Given the parlous state of Australia's power systems, I've been considering buying a standby generator. One marketing point of some of the inverter bases models is their suitability for 'sensitive electronics' with computers given as an example. This appears to be based on the fact that they'll provide a consistent sinewave output.
But given that computers invariably use switch-mode power supplies, are they actually going to care what waveform they see - from square wave thru 'modified sinewave' thru pure sinewave?
I haven't experienced any power interruptions here in Sydney for many months so the supply's not exactly parlous where I am. My cheap UPS doesn't output a clean sine wave but the PC and monitor (switching supplies), answering machine and modem power supplies (50Hz transformer plugpacks) all work quite happily from it when it kicks in. I doubt that exact waveform makes much difference to most power supplies, especially switching supplies. Just my 2c worth...
what exactly do you want to use it for? Equipment? the power requirements of each item? duration? fuel?
I expect that most stuff doesn't really care, but you will never know until you try it. I've heard comments about some cheap inverters (steppy waves) some laptop power supplies run hot, but not chased up the details.
The only apparatus that usually needs pure or as close to it as you can get is stuff that is switching with mosfets(?) which need to sense the zero crossing.
NSW is in a better condition. The other states show predicted reserve shortfalls in the coming months.
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In some ways, though, reserve shortfalls are not such a huge concern, because the resulting blackouts get shared around, with no individual group of cumstomers subject to extened periods without power.
Of greater concern are overloaded transformers. If they fail it can take quite a long time for supplies to be restored. In periods of hot weather such events have been known.
So what's the big deal if it *does* happen? Not the end of the world. Go for a walk, go shopping, go visit a friend, read a book by torch or candle light, and countless other things you can do without mains power.
The other week I was stuck in a lift (in Frenchs Forest of all places) for more than an hour during a blackout, it was actually quite fun.
You'll survive, really, no need for a generator when you live in Frenchs Forest.
**Doesn't matter. A standby generator will deliver a 50Hz sine wave. It is a mechanical device, comprising a petrol or diesel motor, linked to an alternator. Inverters are for use with battery storage systems (VERY expensive) Make certain you do the following:
Ensure your generator can cope with fridges and the like. Fridges and other motorised devices have huge switch-on demands and can cause generator output to fall dramatically, thus risking damage to the motor (load).
Do not even THINK about a large air con with anything but a very large generator, UNLESS you are using an 'inverter' type air con. These have a 'soft start' and are suitable for use with most generators.
Get a Diesel or a 4 stroke type.
Buy one which has a lot more capacity than you think you'll need.
And have a place out side that gets a good breeze flowing away from the house to run it. The USA provides a continual stream of stories of people who ran the generator inside and experienced why you do not do this.
I attended the funeral of someone who also discovered it the hard way. You'd think the number of people using a car exhaust to commit suicide might give some clue though.
**That's the figure I've been told. However, I suspect it has a lot to do with the manufacturer. Quality manufactured products probably have short term overload capacity built in. Those cheap, Chinese generators from Bunnings probably barely meet their own specs.
**Indeed. It's amazing how stupid some people can be. I'm clearing 30-odd cu Metres of soil and rock from under my house. I'm doing it by hand, or with electrically powered tools only. It's bloody hard yakka. A few smartarses have suggested I should hire a DingoT and get the job done in a few days. Sheesh! There's no air flow under there and almost no viable method to push much air through either. I'd be lucky to last 30 mins.
**You guessed right. Logistics beat me everytime I thought it through.
I'd need to remove two door frames (not such a huge deal, but inconvenient). There's around 2cm clearance for a DingoT at present. I'm told that is sufficient to guarantee damage. Then there's the (lack of) security thing, whilst the job is progressing.
I'd need to organise bins to cart away the 50cu Metres (as you probably know, the stuff 'fluffs' up, when you dig it) of stuff. I can only manage 2 cu Metre bins at any one time.
Based on the above, I'd need a DingoT for a great deal longer than the optimum period of 2 days. I'd reckon on at least a month. Too expensive.
I'm not in a desperate hurry. If I was, I'd pay some guys to do it.
Honda (and possibly others) now offer generators with an inbuilt sinewave "inverter" in order to provide high quality power (presumably crystal locked to
50hz) for sensitive equipment regardless of generator motor speed fluctuations etc. This would also allow lower engine speeds at low load to save fuel, without affecting the output frequency
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Another advertised advantage of this system is the ability to link 2 of these units together in parallel via a special cable (available from Honda) in order to increase the total output capacity. This would probably have extra wire(s) to ensure the inverters outputs are synchronised, their output voltages as close as possible to each other to keep the load balanced between the 2 inverters/generators ?
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this provides 30a @ 120v (equivalent to a 15A 240v socket.) (note - this is for US use only, there would be an Australian version.)
The other advantage that this dual system MIGHT have is the ability to keep critical equipment in the home (such as life support) running in the home if one of the two generators fails, as long as the total load is sufficient for one unit. (NOTE: I don't want to go round giving advice on this, or saying its
100% foolproof, or legal, or safe in case Im wrong and someone is hurt or dies, please seek expert advice from the supplier or manufacturer or other expert before using or relying on this or any other method of powering life support)
For most people, I think this sort of unit would be an good choice for occasional temporary emergency home use of lighting, computers, phone charges etc etc and you can be sure it will run ANY sensitive equipment just as well as off the mains. Gas rings would be more efficient for cooking, boiling water etc.
Trevor's comments on selecting a generator should be noted also. regarding large loads, fridges air cons etc,
2 problems I can recall with use of non-mains power are :
Note there was a letter from a reader in silicon chip recently regarding use of a generator powering a battery charger on a boat, the battery charger wouldn't start at all with one particular generator (probably because of low quality or noisy power) and worked perfectly with another.
Another problem I have had personally is with my Dewalt cordless drill I bought in the 1990s when they first came out. It charged perfectly on the mains, but wouldnt charge on a modified square wave inverter (note: true sine wave inverters/generators wouldn't give this problem) we used in the work van. IT turned out to be a "series capacitor" type power supply (transformerless). Fortunately it charged pretty fast compared to the older cordless drills, and armed with a spare battery we just charged it off the mains at places where we were doing jobs.
These are examples of where a TRUE SINEWAVE inverter generator would be of benefit.
I dont think a PC would need this and would work happily off a square wave or modified square wave inverter (this is what most UPS provide.
**Yep. Already done. Badly, but the previous owner did it. I intend improving significantly.
**I think I'll do it by hand. It's good for the soul and feels great to jump in the pool after a hard day's digging.
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