Author Topic: Power outages  (Read 497 times)

glort

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Re: Power outages
« Reply #15 on: November 29, 2018, 08:27:07 AM »

I got to admit, I have picked up some good equipment over the years from the side of the road cleanups and more recently stuff being sold Cheap on gumtree and the like.  It really only takes a Gummed up carb or a whisker across a plug and people throw perfectly good stuff out.
Seems every new generation of gets built cheaper and weaker and less up to the job.

I was looking at an edger last night for the paths and garden beds. Found an older Kawasaki going cheap supposedly with spark problems.
Mrs came in and saw it and asked if the engine was any good. I said I couldn't care less. She said what if you can't get it going? I laughed and said 1, that's unlikley and 2, I have a spare petrol and a Diesel up there that will fit I can just put on. the rest of the thing is built like a tank, the price is right, so what.

I reminded her my plough wasn't working either when I got that but it cost me $50, I spent another $50 on a motor and 420 on a pulley and the thing is a ripper as I had showed her on the weekend working on some garden beds she wanted to re do.

Better go check Dumbtree if the seller has got back to me about that one .

Johndoh

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Re: Power outages
« Reply #16 on: November 29, 2018, 08:37:42 AM »
I like reading the posts about generators always good to learn something. I am warming to Chinese machines a little but God there's still some crap around.

https://www.gumtree.com/p/generators/brand-new-silent-6.5kw-mill-german-generator/1322198385

These seem particularly cheap and nasty they are on all the local selling websites usually being sold by guys with thick Irish accents and driving white vans. I was reading somewhere recently that the windings in these generators are aluminium which I doubt is a good thing.
It is better to light a candle than to curse the darkness

ajaffa1

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Re: Power outages
« Reply #17 on: November 29, 2018, 11:58:56 AM »
Hey Johndoh, when I lived in the UK there were no end of Irish travelers trying to sell stuff to the workers on my building sites. It all looked good but was made from mild steel rather than high carbon steel. Had to ban these guys from site and make it by appointment only with reputable dealers.

Aluminium is a better conductor than copper but melts at 660 degrees Celsius, Copper melts at around 1085 Celsius, I`m sure you can work out the difference for yourself.

Bob

glort

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Re: Power outages
« Reply #18 on: November 29, 2018, 01:12:39 PM »

I think that's bit of a moot point Bob.

The insulation varnish on whatever windings will be well and truly Kaput at 300o no matter what the windings are made of! There are a lot of advantages of copper over ally, price is about the only drawback but given the same units in each, I doubt the difference would be that much.

Maybe biggest problem with ally windings is if they cheap out on the coils, they probably make everything else as cheap and dodgy as they can as well.

Johndoh

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Re: Power outages
« Reply #19 on: November 29, 2018, 02:40:05 PM »

I think that's bit of a moot point Bob.

The insulation varnish on whatever windings will be well and truly Kaput at 300o no matter what the windings are made of! There are a lot of advantages of copper over ally, price is about the only drawback but given the same units in each, I doubt the difference would be that much.

Maybe biggest problem with ally windings is if they cheap out on the coils, they probably make everything else as cheap and dodgy as they can as well.

In Ireland we refer to travellers as them fcukers!
It is better to light a candle than to curse the darkness

BruceM

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Re: Power outages
« Reply #20 on: November 29, 2018, 04:24:40 PM »
"Aluminium is a better conductor than copper but melts at 660 degrees Celsius, Copper melts at around 1085 Celsius, I`m sure you can work out the difference for yourself."

Copper is the better electrical conductor by far. (Also better for heat conduction.)
https://www.engineeringtoolbox.com/copper-aluminum-conductor-resistance-d_1877.html

The problem with aluminum wire is usually the larger size to carry the same current, and the problem of dissimilar metals and corrosion at connections. My neighbor's ST-3 with aluminum windings on the rotor failed- with an open winding on one rotor coil.  The failure was NOT at the terminals, but somewhere in the middle of the winding.  So I would conclude that it was a flaw in metalurgy. I've never seen that happen in copper but don't know enough about aluminum wire failures to be certain.

mikenash

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Re: Power outages
« Reply #21 on: November 29, 2018, 06:17:17 PM »
FWIW the generator guys that we deal with say they have never seen an actual alternator failure on the China gensets and were quite dismissive of the idea - "you never get an alternator failure - things like AVRs, yes, but never the windings"  Probably not a lot of load on a 2-10kVA unit actual copper windings?

glort

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Re: Power outages
« Reply #22 on: November 29, 2018, 09:11:53 PM »

Being that I regularly wake from Nightmares and can't go back to sleep, I was just reading the Australian Electricity Market Operators  AEMO summer prediction for power.

