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# 239361 13-Jul-2018 15:04
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A few years ago, off the back of a post here, I bought an inverter generator from TWG for an emergency backup; some @rse stole it out of our garage, and ever since I've debated getting another to replace it. What's put me off is that the ones that are at the 'affordable' end of the market are relatively low-powered, and I think to be really useful I'd like to be able to run a microwave off it (even if not running at 100%).


I saw today SCA has its smaller inverter models on discount, but the larger of these is 1700W. There is, however, a bigger beast (an open model, 2000W continuous) for only $600.


So, my question is, would one or both of these generators (or others of equivalent specs) be ok running a microwave, and could this be at full power or need to be reduced?


I understand that 'normal' microwaves require substantially more power at start-up, but I'm wanting to run an inverter model - website just states 1200W so I'd need to check the device itself or manual to get more detail than this - which I understand doesn't have this issue.


Also, are there many practical differences between the enclosed and open generators? I note the specs of the models linked to above suggest the same volume: clearly the open-frame model is also larger and heavier, but other than that is there anything to be mindful of?


Thanks in advance.



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  # 2055951 13-Jul-2018 19:38
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Noise is the difference. Seems that all powercuts happen at night around here which means I cant really run it much which defeats the purpose.


Friend has a non cheapie honda generator that he takes onsite to places and its really really quiet. Does rev up a little running a giant coffee machine but even at that it would be way quieter than my ozito or supercheap auto one on idle.


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  # 2055965 13-Jul-2018 20:14
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Reading through the manual its a 1.7kva and so that usually means it will only supply a max load of about 1.5kw


An 800 watt microwave starting up normally requires a generator of about 4kw output. It also depends if your microwave is an inverter or not - a 1000 watt microwave set to power level 8 still uses 1000 watts for 8 seconds out of every 10 of runtime, where as an inverter microwave will lower its draw to 800 watts. 




I keep a honda EU20i on the back of my ATV for doing hilltop site work. The reason is I have a honda ATV and so they both get taken into the local honda dealer every 6 months to be properly serviced - I like the generator to start first pull every time. 


For power cuts at home, I keep one of these little mini ovens. Much more compact than a bbq. Its also a resistive load and the one I have uses about 800 watts so is quite okay to use on the generator. 

Ray Taylor
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  # 2056018 13-Jul-2018 23:20

You also need to consider power factors. As appliances that contain inverters can easily have power factors as bad as 0.5 This means that you double the power rating to get the VA rating. So your 1000W microwave would actually be 2000VA. And that microwave power rating might actually be the cooking power. If so, 1000W of output would be at least 1200W of input. (as a microwave will never be 100% energy efficient) Then you allow for power factor. And your 1000W microwave is running a normal 10A power socket right to the limit (2400VA).


It gets worse when you consider the peak current available from a normal power socket. A typical C curve circuit breaker (most common type in new switchboards), will allow through around 8 times it's rated current for around 3 seconds. Assuming it is a 20A circuit breaker, that is 160A. And if you run that 20A circuit breaker at 29A, it will take 1 hour to trip. (ratio of 1.45)


Yet the bigger generator linked above only has a peak to rated capacity ratio of just 1.1, so you can't run appliances with large startup loads from it reliably. You have to assume that it is only rated at around 275W output, assuming that you need similar peak starting capacity to what mains power can provide.




What are you wanting to cook, that has to be done using a microwave? Can you use a portable gas cooker instead? Especially as gas is almost completely silent, it doesn't go stale (unlike petrol). And if the built in starter doesn't work, you can use matches to get it going.




MCB trip curves. Note they are calculated at 30deg ambient temp. Colder temps mean even larger currents. link goes to a PDF.

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  # 2056019 13-Jul-2018 23:29
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Also the spraypaint sized cans of butane for a cheap stove are so damn cheap at bunnings and the warehouse that you can have a decent number sitting around and so long as they are dry they seem to last for ages.


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