buy one to use with bigger woodworking machinery on a dedicated circuit in a workshop?
Obviously it would only be powered up when required. What are the thoughts on members of the site please?

 

[Myfordman]

No 3 phase in the village is exceptionally unusual as all power is generated as 3 phase and houses connected to 1 phase and neutral in rough sequence along the road to keep the load balanced. It is quite possible that giving your 3 phase will be an expensive option.

However, if that is the case then look for a 4 pole diesel machine with electric start. This will then have the possibility of remote starting the genny in a separate shed and run at 1500 rpm which will be quieter than a traditional 2 pole which has to run at 3000 rpm.
Make sure the VA (NOT WATTS) is about 50% higher than the VA of your largest machine plus dust extraction. Check with your sparky about this, he should understand even if not clear to yourself

 

[flh801978]

Thats really the only solution if you have larger machines than 3 hp
under that size i would put VFD's on the machines if possible

 

[ivan]

If your village wires are overhead on poles, you would expect to see 4. One each for the 3 phases, and one neutral. As myfordman says. you would be fed by one of the 3 phases and neutral (230V). We got lucky being on site at our house under construction, on connection day, and persuaded the crew to pull through a 3 phase cable instead. About 30 yrs ago it cost an extra £100.

 

[Homeless Squirrel]

Myself would build my own genny.
you can source a lot of bits off old broken ones ie switch gear/clocks/tank.
Find a diesel engine like the 1.9TD or non turbo from pug/citroen etc or whatever you can find water-cooled will be quieter and last longer than air cooled
Scrap car will give you most of what need.
will run all day in near silence for little fuel and if get big enough generator can run whole workshop.
you can buy Gen packs do come up from time to time but often "Big".
Uncle had some decent ones running farm trouble is many use an air cooled clunker 1/2 sometimes 3 cylinders but there noisy

 

[Jameshow]

Myself would build my own genny.
you can source a lot of bits off old broken ones ie switch gear/clocks/tank.
Find a diesel engine like the 1.9TD or non turbo from pug/citroen etc or whatever you can find water-cooled will be quieter and last longer than air cooled
Scrap car will give you most of what need.
will run all day in near silence for little fuel and if get big enough generator can run whole workshop.
you can buy Gen packs do come up from time to time but often "Big".
Uncle had some decent ones running farm trouble is many use an air cooled clunker 1/2 sometimes 3 cylinders but there noisy

Perkins 4.108 or izuzu too.

Finding a Genny and control panel will be more difficult I expect.

 

[sawtooth-9]

Interesting.
I had a similar problem when we moved onto a small farm. Here it would have cost a fortune to have 3 phase run to the property.
Ended up buying a near new Kubota SQ 3200 ( 20 KVa ) - a super quiet 4 pole diesel genny, which is hard wired to a sub board in the workshop. It provides all the power I need to run motors 5 Hp.
20 KVa might seem an overkill, but start currents on larger motors can be quite high.
There are two negatives in my set up
1. The generator does not work hard, so occasionally I run all the machines at once to give the genny a good load and reduce glazing of the cylinders
2. Because it a larger genny, it costs more in fuel to run. But it's still cheaper than the cost of running 3 phase power

 

[deema]

A domestic electrician,…..typical! Probably only ever seen single phase in the village!
If you want a connection follow the link. I’ve never heard of any area on the grid not having 3 phase, it’s needed to ensure a balanced supply.

https://www.ofgem.gov.uk/publications/how-get-electricity-connection

 

[nickds1]

They may have only seen one phase at a time, but there may well be all three phases in use in the village...

We have 3ph as our house was once an industrial farm building (an oast) complex, but 90+% of the properties here will be on a single phase.

There should be 3ph in the road or poles. It'll probably cost serious £££ to get it into your property though.

 

[Spectric]

Having been told by my electrician that there is no 3 phase in the village

Depends how small the village is, they often run just two phases at 11Kv to a pole mounted transformer from where the 230 is then taken, no point in running the third conductor for full three phase if no large farms or industry.

