Generators In Thailand

[Naam]

Observer: "Most synchronous generators are designed to support 300% of their rated kVA for 10 seconds. From the OP, [(600 amps starting current)(230 volts single phase)]/1000 = 138 starting kVA"

Genset:"a generator with the correct insulation class (H), may also handle high overcurrent for short periods (such as that mentioned in Naams question), but the potential for alternator insulation failure is high', I followed this up more recently with the comment that things just arent made the way they used to be..."

Gentlemen, assuming both claims are valid it is beyond my comprehension that the supplier of generators (main parts engine and alternator) would try to save cost by being stingy as far as insulation class of the alternator wiring is concerned. in Nigeria i bought the generator together with his twin second hand from a german construction company which withdrew from the country. that was end of 1981, both units were most probably 2-3 years old. and now i am told that after THIRTY years of technical and manufacturing development the products are inferior?

Naam,

No, contemporary alternators are not inferior, far from it, but 300% of rated Kva for 10 seconds equates to an enormous amount of heat being generated in the alternator windings. These recommendations exist to extend the life of an alternator at the end of the day Naam... the manufacturer doesnt want you to burn your alternator out through misuse.

one has to add "the manufacturer wants me to spend a multiple of my dough because he is not willing to produce with an additional minimum of my aforesaid dough the sturdiness of a product i have experienced three decades ago".

[genset]

one has to add "the manufacturer wants me to spend a multiple of my dough because he is not willing to produce with an additional minimum of my aforesaid dough the sturdiness of a product i have experienced three decades ago".

At the end of the day Naam, if you size your generator correctly, use it appropriately and service it regularly, it should give you years of trouble free service... I wouldnt like to see you slide into a fit of depression over this now...

Genset

Edited November 22, 2009 by genset

[Naam]

one has to add "the manufacturer wants me to spend a multiple of my dough because he is not willing to produce with an additional minimum of my aforesaid dough the sturdiness of a product i have experienced three decades ago".

At the end of the day Naam, if you size your generator correctly, use it appropriately and service it regularly, it should give you years of trouble free service... I wouldnt like to see you slide into a fit of depression over this now...

Genset

i am not at all depressed Genset. i stated facts and i see a problem. when i see a problem i am looking for a solution. i do not consider "[over]sizing my generator correctly" an acceptable solution assuming there are other ways, assuming Observer's statement "Most synchronous generators are designed to support 300% of their rated kVA for 10 seconds" is correct and especially based on the actual experience i had years ago with a generator (actually alternator) which quite obviously took loads in a stride which seem to be beyond the capability of some nowadays alternators.

so let's look for a solution apart from oversizing. i am neither a stingy nor a poor man. i've told you what i spent on my home. it does not make a big difference to my bank account whether i spend 300k or one million Baht on my generator. but having grown up as a poor boy in a poor environment and working hard for whatever i own now i hate wasting a single penny.

[david96]

Hi Genset, regarding your post 154.

One would agree with you there. I was pre supposing a MEN system. The TT system is the system most used in Thailand and they may switch the incoming neutral.

AS3000/2007 and AS3010 provide information on generator connection the majority of gensets connected to an MEN system do not switch the neutral and use a 3 pole ATS or 2 x 3 pole contactors (for small sets) or a manual 3 pole C/O switch and only one MEN connection per consumer, the MEN is at the main switchboard.

AS3000/2007 7.3.8.1.

The neutral-earth connection (MEN connection) shall be made within the installation at the switchboard to which the electricity generation system is connected.

Note: This may require disconnection of any neutral-earth connection within an electricity generation system, such as an engine driven generating set.

The incoming neutral to a MEN switchboard shall not be switched.

Neutral and earth conductors shall not operate in parallel.

7.3.8.1.2 Switching.

The changeover device for an alternative supply shall be selected to maintain the function of,and prevent damage to, the electrical installation being supplied.

Note: Examples of functions to be maintained include the maintainance of the continuity of the neutral conductor (overlapping of neutrals), the operation of RCDs or the continued operation of uninterruptible power supplies.

The changeover device shall open all active conductors of the normal supplies when the alternative supply is connected.

