Thread: 3-phase Electicity

In reply to ians comment about interferance measured on his instruments.

The context of the thread is that there is no difference between single & three phase electricity concerning their capacity to produce interferance.
It is thaught by some that three phase causes more interferance.
In fact a three phase induction motor running directly off the mains is less likely to produce sprurious emmissions than most types of single phase motor, in particular brush type universal motors as found in most hand held power tools.

It is devices connected to the supply and other factors that produce the interferance.

I have had similar problems One particular customer we were able to trace the problem to a specific pole. It turned out to be a cracked insulator on the 11KV line. Once SEQEB were advised they rectified within a week. Prior channel 2 was unwatchable for streets arround.
Yess this type of interferance will propogate over the grid.

As for the VL lathe current C cick legslation is quite stringent and the electronics should be very clean on any current product.

However if you are in a tin shed like mine any form of radio reception is probably marginal, therfore even the smallest amount of hash will cause a problem.
Try putting the radio near a window or put up an antenna for the FM


Cheers chaps

Don, it seems my original comments re wonky tv signals has gotten out of hand It's a phurphy. As discussed above problems that occur with the grid can be a pain, as to can any sh#t elec install but with increased regulation of electrical installations they becoming as rare as dog eggs

Further to my comments on the VL 300. There is definitely no interference on any radio or T.V. station be it FM or AM.
Prior to moving here we lived in a very marginal reception area for both radio and T.V. and there was no interference there either.
Some of my woody mates did not believe this either until they had a demo!

Some amazing tales develop about things, like 3 phase interfering with TV's and the like. More likely the machine being run had a fault and generated the interference. Some of the earlier variable speed drives had inadequate filtering and caused radio and TV interference but if it's a worry, you can fix this by adding a line filter and anyway they're not allowed to sell them without filters now on new machines.

For example, lathes like the Vicmarc variable speed models all have 3 phase motors. Although they plug into single phase power, it is converted into 3 phase in the speed control box to drive their 3 phase motors. They could never get the power and speed range from a single phase motor.

Three phase motors are smaller and more efficient than their single phase cousins.

Single phase power is just a connection to one of the 3 phases and neutral so is really no different but I'll get off my soapbox now.

At last a sane voice in all this electrical bulldust!
Thankyou Brian!

there is by far a much greater choice of serious wood working machines in 3 phase and generally if you look further than your cardatec catalog you will find out what a quality machine actually is !!!! a bit harsh but true and you will be very suprised at what you can actually get for your folding stuff. if you can get it go for three phase, and yes you will maintain your 240v.

Just some info for the forum on my experience with installing 3-phase in Adelaide.

We upgraded our circa 1930 panel recently for safety reasons and to provide a separate airconditioning circuit. Our house is large with 12' ceilings. We wanted r/cycle and were limited to 3-phase units.

Our electrician requested ETSA (the local distributor) provide 3 phases to our house on the basis that we needed it for airconditioning. ETSA installed this service for no charge, but they would have and slugged us $400 if they wanted to change from aerial connection to submerged. I believe this is their prerogative, but apprently they considered the conversion "not profitable", perhaps because we have a very long (15m+) aerial connection from the street to our house and a thick brick wall to go under.

As part of the upgrade I requested that three phase also be extended into the garage. We already had single phase into the garage with separate light circuit and 6 electrical outlets (still not enough!). Part of the request was to install a separate sub-panel in the shed with 3-phase surge arrestors, RCD and fuses. All up, to run 3-phase conduit, the new shed sub-panel and a 3-phase plug we paid about $1,500. The sparky spent about about 2 days with his coworker in pre-wiring and then connected up all the panels on the day when ETSA actually extended the extra phases.

I sunk to a new low in begging/whinging/pouting until SWMBO agreed to the cost.

Gawd All mighty!

I'd hate to think what would happen if a 4 phase power system was ever developed (if at all possiable)

Can you imagine the length and complexity of the disscussions then !

My poor wee brain is pounding allready...

Still I suppose it was alll steam and real horse power once....

Food for thougth...
Iv'e heard and read stuff about the idea that one day all electricity will be sent totally wireless (something to do with micro waves or was it lasers or something)

No more scrambled extension leads...no more running out of power points.....keep the workshop as far away from SHMBO (aka...leader of the opposition) as possiable ....*sigh*.....

Cableless power!
Do a search on Nikolas Teslar on Google if anybody is interested.
Caused a bit of a kerpuffle in the 60s but disappeared without a trace.

Some old motors use to work on three phase plus neutral, not quite four phase but close!

I found the debate quite entertaining and must say that comparing three phase equipment you can buy at auction rather cheap, with single phase hobby equipment (usualy overpriced for the quality you get) is like comparing a scooter to a Ford Bronco.

Go 3 phase anytime, you have 240 just by taking one phase and neutral. Make sure your electrician balances the load evenly on all three phases at the board. IF you have more than one single phase motor, or perhaps an electric welder, make sure you have them wired off different phases.

Hi,

The Three phase and single phase debate has been going on for a long time. Experience in this field shows that the difference with Three phase is that you can get higher horse power and are not limited to the torque value when under load ( depending on the horse power rating.) Where as single phase is generally limited to a max of 3HP for home use and torque value is now dependent on how hard or fast you push your material into the cutter or blade.
Single phase in Australia for DIY (home use) is a premimum requirement as everybody has this available at no extra cost to the home owner. To install 3 phase in a private house firstly it may prove difficult to achive to convince the power supplier to install and secondly the costs can be absolutly and totally prohibitive.

We have heard from different customers from across the board anything from $3000 to $15000/ $20,000 . This is fairly common for those living in the bush around Australia.
There is a unit called a Phase Converter which is English Manufactured and is a good quality unit that can on average to handle upto 5.5HP 3phase for approx $2900 + GST

I hope this answers some of the Questions

Regards
Mark
Advanced Woodmachine Technologies Pty Ltd:

Hi guys

I was surfing the net and found this forum. I've already been down this path and thought I should reply.

I saw an ad in our local paper and ended up buying a 4KW 240V to 415V 3 phase converter from an Aussie manufacturer in Sydney for $2000 all up. It works really well. They also make bigger sizes.

From what I understand - I am a sparky by the way - the trick to converters is being able to start motors under load and not all converters do this well, so check out what you are buying before you commit to it.

they hava a very informative web site, www.powerchange.com.au

Hope this helps

Markus

Hello, just wondering if someone could tell me how running 3 phase would reduce my power bill?

Thanks

Ben

using three phase is not likely to reduce your power bill in any significant way.

any way if you are using enough power to require three phase minor variations in your power bill are the least of your problems.