Generators In Thailand

[david96]

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.

[genset]

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 November 6, 2009 by genset

[Marvo]

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.

[genset]

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

[elkangorito]

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.

[david96]

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.com.au/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.

[Naam]

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

-

[Naam]

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.

[genset]

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.co.za/kiporsa.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

[genset]

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

[genset]

Apologies for the delay in responding to posts, but I'm working flat out, 7 days a week at the moment.

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.

"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 November 8, 2009 by genset

[genset]

thanks, amazing! based on that i am considering a "preventive" installation within the coming months.

The amazing thing is that when I eventually begin selling these generators directly, I will be able to knock another 15% off the price...

Genset

Edited November 9, 2009 by genset

[Naam]

Apologies for the delay in responding to posts, but I'm working flat out, 7 days a week at the moment.

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.

Honourable Experts Elkangorito et Genset, Esqs.,

may i humbly add actual (measured in my presence) starting amps?

Daikin "13,000" manufacturers figures:

cooling capacity 3,200 kcal/h = 12,690 btu/h

compressor/condenser running watts 1,105 watt, running amps = 5.17

measured starting amps 8.5

Daikin "24,000"

cooling capacity 5,680 kcal/h = 22,500 btu/h

compressor/condenser running = 1,970 watts, running amps = 9.10

measured starting amps 22.5

Daikin "36,000"

cooling capacity 8,900 kcal/h = 35,300 btu/h

compressor/condenser running = 4,060 watts, running amps = 19.5

starting amps not measured!

the big'un is used to heat my pool water and at the same time cool the pool area but there is no need to add it to a load calculation.

[genset]

Honourable Experts Elkangorito et Genset, Esqs.,

may i humbly add actual (measured in my presence) starting amps?

Hi Naam,

If you measured the current drawn by these circuits directly through the use of a tong tester or the like, I see no reason to question them.

My area of expertise... is the manufacture and installation of generators and not, unfortunately, the specific characteristics of AC motors (why some are more efficient than others).

When calculating the load requirement for a home or business, my preference (if on site), would be to use a tong tester to accurately measure the current drawn by motors such as these on startup. If I am offering advice by email, I am looking for the house/business owner to provide me with as much information as possible, the locked rotor amps (startup) or full load amps (running) if available; and if not, the watt rating stamped on the data plate. If the latter is the only information available, I would normally mulitiply this figure by 3 to give me an approximate startup requirement. For the type of small motors typically found in the home, this general rule of thumb allows me to ensure that the generator selected, is of a sufficient size to handle their power requirements on startup (even if oversized a tad) and is not undersized in relation to your overall load requirement (the less desirable of the two options).

Having said that, I am happy to see that your AC motors are so efficient, aside from saving you money when running on the utility supply; should you choose to purchase a generator, they will place less stress on the engine and alternator when running on the generator supply.

Genset

Edited November 12, 2009 by genset

[Naam]

Honourable Experts Elkangorito et Genset, Esqs.,

may i humbly add actual (measured in my presence) starting amps?

Hi Naam,

If you measured the current drawn by these circuits directly through the use of a tong tester or the like, I see no reason to question them.

that's exactly how it was measured and i was surprised with the results and have no explanation for the rather low values. in olden times we always used "factor 3" but then we were dealing with piston and not with rotary compressors. what i am trying to find out is the reason and i will of course measure again.

going back in history. in ancient times (Nigeria 1982-1983) a 70kva single phase generator was my primary energy source for 1½ years which served 4 houses. if i recall correctly the total number of 1ton aircons was 12 plus 4 2ton units. these were the old rattlers built in the wall, had piston compressors, were drawing more than double the wattage of modern units and ran 24 hours seven days a week. a rough calculation results in a total load 45 kilowatts (~200 amps). engine oil of the generator, plus whatever my chief engineer deemed necessary was checked every day; the service lasted about 10 minutes and then the set was started again. these 10 minutes did definitely exceed the time of the relays which prevents an aircon compressor to start before pressure in suction and pressure pipe was equal.

my question is "how could the diesel and the generator cope with starting amps of 600 (using factor 3)?"

[Marvo]

Daikin "13,000" manufacturers figures:

cooling capacity 3,200 kcal/h = 12,690 btu/h

compressor/condenser running watts 1,105 watt, running amps = 5.17

measured starting amps 8.5

Wow, those 13,000 Daikins have a REALLY low start-up ampage! Less than 2x.

