Urgent, need advice please. What's the difference between 1, 2 and 3 phase power?
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it doesnt. it is just a lighthearted joke about the contrast between rob's humbleness, and his vast knowledge. and only said because he is so completely the opposite of that.
Yes, but he might not take it as a joke. Thanks for clarifying.
Roger
Roger
Yes, and I have mates who do just that. A few $k buys you a decent 3 phase generator. I also have mates with electronic phase converters, that convert single phase supply (even SWER) to 3 phase, including fully variable voltage (for slowing motors) and reversible supply (for reversing motors). A third option is to replace the 3 phase motor with a single phase one. I have done that a couple of times. Rob helped one of us obtain a single phase motor to power a 3 phase hoist, by organising a special motor to be made by the manufacturer in Melbourne.
Or you could just forget about 3 phase gear and buy single phase.
Roger
What you have then is a composite of the pdf.
If you removed the secondary of the the first transformer and removed the primary of the second transformer and grafted the remaining windings into a second transformer - then that is what you have.
Ie you have a 22kv to 480v ct transformer.
Makes sense and does the job with minimum parts.
I'll have to read up on SP Ausnet distribution practices - It's something I know about in general terms but not in specific detail.
Yes, that's what I have, but I would describe it not as a composite but as something that completely does away with all the SWER stuff.
I'm curious what exfrogger has.
Roger
Yep. If 3 phase is essential then this mob make phase convertors ... at a price...
http://www.phasechanger.com/
They really aren't complicated in theory.
A single phase "motor" is powered by the available supply. The motor has additional windings which are in a three phase configuration. A synchronous rotary transformer if you will.
Both the motor primary and secondary are acted upon by SCR (silicon controlled rectifiers) under control of microprocessor system. There is fiendish complex firmware to main frequency and phase balance.
The idea is not new, but powerful microprocessors and reliable SCR technologly has made them feasible and affordable.
They seem to work really well.
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No offence taken. I know Alexander well enough by now.
I'm definitely not an academic. I battled maths throughout my studies.
However it becomes much easier to see how electrical stuff works when interest rather than the necessity of passing exams motives oneself.
Australian Standard Voltages
Australian Standard Voltages are as follows:
Single Phase is 230 volts
Three Phase is 400 volts
This was introduced a few years ago to align Australia with the European Standards
Australian Standard Voltages are as follows:
Single Phase is 230 volts
Three Phase is 400 volts
This was introduced a few years ago to align Australia with the European Standards
Great discussion, but as usual on AF you have forgotten the three points that he wishes to ask.
Free 3phase power installed.
Let me explain by telling you what happened to me.
I have built onto my single story house a 8m by 7.5m three story extention onto the front of it.
As I needed a new point of attachment and I also didn't want one on the nice new house, I rang my supply authority about getting a underground supply put in to the boundary of the property.
Now here is the good bit, they would supply a 16mm 3phase supply to the pit from across the road, if it was less than 30m and if they could choose which side, for free.
I, at the time was working somewhere where my foreman had some spare 30m of 16mm orange circ and 50mm orange conduit, which I dug and installed, all free.
The only cost I had was the truck appointment to have it connected and a inspector, as I signed off my own work as the sparky, it was $350 from pit to having power turned on.
But the point in this is, do your own homework don't trust anyone ie-sparky you can ring around yourself if you really could be bothered and by getting the correct information could be saving yourself thousands.
Whether Peter could get free 3phase installed to his boundary in Gero, I don't know but a couple phone calls to the correct authority would be a good starting point.
Free 3phase power installed.
Let me explain by telling you what happened to me.
I have built onto my single story house a 8m by 7.5m three story extention onto the front of it.
As I needed a new point of attachment and I also didn't want one on the nice new house, I rang my supply authority about getting a underground supply put in to the boundary of the property.
Now here is the good bit, they would supply a 16mm 3phase supply to the pit from across the road, if it was less than 30m and if they could choose which side, for free.
I, at the time was working somewhere where my foreman had some spare 30m of 16mm orange circ and 50mm orange conduit, which I dug and installed, all free.
The only cost I had was the truck appointment to have it connected and a inspector, as I signed off my own work as the sparky, it was $350 from pit to having power turned on.
But the point in this is, do your own homework don't trust anyone ie-sparky you can ring around yourself if you really could be bothered and by getting the correct information could be saving yourself thousands.
Whether Peter could get free 3phase installed to his boundary in Gero, I don't know but a couple phone calls to the correct authority would be a good starting point.
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I did quote the Australian standard not the Office of the Regulator General, Jan 2002. (Victoria).
I'm in Tasmania and we are aligned to the Australia Standard.
I don't know where you got that from Rob, but that is not any official standards document that I have ever seen, but don't ask me which reg book or where I've put my reg books.
I might add though I did actually open one last year in QLD to teach the young deputy EEM on the mine a couple things.
Double Single Phase - 480 volt.
Hi.
On our farm we had a dairy that had 480volt AC motor driving the vacuum pump. Would have been installed in the 1960's.
Later I worked in the rural industry. We had wool press's that had 3HP (2.2kW) single phase electric motors. These were available in either 240V-1Ph-50Hz or 480V-1Ph-50Hz options. Amperage halved for 480volt. We also had 415V-3Ph-50Hz motors. I spoke to many rural electricians and 480 volt was often referred to as Double Single phase. It must have had the phases 180 degrees to obtain the phase to phase 480V. It was fairly common and had fewer problems with volt drop under load.