Note.

One has to make allowances for Thailand. In Australia we regard neutrals, earthing and equipotential bonding seriously. In Thailand they do not. One may have to use alternative methods as long as electrical safety is not compromised.

[InterestedObserver]

Naam:

According to the NEMA MG1 Standards, a synchronous generator should have the capability of supporting 300% overcurrent for 10 seconds. The question thus becomes how much of a voltage dip (sag) are you willing to tolerate and still be able to start all your motor loads. Is it acceptable for the lights to noticeably flicker or dim every time an AC starts, what about all your electronics? A lot depends on the generator windings, exciter, voltage regulator, and motor characteristics. If you require an exact answer the manufacturer will have to supply a motor starting capacity curve, or similar analysis, that details the ability of the generator set (as sold) to handle motor starting loads. Without such data being readily available we can only speak in generalizations. And yes, they don't build 'em like they used to.

Edited November 23, 2009 by InterestedObserver

[genset]

whether i spend 300k or one million Baht on my generator. but having grown up as a poor boy in a poor environment and working hard for whatever i own now i hate wasting a single penny.

Hi Naam,

I appreciate your comments, have attempted to answer your questions to date as honestly as I can and will continue to do so.

so let's look for a solution apart from oversizing

Ok, the first thing we need to correctly size a generator for your needs, is an accurate load calculation based on the starting load requirement of each motor you intend to run and all your other appliances.

Genset

Edited November 23, 2009 by genset

[genset]

According to the NEMA MG1 Standards, a synchronous generator should have the capability of supporting 300% overcurrent for 10 seconds.

NEMA MG1 further states that (although each insulation class (A,B,F,H) has different characteristics (maximum operational temperature at each class)), under normal, continuous operating conditions, the insulation will have a minimum life expectancy of 30,000 hrs... thats 60yrs at the recommended standby (LRP) rating of 500hrs operation a year... so with a change of engine, you should be good to hand it down to the next generation...

The question thus becomes how much of a voltage dip (sag) are you willing to tolerate and still be able to start all your motor loads. Is it acceptable for the lights to noticeably flicker or dim every time an AC starts, what about all your electronics? A lot depends on the generator windings, exciter, voltage regulator, and motor characteristics. If you require an exact answer the manufacturer will have to supply a motor starting capacity curve, or similar analysis, that details the ability of the generator set (as sold) to handle motor starting loads. Without such data being readily available we can only speak in generalizations. And yes, they don't build 'em like they used to.

Agreed, although I appreciate Naams comments, without the accurate starting load data (as part of a fully comprehensive load calculation) it is difficult to give a precise answer to this question and recommend an appropriate generator size for Naams requirement.

Genset

Edited November 23, 2009 by genset

[genset]

assuming Observer's statement "Most synchronous generators are designed to support 300% of their rated kVA for 10 seconds" is correct and especially based on the actual experience i had years ago with a generator (actually alternator) which quite obviously took loads in a stride which seem to be beyond the capability of some nowadays alternators.

Hi Naam

I missed this initially (rushing to read your message before running out to work...), but I wouldnt categorize the statement underlined above, as the alternator taking the load in its stride... or as a reflection of an alternators capability to handle the load requirement of motors on start up. Under normal operating conditions (starting motors etc), the alternator should not be required to venture into this territory (we discussed alternator insulation ratings in post #75, if anybody is confused by this disussion I would ask them to read that post again, it contains information relevant to this exchange).

The ability to support 300% of rated Kva for 10 seconds is a safety factor, built in to protect the alternator windings from catastrophic failure and it should not be used as a basis for calculating a load requirement.

The 10 second rating is designed to allow the overcurrent protection device fitted on the generator, to operate effectively and trip the supply from the generator should such a situation occur.

