Have searched the net for info, but can't seem to find a simple answer. I have used a standard generator before on a building site. So how does a inverter generator work? Does it draw off the car battery? Can this flatten the battery? What can I run from it?
brian said
10:17 AM Mar 19, 2014
arthur wrote:
Have searched the net for info, but can't seem to find a simple answer. I have used a standard generator before on a building site. So how does a inverter generator work? Does it draw off the car battery? Can this flatten the battery? What can I run from it?
A standard generator simply outputs a 240v AC sine wave, the frequency (number of cycles per second or Hz) of which should be 50Hz in Australia to be in common with our mains supply.
That frequency is directly controlled by the revolutions (RPM) of the generator which is in turn controlled by the RPM of the mechanically connected motor that is driving it.
When you apply an electrical load to a generator, the resistance to it turning is increased, this puts more load on the motor, which must then attempt to increase its power output to thus return its speed back to that which gives the 50Hz output from the generator.
As you can see, this reaction will not be immediate, and sometimes not even possible if the load is too great.
This results in a fluctuating frequency and voltage, and a distorted waveform, all of which cause problems to connected appliances.
An inverter generator works a bit differently, it still produces AC but normally more than one sine wave (multiphase), and often at a voltage that is not 240v, it may be lower or higher depending on the brand of generator.
This Multiphase AC is then rectified and filtered to provide a fairly smooth DC.
The DC is then electronically inverted and regulated to a 240v single phase pure sine wave output.
Because the inverter section is simply changing a direct current to the AC output, it is little concerned with the RPM of the motor and so is not so much affected by variances in the connected load.
Obviously, loading the generator too heavily will ultimately cause the electronics to be incapable of compensating for that load, and you can experience waveform and frequency distortion, but generally they are far superior to a standard generator.
Hope this helps.
-- Edited by brian on Wednesday 19th of March 2014 10:42:38 AM
KFT said
10:31 AM Mar 19, 2014
Hi Arthur
Brians reply gives you a very good description of how both styles of genset produce the AC power at the outlet.
If you google Honda Eu20i or look for inverter generators you will see several examples of these machines.
they have a much smaller engine than the older style gennys and are much more portable.
frank
arthur said
11:45 AM Mar 19, 2014
Thanks for info. I'm completely blonde when it comes to discussing electrical power, watts etc. So my assumption that they are connected to a battery is incorrect? That is they are a stand alone unit?
-- Edited by arthur on Wednesday 19th of March 2014 11:46:50 AM
-- Edited by arthur on Wednesday 19th of March 2014 11:49:47 AM
brian said
11:58 AM Mar 19, 2014
arthur wrote:
Thanks for info. I'm completely blonde when it comes to discussing electrical power, watts etc. So my assumption that they are connected to a battery is incorrect? That is they are a stand alone unit?
-- Edited by arthur on Wednesday 19th of March 2014 11:46:50 AM
-- Edited by arthur on Wednesday 19th of March 2014 11:49:47 AM
Unless they are an electric start model, they don't require a battery to be connected to them.
arthur said
12:03 PM Mar 19, 2014
OK, thanks, so what output (watts?) should I be looking at for general caravan use? I'm planning on setting up on some land I own and building a house, while I live in the van. I will eventually get temporary builders power supply.
Is this too cheap and nasty? http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
brian said
12:46 PM Mar 19, 2014
arthur wrote:
OK, thanks, so what output (watts?) should I be looking at for general caravan use? I'm planning on setting up on some land I own and building a house, while I live in the van. I will eventually get temporary builders power supply.
Is this too cheap and nasty? http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
It's certainly cheap.
A lot will depend on how much use you intend to give it when building your home.
It has sufficient capacity to drive a large power saw or compressor separately, and maybe small ones in concert.
No dB rating supplied but probably a bit noisy to endear yourself to neighbours when camping, but then very few generators are tolerable to other campers.
No weight supplied, so might be a bit heavy for camping also, the cheapies seem to be very heavy.
12 months warranty might be an advantage provided you do your building within that time frame.
arthur said
02:00 PM Mar 19, 2014
Thanks brian, you are a champion!
aussie_paul said
10:27 PM Mar 19, 2014
41.5 kg. Might have a look at that myself. Should run aircon ok. Thoughts??
Aussie Paul.
arthur said
09:24 AM Mar 20, 2014
aussie_paul wrote:
41.5 kg. Might have a look at that myself. Should run aircon ok. Thoughts??
CAUTION Arthur, that particular unit is not an inverter and as such it is not a PURE SINE WAVE unit. Thus as was explained earlier the frequency and shape of the electrical signal may give you problems, especially if you plan to run a computer, phone chargers etc. It is also worth noting that it is big and heavy, with many more powerful inverter units much smaller, and much lighter.
