(Another) Question for the Sparkys

[DeanoH]

It's that time of year again, summer in most parts of Australia except for down here in West Gippsland.

Last summers fires with the authorities cutting off the power for several days along with gloom and doom predictions of power outages raises the annual question of standby power. In the past I've used several small generators (under 2 KVA) along with inverter power from the Oka. A bit messy but 'gets the job done'.

This year I've decided to bite the bullet and go for a proper (manually) switched backup. I want enough power to run two small (2 KW & 4.5 KW cooling power not electrical power) Panasonic inverter air conditioners, fridge, freezer plus miscellaneous lights, TV, computer, modem etc.

Would have been nice to go for a 7 KVA Honda or even the Briggs & Stratton 6.5 KVA petrol inverter generators or even one of the many 'small' single phase diesel 'silent packs' but I couldn't really justify the expense. In the end I bought a 9.5 KVA Sydney Tools single phase inverter generator. Cheap as chips (comparatively) at $1650. I had a bit of a play last weekend adding and subtracting load up to about 6 KW including stop/starting my 2 1/2 HP compressor. Voltage and frequency remained rock solid as I would expect from the inverter.

What I'm unsure of is if the transfer switch can go on the meter side of the house solar so that it can add to the generator output. Are there regs relating to this or is this an undesirable setup for some reason ?

Deano :)

[Homestar]

Putting in a manual transfer switch is a job for a licensed Electrician and depending on how you want it set up, could be Prescribed wiring requiring an Electrical Inspector to sign off on it. Will check the latest copy of AS3010 as a lot changed last year in this regard. The Solar MUST be disconnected as well when switching occurs as your gen can’t synchronise to the inverters output and lots of smoke will ensue from it - and most likely the genset as well as it won’t have good protection of the voltage regulation circuit - all around not pretty - DON’T try this, it will destroy things immediately. It’s also a requirement of the regs that the solar is isolated when running off a genset. It’s not overly complicated but does require some care.

[Homestar]

Ok, section 4 and figure 4.3 of AS/NZS 3010:2017 - Electrical Installations - Generator Sets, covers the additional requirements of a single phase installation through a manual transfer switch and a portable genset through an appliance inlet. Section 2 covers the general requirements.

Given the size of your genset, I’d go a 32 amp single phase Clipsal type inlet and plug arrangement as this will take the full load of your genset. Please note on the pic attached, that the MEN link must be removed from the genset when connecting this - which begs the question about if you should be running a genset with an outlet connected but without any MEN link - I would have said no and I think this breaches another reg, but I’ll check that. Note that if you set it up like this, you shouldn’t use the genset for anything else as using it without the MEN connected when it isn’t connected to the house - like just running it and plugging in a welder, etc when it’s not running the house - it will cause a floating neutral and can be quite dangerous. If it’s just for the house, I’d recommend removing any other outlets and wiring just the one 32 amp outlet on it so it can only be used when connected to the house.

As a caveat - I’m usually giving advise to other Electricians on hardwiring gens, I’m not completely familiar with single phase plug in arrangements like this, but you get the idea and that it’s not a DIY proposition. Please note that this is prescribed wiring so needs to be done by a Licensed Electrician and Inspected by a Registered Electrical Inspector and signed off. You will get a Prescribed Certificate of Electrical Safety that you can supply to your insurance company to prove compliance. This will cost you more than the genset unfortunately.

Regs around solar is that all other supplies SHALL (meaning mandatory) be disconnected when switching over to the generator supply.

156222

[DeanoH]

Thanks for the informative and prompt response :)

Have no fears, I have no intention of "leaving it to Beaver", there's a sparky in a nearby town that does this type of work and I'll be asking him to do the work. I just wanted an understanding of the rules and requirements. Have no fear, I've actually seen the results of a genset incorrectly synced and it wasn't pretty. That was back in the days of syncing the lights, throwing the couple switch (and praying). Lots of smoke and threw the genset off its bed. Very educational as a young trainee.

