Buying a Generator

[Ean Austral]

Gday All,


Looking at a generator for power back-up in the case of cyclone or power outages. My last 1 was I think 4.5kva but think that was peak and only for short bursts, was most like 3.5kva continuous.
Am looking at 10kva but notice most are only 7.5kva with 10kva max output, so wondering if this would be the same. Seems a big variation of 2.5kva but it may just the ratio ie 25%.


So does anyone have back-up power generators and if so what Kva. Need to run basic stuff as 1 fridge/freezer, few fans, fish tank, phone and light charger, stuff like that.


We have gas for cooking so no problems there, but just want to buy something that will be enough incase need to add any extra stuff.


Cheers Ean

[blitz]

if you want to run every thing you need to work out the total power consumption of your house. As I am thinking of the same myself, I am looking at a diesel self starting of at least 7.5 but probably closer to 10kva, but as I am an electrician as well I am going to probably go a bit over board and make it auto start for no real reason other than I can. It will also be a super quite jobby. I am going that size as I want it to be able to run air conditioners as I have become a softy. oh and use it for the workshop as well.

[Homestar]

5KVA will run all that without issue, but if you wanted to run AC, etc then you may need a bit bigger. Like Blitz, I'm a Sparky, and my job is Standby Diesel Power Generation, so I will make mine all singing, all dancing. I've got a 10KVA single phase, 4 pole genny - a diesel that runs at 1500 RPM, so quieter than the small handyman jobs that are 2 pole and run at 3000 RPM.

I've got a very sweet control system and ATS (auto transfer switch) for mine too, so it will do everything itself, and even do a closed transition to mains on return so I don't get a second blackout when the mains is retuned.

Anyway, 5KVA is fine for most houses, 8 to 10KVA if you have a few extra dollars and want to future proof things a bit or run absolutely everything in your house and make the neighbours jealous.:)

Oh, and make sure that's a single phase unit - not 3 phase unless your house is. 10KVA single phase gives you 43 ish amps of that one phase, but a 10KVA 3 phase will only give you 14 amps but on each of the 3 phases. If you only have a single phase supply to your house, make sure you get a single phase genny.

[Piddler]

5KVA will run all that without issue, but if you wanted to run AC, etc then you may need a bit bigger. Like Blitz, I'm a Sparky, and my job is Standby Diesel Power Generation, so I will make mine all singing, all dancing. I've got a 10KVA single phase, 4 pole genny - a diesel that runs at 1500 RPM, so quieter than the small handyman jobs that are 2 pole and run at 3000 RPM.

I've got a very sweet control system and ATS (auto transfer switch) for mine too, so it will do everything itself, and even do a closed transition to mains on return so I don't get a second blackout when the mains is retuned.

Anyway, 5KVA is fine for most houses, 8 to 10KVA if you have a few extra dollars and want to future proof things a bit or run absolutely everything in your house and make the neighbours jealous.:)

Oh, and make sure that's a single phase unit - not 3 phase unless your house is. 10KVA single phase gives you 43 ish amps of that one phase, but a 10KVA 3 phase will only give you 14 amps but on each of the 3 phases. If you only have a single phase supply to your house, make sure you get a single phase genny.

Any chance of more info? like photos and brand etc?
Sounds awesome, we loose our power heaps where we are.
Cheers

[rocket scientist]

5KVA will run all that without issue, but if you wanted to run AC, etc then you may need a bit bigger. Like Blitz, I'm a Sparky, and my job is Standby Diesel Power Generation, so I will make mine all singing, all dancing. I've got a 10KVA single phase, 4 pole genny - a diesel that runs at 1500 RPM, so quieter than the small handyman jobs that are 2 pole and run at 3000 RPM.

I've got a very sweet control system and ATS (auto transfer switch) for mine too, so it will do everything itself, and even do a closed transition to mains on return so I don't get a second blackout when the mains is retuned.

Anyway, 5KVA is fine for most houses, 8 to 10KVA if you have a few extra dollars and want to future proof things a bit or run absolutely everything in your house and make the neighbours jealous.:)


Oh, and make sure that's a single phase unit - not 3 phase unless your house is. 10KVA single phase gives you 43 ish amps of that one phase, but a 10KVA 3 phase will only give you 14 amps but on each of the 3 phases. If you only have a single phase supply to your house, make sure you get a single phase genny.

I have a 5 kva running as a back up on our solar system.
Though probably strained it has been doing the job for many years.
I do need to replace the generator head that was on my 2cyl Lister diesel.
Preferably 3 phase so it can run some machinery.
With respect taking power off either of the phases, will that damage the generator over a period of time. Do you need to balance the load by taking similar load off each phase at the same time?

Pete.

[Homestar]

I have a 5 kva running as a back up on our solar system.
Though probably strained it has been doing the job for many years.
I do need to replace the generator head that was on my 2cyl Lister diesel.
Preferably 3 phase so it can run some machinery.
With respect taking power off either of the phases, will that damage the generator over a period of time. Do you need to balance the load by taking similar load off each phase at the same time?

Pete.

Damage to the alternator is unlikely by just using one phase, the issue is more about integration into an existing single phase switchboard by the installing Electrician and if you just use one phase to run the house, then your wasting 2/3rds of the machines output. But if you have a need for 3 phase power, then go for a 3 phase gen.:)

[Homestar]

Any chance of more info? like photos and brand etc?
Sounds awesome, we loose our power heaps where we are.
Cheers

My setup is just a pile of parts at the moment, but the controller I'll be using is a Comap Inteligen unit - ComAp - Power Generation and Drive Power Controllers (http://www.comap.cz). I use them on all our big gensets at work, and their flexibility and power is best in market. I've also been involved with the development of the software for this unit to get it to do things they don't do anywhere else in the world. Australian supply authorities have some very specific requirements for how gensets need to operate against the grid which no where else does. I've been helping develop that system for years.

