192 replies to this topic
Posted 2009-11-01 15:01:41
 tjo o tjim, on 2009-11-01 13:10:17, said:
Genset-- I know the Cummins document very well; the challenge is finding reliable capability curves for any system. Specific to Cummins, even their MW class machines choke on a few hundred kVAR... and don't get me started on their dam_n MCRS system.
But specific to readers needs, computers and UPS systems do create enough of a leading power factor to cause a problem for a generator designed for 0.8PF lagging loads. Inverter-based AC systems don't help things either.
So, my question remains-- do you have a capability curve for the generators you are representing?
Genset
Edited by genset, 2009-11-29 19:02:49.
Posted 2009-11-01 15:16:09
bilinlos, on 2009-11-01 14:22:55, said: Genset,
I plan to use a combination of solar power and a genset. What is your opinion of this. Also I have considered using propane in my home and had thought with a larger propane tank, I could power a genset with it also. What do you know of Propane powered gensets. I realize there could be a conversion from Gas to Propane but is that common in Thailand?
This seems to be a popular idea, I have received a number of similar enquiries through my website and if you like I can provide you with the email address of a guy who works on hybrid photovoltaic systems. Personally, I have no knowledge of solar power systems, so I can't offer you an opinion I'm afraid.
Again, my knowledge of propane powered gensets is wafer thin. I work exclusively with diesel generators and the odd petrol genny thrown in for good measure. I did visit a pig farm in Thailand recently (with a Thai tech fitting a ComAp unit) and saw an interesting system... they collected and pressurized the methane gas pig emissions from the pig houses and ran the generator from it... amazing.
In answer to the second part of your question, I believe there are generators running on propane in Thailand, but I have no knowledge of their operation or cost I'm afraid. If you absolutely must go the propane route, I can certainly make some enquiries on your behalf, drop me a line @ john@generatorsolutions.org if you wish.
Genset
Edited by genset, 2009-11-29 19:03:30.
Posted 2009-11-01 15:34:48
Quote I am in the process of calculating all my equipment i have to opperate a large selection of fish tanks, all the pumps and various items are marked in w, i have a chiller that has the following info Electrical current 4.2A, Power 1 1/4 HP. Can someone please inform me what this amounts to in W.
Electrical Horsepower: 1HP = 746 Watts, so 1.25HP = 933 Watts. That's the best answer you can get without getting into all sorts of electrical stuff such as motor efficiency, power factor, rated voltage etc.
Dont forget that the calculation posted by InterestedObserver, based on your nameplate data is the running watts. Multiply this by 3 (an approximation) and you will have a rough estimate (for the purposes of calculating your load requirement) of your starting watts.
Genset
Edited by genset, 2009-11-29 19:04:01.
Posted 2009-11-01 19:16:10
genset, on 2009-11-01 15:54:40, said: Naam, on 2009-11-01 09:15:31, said:
I am waiting for the distributor to get back to me with the latest price, I will add it to the post when I receive it and PM you to let you know.
can't you shoot from the hip?
I can tell you that the KDE20SS3 is more costly than the KDE16SS, but not by how much until I speak to the distributor I'm afraid, if you could give me a couple of days I will post the details for you. Thanks for your patience.
weighs 790Kg
big crane needed. distance from roadside to projected installation site straight 15-16m plus must be lifted over servants quarter 4.5m high 
Yes, it's a hefty weight. These sets are normally delivered on a flat bed with hydraulic lifting equipment to position it. To place it 15m from the delivery vehicle and over your servants quarters will certainly require the use of a crane, make sure you find a competent operator...!
Electric start, the unit also features a digital control panel with a remote start facility and additional features such as a periodical exerciser function.
remote start facility a must. what's an "exerciser function"?
This is a function of an electronic control unit which can be set to periodically start and stop the generator. For example; you could set the exerciser function to automatically start the set once a week, on a saturday morning at 10:00 and to run for 30 minutes, or every fortnight, or once a month as you see fit.
A standby generator should be able to go from a cold start to fully operational and on load in less than a minute. This can place a lot of strain on engine parts; regular exercising of the generator, circulates fluids, keeps engine parts lubricated and moves diesel fuel through the system, allowing it to be used before it begins to deteriorate; all of which increase the reliability of engine starting. Having said this, long periods of generator exercising with 'no load' should be avoided, it is far better to let the generator run on load for the period of exercising by switching your load from mains to generator during the exercise period.
Unit features ATS connections and is compatible for use with an automatic transfer switch. This enables completely automated operation in the event of a power failure or deep brown out.
automatic transfer (unfortunately) not possible as most probably too many consumers online when brown out or complete black out happens. have to re-evaluate my situation as rewiring of mandatory consumers to one phase should make it possible to use automatic transfer. anything wrong in my thinking?
Are you saying that the load would exceed the maximum rated output of the generator, if an automatic transfer between mains and generator supplies took place, given your current distribution configuration, as we discussed in your earlier post? If this is the case, then I do understand why you feel an automatic transfer switch would not work for you.
As for running all your mandatory customers from one phase... No, unfortunately that would present a problem. When operating a 3 phase generator, the load must be balanced, or distributed as evenly as possible over the three phases, you cannot load one phase to the gills and have no load on the other two phases.
additional information: brown outs of one or two phases happen quite often. i spent a fortune on replacing burned pump and compressor relays till i had a gadget installed which shuts off a phase completely if voltage drops below a certain value (value can be adjusted, settings are presently at 200 volts).
Edited by genset, 2009-11-01 19:18:18.
Posted 2009-11-02 10:47:19
The Effects of UPS systems on a Generator.
The designer shall ensure that the generator is suitable for the operation with the UPS load.
When the UPS rectifier load is more than 50% of the total load connected on a generator,
the following special measures shall be considered to ensure stable and reliable operation
of the generator.
1. Using a 3 phase AVR.
2. Using permanent magnet field excitation.
3. Using an electronic governor.
4. Oversizing the alternator compared with the kW rating required.
5. Specifying the UPS with filtering to limit the amount of harmonic distortion, where possible.
Where the UPS equipment represent a significant load on the generator, that is at or close to its max. output, overloading shall be prevented by inhibiting or limiting the battery charging function of the UPS when connected to the generator supply, where possible.
Autostart Generators.
Auto start generators connected to a switchboard though an ATS sense the loss of voltage,loss of phase or phase imbalance % by the use of a phase failure relay, with a time delay in secs so as to avoid transient events. The setting is usually 5 secs but in some critical circumstances may be less. There is usually an adjustable time delay after power has been restored before the ATS changes over to mains power. There is a run on time usually 20 mins and then the generator will shut down, however if there is a power failure in this time the ATS will transfer load to the genset and it will continue running.
The phase failure relays, one for mains supply and one for generator supply are generally located in the ATS switch.
Generator selection.
The generator supplier needs to know the type and size of proposed load in order to recommend a generator that is suitable. And if you are going to use manual start with manual changeover switch or auto start with an ATS.
Remember you have the cost of the genset and then you have the cost of installing, testing and commissioning into service.
Good design will eliminate a lot of potential problems.
Edited by david96, 2009-11-02 10:49:02.
Posted 2009-11-02 19:48:15
david96, Re: The Effects of UPS systems on a Generator. Nowhere do I see a reference to leading power factor caused by UPS systems and other non-linear loads. Are you trying to say that the problem does not exist or that it should just be ignored whenever encountered? What do you do when sent to install a standby generator at an existing data center where the power quality (PQ) analysis shows significant harmonics present and at times a leading power factor?
Posted 2009-11-03 06:02:29
InterestedObserver, on 2009-11-02 19:48:15, said: david96, Re: The Effects of UPS systems on a Generator. Nowhere do I see a reference to leading power factor caused by UPS systems and other non-linear loads. Are you trying to say that the problem does not exist or that it should just be ignored whenever encountered? What do you do when sent to install a standby generator at an existing data center where the power quality (PQ) analysis shows significant harmonics present and at times a leading power factor?
The designer shall ensure that the generator is suitable for the operation with the UPS load.
If you read this line it means that the designer of the system must take into consideration the UPS that is to be connected. The designer has to comply with the required standards in this case:
AS3000/2007 Wiring rules
AS3010. Electrical Installations - Supply by generator set.
AS62040. Uninteruptible Power Systems (UPS).
These are only some of the standards. The Standards set the requirements regarding a leading PF and the effect of harmonics.
The designer will be usually be a qualified Electrical Engineer. The Installer will be a licensed Electrical contractor.
Posted 2009-11-03 10:12:43
InterestedObserver, on 2009-11-02 19:48:15, said: david96, Re: The Effects of UPS systems on a Generator. Nowhere do I see a reference to leading power factor caused by UPS systems and other non-linear loads. Are you trying to say that the problem does not exist or that it should just be ignored whenever encountered? What do you do when sent to install a standby generator at an existing data center where the power quality (PQ) analysis shows significant harmonics present and at times a leading power factor?
The biggest thing that you have to do for generator compatibility with UPS rectifier is ensure that you disengage harmonic filters when on generator. Unfortunately, many of the computer power supplies themselves have leading power factor (-0.97 is becoming typical from the facilities we work in), which makes for a problem when the UPS goes to bypass. We are adding line inductors to a number of sites to fix things, but it is an awful solution.
Harmonics though (at a data center scale) have pretty much been eliminated as a problem in all the sites we work in.
Posted 2009-11-03 10:34:04
Are you saying that the load would exceed the maximum rated output of the generator, if an automatic transfer between mains and generator supplies took place, given your current distribution configuration, as we discussed in your earlier post? If this is the case, then I do understand why you feel an automatic transfer switch would not work for you.
because the sum of all consumers normally running (plus the potential ones on timers or on demand such as pool pump, deep well, waterfall, pond filter) would exceed 13.6 kW. only the dedicated solution (max 10 kW) wired to one specific phase, combined with a single-phase generator would make an autostart/transfer possible.
As for running all your mandatory customers from one phase... No, unfortunately that would present a problem. When operating a 3 phase generator, the load must be balanced, or distributed as evenly as possible over the three phases, you cannot load one phase to the gills and have no load on the other two phases.
i meant of course dropping the three-phase idea and go for a single-phase unit. that would make an autostart/transfer possible.
Edited by Naam, 2009-11-03 10:43:56.
Posted 2009-11-03 15:13:59
tjo o tjim, on 2009-11-03 10:12:43, said: The biggest thing that you have to do for generator compatibility with UPS rectifier is ensure that you disengage harmonic filters when on generator. Unfortunately, many of the computer power supplies themselves have leading power factor (-0.97 is becoming typical from the facilities we work in), which makes for a problem when the UPS goes to bypass. We are adding line inductors to a number of sites to fix things, but it is an awful solution.
Nicely said, all those nasty switched mode power supplies with PFC, thus typically leading power factors, load up the standby generator.
Posted 2009-11-04 15:25:23
Naam, on 2009-11-01 09:15:31, said:
I am waiting for the distributor to get back to me with the latest price, I will add it to the post when I receive it and PM you to let you know.
can't you shoot from the hip?
Hi Naam,
I have added the price for the KDE20SS3 in post No 42.
Genset
Edited by genset, 2009-11-04 15:36:20.
Posted 2009-11-05 07:47:39
tjo o tjim, on 2009-11-01 13:10:17, said: Genset-- I know the Cummins document very well; the challenge is finding reliable capability curves for any system. Specific to Cummins, even their MW class machines choke on a few hundred kVAR... and don't get me started on their dam_n MCRS system.
But specific to readers needs, computers and UPS systems do create enough of a leading power factor to cause a problem for a generator designed for 0.8PF lagging loads. Inverter-based AC systems don't help things either.
So, my question remains-- do you have a capability curve for the generators you are representing?
My apologies for the delay in responding to your post, I have been in touch with an agent at Kipor and he has informed me that he doesn't have the capability curve graph/data you requested, available to him.
Whether this specific data was required to be submitted by Kipor during CE conformity test verification (EN12601:2001 Low Voltage Directive 2006/95/EEC) or not is a question I can't answer; unfortunately I don't know enough about the verification process to tell you whether it is a prerequisite to certification; but these generators do conform to the requirements of the specific EEC/CE directives.
I think I messed with the agents head a little to be honest. I ran him ragged looking for info and I'm not entirely sure he knew what he was supposed to be looking for, (his primary role is simply to take sales orders). He was most apologetic and insisted that this was the first time he had ever been asked for this type of specific information… I can't say I'm surprised at his response, I've yet to be approached by a customer asking this kind of question...in all the years I've been working with generators, most of my customers are happy if they can figure out how to turn it on and fill it with diesel; hardly surprising really, the effects of leading power factor on a generator is of minor concern to most farmers.
Having said that, I appreciate your reason for posing the question and I have asked the agent to forward my email address to a member of their technical team, who may be in a better position to cough something up. If I make any headway I'll be sure to let you know.
On your comments regarding Cummins generators; generally Cummins feature Stamford aternators, Stamford as you probably know, is a large, reputable alternator manufacturer. If you are disappointed with the performance of Stamford alternators in respect to leading power factor, the chances of a Kipor alternator fairing any better are fairly slim I'd say.
Where non-linear loads are present, and no other option exists, I would normally advise a customer to consider purchasing a generator with an increased Kw rating (beyond their calculated load requirement), as I believe (and again, my techy mates at Mecc Alte advised me on this), that it will diminish the effects somewhat.
Genset.
Edited by genset, 2009-11-05 16:37:48.
Posted 2009-11-05 15:15:05
david96, on 2009-11-02 11:47:19, said: The Effects of UPS systems on a Generator.
The designer shall ensure that the generator is suitable for the operation with the UPS load.
When the UPS rectifier load is more than 50% of the total load connected on a generator,
the following special measures shall be considered to ensure stable and reliable operation
of the generator.
1. Using a 3 phase AVR.
2. Using permanent magnet field excitation.
3. Using an electronic governor.
4. Oversizing the alternator compared with the kW rating required.
5. Specifying the UPS with filtering to limit the amount of harmonic distortion, where possible.
Where the UPS equipment represent a significant load on the generator, that is at or close to its max. output, overloading shall be prevented by inhibiting or limiting the battery charging function of the UPS when connected to the generator supply, where possible.
Hi David96,
Since the inception of this thread, you seem to have taken a position (based on your earlier posts, No36 for example) contrary to the assertion that under certain conditions (when running on generator power), UPS systems may not operate as designed or cause problems with generator operation.
This is your prerogative and your opinion is welcome, of course, but if you choose to continue discussing this particular aspect of generator use, then I would be grateful if you ensure that the content of your post, (when that content is drawn from other sources) is a complete and accurate reflection, of the portion of the document from which it is copied. Only then can your post be read in proper context.
It would also be helpful if you would credit the source of your text and perhaps offer a link, so that readers may read the document in full, should they so wish.
Unfortunately, you have chosen to omit a paragraph from your post, which is present in the original document and contains the premise for the entire sub-section in which it appears, it also places the 5 points you cite in context. The lack of context appears to have been the reason for InterestedObservers post No66, in your response you have referred to one line from the missing paragraph by citing Australian Standard 'AS62040. Uninteruptible Power Systems' (UPS); please lets not play games here... I had hoped this thread would be a source of good information for people considering the purchase of a generator.
Quote If you read this line it means that the designer of the system must take into consideration the UPS that is to be connected.
The designer has to comply with the required standards in this case:
AS3000/2007 Wiring rules
AS3010. Electrical Installations - Supply by generator set.
AS62040. Uninteruptible Power Systems (UPS).
These are only some of the standards. The Standards set the requirements regarding a leading PF and the effect of harmonics.
You have mentioned that these are only 'some' of the standards, but have again, chosen not to mention two others, which would appear to have a direct bearing on the issue in question, and which appear in the omitted paragraph, namely... 'AS2279 Disturbances in Mains Supply Network and AS/NZS 61000 Electromagnetic Capability (EMC) '. I can only conclude that you have omitted this paragraph as it runs counter to your original stance on this issue.