In summary, due largely to the closure of Coal fired power stations over the last couple of years amid all the green environmental Hoopla, they are predicting wide spread Load shedding ( Blackouts)  Over Victoria and SA especially with a very high risk to NSW.
The report contains more waffle than one of my tirades and certainly a lot less fact.  There are endless phrases like " AEMO will be working with operators to ensure the best possible supply reliability" But give little to no specification of what that actually entails.

The boogieman is well and truly leveled at weather and the increased demand on the grid from air conditioning.

There are a few points that stand out to me.

The much heralded Big Blattery is of limited usefulness.  Once it is called on for its power, It is out of action for 24 Hours. Much different to the impression I had that the thing could charge up again almost immediately power was available from the solar farm it is attached to. Apparently this recovery time has been kept pretty secret outside the industry.

The next Biggest Contingency and threat to supply apart from the weather is, the weather.
With all the reliance on Renewables, there is clearly a fear factor in a lack of wind and cloudy conditions over solar farms which are outside the city's while the citys receive high temp weather events. Wind certainly seems to be the most unreliable supply and poses the biggest threat to their balancing act calculations.  Clearly without it, blackouts WILL happen.

Private solar PV input is largely saving their arses as much as the power co's are trying to limit it atm.
They not that while overall power consumption is increasing, demand on the grid is stable as it is being offset by the PV input.  It also notes the risks of localised load shedding in the city centered is greatest because of concentrated demand and low localized PV input ratio.

There is a lot of talk ( complaint) by power cos about excess midday power from private PV generation.  The market operator's own figures show this time as having 90% the demand of peak useage. In other words, the excess power at midday is no where near as much as they make out at all.
This confirms what I said earlier this week in a discussion about this that people just don't leave home of a morning and go to work on another planet.
If they are not using power at home, they go to work and boot up computers, machinery, turn on lighting, AC and use power at work.
The power private PV systems backfeed to the grid is not an excess with no use as constantly made out, it's simply used in places other than homes.
Didn't need to be Sherlock to work that out.

Another "Inference" if not outright statement I got from elsewhere on the site indicated that the majority of private PV power is consumed within 2km or less of where it is generated, even in area with the highest rate of PV installations.  Something else I have maintained. In most areas I can think of, there are shops, businesses, factories, hospitals and other huge power users within a short distance of housing  concentrations. I can only Imagine the amount of power one shopping centre sucks down and it's not hard to imagine that being all the PV generated within a 2KM radius. that won't be the only large power draw within that radius so I'm sure the circles on a map  overlap extensively. "

The highest probability of Blackouts will occur about 8PM. This is when demand is still high thanks to summer days being longer and hotter and daylight saving time in conjunction when the PV input from solar farms and private generation disappears. People come home to Houses that have heat soaked all day long, the ambient temps haven't fallen much as the sun has only just gone down and they want to cool the place off so fire up the AC.
 This time frame leaves the greatest potential power shortfall as even though some areas will still have light, there is only so much power that can be transferred and the distances for the areas that have solar are too great to send much to the areas that are now dark.
 Again, if that wind isn't blowing down south, it's going to be candle time for them.


It is pretty clear that the reliance on fossil fueled power is really the hinge pin of the whole system.  They are trying to reserve a LOT of Renewables but clearly are nervous about their reliability and their ability to be available when needed.  Coal and gas stations however are clearly what is going to be keeping the lights on in anything but a perfect weather outcome.


Having your own generator(s) Bob will be far from being pedantic or over cautious. It may be the smartest thing you could do in fact. You seem to be in about the best location, far away from the Mexicans where the greatest risk to supply is but there is also the risk of a cascading effect.

Reading this I'm seriously considering getting a couple of decent sized used batteries and setting up my system I had before with the panels and inverter.
Might also re motivate me to set up that 10Kw genny I was trying to do before. May well come in very handy.


BruceM

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Re: Power outages
« Reply #23 on: November 29, 2018, 09:39:45 PM »
You'll see a lot of PCM or ice freezing A/C assist cool storage systems in the near future.  The power co.s will push peak power rates so high you'll do anything to avoid them.  It's going to get ugly, and the Power Co.s will do anything they can to keep the status quo.

For off grid, freezing/PCM  to store cool is clearly the way to go.