[david96]

Daikin "13,000" manufacturers figures:

cooling capacity 3,200 kcal/h = 12,690 btu/h

compressor/condenser running watts 1,105 watt, running amps = 5.17

measured starting amps 8.5

Wow, those 13,000 Daikins have a REALLY low start-up ampage! Less than 2x.

Here are the specs for 5 models of Daikin airconditioners available in Thailand.

They use inverter technology, in other words they have a variable speed drive

and thus reduced voltage starting.

KW 2.5 / BTU 8500 Run amps 4.0 Power consumption 700W.

KW 3.5 / BTU 11900 Run amps 5.0 Power consumption 1035W.

KW 5.0 / BTU 17100 Run amps 6.5 Power consumption 1400W.

KW 6.0 / BTU 20500 Run amps 8.2 Power consumption 1780W.

KW 7.1 / BTU 24200 Run amps 10.8 Power consumption 2360W.

Reduced voltage starting currents are a lot less than DOL starting.

This will explain the lower starting currents.

[InterestedObserver]

Honourable Experts Elkangorito et Genset, Esqs.,

may i humbly add actual (measured in my presence) starting amps?

Hi Naam,

If you measured the current drawn by these circuits directly through the use of a tong tester or the like, I see no reason to question them.

that's exactly how it was measured and i was surprised with the results and have no explanation for the rather low values.

I assume this tong tester (clamp-on ammeter) had a maximum save function for recording starting current. If not, them you may have observed an artificially low current reading. Just a comment for those interested, not questioning anybodies technical ability.

Edited November 13, 2009 by InterestedObserver

[elkangorito]

Another thing that has a big affect on motor starting current is the nominal speed of the motor. The higher the nominal speed, the higher the starting current.

[InterestedObserver]

Here are the specs for 5 models of Daikin airconditioners available in Thailand.

They use inverter technology, in other words they have a variable speed drive

and thus reduced voltage starting

That would necessitate the use of a True RMS tong tester (clamp-on ammeter) with maximum hold function to get a really good starting current reading.

[Crossy]

Here are the specs for 5 models of Daikin airconditioners available in Thailand.

They use inverter technology, in other words they have a variable speed drive

and thus reduced voltage starting

That would necessitate the use of a True RMS tong tester (clamp-on ammeter) with maximum hold function to get a really good starting current reading.

I'm wondering what the interesting VI waveforms produced by these VVVF drives will do to the AVR on the Genset. Ref our conversation on UPSs and PC PSUs with active PF correction.

Any A/C load will likely be a significant percentage of the overall consumption along with CFL lighting and switching PSUs.

[Naam]

Here are the specs for 5 models of Daikin airconditioners available in Thailand. They use inverter technology, in other words they have a variable speed drive and thus reduced voltage starting

That would necessitate the use of a True RMS tong tester (clamp-on ammeter) with maximum hold function to get a really good starting current reading.

I'm wondering what the interesting VI waveforms produced by these VVVF drives will do to the AVR on the Genset. Ref our conversation on UPSs and PC PSUs with active PF correction.

Any A/C load will likely be a significant percentage of the overall consumption along with CFL lighting and switching PSUs.

nope Gentlemen! none of my units have variable speed compressors. when we built the house 4 years ago i opted for straight ac/ac compressors as we had ongoing problems with inverter units installed in an apartment the Mrs. owns in another country. they were installed in 2002 (?) when the technology was rather new and the technicians of the supplier were rather helpless

by the way, i called a friend in Germany, he very much doubts that the amp readings i posted here are correct and suggested, no matter what the new readings are, that "Genset" installs for each unit individual "delay relays", each with a time difference of one minute.

i also hope, when the time has come, that ElKangorito makes his expert knowledge available. he does not live far away and has been a guest in my house.

as far as cranes and lifting a ton or more are concerned i shamefully admit that i did not see the forest because of all the trees when discussing the problem with Mrs. Naam she cooly said "males create or see too often problems where there are none!" and then pointed out with a few words how a crane can place the generator without lifting it over any building. lesson learned: having a wife who has a Ph.D. in anthropology (and one in another breadless art) helps to solve technical problems.

[genset]

.