I dont understand how it was obtained, as power is generated in Victoria (and Australia) and distributed as three phase, with 120 degree vectors or phase shift, at various voltages. So I don't understand how 180 degree vector angle is obtained from the distrubtion network?? Logically I dont think it can be, a single leg of the three phase must have been used and reduced to 480 volt? Other phases would have been sent to different consumers for load balancing.
We also had many issues with farms that had SWER lines particularly as increasing load was applied to the supply. Volt drop was the killer and long extension leads also contributed. As has been articulated previously they relied on the earth return and in dry years the conductivity of the earth was poor and resulted in volt drop under load. I have heard stories of cattle rubbing against the power pole, breaking the retun wire and therfore becoming the circuit to ground, therefore were electrocuted. I have not heard or seen this first hand.
Three phase is king particularly with electric motors, it has much more grunt and performs particularly well when motors are started, compared to single phase. It can also accomadate overload to a greater capacity than single phase. I now work in an industry and our 3 phase motors get to synchronous speed in three cycles. Single phase motors usually require an additional start winding and associated centrifical or timer switches.
Submitted for what its worth.
Hi.
On our farm we had a dairy that had 480volt AC motor driving the vacuum pump. Would have been installed in the 1960's.
Later I worked in the rural industry. We had wool press's that had 3HP (2.2kW) single phase electric motors. These were available in either 240V-1Ph-50Hz or 480V-1Ph-50Hz options. Amperage halved for 480volt. We also had 415V-3Ph-50Hz motors. I spoke to many rural electricians and 480 volt was often referred to as Double Single phase. It must have had the phases 180 degrees to obtain the phase to phase 480V. It was fairly common and had fewer problems with volt drop under load.
I dont understand how it was obtained, as power is generated in Victoria (and Australia) and distributed as three phase, with 120 degree vectors or phase shift, at various voltages. So I don't understand how 180 degree vector angle is obtained from the distrubtion network?? Logically I dont think it can be, a single leg of the three phase must have been used and reduced to 480 volt? Other phases would have been sent to different consumers for load balancing.
We also had many issues with farms that had SWER lines particularly as increasing load was applied to the supply. Volt drop was the killer and long extension leads also contributed. As has been articulated previously they relied on the earth return and in dry years the conductivity of the earth was poor and resulted in volt drop under load. I have heard stories of cattle rubbing against the power pole, breaking the retun wire and therfore becoming the circuit to ground, therefore were electrocuted. I have not heard or seen this first hand.
Three phase is king particularly with electric motors, it has much more grunt and performs particularly well when motors are started, compared to single phase. It can also accomadate overload to a greater capacity than single phase. I now work in an industry and our 3 phase motors get to synchronous speed in three cycles. Single phase motors usually require an additional start winding and associated centrifical or timer switches.
Submitted for what its worth.
Col, put an accurate voltmeter on your supply. I bet my left one it's closer to 240v than 230v.
Supply companies will always avoid a "brown out" and hover on the high side.
Having a higher supply voltage increases the power cost for the consumer because a higher voltage ends up having higher Kw/hour readings on the meter!
There is no motivation sit dead on the low end of the "standard" voltage. Especially when there is standard range.
As always, blown away by the knowledge & information some of you have stashed away in you heads!! I can't come close.....
These days, modern engineering equipment runs happily on single phase, including big lathes 7 moderately sized mills. But older, exceptionally heavy & stable machines can be had very cheaply, because they run on 3 phase.....
These days, modern engineering equipment runs happily on single phase, including big lathes 7 moderately sized mills. But older, exceptionally heavy & stable machines can be had very cheaply, because they run on 3 phase.....
Col, put an accurate voltmeter on your supply. I bet my left one it's closer to 240v than 230v.
Supply companies will always avoid a "brown out" and hover on the high side.
Having a higher supply voltage increases the power cost for the consumer because a higher voltage ends up having higher Kw/hour readings on the meter!
There is no motivation sit dead on the low end of the "standard" voltage. Especially when there is standard range.
Rob would you put your right one up that your right or Col is?
Because if you do you owe him your right knacker. Col is correct, AS/NZ Standards now state 230V and 400V and all calculations are now made with those figures.
You can still keep your left one because if he put a meter he would more than likely be closer to 240V than 230V.
alexander, I now realise that when I responded to this question from you, in my cursory look at Rob's diagram I missed the transformer on the left that converts two-wire single phase into SWER. By the time I replied to Rob's post saying I had a composite of his diagram, I had noticed it. I hope that explains any discrepancy you might have noticed in my responses to the two of you.
Roger
Yes, the legs of 3 phase are 120 degrees apart. Yes, the two legs of 480 volt are 180 drgrees apart. The 480 volt secondary winding on the transformer is centre tapped, to give 2 x 240 volt "phases", 180 degrees apart. If you use the centre tap and one of the "phases" you get single phase, if you use each "phase" you get 480 volt. It would not matter what you fed into the primary winding as long as the number of turns in the winding was correct, the two legs of the 480 volt secondary would be 180 degrees apart becasue of the centre tap. I think they feed the primary winding of such a transformer with two phases of a 3 phase 22kv line.
Roger
Standards are standards are standards. The tell what SHOULD happen.
In practice standards rarely happen. Just like the people that write them are unlikely to design a network distribution system or wire a switchboard or connect a consumer mains.
After 15 years in electrical engineering design and writing electrical specs for drive ins and hardtops, I know for sure my left one is safe.
It's called the school of hard knocks.:headbang: