Diesel Generator Questions

1. Depending on th equality of the generator it may work just fine pulling the full load off of one phase. Some can do this some cant.

2. Most likely your voltage regulator burned out which is why your not getting any voltage now.

3. Just tying all three together as they sit will put the outputs in a dead short. Two of the three outputs need to have their connections changed end to end and put across the third winding in a specific way for that to work. But that method requires you to separate the 6 leads that it uses to produce the 230/415 volt output and reconfigure them into a 'Z' connection so that all three phases are working together to produce a full single phase output while still using all three winding sets together in a more balanced manor. However that does take some knowledge and understanding of three phase power and how each phase is 120 degrees off from each other but when properly configured they can all still work together to produce a single output with the generators full rated capacity.

Without knowing the make model and wiring system I can only guess at all of this so far.

1. Chinese budget model. Is used to back up batteries on a Solar off-grid South Australian country property.

2. Will this be something that is obvious to the eye? nose? taste?

3. Are you talking about the outputs at the alternator itself? is this Z connection something that is easily, and most importantly, cheaply doable?

It's a cheap(depending on your viewpoint) Chinese model. I have heard very good things about these generators and find few complaints online.

Is there a remote voltage adjusting pot on the panel, if there is check it I've had that problem several times on gensets, the vibration gets to them, you can always short them and use the rough adjusting pot on the voltage regulator.

The specs state that this is a 415/240 genset, so I would guess that the 3-phase output is 415v, and the three 1-phase outputs are 240v (line-to-neutral). A single large 1-phase 240v load would be significantly unbalanced. If that is what the load actually is, why choose a 3-phase genset? A 1-phase 415v load (such as a heater) would also be unbalanced, but not as much, being shared by two phases.

Some more detail on the actual load(s) and its/their volts/amps/#phases might help.

We bought a 3 phase as we followed someone's advice. Essentially now we have it we are stuck with it. WE do have some three phase stuff that will be run off it (very rarely) but its main job is to feed 240V single phase to a raps-5-48 inverter as a backup when using more power than the inverter can supply and also to back up the battery bank(24x2V 600ma Sonnenschein batteries).

Hello:

Why not transform the 3 phase 415 V down to 48V which I presume is your overall battery voltage and then rectify the 3 pases into DC to charge your batteries and supply a new inverter to handle the increased loads? Of course this requires investment in a transformer diodes and a second inverter. This inverter can be used also as a standby to your original inverter should it fail. Also you could put in a new set of batteries (as a second phase to your upgrade) to be used only for the higher power draws. That way you will have inverter and battery redundancies for reliability.

Does this make sense considering conversion losses and added hardware costs?

Ted T

1) If the generator is permanantly being run with load on one phase only, its life will be drastically shortened, I have no doubt about it.

One option for you is to provided dummy loads (heaters etc.) to keep the overall loading more or less balanced, another is to arrange a three phase to single phase conerter transformer. (You will have to take into consideration time of manufacture for this transformer and its cost).

2) Voltmeter can be damaged, confirm with a portable meter or a lamp connected to the generator 220 v socket, in case voltage is not there my suggestion is to forward the generator to the supplier for rectification.

3) Interconnecting three phase wiring constitutes short circuit, your generator may get permanantly damaged

What sort of cost (ball park) would this 3 to 1 converter entail?

Definitely no voltage coming out of the system at all

Forwarding to the supplier is a major problem as freight costs are prohibitive.

I wouldn't interconnect anything without definitely knowing the outcome of my actions(I don't want to die or kill anyone). One person above mentioned a Z wiring configuration which sounds interesting but is well above my knowledge level

Making a converter unit is just a matter of finding a pair of 240:240 3 KVA isolation transformers. The most common ones are 120/240:240/480 type and go for around $100 -$150 on online auctions.

You only need two transformers because one of the original phase to ground connections is being supplied by the generator and the two transformers are just to make the necessary isolation between the other two phases so that their respective connections can be reconfigured externally of the machine.

What you will end up with is one original phase supplied by the generator and four connections that go in a specific order to make a mirrored power balance off of the other two phases that are in sync with the first one.

The short answer is one your not going to like.

You need to get yourself a single phase 6kva generator to do what you want. Keep the 3 phase generator for running those things which are 3 phase.

The longer answer you're not going to like either,

You have most likely fragged the AVR board on your generator, which will require replacement. There may also be other issues associated with the AVR board failing so it's going to have to be sent back to the agent for repair. I don't think they'll cover the repair under warranty unless you have it in writing that it was fit for your intended purpose. I.E. running mostly on one phase only.

I have a friend who has an off grid property, out the back of bathurst NSW. He gave up on the chinese generators, bit the bullet and bought a locally assembled one. He has 3 generators all up, all diesel due to altitude of his property. A single phase 6 kva to run basic house requirements and recharge the solar batteries. A single phase 12.5kva for when he has guests and needs to run lots of space heaters and the extra hotwater heaters (It do get retchedly cold up there). Lastly a 3 phase 35Kva for his shed to run compressors and lathes, welders etc. Only the 6kva did he buy new, He got fed up with the poor speed/frequency regulation of the chinese generators, which upset all manner of things including his UPS's.

You might find the odd bargain on ebay

http://cgi.ebay.com.au/GENERATOR-Genuine-Army-10kva-/220660980968?pt=AU_Militaria

Yes I know its petrol, but you could replace the VW motor with a diesel one like this.

http://cgi.ebay.com.au/Ruggerini-diesel-stationary-engine-farm-pump-generator-/140446428464?pt=AU_HeavyMachineryParts

Just a thought.

Um wiring the three phases together is not good, to quote from the movie Ghost Busters,

"Crossing the phases is bad , very bad."

If you have to run the generator you need to load the other two phases. Put all (or most) outside lights on one "spare" phase and some of the others and the hot water heater on the other "spare"phase, that will help some. Won't be perfect but at least all three phases will have some load.

You'll need to do some maths with regards the number of lights load per phase, remembering that a hot water heater (in Oz on 240Vac) will draw 2400 watts

To continue along these same lines, as sharing the load amongst the phases is the most reasonable course of action.

You may be able to find a 3 phase battery charger or in some other way reconfigure the charging of the batteries

the failure of the AVR is likely due to restarting under a load, more details about the transfer switch would help make a determination.

First up, I'd ask the supplier to ship you an AVR board which should be easy enough to swap out with the old one. That is the most obvious reason why you have zero volts.

While you are inside, check all the wiring and make sure you don't have a wire off somewhere, which could also be the reason for zero volts (no neutral will do it). Check for internal fuses and circuit breakers while you're at it.

If you do get it going again, do as several have said and load the other 2 phases with whatever you can find up to 2kVA (say about 1500 to 1700 watts). Have you got any header tanks which need to be refilled? Look around and see what you can run at the same time so you get the most benefit. Alternatively, connect 2 new battery chargers to the 2 spare phases and make sure they have the same charge parameters as the existing one.

the unbalanced load will not shorten the generator life, but will get only the third if its capacity, 2 kva in place of 6, if this is enough to you, dp nothing just repair your AVR.. if not you have to buy to transformer 4kva each 415/240 and connecthem in a open delta configuration, but you still do not get the max of your generator, you will get about 4kva regards

a

Luddite,

Do not do the transformer business others are mentioning. Yes, it they are correct but you are in the outback, so keep it simple.

Do you have any mains power or are you 100% off grid?

Your batteries are good, save up to double them (in quantity) so on a good day, with the sun shining, you can get a few days up your sleeve. I think you might be charging and discharging everyday which is not so good life-wise for your batteries. You need to cut off at about 46 volts I think *waits to be shot down* and your max is about 54 volts.

Basically I am saying, the more batteries, the better. Start a new string in parallel (+ to +, - to -) of the same type of batteries. I think you might be a little under-power there with your battery 'array'.

You mentioned your solar array. Can you share its specs with us. Just that the 'brains trust' here might be able to help you more with better info. Take pics if u want. Always helps.

Cheers, Mark

You can find pictures here. We aren't outback but still far enough away to make the transportation of a 180KG generator problematic. The supplier is sending me an AVR through the mail with simple to follow instructions on its replacement.

The batteries are over a $1000 each(x24) so another array isn't on the cards just yet. The Inverter is a RAPS-5-48. After the boost/equalisation charge the batt. bank sits at around 55V. The generator autostarts to take up surplus load or when the bank gets below 46.8V(I think memory a bit fuzzy). Inverter shut off is at 44.6V.

We plan on adding more panels and also wind generation in the near future (when the main house is completed). We aren't quite hippies but when the electric company said $77,000 to connect the juice and a quarterly bill we thought we would go another way. In summer the generator hardly has to run but this winter has been very bad and the sun has shown its face maybe ten times in total.

You will see in the pictures our original Dunlite diesel generator 6KVA single phase based on a Honda GD411 single cylinder diesel. Out of warranty and having served a total of 912 hours(6 years) the engine died in a HUGE WAY. It cost $5,500 and was supposedly the best available(LOL - jokes on me). Repair was prohibitively expensive (a replacement GD411 motor alone is over $4000).

If it can go wrong it has here in the last six months (imagine self unscrewing sump plugs in your car sort of trauma and the resultant highway disaster - that was two days after the first generator died). 2KVA wouldn't even boil a jug and having had so little sun and having gone through so much money in the last six months I can't even heat up my baked beans for dinner(an exaggeration but you can see where I am coming from).

I really need a way to pull more than 2 KVA out of this generator and not unbalance it and kill it.

Tamu,

Even you got a good answer rate, I didnt get your suggestion

you want him to buy two 24 volts chargers 1700 watt? 1700w at 24 volts it is 70 amps, not cheap at all, especially for telecom batteries...

you want him to connect a cheap charger on a 24000 dollars worth batteries, this will DEFINITELY destroy them.....

than you suggest hinm to connect each charger to a 12 batteries string , right??

you will have two chargers in series on the same 48 v string, the 2 set of batteries will not charge equally and the main charger will not be able to egalize....

this also will lead to a short life of the batteries...

please do not advice on subjects you are not expert with,

than you suggest another solution for phases balance, even you said unbalance is not a problem....i agree with you unbalance is not the problem in itsself.

you suggest to burn 3 times of fuel on an isolated site, this means 3 times more trips to civilization for refueling, not to talk about "green" issues....

to uninformedLudit:

By my humble understanding, your load on one phase make it to get barely overloaded not to the limit of tripping but to get a chinese AVR disturbed, any attempt to balance the load on the generator will not correct the situation ....

the solution is to distributed the currents consumed by your chargers on the 3 phases as equally as possible,

the easiest and cheapest solution that I can see is to use transformer, you can use one 415/240 v transformer 4kva, you will have your current distributed over 2 phases , two is better than one

cheers

Dear Le Noble,

If you read what I had said, I specifically said, 'turn off the eq on the RAPS unit'.

We had a similar problem before with an off-grid in Indonesia. A teleco at a remote site. Out on a remote island with a 70 meter tower, a key node : fiber coming out of the ocean and microwave links and a 3 phase genset hauled up the hill from the boat. Left "Fitzcarraldo" for dead. That 55 amp charge rate (allow 90% efficiency) is going to tumble down across the first 10 minutes as the RAPS has a cut out at say 46 or so volts on the batteries. So you've only got to cross the road from 46 to 56 volts. That isn't so far.

That was 5 years ago and it's still working. We did put some space between the batteries to allow for the heat to dissipate.

DC is forgiving. So am I.

Dear Mark

this will change nothing in the figure, a 1700W 24V charger suitable for stationary batteries as shown in in pictures is not cheap, much much more than 300$ for a pair, a cheap charger will definitely destroy those batteries, especially when you turn off the egalize function.

