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neb

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  Reply # 2014450 11-May-2018 23:51
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Hunter: Ran our house water pump easily, our deep freezer, and my PC as well. Not at the same time of course.

 

 

Or in that order. As everyone here knows, the priority would be: Router + WiFI + PC, then, um, stuff. Other stuff. Less important.

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  Reply # 2014451 11-May-2018 23:58
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Coil:

Things with generators, motors and "buy it for life" doesn't go hand in hand with "Cheap"


 


Imported chinese generators before, Don't even bother. These were the brand BOLD and were really good until little things started to fail.



Lots of the cheap Chinese generators actually output 120V -0 -120V With the output sockets wired phase to phase to get 240V. Not good for sensitive electronics that need a proper neutral reference. And if you plug that generator into a generator input socket on a building. The MEN link in the switchboard short circuits 1 of the generators windings.





 
 
 
 


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  Reply # 2014453 12-May-2018 00:12
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neb: A general comment on generators, or at least generators of some years ago, don't know what they're like today, you're going to see issues of voltage and frequency fluctuation that you won't see in normal mains power supplies. For example when you connect/switch in a load there'll be a sudden slowdown of the prime mover until the servomechanism can adjust the fuel flow to provide more power to compensate. This can lead to a change in frequency, but you can also get changes in voltage as the load changes.

So it depends what you want to power. Keeping your fridge running is one thing, but I'd be a bit nervous about running expensive computer gear off one. In theory a switchmode supply will deal with all sorts of out-of-spec crap, but I'd still be a bit nervous about it. You then also run into issues with trying to deal with generator issues, e.g. putting a ferroresonant conditioner behind one would seem to be an ideal solution except that ferros don't deal with frequency glitches well.


This glitch problem can easily occur with inverter generators as well. Since a lot of them run the engine at a slower speed when operating at less than 100% load. When a big load gets switched on, or an appliance draws a large in rush surge. There is not enough power available to the inverter to maintain output. As the engine can't instantly speed up.

This happened with a fancy Honda inverter generator being used on a construction site. Whenever someone started a power tool, the fluro lights turned into strobe lights for a couple of seconds. The generator was being used in eco mode to reduce noise and fuel use (variable engine speed). It did have another mode where the engine is held at max speed regardless of load. Generator would have been rated at around 5KW.





neb

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  Reply # 2014455 12-May-2018 00:18
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Aredwood: This glitch problem can easily occur with inverter generators as well. Since a lot of them run the engine at a slower speed when operating at less than 100% load. When a big load gets switched on, or an appliance draws a large in rush surge. There is not enough power available to the inverter to maintain output. As the engine can't instantly speed up.

 

 

Ouch! That's good to know, several of the ones I had a (quick) look at advertised an eco mode where they run the prime mover at a much-reduced speed under low loads to save fuel and reduce noise. It'd be interesting to see how those perform, whether they have any built-in headroom to run the inverter for a few seconds under the higher load while the prime mover ramps up.

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  Reply # 2014456 12-May-2018 00:24
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neb:
timmmay:

You could always put a small UPS in front of anything sensitive.



You'd want to look at what the UPS is capable of dealing with both in terms of conditioning the power passing through it and dealing with arbitrary changes in voltage or frequency. They're designed to handle outright cuts and brownouts, but I don't know how many will deal with frequencies or voltages wandering above and below spec. That's why a ferro is good if you're worried about voltage drift but not frequency drift (as well as taking care of all sorts of crap on the mains, they're pretty impressive devices).


Get a full online type UPS. As they convert the mains to DC, provide it to the battery, and then convert the battery voltage back to mains again. Higher conversion losses, but gives the best output. And zero transfer time if a glitch happens. As the inverter is already supplying the load. And this would be the only type that can correct for frequency variations.

Cheap UPS are unlikely to be full online. As you need a big DC step down power supply and an inverter + batteries all in the same unit. Which costs more to build compared to passing through the mains and swapping the load between direct to mains or a standby inverter.





neb

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  Reply # 2014457 12-May-2018 00:35
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Here's a video of a (non-inverter) generator switching from no-load to 50% load condition. Note the frequency displayed, which should be 60Hz (US model). Ouch.

neb

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  Reply # 2014458 12-May-2018 00:46
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Aredwood: Get a full online type UPS. As they convert the mains to DC, provide it to the battery, and then convert the battery voltage back to mains again. Higher conversion losses, but gives the best output. And zero transfer time if a glitch happens.

 

 

The problem with putting a UPS after a generator or similar is that they're designed to protect the equipment behind them from power line issues, which means that if they detect any kind of anomaly in the incoming power they'll switch to battery. Worst case, with a non-inverter generator, the UPS will see the garbage the generator is putting out and run off battery the entire time because it sees the generator output as invalid line input. With an inverter generator you're mostly outputting a signal that won't trigger the UPS, and then using the UPS to ride through load changes until the prime mover can be brought up to speed. That's probably a rather expensive use for an online UPS...

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  Reply # 2014459 12-May-2018 00:58
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neb:
Aredwood: This glitch problem can easily occur with inverter generators as well. Since a lot of them run the engine at a slower speed when operating at less than 100% load. When a big load gets switched on, or an appliance draws a large in rush surge. There is not enough power available to the inverter to maintain output. As the engine can't instantly speed up.
Ouch! That's good to know, several of the ones I had a (quick) look at advertised an eco mode where they run the prime mover at a much-reduced speed under low loads to save fuel and reduce noise. It'd be interesting to see how those perform, whether they have any built-in headroom to run the inverter for a few seconds under the higher load while the prime mover ramps up.

 

 

 

There was definitely not enough headroom with that Honda generator running in ECO mode. Baseload would have only been around 200W (couple of magnetic ballast fluro lights and some cordless drill battery chargers). Yet the startup load from large power tools would have required full capacity. It was being asked to instantly ramp from less than 5% of max load to providing it's full output. You would need some very big capacitors to store enough energy to run say a 3KW load for a few seconds.

 

 

 

Edited to add

 

 

 

If there was a UPS connected to that generator as well, It would have been forced to transfer to battery whenever a power tool got started.






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  Reply # 2014461 12-May-2018 01:53
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neb: Here's a video of a (non-inverter) generator switching from no-load to 50% load condition. Note the frequency displayed, which should be 60Hz (US model). Ouch.

 

Agree on the unstable frequency part. But non inverter generators (assuming that they are a full synchronous design). Are better at handling very short term but very large inrush surges. Imagine loads such as switch mode power supplies that consist of a bridge rectifier connected to a large filter capacitor. And also loads such as older audio amplifiers that have a large iron core transformer, that in turn feeds a rectifier and then some big filter capacitors. Imagine the switch on surge if the power switch happens to be turned on, right when the inverter is outputing 360V at the peak of the mains waveform.

 

With an non inverter synchronous generator, you still get a pure sine wave output. And the generator can easily start those above loads, as the momentum in the prime mover and generator armature. Combined with the fact that the generator directly feeds the load. Allows for very high short term surge capability. As long as the surge clears before the windings overheat.

 

The 200W switchmode power supply in my old 486 PC momentarily dimmed the lights in my house whenever I switched it on. It has such a big switch on surge, that it would cause a noticeable voltage drop in the mains cable between my house and the powerlines in the street. Good luck to an inverter trying to successfully start that power supply without causing a glitch.

 

Also some inverters cant run capacitive loads. So beware things like magnetic ballast fluro lights, as some of them have power factor correction capacitors wired directly across the mains input terminals. It is lucky that the builder didn't destroy that Honda generator with those fluro lights. While a non inverter synchronous generator wont care about poor power factor loads, as long as it's output current rating isn't exceeded.

 

 

 

Sure, In most cases an inverter generator is better. But not always.

 

 

 

I have a 3 phase Honda generator. Full synchronous, but only rated at around 4KW. Which means it can only output around 5A per phase (boo!!) Its engine speed governor (and therefore output frequency governor) is completely mechanical, so it behaves the same way as in the above video. Considering that it would be at least 30 years old, yet still starts easily. And will happily run my refrigerator, power tools etc. The only electronics that it has is a small voltage regulator board. Which would likely be simple enough for me to be able to repair it or make a whole new one if it fails. How many inverter generators are going to get scrapped due to electronics failures in the inverters? And spare parts being impossible to obtain.






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  Reply # 2014476 12-May-2018 06:52
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Hunter: I was like you, worried about the changing weather pattern.

So some 6 months ago, bought a 2000w Honda inverter, 20i
Then it got left sitting around and I was wondering that I just paid a huge amount of money for just doing nothing.

Then we had the big Auckland Power Cut, and boy did that inverter came useful.
Ran our house water pump easily, our deep freezer, and my PC as well. Not at the same time of course.
Petrol consumption is not too bad, one tank lasted quite a long time, with the inverter running at full tilt
Did not timed it, so cannot tell you how long it was.

Made a Suicide Plug, ie male plug on both ends, and plug into a power point, MAKING sure mains is off at power board and at meter for good measure.
Apparently the inverter can literally blow up when power comes on.

I did thought about diesel, but came to following conclusion.
1. Diesel more expensive, for brand name Inverter, and heavier.
2. Harder to pull start a diesel, especially cold. Forget about battery start, another complicating factor.
3. Cannot store diesel for long, I cycle my petrol containers thru my car.

Being a last resort equipment, I decided to get something that I can truly rely on, regardless.
So it only brand name for me.