I'd like to begin this post by thanking all those who have contributed to this thread.

In addition to offering fundamental advice and promoting a specific line of generators, my goal here, has been to prove that a market exists within the expatriate community for the services I intend to offer. I have received a flood of emails that I am slowly working my way through and significant interest does indeed appear to exist; interest which in large part seems to have been ignited by this thread.

Another reason for my posting in a sub-forum occupied by a knowledgable collection of individuals, was the hope that I could draw on your collective experience and highlight any potential issues specific to the use of generators in Thailand, in anticipation of rolling out a comprehensive service in 2011.

As discussed earlier in the thread, one such issue that has been raised, may be the propensity for expatriate homes to house numerous UPS systems, variable speed motors (in the case of the Daikin AC units cited by Naam) and other rectifier based, non-linear loads.

I'm wondering what the interesting VI waveforms produced by these VVVF drives will do to the AVR on the Genset. Ref our conversation on UPSs and PC PSUs with active PF correction.

Any A/C load will likely be a significant percentage of the overall consumption along with CFL lighting and switching PSUs.

After consulting with my tech mates at Mecc Alte, their opinion on the most likely effect of the 'interesting VI waveforms' on the AVR, is one of voltage oscillation and frequency instability; a condition which will further serve to exacerbate the problem.

Their recommendations included:

• Derating (oversizing) the generator where the load is predominantly non-linear.
  
• The possible addition of a small linear load (a load bank sized for approx 10% of the alternators rating for example) where a load is predominantly non-linear so that some resistive load is on the generator as the non-linear loads begins the ramp on process. This should aid in stabilizing the system somewhat.
  
• The use of a single phase or three phase, true RMS sensing AVR. This should provide reliable voltage regulation for generator sets serving non-linear loads. They will sense voltage level more accurately, regardless of the distortion of the voltage waveform.(the SR7 AVR from Mecc Alte is one such AVR, circa 500 sterling).
  
• The use of an alternator featuring Class H insulation. This provides additional thermal protection to offset alternator over-heating caused by non-linear loads.
  

I dont want to overstate the problem, there are thousands of generators operating satisfactorily, in prime and standby applications throughout Thailand; but in the event that a load is comprised totally, or in large part of non-linear loads, the only way to know for sure how a generator will perform (regardless of whether the machine is worth 200k or 2m baht...) is to get on site and 'test' the generators ability to operate satisfactorily with the proposed load prior to purchase and installation.

I will contact the distributor next week and discuss the possibility of providing a generator specifically for the purposes of testing the ability of the generator to operate with predominantly non-linear loads, where a potential expatriate customer has shown interest in a purchase.

I welcome and look forward to your opinions and comments on this issue; particularly those of InterestedObserver, who has a lengthy and comprehensive experience in generator operation and control.

Genset

[genset]

nope Gentlemen! none of my units have variable speed compressors. when we built the house 4 years ago i opted for straight ac/ac compressors as we had ongoing problems with inverter units installed in an apartment the Mrs. owns in another country. they were installed in 2002 (?) when the technology was rather new and the technicians of the supplier were rather helpless

by the way, i called a friend in Germany, he very much doubts that the amp readings i posted here are correct and suggested, no matter what the new readings are, that "Genset" installs for each unit individual "delay relays", each with a time difference of one minute.

Hi Naam,

You beat me to my reply to Crossy, but my previous post is still relevant with regard to homes where predominantly non-linear loads are present. The news that your AC units do not feature inverter technology (given the percentage of your load taken up by AC units), is great from an operational viewpoint. You would, of course, still need to nail down your load requirement. If you dont already own a tong tester (clamp on ammeter), you may wish to pick one up, if you do, try and get a true RMS version with peak hold function as suggested by InterestedObserver, they're relatively cheap and worth having.

