Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308
Posted: 04:54pm 18 Dec 2017
Copy link to clipboard
Print this post
Today I bought myself a listeroid 12/2 engine with a 6Kw gen head.
I would like to have the capability to power the house with it in case of ( Imminent) blackouts.
The mains coming into the house is 3 phase. The only thing that requires 3 phase power is the AC and the stove... which is actually 2 phase, 380 instead of 415 i'm told although not sure how that works....
Anyway, with those 2 things aside, is it possible or a problem to wire a transfer switch to feed all the other circuits in the house from the single phase Genny?
The AC has it's own breakers as does the stove so I'm thinking all I have to do is join the other 2 phases through the transfer switch so they all get power in that connection then go back to separated phases on mains. It would seem with a 2 pole transfer switch this should be OK as it will keep the phases isolated when not running off gen power.
What am I missing?
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 11:08pm 18 Dec 2017
Copy link to clipboard
Print this post
I think you might need a three pole transfer switch.
In the "grid" position all three phases just go straight through.
In the "generator" position all three phases can be connected together and fed with 230 volts with respect to neutral.
The stove will work fine, as its two 230 volt loads with respect to neutral, nothing in the stove will be wired phase to phase.
The air conditioner obviously is not going to run, but it should not be damaged. The control system will be 230v with respect to neutral from one of the phases. The main compressor motor will be delta connected without a neutral, so when the motor contactor within the air conditioner closes, it will just see zero voltage.Cheers, Tony.
George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308
Posted: 09:40am 19 Dec 2017
Copy link to clipboard
Print this post
Thanks mate. This is much as I thought. I already ordered a couple of 3 pole rotary switches for the job.
The description of the things are in Chinglish of course but from the pictures on the stickers on the things seem to indicate they can be wired in such a way as to increase their capacity from the 20A they are rated. See if I can figure it out when I get them.
I thought I'd get these to look at and if are OK I'll order decent ones that will have a much higher amp rating. 20A would be OK from the genny but I'll need 80A to be on par with the mains. Probably never need that but I don't want any weak links in the system. The little ones will be good for phase changing on the solar inverters in any case.
I wasn't sure about the stove as I was of the belief there was no such thing as 2 phase but I think I understand better now.
AC I'm not worried about. It's on it's own set of beakers so I will just leave them as is. If I can have everything else but not air, I guess I'll be doing OK... unless it's a 44o day like it was here today then I'll be buying a 3 phase head for sure. :0) I changed some circuit phases a while back and mate forgot to mark the phase order of the AC wiring. Apparently the one I have just tells you if it's wrong and isolates itself. just a matter of changing the combinations till you got it right. mate got it first time with following wires and a lot of intuition.
I won't be that sorry when that thing carks it. They have all gone back to single phase inverters now for AC so will be able to run one easily from the solar or generator.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 08:08pm 19 Dec 2017
Copy link to clipboard
Print this post
The two phase stove thing is not uncommon in Australia, and there is a history behind that.
Back in the 1920's or 1940's (or whenever it was) when the suburbs were first hooked up to the grid, every home received a standard 20 amp feed from the pole out in the street as the normal connection.
If you had a larger house, or a new fangled electric stove, 20 Amps was not going to be enough, so what you received were two 20 amp feeds from different phases using all standard hardware from pole to your power board. The stove elements were split between two phases, and there were two fuses for the stove at the main power board.
Many original weatherboard houses are still wired like that, and so are the stoves.Cheers, Tony.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 08:36pm 19 Dec 2017
Copy link to clipboard
Print this post
One final thought, and something to check with your stove.
If the stove is connected to two 120 degree phases, and if for example it draws 12 amps from one phase, and 12 amps from the other phase, there will be 12 amps in the neutral wire.
But if the two loads are paralleled at the source, its possible to have 12 amps on one phase, 12 amps on the other phase, but the neutral current will now be 24 amps. Better check that is not going to be a problem.Cheers, Tony.
George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308
Posted: 08:40am 20 Dec 2017
Copy link to clipboard
Print this post
Thank you for the heads up. I will look into it. What you say of course makes sense and I'll check the wiring. A switch on the thing broke recently but we are looking at having it replaced after xmas so I'll pay particular attention to how a new candidate is wired.
I appreciate all your generous help and insight. You are a wealth of knowledge and a real asset to everyone here.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 08:52am 20 Dec 2017
Copy link to clipboard
Print this post
Thanks George. I have sometimes had to learn things the hard way from my own mistakes !!Cheers, Tony.
Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664
Posted: 08:09pm 21 Dec 2017
Copy link to clipboard
Print this post
Wish I had a digital camera or Smart Phone 50 years back....
My grand parents on one side had the power (Rural Property) connected in 1963. Would love to be able to see what they actually had back then.
The other GP's, also on the land, had 32V. Vaguely remember the shed up the back with a Genset & batteries.
Think they left the farm when I was 5, so have just the vaguest of memories.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 08:26pm 21 Dec 2017
Copy link to clipboard
Print this post
The old houses had a pilot light burning all the time too, must have been so you knew the power was on. An uncle of mine who has retired now worked for the electricity company in Toowoomba, they had a call once from an old lady. She had been away and came back home and saw through the window that a power point was turned on. So she called up in a panic for them to come around and let the electricity out of her house so it would be safe to go in.There are only 10 types of people in the world: those who understand binary, and those who don't.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Print this post