I have contacted you twice and politely requested that you consider editing your post and placing it into context for readers of this thread. Despite responding that it was not your intention to mislead, you have decided not to do so, and I will therefore place your words in context myself.
The following is an accurate reflection of the section in question from an Australian Defence Dept technical/policy document http://www.defence.gov.au/IM/policy/techni...equirements.pdf and should be compared with your original post to better place your comments in context, the missing paragraph is No30 below. The sub-section containing the text appears on page 8 of the PDF document.
The Effect of UPS on the Generator
30. The controlled rectifiers of UPS systems can be a major source of harmonics which can produce distortions of the voltage and current waveforms and may have a detrimental effect on a variety of electrical equipment both upstream and downstream of the UPS system. The designer shall ensure compliance with relevant Australian Standards AS2279 Disturbances in Mains Supply Network, AS/NZS 61000 Electromagnetic Capability (EMC) and AS 62040 Uninterrupible Power Systems (UPS) to minimise the effects of harmonics on electrical equipment.
31. The designer shall ensure that the LEG is suitable for operation with the intended UPS load. When the UPS rectifier load is more than about 50% of the total load connected on a generator, the following special measures shall be considered to ensure stable and reliable operation of the generator:
a. Using a three phase voltage regulator;
b. Using permanent magnet field excitation
c. Using an electronic governor;
d. Oversizing the alternator compared to the kW rating required; and
e. Specifying the UPS with filtering or 12 pulse rectifiers to limit the amount of
harmonic distortion, where possible.
32. When the UPS represents a significant load on a generator that is operating at or close to its maximum output, overloading shall be prevented by inhibiting or limiting the battery charging function of the UPS when connected to the generator supply, where possible.
One of the aims of this thread is to deliver accurate and helpful information for anybody taking the time to read through it. I would be most grateful if posters (especially those with an engineering or electrical background), would make an effort to avoid posts which are out of context or may serve to mislead a reader, even if that is not your intention.
Genset 
Edited by genset, 2009-11-05 20:50:06.
Posted 2009-11-05 22:16:17
Hi Genset et al, thanks for a great informative thread. My situation is that I will soon be looking for a Silent PRP generator (12kVa -ish single phase) as electricity is 800m away from my plot. I still have to calculate if a generator is a viable alternative to paying out about 700,000 baht to have the grid delivered to my door as 220v. Comments welcome.
My issue is how many litres of diesel per hour (rather baht per hour) will it burn? That 12 kVa will be enough to start up the well pump, and a small a/c unit if switched on at he same time, but for most of the time I'll only be using a TV, a computer, fridge freezer, a couple of fans and some lights at night time. The generator for all this time will be running at what? 50%, 70%? burning diesel and baht like crazy to deliver 1-2 Kw max. What's my solution?
Thanks,
Marvo.
Posted 2009-11-06 06:09:00
Here is the website of KIPOR in NZ. Just follow the links for further information.
http://www.kipor.co.nz/
Gives the full specifications of their genset range, size, ratings and fuel consumption.
The generator sets are manufactured in China.
Posted 2009-11-06 07:48:28
Marvo, on 2009-11-05 23:16:17, said: Hi Genset et al, thanks for a great informative thread. My situation is that I will soon be looking for a Silent PRP generator (12kVa -ish single phase) as electricity is 800m away from my plot. I still have to calculate if a generator is a viable alternative to paying out about 700,000 baht to have the grid delivered to my door as 220v. Comments welcome.
My issue is how many litres of diesel per hour (rather baht per hour) will it burn? That 12 kVa will be enough to start up the well pump, and a small a/c unit if switched on at he same time, but for most of the time I'll only be using a TV, a computer, fridge freezer, a couple of fans and some lights at night time. The generator for all this time will be running at what? 50%, 70%? burning diesel and baht like crazy to deliver 1-2 Kw max. What's my solution?
Thanks,
Marvo.
Hi Marvo,
This is a great question, I'm glad you've asked it.
In a direct, side by side comparison, you won't come close to besting the kWh rate for a residential single phase utility supply through the use of a diesel generator.
Your situation is different, in that you currently have no utility supply available. Long term, it is absolutely going to be cheaper to have the utility supply run into your home. If you can't afford, or simply don't want to tie up/invest 700k right now, using a generator as a prime power source will represent a less significant investment in the short term, allowing you to free up your money for other things and perhaps allow you to save the 700k you need over the next few years for the utility installation, leaving you with a standby generator to boot. Having said that, if you stick solely with the prime power generator for long enough, eventually you will eat through the 700k cost of the utility supply installation and it will become a significantly more expensive option for you to power your home.
It may sound like I'm trying to talk you out of buying a generator… perish the thought...  ,but you deserve an honest assessment, so lets crunch the numbers and see how they pan out.
This thread has attracted some knowledgeable individuals, I would appreciate them jumping in and correcting me if I err in the assumptions or calculations I am about to make…
This link http://www.mea.or.th/internet/neweng/ElectricRate.pdf , provided by Crossy in another thread, is a guide to the MEA Electricity Tariffs. Section 1.1 of the Residential Schedule shows how the price per kWh increases as your consumption increases.
Including fuel surcharge and VAT, the MEA/PEA tariff falls somewhere between 3.5 and 3.9 baht per kWh on average; let's call it 3.5 baht per kWh.