You really need to understand what you want to power first, then settle on a generator to suit. So spend a bit of time working out what you are likely to want to run when, look at how many watts they use. Add all the ones that you want to run at once together, add 50% and that would be roughly the size of teh generator you will need. THen come back and look for advice on a suitable unit.
Beware of things like air conditioning, as they typically have starting loads much higher than what they need to keep them running.
Sorry to be a negative voice, but a little bit of effort to understand your needs up front will probably save a lot of regrets later.
arthur said
09:32 PM Mar 20, 2014
Yes thanks, Plendo. As it is probably my computer and mobile, which I will need to keep powered. I will probably spend a bit more money to get the right unit.
-- Edited by arthur on Thursday 20th of March 2014 09:26:07 AM
-- Edited by arthur on Thursday 20th of March 2014 09:28:51 AM
aussie_paul said
10:56 PM Mar 20, 2014
Plendo wrote:
CAUTION Arthur, that particular unit is not an inverter and as such it is not a PURE SINE WAVE unit. Thus as was explained earlier the frequency and shape of the electrical signal may give you problems, especially if you plan to run a computer, phone chargers etc. It is also worth noting that it is big and heavy, with many more powerful inverter units much smaller, and much lighter.
You really need to understand what you want to power first, then settle on a generator to suit. So spend a bit of time working out what you are likely to want to run when, look at how many watts they use. Add all the ones that you want to run at once together, add 50% and that would be roughly the size of teh generator you will need. THen come back and look for advice on a suitable unit.
Beware of things like air conditioning, as they typically have starting loads much higher than what they need to keep them running.
Sorry to be a negative voice, but a little bit of effort to understand your needs up front will probably save a lot of regrets later.
Which one does not have the inverter? Bunnings or BCF. I notice the Bunnings one does not supplying 12 volt. BCF is 2 stroke.
I guess for my purposes with aircon, what are the negatives of the Bunnings unit. http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
Aussie Paul.
brian said
08:35 AM Mar 21, 2014
aussie_paul wrote:
Plendo wrote:
CAUTION Arthur, that particular unit is not an inverter and as such it is not a PURE SINE WAVE unit. Thus as was explained earlier the frequency and shape of the electrical signal may give you problems, especially if you plan to run a computer, phone chargers etc. It is also worth noting that it is big and heavy, with many more powerful inverter units much smaller, and much lighter.
You really need to understand what you want to power first, then settle on a generator to suit. So spend a bit of time working out what you are likely to want to run when, look at how many watts they use. Add all the ones that you want to run at once together, add 50% and that would be roughly the size of teh generator you will need. THen come back and look for advice on a suitable unit.
Beware of things like air conditioning, as they typically have starting loads much higher than what they need to keep them running.
Sorry to be a negative voice, but a little bit of effort to understand your needs up front will probably save a lot of regrets later.
Which one does not have the inverter? Bunnings or BCF. I notice the Bunnings one does not supplying 12 volt. BCF is 2 stroke.
I guess for my purposes with aircon, what are the negatives of the Bunnings unit. http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
Aussie Paul.
You will probably find that neither of those units are inverter generators Paul.
Generally, if they don't state that it is an inverter generator, then it likely is not, and inverter types are normally more expensive as well.
This doesn't mean that it doesn't put out a pure sine wave - an AC generator of any persuasion will do that, it's just that the frequency of that sine wave, and also the output voltage under fluctuating loads will vary much more than will the inverter type.
Greatly varying loading can create a distorted waveform but most appliances can handle that provided it doesn't get too much, or the voltage drop too great.
Induction motors (fridge, washing machine etc.) are designed to run with up to 5% frequency and 10% voltage variation, and universal motors (most power tools, small appliances) with up to 5% frequency and 6% voltage variation.
Voltage and frequency reduction in concert will cause excessive slip (the amount by which the shaft RPM lags the field RPM) and other factors which will generally cause the motor to have lower starting torque, slower speed, and overheating problems. Electronics will be less affected provided the changes are not too great.
This is the reason that I suggested that the smaller unit is not a good choice if intending to use decent sized power tools from it.
Have searched the net for info, but can't seem to find a simple answer. I have used a standard generator before on a building site. So how does a inverter generator work? Does it draw off the car battery? Can this flatten the battery? What can I run from it?
A standard generator simply outputs a 240v AC sine wave, the frequency (number of cycles per second or Hz) of which should be 50Hz in Australia to be in common with our mains supply.
That frequency is directly controlled by the revolutions (RPM) of the generator which is in turn controlled by the RPM of the mechanically connected motor that is driving it.
When you apply an electrical load to a generator, the resistance to it turning is increased, this puts more load on the motor, which must then attempt to increase its power output to thus return its speed back to that which gives the 50Hz output from the generator.
As you can see, this reaction will not be immediate, and sometimes not even possible if the load is too great.
This results in a fluctuating frequency and voltage, and a distorted waveform, all of which cause problems to connected appliances.
