OT: Power outage.

Ouch! Nasty. My daughter lives in Darwin, and they go through a power outage every time there is a major storm, which is fairly regular in them neck of the woods. I managed to talk her into UPSs all over the place to protect her computer, big screen TV etc. Most of which she has blown up in the past.

Not sure if you had good luck or bad luck. I guess the fact that the house is still intact, is a blessing.

Good luck with the relevant G.D.

--
Don McKenzie 

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** Hmmmmm....

A Chinese petrol powered, inverter / sine wave generator called KIPOR ?

So is " KIPOR " pronounced the same as kipper ??

In any case it sounds very fishy to me....

Easy to find reviews from unhappy customers on the net, some with a similar story but none with runaway petrol fires.

.... Phil

Trouble is, it seems easy to find reviews from unhappy customers for practically any product. It's hard to form a view as to the overall reliability or safety.

Sylvia.

You're lucky to get *any* estimate. The last few outages we had here described the area affected (in neither case did it include *our* location!) and "unknown causes" with no projected repair time.

"Press 1 to leave your number for notification when the repairs are complete"

And, the notification never comes. I guess they figure you'll see the lights come on and know (assuming you are on the affected premises!). In which case, why even *offer*?

That's one of the reasons *for* the UPS -- to act as a *clean* switch. I don't believe UPS's *or* PC's should come back on-line automatically after an outage, either (admittedly, a different issue for a data center)

And, the spare fuel stored nearby? :>

It is amazing how many people *don't* have fire extinguishers in their homes! We keep one by the stove (tiny unit), one out back (think: barbeque) and two in the garage. They're not the sorts of things you wnat to have to go

*looking* for when the need arises!

"Can't Happen" does!

I was pondering the requirement for solar panel inverters to shut down during an outage.

How exactly do they recognise an outage? The obvious answer is that the voltage drops.

But how many solar power systems in a small suburban area does it take to prevent the voltage from dropping low enough for the inverters to disconnect?

Could this explain why the voltage didn't vanish completely - for quite a while, it remained high enough to energise the displays of some of my appliances, which was confusing to say the least. At first, I thought we'd only lost one phase (we have two, out of the possible three here in Sydney).

Sylvia.

You don't want pushing power into the grid when it is "assumed" to be "off". E.g., local substation caught fire, here. In theory, there should be *no* power on any of the mains to the homes serviced by that substation. If, instead, cogenerators are pushing power *blindly* onto the network, it presents a safety hazard for folks working on it.

Conveying "Man on line" to everyone who may be cogenerating on that subnet can be a huge task -- esp if records aren't up-to-date. (that's why we have Codes!)

Good question (see above). I think the assumption is the generation capability on a particular sub-net is much less than that provided by the utility/consumed by the typical load.

Of course, it is conceivable that a large surplus cogeneration capability could be present on a particular subnet that is capable of substantially powering that subnet during an outage/failure. While this could be good for the consumers, there, it could be a problem for the utility and those charged with maintaining the distribution network.

Assuming the problem wasn't local to your home (a neighbor had a partial open in one leg in his fusebox causing it to catch fire, melt some conductors, etc), neighborhood, etc. it could represent any overload of the distribution capability of the network. It takes time for protective switch gear to actuate. And, time for it even to know there is a fault. A partial fault in a transformer can persist for a while, etc. A partial open can lead to a big IR drop at the open, etc.

[I worked on a CPU with a 100A -5.2V power supply. You could short the supply and it wouldn't blink! Wires would get a tad warmer...]

** An enormous number I expect.

** If the sub station/local transformer breakers open on one or two phases, a load connected across the phases will tend to hold up the voltage on the open ones. 3 phase motors air conditioners would be the main examples in suburban areas.