Sydney's climate is pretty mild.
https://weatherspark.com/y/144544/Average-Weather-in-Sydney-Australia-Year-Round

If this is correct, a super insulated home would likely need very little cooling if any.  Little enough that cooling the water for the in-floor pex could do it, as I plan to do and which is very well proven. The cooling could be during the sunny (PV) day. 

In the past, mild climate homes get little or no insulation, and owners just throw energy at the problem.  Those days will be coming to a close in the next 30 years. 




« Last Edit: November 29, 2018, 10:01:54 PM by BruceM »

ajaffa1

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Re: Power outages
« Reply #24 on: November 29, 2018, 10:26:22 PM »
So the Australian power grid won`t be able to meet demand if it gets hot in the summer. When was the last time we had a cold summer? The energy companies need to wake up to reality and make the much needed investment in new generating capacity. Something they are not going to do until the politicos stop fighting among themselves and introduce a long term energy plan.

The idea that we should all switch from internal combustion engines to electric vehicles is plainly nonsense. I`m sure there must be scientists and engineers that know this, so why are we all being lied to?

Definitely need to get a wriggle on with my CS project. One of the questions I have is about my grid tied inverter. When there is a power outage there is no 50 Hz signal to drive it so it produces nothing, would the output from a generator be stable enough to provide that 50 Hz? My second worry is that the output from said inverter would then reduce the demand on the generator, would the governor react quickly enough to prevent over voltage or would I end up cycling the two against each other and blow something up?

Perhaps I should be looking at a second stand alone inverter and array with generator backup. If I did that the grid tied system could export it`s entire production and the electric company would end up having to pay me money!  :laugh:

Bob

BruceM

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Re: Power outages
« Reply #25 on: November 29, 2018, 10:38:01 PM »
As you suspected, Bob, you will need a stand alone inverter.  The grid tie inverter won't do the job. There are some new models that do support a backup power mode when the grid is down.
If you hook it to a generator, the poor bugger will try to pump power back onto the generator, which will then overvoltage and turn off the inverter almost immediately. 

All inverters should have at least a dual stage common mode choke filter on inputs and outputs.  Dirt cheap health insurance.

ajaffa1

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Re: Power outages
« Reply #26 on: November 29, 2018, 10:52:14 PM »
Thanks Bruce, thought that would be the case, I`ll start looking for a decent second hand stand alone inverter. Wonder if I should get more panels or put a diverter switch on the panels I have?

Bob

glort

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Re: Power outages
« Reply #27 on: November 29, 2018, 11:37:24 PM »
Sydney's climate is pretty mild.
https://weatherspark.com/y/144544/Average-Weather-in-Sydney-Australia-Year-Round


I don't know where they got those numbers but I suspect it was a spot very close to the beach where teh temps are always a LOT cooler.
I'm on the western outskirts where you start to see cow paddocks which are fast being bought up for houseing estates where they shove as many people into the tighest area they possibly can to ensure all sorts of social problems of the future.
It's about 50KM as the crow flies from the CBD and the coast.

Here it's common to have days in a row over 40oC or your 100 antiquated measures that even the people that invented it have abandoned :0)
On average it's 15oC hotter and Cooler than in the city and suburbs.  In the last 12 months we have had  47oC days and a -5's as well.
I'd say it's anything but mild.
Back closer to the thermal limiting heat bank of the ocean, much less variation but I find that chart pretty " massaged" for Tourist comparability.

What is PCM freezing?  Storing cold for later use?
Must remember to quizz my fridgy mate on the practicalities of putting a much oversize Compressor unit in a chest freezer.

BruceM

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Re: Power outages
« Reply #28 on: November 30, 2018, 01:32:45 AM »
Yes, PCM is phase change material.  For a cooling system just water freezing at 0C is OK, but for colder temperatures, other materials can be used or a bit of antifreeze added.

Your bigger temperature swings don't change the situation regarding super-insulation.  The peaks don't really matter; I have temps over 100F regularly in June, but the house stays around 68-71F.  Cool night time air, with open windows is all I need to drop it back down to 68 overnight. I occasionally get tricked by late clouds and a warm night, but not often.

As long as the total demand for cooling isn't too high, and the humidity isn't high, the in floor pex for heating can be used for cooling, with water temperatures around 55-60F.  If the water is too cold, or house is too humid, you get condensation on the tile floor.  A higher volume pump would help avoid cold spots.

BruceM

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Re: Power outages
« Reply #29 on: November 30, 2018, 01:38:42 AM »
Bob, I can't remember the big picture of your homestead power. One of the dual use inverters might be good for you, with a modest battery bank which could be augmented with Lister power.