So, with an investment of 700k you will have a single phase utility supply in your home and you will then pay 3.5 baht for every kWh used (inc surcharge and VAT).
Now let's look at the cost of purchasing and running a prime power generator. You suggested that a 12Kva, single phase set would be a suitable size for your needs. I am presuming that you based this assumption on my earlier post indicating that the optimum size for a generator would be one that provided your maximum load requirement @ 70 to 80% of the generators maximum load rating.
12Kva = 9.6Kw and 80% of 9.6Kw = 7.68Kw (if you didn't calculate the generator size using this method, please let me know and I will recalculate this for you)
So your maximum load requirement with AC, well pump, fans, computer, TV etc, all starting and running simultaneously, is approx 7.5Kw… but you mentioned that this would only be a requirement for 50 to 70% of the time… (going off at a slight tangent here; in answer to your question regarding a possible solution to only requiring 1-2Kw for half of the day (night time...?). A battery bank/inverter arrangement would seem like the most obvious solution for your overnight power requirements and could be recharged during the daytime, by the generator… I know nothing about these systems however, so advice from elsewhere would have to be forthcoming if this idea interests you…).
Lets go with the assumption that your AC and well pump are running flat out for the 12 hour running period of the generator; Although your maximum load requirement of 7.5Kw would be drawn on start up of all your pumps and motors simultaneously, the reality is that the starting wattage (which accounts for a large part of your maximum load requirement), will only be drawn for a relatively small percentage of time during that 12 hour period.
These are approximations, but if your load requirement averages out at approx 4.5kWh the KDE16SS will provide a total of 54kWh for the 12 hour period.
How does your 54kWh per day requirement translate into the cost of diesel fuel…?
Diesel fuel has an approximate density (depending on grade) of 850g per litre. The KDE16SS is rated at 10.4Kva PRP (prime power), 13Kva LRP (standby power) and burns less than, or equal to 320g per kWh at 75% of the maximum LRP load rating. As your load averages out at approx 50% of the generators maximum LRP load rating, it will burn slightly less fuel.
280g x 54kWh = 15,120g
15,120g / 850g per litre = 17.78 litres.
So the KDE16SS, delivering approx 4.5kWh (with surges of power on AC and pump startup) continuously for 12 hours, will burn approx 18 litres of fuel.
According to the Nation http://www.nationmultimedia.com/breakingne...newsid=30023359 , the current price of diesel is approx 23 baht per litre (wow.. is that correct…? I haven't looked at the diesel price in Thailand in a while (back in the UK now), the price has really dropped quite significantly…).
18 litres x 23 baht per litre = 414 baht.
That's your approximate cost in fuel per day, 414 baht. In addition and as a result of the increased running hours of the machine, the service interval will be reduced. Running 12 hours a day the machine will rack up approx 360 hours a month, based on this runtime, I would recommend servicing the machine once every two months. The service should include an oil change, oil filter change, fuel filter change, etc, the oil and filters represent the majority of the cost of a service and you should anticipate the cost to be approx 3,000 baht, if you conduct the service yourself.
Let's collate this information and see what we're left with….
KDE16SS price to purchase: 201,000 baht inc VAT
Cost of fuel per day (12hours): 414 baht (x 365 days)
Cost per service (6 per year): 3,000 baht per service (x 6)
Total cost in first year (including genset purchase): 370,110 baht
Total cost to run and service for each additional year: 169,110 baht
After running this generator 12 hours a day, every day, for four years you will have spent more than it would have cost you to have the utility supply installed, approx 877,440 baht.
If you went ahead now with the utility installation, over the next four years, including the cost of installation you would have spent approx 975,940 of which 275,940 would be tariff charges.
I appreciate that these are large numbers in respect to the cost of operating a generator, but readers should understand that Prime Power Generation (in the absence of a utility supply), can be a fairly expensive business. The majority of generator sets (for the average application in Thailand) are purchased as Standby Power Generation solutions… a safety net in the event of a power outage or deep brown out… When used as a Standby Power Generation solution, run times will be a tiny percentage of those experienced by Prime Power sets and the resulting fuel costs vastly reduced. In this particular instance Marvo posed a straight question and deserved a straight answer, I hope this has been of some use to you Marvo.
Genset.
Edited by genset, 2009-11-07 06:28:49.
Posted 2009-11-06 09:46:25
Genset, thanks a bundle for those comprehensive calculations. They're going to take me an hour or two to digest!
One figure that I may have misled you on is the "on" time I'm anticipating for the genny. I am anticipating that I would be capable of surviving with the generator running for just, say, 4 hours a day as lomg as in that time it was able to charge enough batteries to power a TV/DVD, Fridge freezer, computer, a couple of fans, some low energy lights for the rest of the day between generator/battery charges. The 50% -70% figure I mentioned was my estimate at the generating capacity the genny would be running (burning diesel) at for the, let's say, 4 hours a day up-time.
I appreciate that the battery solutions dept is not your area of expertise and neither is it mine, but I guess to answer my questions I need to factor in the cost of a battery bank (whatever that may be), set against the reduced use of diesel for the lower generator running time and lower servicing costs.
Posted 2009-11-06 15:25:31
Quote I am anticipating that I would be capable of surviving with the generator running for just, say, 4 hours a day as lomg as in that time it was able to charge enough batteries to power a TV/DVD, Fridge freezer, computer, a couple of fans, some low energy lights for the rest of the day between generator/battery charges.