An inverter generator works a bit differently, it still produces AC but normally more than one sine wave (multiphase), and often at a voltage that is not 240v, it may be lower or higher depending on the brand of generator.
This Multiphase AC is then rectified and filtered to provide a fairly smooth DC.
The DC is then electronically inverted and regulated to a 240v single phase pure sine wave output.
Because the inverter section is simply changing a direct current to the AC output, it is little concerned with the RPM of the motor and so is not so much affected by variances in the connected load.
Obviously, loading the generator too heavily will ultimately cause the electronics to be incapable of compensating for that load, and you can experience waveform and frequency distortion, but generally they are far superior to a standard generator.
Hope this helps.
-- Edited by brian on Wednesday 19th of March 2014 10:42:38 AM
Brians reply gives you a very good description of how both styles of genset produce the AC power at the outlet.
If you google Honda Eu20i or look for inverter generators you will see several examples of these machines.
they have a much smaller engine than the older style gennys and are much more portable.
frank
Thanks for info. I'm completely blonde when it comes to discussing electrical power, watts etc. So my assumption that they are connected to a battery is incorrect? That is they are a stand alone unit?
-- Edited by arthur on Wednesday 19th of March 2014 11:46:50 AM
-- Edited by arthur on Wednesday 19th of March 2014 11:49:47 AM
Unless they are an electric start model, they don't require a battery to be connected to them.
OK, thanks, so what output (watts?) should I be looking at for general caravan use? I'm planning on setting up on some land I own and building a house, while I live in the van. I will eventually get temporary builders power supply.
Is this too cheap and nasty? http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
It's certainly cheap.
A lot will depend on how much use you intend to give it when building your home.
It has sufficient capacity to drive a large power saw or compressor separately, and maybe small ones in concert.
No dB rating supplied but probably a bit noisy to endear yourself to neighbours when camping, but then very few generators are tolerable to other campers.
No weight supplied, so might be a bit heavy for camping also, the cheapies seem to be very heavy.
12 months warranty might be an advantage provided you do your building within that time frame.
Thanks brian, you are a champion!
41.5 kg. Might have a look at that myself. Should run aircon ok. Thoughts??
Aussie Paul.
or this one?
http://www.bcf.com.au/online-store/products/Scorpion-650W-Generator-8-kVA.aspx?pid=128273&menuFrom=571641#Cross
-- Edited by arthur on Thursday 20th of March 2014 09:26:07 AM
-- Edited by arthur on Thursday 20th of March 2014 09:28:51 AM
Getting a bit small for running any decent power tools.
CAUTION Arthur, that particular unit is not an inverter and as such it is not a PURE SINE WAVE unit. Thus as was explained earlier the frequency and shape of the electrical signal may give you problems, especially if you plan to run a computer, phone chargers etc. It is also worth noting that it is big and heavy, with many more powerful inverter units much smaller, and much lighter.
You really need to understand what you want to power first, then settle on a generator to suit. So spend a bit of time working out what you are likely to want to run when, look at how many watts they use. Add all the ones that you want to run at once together, add 50% and that would be roughly the size of teh generator you will need. THen come back and look for advice on a suitable unit.
Beware of things like air conditioning, as they typically have starting loads much higher than what they need to keep them running.
Sorry to be a negative voice, but a little bit of effort to understand your needs up front will probably save a lot of regrets later.
Yes thanks, Plendo. As it is probably my computer and mobile, which I will need to keep powered. I will probably spend a bit more money to get the right unit.
Which one does not have the inverter? Bunnings or BCF. I notice the Bunnings one does not supplying 12 volt. BCF is 2 stroke.
I guess for my purposes with aircon, what are the negatives of the Bunnings unit. http://www.bunnings.com.au/full-boar-2800w-petrol-generator_p6290304
Aussie Paul.
You will probably find that neither of those units are inverter generators Paul.
Generally, if they don't state that it is an inverter generator, then it likely is not, and inverter types are normally more expensive as well.
This doesn't mean that it doesn't put out a pure sine wave - an AC generator of any persuasion will do that, it's just that the frequency of that sine wave, and also the output voltage under fluctuating loads will vary much more than will the inverter type.
Greatly varying loading can create a distorted waveform but most appliances can handle that provided it doesn't get too much, or the voltage drop too great.
Induction motors (fridge, washing machine etc.) are designed to run with up to 5% frequency and 10% voltage variation, and universal motors (most power tools, small appliances) with up to 5% frequency and 6% voltage variation.
Voltage and frequency reduction in concert will cause excessive slip (the amount by which the shaft RPM lags the field RPM) and other factors which will generally cause the motor to have lower starting torque, slower speed, and overheating problems. Electronics will be less affected provided the changes are not too great.
This is the reason that I suggested that the smaller unit is not a good choice if intending to use decent sized power tools from it.