Genset

Edited November 23, 2009 by genset

[Naam]

The ability to support 300% of rated Kva for 10 seconds is a safety factor, built in to protect the alternator windings from catastrophic failure and it should not be used as a basis for calculating a load requirement.

that goes without saying but at the same time i read in the recommendations of an alternator manufacturer (you sent by e-mail) of starting currents which are FIVE to TEN times the flying amps. for an electrical layman like me that all sounds very confusing. what i will do is measure the starting currents of the two types of a/c units (12 and 24k btu) i am planning to use as well of the two huge fridges/freezers in my kitchen. unfortunately the chap whom i sent out to buy a "clamp amp" brought a model without peak hold. calling the shop the answer was "no habb". inspite of this i will still try to measure the two units. besides considering these loads i still insist on either manually or otherwise "one after the other switching (after the breaker or with a gadget that replaces the braker) first off and than on.

all my electronics (PCs, TVs, etc. as well as my house water suplly) are on inverters and batterie back-ups. there seem to be another problem to be solved, i.e. (according some experts here) separating the inverters from the net as long as the generator is running. other experts beg to disagree but if necessary that should not be a big problem to solve.

if you look at the sketch i posted even the "comfort version" is a total of only 12 kW out of which the highest "consumer" draws 2.2 kW. the 12kW contain already an aircon which is not really needed. as i don't have split personalities it is highly unlikely that i sit in front of my screens in my study and watch at the same time news in my TV-room using in both room an aircon simultaneously

needless to say is that during generator use neither pool pump, nor pond pump, nor waterfall, nor irrigation pump, nor deep well pump will be used.

[david96]

Alternator protection. General.

Overvoltage

Undervoltage

Overspeed (Hz)

Underspeed (Hz)

Short circuit protection.

Overcurrent protection.

Earth fault protection. TT systems.

1. Overvoltage, undervoltage, overspeed and underspeed characteristics should be

incorporated in the AVR.

2. Short circuit and overcurrent protection by a MCB or MCCB of suitable rating.

3. Earth fault protection for generators connected to a TT system.

Earth fault protection is not mandatory in Thailand on TT systems. An earth fault may not operate a protective device.

On a TN (MEN) system an earth fault must be cleared within 0.4secs, the fault current path via the neutral conductor to the source of supply.

[genset]

i read in the recommendations of an alternator manufacturer (you sent by e-mail) of starting currents which are FIVE to TEN times the flying amps. for an electrical layman like me that all sounds very confusing. what i will do is measure the starting currents of the two types of a/c units (12 and 24k btu) i am planning to use as well of the two huge fridges/freezers in my kitchen. unfortunately the chap whom i sent out to buy a "clamp amp" brought a model without peak hold. calling the shop the answer was "no habb". inspite of this i will still try to measure the two units. besides considering these loads i still insist on either manually or otherwise "one after the other switching (after the breaker or with a gadget that replaces the braker) first off and than on.

If you are not in a rush and in an effort to get an accurate load requirement and generator sizing, perhaps you would prefer to wait until I come back in the new year, I would be happy to help you out with this in person.

Genset

Edited November 24, 2009 by genset

[Naam]

Naam:

According to the NEMA MG1 Standards, a synchronous generator should have the capability of supporting 300% overcurrent for 10 seconds. The question thus becomes how much of a voltage dip (sag) are you willing to tolerate and still be able to start all your motor loads. Is it acceptable for the lights to noticeably flicker or dim every time an AC starts, what about all your electronics? A lot depends on the generator windings, exciter, voltage regulator, and motor characteristics. If you require an exact answer the manufacturer will have to supply a motor starting capacity curve, or similar analysis, that details the ability of the generator set (as sold) to handle motor starting loads. Without such data being readily available we can only speak in generalizations. And yes, they don't build 'em like they used to.

Observer,

i think i emphasised from the beginning that i am planning to go with my idea of switching loads one after the other. if this problem is solved the generator of my liking

http://www.kipor.com/prouducts_detail.asp?info_id=577

with a continous output of 30kW should not have any problems to deal with the "comfort" solution (12kW) i want to achieve. the unit has to deal only at start with the heavier load of the selected aircons. reason: whenever we lose a phase or even two the remaining aircons work continously, never switch off and because of that no fluctuation (except perhaps a minor one from the fridges) occurs. all my electronics are (as mentioned) on inverters (three sets of them, each with a 24v battery back-up capacity 320ah).

light flickering should also be eliminated as no aircon will switch off and then on again during generator use (see above). besides, having lived and worked 15 years in the desert, the bush and the swamps a little light flickering wouldn't do any harm

[david96]

Re. #166

Reading the specs of that particular generator, no mention is made of alternator protection,

provision for remote (eg 3 wire) starting or provision for auto start function on loss of mains supply.