Interesting re the MEN link. I checked on the genset circuitry to ensure that it actually had one as I'm not terribly trusting of cheap Chinese consumer products. What was interesting is that (to my circuit reading) that it is shown on the incorrect terminal. This may be just poor circuit drawing and I was going to check this physically before replacing one of the 15A outlets with a 32A outlet (as you suggested).

Don't know if I'm too keen on having a portable genset with no MEN link, sort of OK if it's hard wired but IMO hardly 'optimal' for a mobile unit especially with additional 15A outlets. Maybe some sort of CO switch incorporating the MEN link and 'hard wired' OR portable outlets ? A bit messy though and difficult to make 'fool proof'. Perhaps it's best just to hard wire the whole thing as I don't really need portability but I can't really see the generator hire companys removing the MEN link on their units, so there must (hopefully) be another answer.

Regarding the solar, does it mean no re connecting of solar to a running generator ? It's not a big deal for me but every little bit helps :) One of the reasons I went for the inverter generator was so that the solar inverter would have a stable supply to sync with.

Deano :)

[Old Farang]

Regarding the solar, does it mean no re connecting of solar to a running generator ? It's not a big deal for me but every little bit helps :)
One of the reasons I went for the inverter generator was so that the solar inverter would have a stable supply to sync with.
You cannot sync ANY inverter supply together in this context. Homestar has already posted this. Please do not consider it! Cheers

[Homestar]

Thanks for the informative and prompt response :)

Have no fears, I have no intention of "leaving it to Beaver", there's a sparky in a nearby town that does this type of work and I'll be asking him to do the work. I just wanted an understanding of the rules and requirements. Have no fear, I've actually seen the results of a genset incorrectly synced and it wasn't pretty. That was back in the days of syncing the lights, throwing the couple switch (and praying). Lots of smoke and threw the genset off its bed. Very educational as a young trainee.

Interesting re the MEN link. I checked on the genset circuitry to ensure that it actually had one as I'm not terribly trusting of cheap Chinese consumer products. What was interesting is that (to my circuit reading) that it is shown on the incorrect terminal. This may be just poor circuit drawing and I was going to check this physically before replacing one of the 15A outlets with a 32A outlet (as you suggested).

Don't know if I'm too keen on having a portable genset with no MEN link, sort of OK if it's hard wired but IMO hardly 'optimal' for a mobile unit especially with additional 15A outlets. Maybe some sort of CO switch incorporating the MEN link and 'hard wired' OR portable outlets ? A bit messy though and difficult to make 'fool proof'. Perhaps it's best just to hard wire the whole thing as I don't really need portability but I can't really see the generator hire companys removing the MEN link on their units, so there must (hopefully) be another answer.

Regarding the solar, does it mean no re connecting of solar to a running generator ? It's not a big deal for me but every little bit helps :) One of the reasons I went for the inverter generator was so that the solar inverter would have a stable supply to sync with.

Deano :)

We leave the MEN connected on all our Hire sets when they go out on hire - the installing Electrician will remove it if the machine is destined to be hard wired to a premises. We make them easily disconnectable so that is an option for yours. If you understand when and when not it needs to be connected, no reason you can’t do something similar on your machine. 👍

And as I said earlier and Old Farang just reiterated - BIG NO to connecting the solar when the genset is on, and the wiring the Installing Electrician will have this so that operating the switch will prevent this as the Regs demand - Big Bang and toasted Inverter and genset will be the result if this is tried, but it would mean the wiring rules have not been followed if it allows you to do this - but just don’t - ever...

[DeanoH]

Thank you gentlemen for your your definitive responses.

Regarding the solar inverter. I wanted to clarify that

................. Regs around solar is that all other supplies SHALL (meaning mandatory) be disconnected when switching over to the generator supply ..............

did not infer it was OK to reconnect after switching over to the generator supply. The answer is clearly NO.

As I noted earlier definitely not a job for Deano :), I know what I don't know, but am interested in the configuration. From a more general viewpoint it also helps me to assess if the proposed contractor is on the ball.

I'll leave the generator config to the contractor as he specialises in this field so should be on top of it. My biggest concern here is safety. It's one thing for me to be conscious of the pitfalls of removing the MEN link but whatever happens the generator needs to be safe to use by anyone in any situation.

Thanks again for the information (and warnings). I'm looking forward to a blackout free summer :)

Deano.

Deano :)

[Old Farang]

Just as a general point of interest, and in case somebody tries to tell you otherwise!

Inverter type generators are a relatively modern development, in fact I have never seen one! Standard "old" type synchronous generators can and are connected in parallel, something that I used to do everyday for many years. There are basic rules and procedures that have to be followed to prevent what you have mentioned previously occurring.

I bit of research into these new fangled machines show that 2 inverter type GENERATORS can be connected in parallel. There are "kits" available to do this, and although I am yet to find any circuit information, it appears that those units designed to be paralleled have provided connections to plug in interconnecting cables. This indicates that the control is probably done BEFORE the actual inverter with some from of sensing that allows both synchronisation, and load sharing between both generators output.

Brilliant idea as far as I can see, providing you have enough money to buy two generators! Use one to provide a "base load" and plug in the other one when more output is required. If one of them should fail, then you still have some power available. Also, the idea of throttle control being part of an inverter type generator makes them much more efficient. Cheers

[DiscoMick]

Just as a general point of interest, and in case somebody tries to tell you otherwise!

Inverter type generators are a relatively modern development, in fact I have never seen one! Standard "old" type synchronous generators can and are connected in parallel, something that I used to do everyday for many years. There are basic rules and procedures that have to be followed to prevent what you have mentioned previously occurring.

I bit of research into these new fangled machines show that 2 inverter type GENERATORS can be connected in parallel. There are "kits" available to do this, and although I am yet to find any circuit information, it appears that those units designed to be paralleled have provided connections to plug in interconnecting cables. This indicates that the control is probably done BEFORE the actual inverter with some from of sensing that allows both synchronisation, and load sharing between both generators output.

Brilliant idea as far as I can see, providing you have enough money to buy two generators! Use one to provide a "base load" and plug in the other one when more output is required. If one of them should fail, then you still have some power available. Also, the idea of throttle control being part of an inverter type generator makes them much more efficient. CheersCan I just clarify if you are talking about this kind of inverter generator, which I just bought, or something different? Mine is obviously smaller than the OP's, of course.
I'm just trying to figure out this stuff.
We would only use ours to run a water pump to use toilets and fridge and freezer in a blackout, not the whole house

WESTINGHOUSE DIGITAL INVERTER GENERATOR - IGEN2500 (https://www.camec.com.au/westinghouse-digital-inverter-generator-igen2500)

[Old Farang]

Can I just clarify if you are talking about this kind of inverter generator, which I just bought, or something different? Mine is obviously smaller than the OP's, of course.
I'm just trying to figure out this stuff.
We would only use ours to run a water pump to use toilets and fridge and freezer in a blackout, not the whole house

WESTINGHOUSE DIGITAL INVERTER GENERATOR - IGEN2500 (https://www.camec.com.au/westinghouse-digital-inverter-generator-igen2500)
I doubt it mate. As I posted, SOME can be paraelled but have to have that facitity built in. I cannot see those connection points on a photo of yours.

[DiscoMick]

Thanks.
Just did some research and Westinghouse says it's Australian generators cannot be paralleled.
Doesn't worry me as I didn't buy it to run the house. In a blackout I would just plug in the fridge, freezer and water pump for the toilet.

[DeanoH]

.................... Inverter type generators are a relatively modern development, in fact I have never seen one! Standard "old" type synchronous generators can and are connected in parallel, ................... Cheers

Reminds me of the beginning of a 'Star Wars' movie. .............. "A long time ago in a galaxy far, far away" .................., well I also worked in a similar galaxy some 40+ odd years ago. No such thing as inverters then, new technology in the predominately DC area I worked in was relatively high current (200A+) semiconductor diodes. I still remember as a trainee 'basking in the glow' of massive glass mercury bath/vapour rectifiers (Tramways Power Station), it was quite a surreal experience that purple glow. Worked with some pretty good gear (for its day) including much pre war generating plant. I'm way out of touch now, the principles are the same but the technology is way different, as for current regs. no (well little) idea.