Hi Marvo,
After calculating your daily load requirement as approx 54Kw per day, I transposed the numbers and made the fuel calculation based on 45Kw per day… Apologies, it was 02:00 and I was a little bleary eyed… I have amended the post and corrected the figures.
Based on your updated running hours, your costs would be reduced to one third of those previously posted, here are the figures:
4.5kWh x 4 hours = 18kWh
280g x 18kWh = 5040g fuel used
5040g / 850g per litre = 5.9 lets call it 6 litres
6 litres x 23 baht per litre = 138 baht per day.
4 hours running time per day equates to approx 120 hours a month. This would reduce your service interval to perhaps two services a year; 2 x 3,000 baht = 6,000 baht annually (if you service the machine yourself).
Thus your running and service costs per year to run the generator for 4 hours per day, as opposed to 12, would be reduced from 169,110 baht per year to approximately 56,370 baht per year.
On the capability of a battery bank/inverter to supply the items you listed and be fully recharged within the 4 hour period (perhaps there is a rapid charger suitable for the task), I simply don't have enough knowledge on these systems to offer an opinion. If anybody has any knowledge of these systems, I'm sure Marko would appreciate a heads up.
Genset
Posted 2009-11-06 23:44:42
If I may, I'd like to present an example of calculating generator size. If I have left anything out, I hope that Genset will correct me.
Again, this is merely an example.
The first thing you need to do is determine the total load that the generator will need to supply. The generator must be sized to accommodate the starting current for each fridge/freezer/motor etc, plus the extra load of the lights, T.V. & phone/fax etc. You may need to look on the compressor of both the fridge & freezer to get the info you need. If possible, try to find the L.R.A. (locked rotor current) of each compressor/motor. This info may be in any operation manual (if you still have them). If the L.R.A. is not indicated, use the F.L.A. (full load current) & multiply it by 4 (this is a minimum value).
L.R.A. is used as the starting current. If this figure is not obtainable, use 4 times the running current (only for fridges & freezers).
The starting current of any motor is assumed to be between 4 to 8 times the running current. The larger the motor, the larger the starting current. For motors less than 1.5kW, assume 4 times the run current.
"Home" generators typically have 2 ratings...a "continuous" rating & a "surge" rating. You may also notice that generators are sized in VA (Volt Amps) & usually not in kilowatts...there is a good reason for this. If you want to know the reason, feel free to ask.
Let's do a sample calculation;
Formula (single phase). W (power) = E (volts) x I (current) x P.F. (Power Factor).
We need to find the current (I) so;
I = W divided by (E x P.F.)
Power Factor is used if you can't find the FLA or LRA of the fridge/freezer & only the wattage is known. Note - I have assumed that the fridge & the freezer have a P.F. of 0.8. If P.F. is unknown, you can assume a value of 0.8.
P.F. is only used for motors (in this calculation).
Continuous Load calculation.
8 x 40 Watt incandescent lights - - - - - - - - - - 320W divided by 220v = 1.5 Amps.
1 x 300 Watt fridge - - - - - - - - - - - - - - - - - 300W divided by (220v x 0.8) = 1.7 Amps.
1 x 300 Watt freezer - - - - - - - - - - - - - - - - 300W divided by (220v x 0.8) = 1.7 Amps.
1 x 100 Watt TV - - - - - - - - - - - - - - - - - - -100W divided by 220v = 0.5 Amps.
1 x 100W "printer" fax/phone - - - - - - - - - - - - 100W divided by 220v = 0.5 Amps.
Total continuous Watts as listed - 1120 Watts at 220 volts.
Total continuous current as calculated - approx 5.9 Amps.
Surge Load calculation.
The only items that will have a surge current are the fridge, freezer.
1 x 300 Watt fridge - - - - - - - - - 1.7 Amps x 4 = 6.8 Amps.
Fridge surge - - - - - - - - - - - - - 6.8 Amps - 1.5 Amps = 5.1 Amps.
1 x 300 Watt freezer - - - - - - - - 1.7 Amps x 4 = 6.8 Amps.
Freezer surge - - - - - - - - - - - - - 6.8 Amps - 1.5 Amps = 5.1 Amps.
Total surge current - 10.2 Amps.
Your generator will need to supply a continuous current of 6 Amps (5.9 amps).
Your generator will need to supply a total surge current of 6 Amps + 10.2 Amps = 16 Amps.
Converting these figures to "Power" (VA);
16 Amps x 220v = 3 520 VA surge.
6 Amps x 220v = 1 320 VA continuous.
Since you will not find an generator with these exact "continuous" & "surge" ratings, you must buy a generator that can accommodate the surge rating. ie you will need a generator with a surge rating of no less than 3 520 VA for the above situation.
Posted 2009-11-07 06:17:20
Marvo, on 2009-11-06 10:46:25, said: Genset, thanks a bundle for those comprehensive calculations. They're going to take me an hour or two to digest!
One figure that I may have misled you on is the "on" time I'm anticipating for the genny. I am anticipating that I would be capable of surviving with the generator running for just, say, 4 hours a day as lomg as in that time it was able to charge enough batteries to power a TV/DVD, Fridge freezer, computer, a couple of fans, some low energy lights for the rest of the day between generator/battery charges. The 50% -70% figure I mentioned was my estimate at the generating capacity the genny would be running (burning diesel) at for the, let's say, 4 hours a day up-time.
I appreciate that the battery solutions dept is not your area of expertise and neither is it mine, but I guess to answer my questions I need to factor in the cost of a battery bank (whatever that may be), set against the reduced use of diesel for the lower generator running time and lower servicing costs.
Here is a site that has information on inverters, battery chargers and deep cycle batteries.
http://www.inverter....category7_1.htm
You could consider solar (PV) power but you would still need a generator for backup.
Capital cost per kW is high. Availability in Thailand is another matter.
Posted 2009-11-08 10:39:23
genset, on 2009-11-04 15:25:23, said: Naam, on 2009-11-01 09:15:31, said:
I am waiting for the distributor to get back to me with the latest price, I will add it to the post when I receive it and PM you to let you know.
can't you shoot from the hip?
Hi Naam, I have added the price for the KDE20SS3 in post No 42.
thanks, amazing! based on that i am considering a "preventive" installation within the coming months. biggest problem is still placing the unit on my site. both possibilities = problems. slightly less problems are moving the unit on my driveway through the open carport on a concrete slab. disadvantage is that my main feed and central electrical installation is on the opposite site of the home, i.e. 5-6m to the home, up 4m into the roof, 26m through the roof and then 3.5m down = total 40m of cabling. advantage would be that no noise pollution to any neighbour (my house is located next to the community's boundary wall. what i will check today is lift by cran from the road outside the boundary wall to a prepared slab. didn't think of it first, Mrs Naam drew my attention to that possibility which seems to be feasible.
questions:
-can the installation and of course inital start-up be done by dealing with one contractor only? i hate "this we don't do, you have to get your local [insert subcontractor]" 
-cost of transport to Pattaya?
-controls (automatic switch/start) with all the bells and whistles including installation.
-cost for whatever i forgot to mention 
-
Posted 2009-11-08 10:51:14
to make a long story short i sent you an e-mail with my mobile number. please call me tomorrow as i am presently in Macau and will return to Thailand this evening.
Posted 2009-11-08 19:47:47
david96, on 2009-11-06 07:09:00, said: Here is the website of KIPOR in NZ. Just follow the links for further information.
http://www.kipor.co.nz/
Gives the full specifications of their genset range, size, ratings and fuel consumption.
The generator sets are manufactured in China.
Hi David96,
Thank you for posting the two links (Kipor NZ and an example of Inverter/Battery for those considering a hybrid power solution).
Here's another link to a Kipor distributor, this one in South Africa http://www.kiporsa.c...rsa.asp?go=home
As word spreads regarding the reliability and competitive price of these machines, more and more Kipor distributors are popping up worldwide.
Genset
Posted 2009-11-08 19:49:42
Naam, on 2009-11-08 11:51:14, said: to make a long story short i sent you an e-mail with my mobile number. please call me tomorrow as i am presently in Macau and will return to Thailand this evening.
Hi Naam,
E-mail received, I will send you a response later today.
Genset
Posted 2009-11-08 20:24:26
Apologies for the delay in responding to posts, but I'm working flat out, 7 days a week at the moment.
elkangorito, on 2009-11-07 00:44:42, said: If I may, I'd like to present an example of calculating generator size. If I have left anything out, I hope that Genset will correct me.
Again, this is merely an example.
Thank you Elkangorito, your explanation of how to calculate the surge load for motors typically found in the home is a very useful addition to the thread. Historically, when L.R.A and F.R.A data-plate info is not available, I have multiplied the running watts by 3 where small motors of the type in your example are present, but I am happy to defer to your experience and electrical knowledge in using a multiple of 4 as you have suggested. As a rule of thumb, because most homes contain appliances with motors such as those listed in Elkangorito's example (and because L.R.A and F.R.A. may not be available on the motor data-plate), I will always post the Kw (alongside the Kva) rating of a machine, based on a power factor of 0.8, to enable accurate sizing and generator selection based on your load requirement.
Quote "Home" generators typically have 2 ratings...a "continuous" rating & a "surge" rating. You may also notice that generators are sized in VA (Volt Amps) & usually not in kilowatts...there is a good reason for this. If you want to know the reason, feel free to ask.
This is a very timely post, as you've opened the door on generator ratings for 'home' use; a subject that I touched on in my original post, but would like to discuss in more detail now if I may, as it can be a source of confusion not only for those seeking information about generators, but also… unfortunately… some who sell them.
When you're considering the purchase of a generator, the very least you should expect is good, accurate information to help you select a generator best suited for your needs, and not just some guy trying to move a boatload of cheap generators, who has little if any more knowledge about the product than you. The misapplication of an under sized generator is the most common problem I see out there and is normally the result of poor advice from the seller/distributor to a customer, an incorrect load calculation, or no load calculation at all.
Let's look at the ISO 8528-1:2005 ratings for generators and then discuss how each rating translates into home use.
There are four ratings; we are only interested in the first three with respect to 'home' use, they are;
ESP – Emergency Standby Power Rating
LRP – Limited Time Running Power (generally referred to as a Standby Rating)
PRP – Prime Power Rating
ESP – Emergency Standby Power Rating
Light duty, portable, single cylinder sets running at 3000rpm; rated to run for a maximum 200hrs a year (that's 3.8hrs a week) with a variable load at the alternators maximum load rating, no overload permitted.