The ATS and compatable control module suitable to interface with the genset controls would be an optional extra. If a manual changeover switch is to be used this would be an extra.

The ATS and control module should be purchased from the same source as the generator to ensure compatability.

[Naam]

intermediate summary:

-i am presently discussing with Genset the transport of the unit and bombard him with photos i made.

-my choice of generator is a 3-phase unit with a net output of 30kW which should be suitable to run not only my "comfort version" but also a water heater which has no starting load.

-the starting amps have become (in my view) irrelevant because i will switch off all airconditioner breakers when when a power cut occurs. the generator is then started by remote manually. when the diesel is up with its revs (there is still the load of lights and other "consumers") i will switch on manually one needed aircon after the other (again with the breakers). during generator run time no aircon will on its own switch off/on. i explained the reason why before.

-the biggest aircon (24k btu) with the highest starting amps will be switched on first. this unit runs daily at full blast 2 hours, cools down my bedroom to 18ºC (Daikin prevents a lower setting than 18ºC) and is switched off when i go to bed. the achieved temperature is during 8 months in a year low enough to keep the slowly warming up bedroom at a comfortable temperature till i get up again. in very hot nights a 12k btu unit is used to prevent the room from warming up above 25ºC.

what is wrong with my thinking? opinions please, but no soft starters, nothing fully automatic, no timers, no complicated additional wiring and control boxes.

[genset]

Re. #166

Reading the specs of that particular generator, no mention is made of alternator protection.

Alternator protection is provided by the AVR (overvoltage) and an ABB MCB mounted on the set (overcurrent) plus genset controller sensing. Further to this, the ComAp ATS controllers I use (combined with an ATS), also monitor overvoltage/overcurrent and will shut down the set when operating outside of user set parameters.

provision for remote (eg 3 wire) starting or provision for auto start function on loss of mains supply.

The auto start function is provided for by the electronic controller on the set and an ATS wiring harness is in place (meaning only a simple connection is required, not at the controller itself, but an easily accessible connection point). The controller will automatically start the set on receipt of a constant 24v DC B+/B- signal, when the signal stops, the set stops.

The ATS and compatable control module suitable to interface with the genset controls would be an optional extra. If a manual changeover switch is to be used this would be an extra.

Yes, the price of these sets does not include an ATS or (if an automatic transfer switch is not required), a manual transfer/chanegover switch.

The ATS and control module should be purchased from the same source as the generator to ensure compatability.

Compatability is seldom an issue (with most simple ATS control panels such as these) as most ATS controllers use a 12/24v DC B+/B- signal to command a set to start and most electronic genset controllers (mounted on the set), will activate the remote start function on receipt of a 12/24v DC B+/B- signal. The only control wiring between the ATS panel and the generator are a 12/24v DC B+, B- (DC Supply to ATS controller and battery charger) and a single wire remote start.

Genset

Edited November 25, 2009 by genset

[stevejones123]

What a change; a thread from a sponsor which tries to give us useful, expert information instead of trying to sell us real estate

I don't live in Thailand but in Sri Lanka, but have just bought a generator as we seem to be returning to the brown-out times of the mid- to end-nineties.

A couple of points about your posts. I am surprised you are recommending small gasoline units for standby. Apart from anything else the cost of an external ATS would erode some of the difference the difference from a specifically designed standby generator.

Another point is that you don't need to back up all the power in the house. You can send the stuff you want to back up, such as computers, lighting, fridges, TV to a separate board and have only that serviced by the standby generator, leaving ACs, clothes dryers and other heavy duty stuff to await the restoration of power.

And a last thing; do you know anything about Tigen generators, specifically the 5.5Kva automatic diesel standby. So far I've had no problems, but who knows?