With time on my hands I thought I'd look up the AS/NZS regs. that Homestar mentioned, well it turns out (to my looking) that it is not freely available on line (or otherwise) and that a fee of several hundred dollars is required to obtain this info. I found this rather strange, I can understand a cost for the provision of written material but for on line access ? A bit like having to pay to find out the road rules but still liable for prosecution if you fail to obey them. Perhaps I'm being unfair but I thought it a little strange.

On a more positive note the sparkys been contacted and will be fitting a manual transfer switch and 'checking out' my generator after Christmas :)

Here's a circuit of the generator from the supplied info.

156346

Here's a close up of the 'pointy end'

https://www.aulro.com/afvb/attachments/non-land-rover-technical-chat/156347d1576644846-another-question-sparkys-generator-cct2-small.jpg



I must be getting out of touch, this circuit has been driving me nuts as I can see no way that the 240V part is correct. The 125V sockets aren't there. There's 3 X 240V 15A sockets with button type circuit breakers and 1 single pole main circuit breaker.

It gets even better (worser ?) I tested the output at the sockets with with a multimeter with the following results. Between the 'normally' active pin and 'normally' neutral pin I read 240V, between each of these pins and the earth pin 120V. The only vaguely normal thing (to my thinking) was that the single pole circuit breaker was in the 'normally' active connection, though I can see that taking the earth return back to the centre tap can give a 'framing' to gnd fault a return path, but not what I'm used to ?

Using the analogy of the 240V output (brown and blue wires) as being from a centre tapped (white wire) transformer I can only conclude that the centre tap is connected to the sockets earth pins. There is no voltage measuring to the frame of the genset which may (or may not) be a good thing as it is insulated from the ground with plastic wheels and rubber feet.

I haven't pulled the front panel off to check, though I'm sorely tempted, I'll leave it to the sparky.

Deano :)

[Homestar]

Standards cost money yes. If you’re in the Trade you are expected to keep up to date with all the relevant standards pertaining to your work - same as keeping any licences up to date. Big companies like mine have a fairly expensive licence that allows us to print copies as needed for any standard at any time. The PDF’s you download expire after a month so it’s print them out or download it again.

Smaller businesses may only buy the ones they need as needed to keep costs down.

Standards Australia isn’t a government organisation, but a not for profit non government peak governing body. Charging for the Standards is how they keep the doors open. 👍

The only thing the Government do is mandate that the Australian Standards are used and make a law saying which copy is currently active for each of them so that we know which one to go by and for regulators to enforce them as required.

[Homestar]

As for the voltages you see, it’s because the neutral has no earth reference as it currently sits. When it’s connected to the building the neutral will be earthed by the MEN link and earth stake so you should see 240 volts between active and neural and active and earth and zero volts between neutral and earth once the machine is running the house through a properly connected switch and wiring.

[Tombie]

Just as a general point of interest, and in case somebody tries to tell you otherwise!

Inverter type generators are a relatively modern development, in fact I have never seen one! Standard "old" type synchronous generators can and are connected in parallel, something that I used to do everyday for many years. There are basic rules and procedures that have to be followed to prevent what you have mentioned previously occurring.

I bit of research into these new fangled machines show that 2 inverter type GENERATORS can be connected in parallel. There are "kits" available to do this, and although I am yet to find any circuit information, it appears that those units designed to be paralleled have provided connections to plug in interconnecting cables. This indicates that the control is probably done BEFORE the actual inverter with some from of sensing that allows both synchronisation, and load sharing between both generators output.

Brilliant idea as far as I can see, providing you have enough money to buy two generators! Use one to provide a "base load" and plug in the other one when more output is required. If one of them should fail, then you still have some power available. Also, the idea of throttle control being part of an inverter type generator makes them much more efficient. Cheers

Sawadee Krup [thumbsupbig]

I have 2 Honda EU22i that do just this...

Works a treat when the power drops.

[Old Farang]

Sawadee Krup [thumbsupbig]

I have 2 Honda EU22i that do just this...

Works a treat when the power drops.
Merry Christmas, Mike. Your Father could probably do with a couple of them! Cheers.