LRP – Limited Time Running Power Rating ('Standby Rating')
Heavier duty, normally a permanent installation, multiple cylinder engines, running at 3000rpm or 1500rpm; rated to run for up to 500hrs a year (that's 9.6hrs a week maximum) with a constant load at the alternators maximum load rating, no overload permitted.
PRP – Prime Power Rating
Heavy Duty, permanent installation, multiple cylinder engines, running at 1500rpm; rated to run for an unlimited period of time with a variable load at the prime rating of the alternator; typically an overload of 10% in any 12 hour period is permitted.
To better understand why a particular rating is attributed to a generator for home use and more specifically, why it is important that LRP Standby Ratings should be limited to a maximum 500hrs operation a year and PRP Prime ratings are not, we need to look at aspects of the engine and alternator.
Voltage and Kva ratings of alternators are dictated by a number of factors; the length and size of the copper windings, the length of the lamination stack and the amount of cooling air passing through the alternator etc.
The class of insulation material used to protect the copper windings is a key factor. Resistance of the copper wire making up the alternator windings causes its temperature to rise as a current is passed through it… the more current, the more heat; the more heat, the shorter the life expectancy of the insulation material, with sufficient heat the insulation material will fail and the alternator will burn out.
NEMA (The National Electrical Manufacturers Association) recognizes four classes of insulation material for use in alternators (A, B, F and H). The difference between each class being the maximum temperature at which the copper windings can operate for each of two duty cycles; continuous use and standby use.
Continuous Use:
Running 24 hours a day, 7 days a week, the maximum operating temperature of the copper windings permitted by the NEMA insulation classes in degrees C are; Class A-100, Class B-120, Class F-145 and Class H-165.
Standby Use:
As standby use involves less running hours (that's the maximum 500hrs a year for standby use remember), the NEMA insulation classes allow the alternator windings to operate at up to 25 degrees C hotter; Class A-125, Class B-145, Class F-170 and Class H-190. The ability of the copper windings to operate up to 25 degrees C hotter for a limited period, allows the alternator to generate more power, hence the higher standby rating.
The maximum operating temperature of the copper windings is made up of two parts; the ambient environmental temperature and the temperature rise resulting from the operation of the alternator. If the ambient temperature is 40 degrees C, then deducting that figure from the maximum operating temperature for each class, gives us the temperature rise permitted for each class due to use.
A 1500rpm engine can be rated for use as a standby or prime mechanical power source, but a 3000rpm engine can only ever be used as a standby mechanical power source…these high revving engines are simply not designed to operate as a prime mechanical power source; this is concrete, regardless of what any dealer or distributor tries to tell you…
So…to simplify and summarize I will use the example of two Kipor generators, the KDE12STA and KDE16SS.
The KDE12STA is a 3000rpm, single phase generator. The alternator features class F insulation and the complete generator (engine and alternator combination) is rated as an LRP set for Standby Power use only. It should be operated at its maximum load rating for up to a maximum of 500hrs a year (9.6hrs a week maximum) and should give you good reliable service over the long term. However, as we have discussed, if you choose to operate this generator at or above its maximum load rating for a period exceeding the maximum runtime, you should fully expect to experience problems with the under rated mechanical power source (engine), or for the alternator insulation to fail and burn out at any time. It is a false economy to 'save' money by purchasing a standby generator only to then commit it to a prime power role. This is misapplication of the generator and you should fully expect to experience problems.
Note; if sufficiently rated, this same alternator driven by a 1500rpm machine could be used as a prime power source, as long as the heat in the copper windings does not exceed the class F temperature rise for continuous use. This is achieved by reducing the maximum output of the alternator from the maximum standby rating to the prime rating stamped on the alternator.
The KDE16SS is a 1500rpm, single phase generator. The alternator features class H insulation (the highest of the NEMA insulation classes) and the complete generator (engine and alternator combination) is rated for use as both a PRP set for Prime Power use and an LRP set for Standby Power use (13Kva/10.4Kw and 15.5Kva/12.4Kw respectively) according to application. The KDE16SS may be operated as a Prime Power source, at its Prime Power rating, continuously, for an unlimited period. However, as with the KDE12STA, if used as a secondary Standby Power source, it should be operated for up to a maximum 500hrs a year at its maximum Standby rating, operating this generator at or above its maximum load rating for a period exceeding the maximum runtime will eventually result in failure of the class H insulation and subsequent failure of the alternator.
Regardless of whether you are considering a generator for a Prime Power or Standby application, I would strongly recommend you follow my earlier suggestion that your generator be sized so that your maximum load requirement falls between 70 and 80% of the alternators rated output (70 to 80% of the Prime rating for Prime Power applications and/or 70 to 80% of the Standby rating for Standby Power applications). Among the benefits of sizing a generator in this way, are a reduction in the amount of fuel used, reduced strain on the engine, reduced thermal stress on the alternator insulation and a reduction in noise pollution; it also allows capacity for growth in your electrical needs.
My motivation for discussing this now, other than to offer advice to readers, is the result of a recent blizzard of emails between myself, the manufacturer and the distributor in Thailand, regarding the rating for the SS (ultra silent) range of Kipor machines. The manufacturer had initially represented their posted rating as being for Standby use (language and terminology issues), but I now have the accurate ratings sorted out and have amended my earlier posts to reflect the change.
I hope I haven't muddied the waters with this explanation; these are important points regarding generator sizing and selection, if you found it a little confusing please try giving it another read through.
Genset
Edited by genset, 2009-11-09 05:35:06.
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