You plugged the generator into your mains?

My understanding is that this is illegal as it can be very dangerous for line workers.

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  Reply # 2014488 12-May-2018 07:56
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neb:
Hunter: Ran our house water pump easily, our deep freezer, and my PC as well. Not at the same time of course.
Or in that order. As everyone here knows, the priority would be: Router + WiFI + PC, then, um, stuff. Other stuff. Less important.

 

Sentry Lite with a 30AH battery will last some time, and powers fiber modem thingy and router. The 8AH they include does about 6h from memory. @jeffnz can sometimes get "second" batteries at a good price.

 

I also got a solar panel that sits in the shed window (too lazy to mount it) that keeps those batteries charged. If I really need it I'll just lay out outside on the ground. You could run an inverter from those, I guess, but I didn't get around to that.





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neb

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  Reply # 2014861 12-May-2018 18:09
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timmmay:

Sentry Lite with a 30AH battery will last some time, and powers fiber modem thingy and router. The 8AH they include does about 6h from memory. @jeffnz can sometimes get "second" batteries at a good price.

 

 

I've been vacillating about those things for years now. On the one hand it's a cool product, but then you end up with a rats nest of components hanging together, and there's not much of a display for battery and power status like in a UPS. The all-in-one unit uses LiIon of unknown capacity, and I'm always a bit nervous about how well they're handled and whose cells they're using because of the fire danger. Then there's the PicoUPS at a fraction of the cost of the Sentry, and if I need to put it together myself I may as well use that. Or the OpenUPS2 in place of the all-in-one, using safer LiFePO4 instead of LiCoO2. Or just a generic UPS since 99.9% of the time it'll be running in pass-through mode so the extra conversion step isn't used, and those have a decent display of what's going on and will tell you about your battery state unlike the Sentry.

 

 

Thus the indecision...

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  Reply # 2014893 12-May-2018 19:05
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Mine's in a cupboard and I never see it. It's a bit ugly but I like the flexibility. 





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  Reply # 2014915 12-May-2018 20:09
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In general: keep in mind that car fuel contains of a lot of chemicals (fuel system cleaners, fuel stabilizer, etc.) which slowly become undone after a relatively short time and can harm the carburator, fuel system, sealings and pipes. It's recommended to defuel all equipment like chain saws, generators, mower and cars when not in use for more than a few month or to add protective measures to keep the fuel in the tank. Be aware that the mixture needs to be flooded once completely through the whole fuel chain, from the tank to the engine's valve(s)! If you don't care, you'll face an unoperable emergency generator when you need it the most - the worst you can expect.

 

Yes, for sure this is valid for Rolls-Royce turbo fan engines as well. wink

 

 

 

LINK added and the small ones.





Nope, English isn't my mother tongue. But that's why I'm here. smile


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  Reply # 2015092 13-May-2018 12:40
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blackjack17:
Hunter: I was like you, worried about the changing weather pattern.

So some 6 months ago, bought a 2000w Honda inverter, 20i
Then it got left sitting around and I was wondering that I just paid a huge amount of money for just doing nothing.

Then we had the big Auckland Power Cut, and boy did that inverter came useful.
Ran our house water pump easily, our deep freezer, and my PC as well. Not at the same time of course.
Petrol consumption is not too bad, one tank lasted quite a long time, with the inverter running at full tilt
Did not timed it, so cannot tell you how long it was.

Made a Suicide Plug, ie male plug on both ends, and plug into a power point, MAKING sure mains is off at power board and at meter for good measure.
Apparently the inverter can literally blow up when power comes on.

I did thought about diesel, but came to following conclusion.
1. Diesel more expensive, for brand name Inverter, and heavier.
2. Harder to pull start a diesel, especially cold. Forget about battery start, another complicating factor.
3. Cannot store diesel for long, I cycle my petrol containers thru my car.

Being a last resort equipment, I decided to get something that I can truly rely on, regardless.
So it only brand name for me.


You plugged the generator into your mains?

My understanding is that this is illegal as it can be very dangerous for line workers.

 

Poster said he switched the mains off so he felt it was safe. Areas of concern are:

 

The process of switching to generator supply relies on the poster remembering to disable network power. Poster remembered to isolate this time but we all know people make mistakes.

 

Is there any one else in the household who knows about this process? is there a lockout enforced on the isolator?

 

Not ignoring a danger to line workers and depending on the nature of the transformer connecting your house to the network (star/delta), I imagine your generator could also suffer if you forget to isolate.

 

Your neighbours would appreciate the free power though.

 

On balance I would say such a situation exemplifies the kind of innovation NZ is proud of but shunning in these health and safety aware times.

 

Get it wrong and energy safe will come calling. Fines are hefty! https://www.ewrb.govt.nz/about-us/news-and-notices/?category=153

 

 

 

 


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