.... Phil

I had a power outage the other day while I was out. When i got home I went to the shed first and no lights but a funny noise coming from a small mill, it was slowly turning over, it has electronic control and I had just turned the speed control down to off and not at power point,(turning it anywhere had no effect,and machine just slowly just rotated) Any way went into house and had part light on one fitting< did some checking and found about 70 volts (next door had power so one phase in street affected apparently) Any way rung power mob who informed me they knew of a problem and it would be working about nine thirty (aprox 3 hours time). It was back up five minutes later, So apparently they just make up what ever time comes into their heads

One manufacturer periodically tries to shift the frequenecy, if the frequency changes then the grid is down and the inverter is islanding. I think it's UL1577 that goes into specifics of how long and at what voltage the islanding can ocurr for.

cheers

OK, I've taken out everything that's damaged, with a view to seeing what might be salvaged - not to repair it in the normal sense, but to see whether I might construct something safer and more reliable out of what's left.

What's left is essentially the engine, ignition coil, carburettor, (stepping?) motor controlled throttle, alternator including a fan, starter pulley and fuel tank. Actually, I'd prefer to do a propane mod on this the engine if possible, and forget about petrol, which is a pain all round in this application.

What appear to be the outlets from the alternator are puzzling. Seven quite thick wires. I've identified two being for a separate 12 7A battery charger output (bridge rectifier, but no smoothing that I can see).

That leaves five which, by their thickness, are all carrying considerable current. FWIW, two are white, and three are black.

Any thoughts?

Sylvia.

In Australia it is AS4777.3 that defines how the inverter knows to switch off or on.

"The grid protection device shall incorporate passive anti-island protection in the form of under- and over-voltage and under- and over-frequency protection...." in addition, "The grid protection device shall incorporate at least one method of active anti-islanding protection. Examples of such methods include shifting the frequency of the inverter away from nominal conditions in the absence of a reference frequency (frequency shift), allowing the frequency of the inverter to be inherently unstable in the absence of a reference frequency (frequency instability), periodically varying the output power of the inverter (power variation) and monitoring for sudden changes in the impedance of the grid by periodically injecting a current pulse (current injection)."

There are similar but different and probably incompatible standards in the USA and the UK and Germany. In Australia, to be permitted, the inverter needs to be chosen from a pre-defined list of permitted inverters as well as actually meeting the standard. (Getting onto that list is complicated and probably involves annual "processing fees" to some politician's brother in law. If you want to try out a US or european inverter that is safe but not yet on the Australian list, good luck with that!)

It's interesting that in the past, feeding power back into the grid used not to be a problem, when it was technique for braking large motors on variable speed drives (e.g. when lowering something heavy on an electric hoist), but now it is suddenly dangerous, coincidentally at the time when people have started to reduce the profitability of utilities by selling them power.

[snip]

There's clearly an issue if power lines that workers think they've isolated, and are safe, can suddenly be energised from someone's house. The length of the isolated section may be small, such that it's not unrealistic for a dangerous voltage to arise on it.

On the face of it, a similar issue might arise with using motors for braking. Perhaps it never was really safe, but the full ramifications hadn't been thought through.

Mind you, I've seen workers deliberately attach thick shorting wires between the phases (and presumably to ground), which would address such issues.

Sylvia.

Ummm...

Let's call it adequately far away and move quickly on.

Sylvia.

"say no more, say no more..."

Lightning? Massive "urban redevelopment" glitches? AKA large over-voltage on steroids.. Guess something like that initially, which zapped not only your stuff,but theirs as well.

Wild guess: Three phase WYE could use the 3 black for power, one white for neutral (center of WYE), and one white for safety ground (generator frame).

The grounding is elsewhere.

I now suspect that three are the stator windows. The resistance between any two of the three is about the same (5 ohms). They're isolated from the other two, which have about 1 ohm between them. I suspect those are connected to a field winding, with the permanent magnets only present so that the thing can bootstrap itself.

Given the thickness of the black wires (thicker than mains cable, but not so very thick), the resistance of the windings, and the total power output (2.6kW) I think these must run at a fairly high voltage, which seems to make finding a suitable off-the-shelf inverter somewhat more difficult.

Sylvia.

A guess maybe, the 3 blacks are your 3 phase out and the whites are the field excitation.

Jamie

Umm, they generate AC within tight parameters and only those that stop when the external voltage gets outside the tight parameters are allowed to be installed in Australia.

The real problem is clowns who try to circumvent this.