[JDNSW]

7.5 kVA should be adequate for your house if you are not running any heating devices. My house has run for twenty years on two 2kVA inverters, and my 7.5kVA backup has been plenty big enough.

Worth noting that as a general rule generators, particularly diesels, are often less than happy running at a very low proportion of rated output. This perhaps applies less to inverter type generators with petrol engines.

John

[nat_89]

if you want to run every thing you need to work out the total power consumption of your house. As I am thinking of the same myself, I am looking at a diesel self starting of at least 7.5 but probably closer to 10kva, but as I am an electrician as well I am going to probably go a bit over board and make it auto start for no real reason other than I can. It will also be a super quite jobby. I am going that size as I want it to be able to run air conditioners as I have become a softy. oh and use it for the workshop as well.

Hahaha why not!! I saw a big coates 20kva silenced diesel one at work broken down for like 6 months i was so bloody tempted to work out some way of getting it out haha probably was only sitting there with a stupid fault that no one knew who to contact about!! But if i had the skills id do the same big auto start diesel one why not ahaha

[Ancient Mariner]

Bacicat Will see your all singing all dancing and raise it:D 200mm concrete plant room. full acoustic lining .40kva. Under ground stainless exhaust system
Nicad start batterys Fully auto stop start change over dummy load control and fire extinguisher system.We have used Deep Sea Electronics controllers for many years without complaint:).Sorry Ean a 7kva would be about right

AM

[Homestar]

Bacicat Will see your all singing all dancing and raise it:D 200mm concrete plant room. full acoustic lining .40kva. Under ground stainless exhaust system
Nicad start batterys Fully auto stop start change over dummy load control and fire extinguisher system.We have used Deep Sea Electronics controllers for many years without complaint:).Sorry Ean a 7kva would be about right

AM

Very nice. Can't beat a 4BT Cummins either.:)

[Homestar]

Hahaha why not!! I saw a big coates 20kva silenced diesel one at work broken down for like 6 months i was so bloody tempted to work out some way of getting it out haha probably was only sitting there with a stupid fault that no one knew who to contact about!! But if i had the skills id do the same big auto start diesel one why not ahaha

If it still belonged to Coates, then I'm the one they should have been talking to.:D

20KVA isn't a big set in the grand scheme of things. We have everything up to 1,400KVA units too...:)

[Ancient Mariner]

If it was a Cummins They are probably waiting on a new card or transfer switch to come from Singapore:( Nice engines and alternators but the way they hang the rest together:no2:

[BadCo.]

I see your 40kva and raise you 120kva. Currently standing next to this 6.8l Turbo Diesel John Deer pumping out 160kva.

http://www.aulro.com/afvb/attachment.php?attachmentid=83907&stc=1&d=1410767862

I cheated though, this powers the essential side of a Supermarket.

The last Generator I did was 1mva (which powered an entire supermarket with room to spafe) and it smoked pretty bad on start. Turns out they never fitted the water jacket heater.

[Homestar]

I'll find a pic later, but I just finished a job that required nearly 18MVA total across 3 sites with the main site running just over 14MVA - 7x1250's and 4x1400's supplying over 8,500 customers out of a zone sub.

That was fun, but didn't get much sleep for a few days. Lots of work for 2 x 8 hour runs.

[BadCo.]

Holy **** that's some money worth there!

[Ancient Mariner]

Done by Bacicat but not by Badco 6 off 16 149 Detroits and 1 -2.3 meg Wartsila They flew a fella out from Sweden to commission it when I asked about the oil slick from under he said no no tis good:D we packed up and left before it got to the pond:o Reminded me of LandRovers:D A fair bit of work for a two man install team


AM

[Homestar]

Nice - there are a lot of mine sites that have huge diesel generation, much bigger than I've ever done, there are some corkers out there.:)

[Homestar]

If it was a Cummins They are probably waiting on a new card or transfer switch to come from Singapore:( Nice engines and alternators but the way they hang the rest together:no2:

Agreed - I used to work for them...

All our big gear (500KVA and up) is Cummins powered, but as mentioned previously we use Comap controllers on them - the Cummins stuff is either past it technically or the newer stuff is diabolical and Cummins try to hold too many secrets back so you can't program the units the way you want without paying for one of their techs. The Comap software (and deep sea too) is all free and easy to use.

[rocket scientist]

Damage to the alternator is unlikely by just using one phase, the issue is more about integration into an existing single phase switchboard by the installing Electrician and if you just use one phase to run the house, then your wasting 2/3rds of the machines output. But if you have a need for 3 phase power, then go for a 3 phase gen.:)

Thanks, I see your point.
To avoid coupling problems I was looking at belt driven alternator.
I could probably run a single phase alternator for normal houshold backup, and a three phase for the workshop.

[worane]

In the Royal Navy on a frigate we had three sixteen cylinder sixteen litre gen sets. ran two at a time and one resting. Paxman diesels

[nat_89]

If it still belonged to Coates, then I'm the one they should have been talking to.:D

20KVA isn't a big set in the grand scheme of things. We have everything up to 1,400KVA units too...:)

Haha sheesh that's what I need well sorry yeah I was talking big in the size for a house set up one, we only use the 20kva ones for our mobile crib huts in the paddock but we have big ones on semi trailers for walking our big electric shovels when the cable is to much work.