[genset]

What a change; a thread from a sponsor which tries to give us useful, expert information instead of trying to sell us real estate

Hi Steve, thanks for your comment, it's nice to know that the effort made by myself and other notable contributors to the thread (to offer some useful information) is appreciated

A couple of points about your posts. I am surprised you are recommending small gasoline units for standby. Apart from anything else the cost of an external ATS would erode some of the difference the difference from a specifically designed standby generator.

I am not 'recommending' small gasoline units for standby use per se, if somebody wants a recommendation for an installation, I will give them my honest opinion based on their specific needs and how much they are willing to invest in a generator. What I am trying to do, is present expats with a range of options for all budgets and standby/prime power needs (which differ greatly from one person to the next). As long as a customer understands the operating characteristics and limitations of high reving (3000rpm) gasoline powered, light duty generators, they are a perfectly acceptable budget option for light duty applications and they will perform satisfactorily when used as per ISO 8528-1:2005 ratings. I have not and never will, attempt to suggest that a 3000rpm genset is acceptable for anything other than limited time operation for light duty applications (for further info on genset ratings please read post #75).

The issue of cost is subjective and should be considered in context, based on a number of different factors. The idea that what you refer to as 'a specifically designed standby generator', should have an ATS located at the generator set (if that is indeed what you are suggesting), is incorrect. Some generators do feature an automatic transfer switch at the set, but my preference is always to locate a separate ATS panel as close as is reasonably possible to the existing distribution board (or sub panel containing critical circuits to be powered by the generator, more below...), but not to mount the ATS on the generator, I particularly dislike the effect sustained vibration can have on an ATS panel when located at the set (furthermore, some users may specify a manual switching option only and forgo the automatic option).

Another point is that you don't need to back up all the power in the house. You can send the stuff you want to back up, such as computers, lighting, fridges, TV to a separate board and have only that serviced by the standby generator, leaving ACs, clothes dryers and other heavy duty stuff to await the restoration of power.

This is true of course, and again, I may be guilty of presuming that most people are aware that a sub-panel linked to critical circuits (in respect to your total load requirement) is a common method of providing a standby generator/ATS partial solution for a domestic installation.

And a last thing; do you know anything about Tigen generators, specifically the 5.5Kva automatic diesel standby. So far I've had no problems, but who knows?

I'm afraid I have never heard of Tigen generators and a google search did not return any results, so I can't tell you if it looks like another generator under a different name. It is very common for large OEM manufacturers to mass produce small generators under many different names for smaller companies. I'm happy to hear the set is running well for you... long may it do so.

Genset

Edited November 28, 2009 by genset

[stevejones123]

I agree with you it is better to have the ATS switch located near the panel, but beggars often can't be choosers. What I was saying though was that a gasoline generator with an automatic start and separate ATM switch is going to be more expensive than just the generator itself (and of course there is still the question of the generator housing and exhaust valve). Manual start ups are great except when you have the power cut after lights out, or when you're asleep so you don't even know the food is rotting in the fridge.

It was 'Tiger', not 'Tigen' generators by the way. My apologies.

I think you shouldn't overestimate the technical nounce of your users. I only know the basics because I spent a long time googling them.

Incidentally, when you are giving maximum usage times, to get the weekly figure you seem to be dividing the yearly figure by 52. This isn't normally how a standy generator is used. If the snow, or coconut trees, bring down the service it may be off for three or four days, and then scarcely used again for the rest of the year. We've been told to expect cuts most days this month but that after the upgrade is finished they should become rare.

[genset]

What I was saying though was that a gasoline generator with an automatic start and separate ATM switch is going to be more expensive than just the generator itself (and of course there is still the question of the generator housing and exhaust valve). Manual start ups are great except when you have the power cut after lights out, or when you're asleep so you don't even know the food is rotting in the fridge.

Yes, unless a generator has an ATS fitted to it, the price of an automatic switch will always be an additional cost if you want to switch your supply automatically.

ATS panels are very convenient as you suggest, but manual changeover is an option for those who prefer it.

It was 'Tiger', not 'Tigen' generators by the way. My apologies.