I noticed in one of your replies earlier in the thread you used the term battery 'array' with the word array in single quotes. Did I misuse the word? Wouldn't surprise me as they just upped my pain medication to morphine and my brain doesn't quite feel like it belongs to me anymore.

Balancing the phases using battery chargers makes great sense as 98% of the generator's purpose is battery maintenance. I have a couple more questions that relate to the same issue but not being at home I haven't got the data to hand that I would need to share to get an informed response. I hope you don't mind if I pick at your brain a little more ;)

Hot water will mostly be provided by solar and diverted excess wind. This will also be boosted in cooler weather by a wetback fireplace. The slab has been set up with underfloor heating which will be very nice in winter. We want to try to avoid as much as possible using fuels that we have to carry onto the property (once again - NOT A HIPPY! We also aren't doing this because of *cough*global warming*splutter*). We plan on using Induction Cooking due to its efficiency and I have been experimenting with solar ovens (great on sunny days). We will be adding wind generation, more panels, and increasing the battery bank size in the near future.

We are living in the completed garage so our power needs are minimal but will undoubtedly increase in the future. Local conditions lend themselves well to wind and solar.

Once I get back to the 'farm'(we do have one chicken so I think that makes me a primary producer) I will post the other couple of questions I have once I have the figures to back up the questions. I hope you don't mind.

Thanks,

Colin

Okay,I'm getting it now. Let me sleep on it and get back to you shortly.

Mark

Thank you for your time and patience

1)It is correct that if you run on only 1-phase permanently then the alternator will be unbalanced shortening its life. But you did not clarify if there is any neutral outcome from your engine. If so, you can use all the three phases with the neutral putting same loads. If not, you can use neutral from ground by making earth pit. Never use stepdown transformer to down the voltage- there are so many de-merits.

2) This problem might not be due to AVR problem. bcos, if AVR fails to work, there will be some voltage still, wether it is stable or not.

There are so many possible reasons for what happened with your engine. For that, please check the safety fuses fitted with your engine first.

I have a similar setup as I think you want.

I have a 60 Kw 480 Gen that I have a 480 to 220/120 step down tranformer attached.

We have 480 connections for my equipment, and welders in my shop and also 220/120 single phase for the rest of the house.

From this I have a 24 Vdc inverter that re-charges my backup batteries, for my solar system when the genset is running.

Has worked flawlessly for the past 6 years.

I am probably being overly optimistic but I want to try and remain as much set up the same way it is already configured as possible. All I need to do that is to have a stable 240V supply that the inverter can plug into. That way nothing has to change, the inverter charges the battery bank, the generator starts automagically, my baked bean dinners get to be warm, and the world can wallow in peace.

Wire the genset to a three phase breaker panel then install single phase breakers for the loads, do some balancing by swapping loads to different phases in the breaker panel, you should be able to use the gensets panel meter, some gensets only use single phase voltage sensing, so watch the voltage. If the output voltage is a problem you should be able to reconnect it for a different voltage, You should be able to reconnect it for single phase but will probably have to derate it to 2/3 its capacity. Did you check the pot.

There is only one single phase load 92.537% of the time

I've just skimmed through this - so if someone has mentioned this - ignore me.

But most larger generators have 6 to 9 windings, configured in series and/or parallel, depending on what is desired. I.e they are made to be able to do either duty.

One set up of connections produces 3 phase. Another setup gives single phase.

It may just be a case of obtaining the installation data giving the "links" set up for the single phase output and you solve this.

Generally it's a 10 minute job - (and 20 minutes of checking it does look exactly like the diagram) Best way is to remove them all and start from 'fresh'. And do isolate or remove all spare wires.

The single phase rating will be about 75% of the 3 phase rating.

6kVA might be a bit small for this 'standardised manufacturing" - but its worth asking the question or just checking the documentation that came with it.