Genset

Edited November 14, 2009 by genset

[Naam]

The news that your AC units do not feature inverter technology (given the percentage of your load taken up by AC units), is great from an operational viewpoint. You would, of course, still need to nail down your load requirement. If you dont already own a tong tester (clamp on ammeter), you may wish to pick one up, if you do, try and get a true RMS version with peak hold function as suggested by InterestedObserver, they're relatively cheap and worth having.

i own one but can't find it Mrs. Naam who knows where to find things flew today to Singapore most probably i will own an additional one tomorrow or day after tomorrow. but i don't understand why a peak hold function is necessary because i will not select an overkill unit which can deal with all the starting amps and waste a few hundred thousand Baht. my initial idea (switch on aircons manually one after the other) is of course stone age Cheap Charly technology but can be translated into modern technology as my german friend (see "adjustable delay relays" above) suggested.

as mentioned in my e-mail yesterday i am willing to go for "the whole -not 9- but 8½ yards" by selecting the "KDE45SS3" which would handle all my needs (Rated power kW/(r/min) 41.6/1500) but NOT all starting amps.

question to all interested experts: "is there any reason why "adjustable delay relays" would not work?"

[elkangorito]

i also hope, when the time has come, that ElKangorito makes his expert knowledge available. he does not live far away and has been a guest in my house.

I'm still here doc

Their recommendations included:

• Derating (oversizing) the generator where the load is predominantly non-linear.
  
• The possible addition of a small linear load (a load bank sized for approx 10% of the alternators rating for example) where a load is predominantly non-linear so that some resistive load is on the generator as the non-linear loads begins the ramp on process. This should aid in stabilizing the system somewhat.
  
• The use of a single phase or three phase, true RMS sensing AVR. This should provide reliable voltage regulation for generator sets serving non-linear loads. They will sense voltage level more accurately, regardless of the distortion of the voltage waveform.(the SR7 AVR from Mecc Alte is one such AVR, circa 500 sterling).
  
• The use of an alternator featuring Class H insulation. This provides additional thermal protection to offset alternator over-heating caused by non-linear loads.

Genset, just out of curiosity, what is the "standard" insulation class of generator windings?

An "inverter class" motor has a minimum Class F insulation. There are other Class "combinations" that can be effective, which depends upon the design of the machine. Please be aware that I'm talking about induction motors.

Also...an apology. I made some minor mistakes in my "generator sizing" calculations. By the time I realised my mistakes, I could not edit the post. Regardless, the methodology is correct.

[Naam]

# Derating (oversizing) the generator where the load is predominantly non-linear.

# The possible addition of a small linear load (a load bank sized for approx 10% of the alternators rating for example) where a load is predominantly non-linear so that some resistive load is on the generator as the non-linear loads begins the ramp on process. This should aid in stabilizing the system somewhat.

# The use of a single phase or three phase, true RMS sensing AVR. This should provide reliable voltage regulation for generator sets serving non-linear loads. They will sense voltage level more accurately, regardless of the distortion of the voltage waveform.(the SR7 AVR from Mecc Alte is one such AVR, circa 500 sterling).

# The use of an alternator featuring Class H insulation. This provides additional thermal protection to offset alternator over-heating caused by non-linear loads.

AAARRRGGGHHHH...

[elkangorito]

by the way, i called a friend in Germany, he very much doubts that the amp readings i posted here are correct and suggested, no matter what the new readings are, that "Genset" installs for each unit individual "delay relays", each with a time difference of one minute.

This will be a tad complicated as each timer would need to rely upon the status of each other. Example, if you had individual start timers on each a/c unit, there would still be nothing to stop 2 or more a/c units starting simultaneously. Therefore, the timers need to "talk to each other". I'll see if I can dream up a control schematic for this situation.

[InterestedObserver]

but i don't understand why a peak hold function is necessary because i will not select an overkill unit which can deal with all the starting amps and waste a few hundred thousand Baht.

question to all interested experts: "is there any reason why "adjustable delay relays" would not work?"

1. The discussion has been about motor starting current, or the peak current drawn by the motor. For that you need a peak hold function. If you are not going the deal with all the starting amps, then you don't need to know what they are.

2. Adjustable delay relays would work just fine, stone age technology still works.

[Crossy]

by the way, i called a friend in Germany, he very much doubts that the amp readings i posted here are correct and suggested, no matter what the new readings are, that "Genset" installs for each unit individual "delay relays", each with a time difference of one minute.

This will be a tad complicated as each timer would need to rely upon the status of each other. Example, if you had individual start timers on each a/c unit, there would still be nothing to stop 2 or more a/c units starting simultaneously. Therefore, the timers need to "talk to each other". I'll see if I can dream up a control schematic for this situation.

How about a quick-and-dirty, just use different delays, 1min, 2 min, 3 min etc