Yes, I see they sell portable gasoline and diesel gensets but I have no working knowledge of how their generators perform. I should add that it's no longer the case that everything finding its way out of China is cheap tat... they have upped their game considerably over the past decade and are producing quality (in many areas) to challenge the domination of big established names at a fraction of the cost. I hope your generator continues to operate reliably for you.

I think you shouldn't overestimate the technical nounce of your users. I only know the basics because I spent a long time googling them.

I dont think I have to be honest... when I wrote my original post at the start of this thread, I tried to lay out the information in a clear, logical manner that could be read and more importantly, understood, by a person with no prior knowledge of generators or how they work. Having said that, when a question is raised and drilled down into by other contributors to the thread, it would be rude of me not to take part in those discussions and offer my opinions. Although some of the theory may seem a little intimidating to some readers (I think this may be your point... ), its not my intention to scare them away, and if they read the original post, they should feel quite comfortable in posing (what they may consider to be) the most basic questions regaring the installation and operation of a generator.

Incidentally, when you are giving maximum usage times, to get the weekly figure you seem to be dividing the yearly figure by 52. This isn't normally how a standy generator is used. If the snow, or coconut trees, bring down the service it may be off for three or four days, and then scarcely used again for the rest of the year. We've been told to expect cuts most days this month but that after the upgrade is finished they should become rare.

I must beg to differ with you on this point. In respect to the operation of a standby generator in Thailand; the way I have chosen to describe the maximum recommended hourly operation of the generator (as a weekly figure) reflects the way a standby generator can be expected to be used in Thailand.

That's some location you're living in, where the risk of power outage from heavy snowfall or falling coconut trees is of equal concern... but seriously... The maximum recommended use for a standby rated generator (Limited Time Running Power LRP) is 500 hours; this total should be accrued during periods of 'limited time running'. Standby generators should not be considered for applications requiring periods of extended use.

For the most part, the utility supply in Thailand is quite reliable, but some provinces in Thailand are affected more than others by a fluctuating utility supply, especially in areas at the end of distribution lines. The most common complaints I hear of, are regular deep brown out conditions, or frequent power outages lasting from 30 minutes to four or five hours on average and occuring throughout the year. They may be more pronounced at certain times of the year (for me, particularly hot summer periods and/or a heavy rainy season up around Khon Kaen spells trouble with my utility supply). Describing the rated use of a standby machine by giving a recommended hourly use per week, is, I hope, something that readers who live in Thailand will be able to relate to.

Genset

Edited November 30, 2009 by genset

[Naam]

The maximum recommended use for a standby rated generator (Limited Time Running Power LRP) is 500 hours; whether that 500hrs is accured during two or three periods of use throughout the year, as in your example, or two or three times a month (24 to 36 times a year...) as may be the case in Thailand, the maximum recommended period of use for the generator is the same.

that's a logic i don't understand. since when is a limitation of something mechanical related to a calendar year?

[stevejones123]

The most common complaints I hear of, are regular deep brown out conditions, or frequent power outages lasting from 30 minutes to four or five hours on average and occuring throughout the year.

Brownouts or load shedding; the usual reasons.

The snow I referred to came from the normal reasons for getting a generator given on US websites. The falling coconut trees are the excuse we get here when it rains and the power goes, though they normally manage to get it up after a few hours.

I think you did miss out the information about not needing to back up everything in the house, or why you must connect to a switch and not directly to the meter. Both points seem overwhelmingly obvious but they might not be to all your readers or to the wife's cousin who installs the generator and inadvertently fries a few electricity board repair men. And you would be advised to mention that you do need to keep a generator away from the rain and that it it's in a building people are likely to use that the exhaust pipe vents through a hole in the wall if it's a gasoline generator.

It might also be an idea of giving the prices of manual and automatic switches and of the appropriate cabling, or even selling both.

Edited November 29, 2009 by stevejones123

[elkangorito]

Hey Genset! Now's your chance...take a break & let steve "fill in" for you while you're relaxing. Don't worry about the damage control until you return.