 

[Jester129]

Thanks to all, @deema - that link is really interesting, thanks again. Looks like it will be VFD's and forget the genny, but it was just a thought. Great knowledge yet again, thank you!

 

[deema]

@Jester129 you don’t need VFDs there is a third option. You can get a digital phase converter. This produces genuine 415V and can support more than one machine. It can also be used as a VFD for speed control. However, the nice feature is that there is no change to your 3 phase machines necessary. Just plug them in and your all good. You can get them up to 15KW so will run most things!

 

[gmgmgm]

I have 3ph, and several machines which use it. But unless you are talking about super-power-hungry compressors/heaters etc. (which you probably won't be in a domestic setting) you can use phase converters/VFDs to power 3ph machinery from a single phase (with a suitably thick cable).

I absolutely would not want to complicate things by using a generator.

 

[Spectric]

I’ve never heard of any area on the grid not having 3 phase, it’s needed to ensure a balanced supply.

It will all be three phase but the three phases are not always used to every end point, it can be balanced over a larger rural area and for any phase inbalance then they just can use different taps on the transformers that give a different phase shift.

An example although on the high voltage side is the railways where they take a single phase 400kv supply to derive the 25Kv supply for the railways.

Look at split phase supplies where because a load exceeds 100 amps the DNO will deliver two phase, look at the poles running across the countryside where you will find the three phase supply and then two phase take offs running eventually to pole transformers where the end users get there 230 single phase from.

 

[deema]

@Spectric Thats really interesting, thank you. I was aware of the railways, I looked after a number of factories at one point for LEM who made a lot of stuff for both the trains and signalling.
I had understood that they brought 3 phase to each pole transformer and then just tapped off what was required. I wasn’t aware that they did 2 phase pole transformers. Again, we made stuff for the electrical distribution boys. Everyday a school day.

 

[niall Y]

I have used a Transwave Static converter, for over 14 years. Not sure what the cost difference between these and VFD's is, but it seems to be a pretty reliable piece of kit. I'm sure someone will come along, and explain just how they work, but, as I understand it they are a fairly low -tech way of producing 3phase, using capacitors to start and run the motor

The only downside is having to trim the load for optimum performance, when you connect up different machines. In other words, you usually have to start the machine on a higher setting and then select a lower one, for the machine to run at its best.

In my workshop the only exception to this, , is the lathe, which starts and runs well, on the same setting. Luckily, this means that I don't have to walk the length of the workshop to alter the controls every time I turn the lathe on, off, and on again.

 

[Spectric]

Hi Deema

I got involved with numerical protection systems for monitoring and protecting substation busbars, overheads and such many years ago, probably much easier now with the advances in microcontrollers and electronics plus I believe they now also use digital signal processors. I think that if they were building the national grid today then the 400Kv & 275Kv side would be Dc and maybe down to 132 Kv but I think that once you get to 400 / 230 volts then Ac would remain if for no other reason than the Ac electric motor. Give it another decade and maybe the brushless Dc motor will take over from the old Ac induction motor.

 

[Spectric]

I have used a Transwave Static converter, for over 14 years. Not sure what the cost difference between these and VFD's is, but it seems to be a pretty reliable piece of kit.

If you are serious about using three phase machinery then either the older static convertor or the modern digital phase convertor are the best options, they allow you to run a three phase circuit where you can use multiple machines from the one convertor and the power available is only limited by the size of the convertor and your available supply from the grid. What you don't get is the variable frequency aspect because the output is fixed at 50 Hertz.

The invertor is ok providing you buy a decent one, Abb, Mitsi, Hitachi or siemens but you need one per machine and are limited in maximum power output, 3Hp due to regulations regarding EMC and power line disturbances.

Where some people make an error is in sizing the VFD which is not an issue for the convertor. The VFD needs a current rating that is at least 1.7 times larger than the full load rating of the motor being driven, people like Hitachi recommends using the 3 phase motor’s full load amperage (FLA) and double it.

Then don't forget to size the electrical supply for the invertor and not the motors FLA.

 

[Jester129]

Thanks again to all. Really interesting stuff. I think it will end up with VFD's.