Doc, the 500 hours is a standard maintenance period. It is considered that equipment, such as generators, that have not accrued 500 hours of operation within a 12 month period, have this maintenance carried out regardless.

At my former place of work (a data centre for a major bank in Australia), 2 gensets were inspected once every 3 weeks (480 hours) & if no additional time was clocked, no maintenance was done until the 6 monthly interval (required due to the critical nature of the establishment).

[genset]

The maximum recommended use for a standby rated generator (Limited Time Running Power LRP) is 500 hours; whether that 500hrs is accured during two or three periods of use throughout the year, as in your example, or two or three times a month (24 to 36 times a year...) as may be the case in Thailand, the maximum recommended period of use for the generator is the same.

that's a logic i don't understand. since when is a limitation of something mechanical related to a calendar year?

Hi Naam,

The ISO 8528-1:2005 rating for limited time running power (standby operation), cites a recommended period of annual use (500hrs) to draw a clear distinction between the capability of specific engine/alternator combinations and how they should be employed.

In a standby application, the generator will normally be expected to deliver its maximum rated output for short periods of time (limited by the alternator insulation grade and capabilities of the engine), thats the reason for tagging an annual hourly use onto the rating. If significantly longer operation is required, a prime power generator should be selected (higher insulation grade and more powerful engine for use over extended periods of time).

Genset

Edited November 30, 2009 by genset

[Naam]

The maximum recommended use for a standby rated generator (Limited Time Running Power LRP) is 500 hours; whether that 500hrs is accured during two or three periods of use throughout the year, as in your example, or two or three times a month (24 to 36 times a year...) as may be the case in Thailand, the maximum recommended period of use for the generator is the same.

that's a logic i don't understand. since when is a limitation of something mechanical related to a calendar year?

The ISO 8528-1:2005 rating for limited time running power (standby operation), cites a recommended period of annual use (500hrs) to draw a clear distinction between the capability of specific engine/alternator combinations and how they should be employed.

but i doubt that the same ISO Norm applies to "whether occurred during... or...". if that is the case i say as an experienced physicist and engineer who was for years in charge of building industrial plants AND running them "ISO = bullshit²!"

addendum: i am irked by the principle, not the 500 hours per year. the latter is for my case irrelevant because my estimated run time is max 50 hours.

Edited November 30, 2009 by Naam

[genset]

Hi Steve,

I think you did miss out the information about not needing to back up everything in the house, or why you must connect to a switch and not directly to the meter. Both points seem overwhelmingly obvious but they might not be to all your readers or to the wife's cousin who installs the generator and inadvertently fries a few electricity board repair men.

Unfortunately, my ability to cover every aspect of generator installation and operation has been limited by the amount of time the thread has been in existence and the inconvenience of having to sleep occasionally (between extended periods of work...). I will continue to try my best to address any and all questions posed, and to highlight specific generator related issues as an opportunity presents itself.

I did however address the issue of a transfer switch in my original post (copied in Italics below...) together with a link to my website where more detail can be found. I would respectfully request anybody reading the thread for the first time at least read the original post before offering their (very welcome) comments and opinions... ;

How do I connect the generator to my distribution board…?

• If you are purchasing a generator as a standby power source for your home, the connection between the generator and your consumer unit/distribution board MUST be made through a manual or automatic transfer switch (I would recommend these connections be made by a qualified electrician). Under no circumstances should you ever attempt to connect the generator directly to your consumer unit/distribution board.
  
• Connecting the mains and generator supply simultaneously requires a complex synchronization process, but this is an expensive option and not required for general automatic mains failure use.
  
• More information on how a transfer switch works can be found here http://www.generatorsolutions.org/#/controls/4534128482
  

The issue of transfer switch use with a standby generator was covered in some detail in a separate thread by myself and Elkangorito (amongst others). It may be a tad heavy going and quite technical, but over the next week or so, I will try to consolidate most of the pertinent information and post it to the thread.

And you would be advised to mention that you do need to keep a generator away from the rain and that it it's in a building people are likely to use that the exhaust pipe vents through a hole in the wall if it's a gasoline generator.

I'm always open to advice when I've failed to perform... On my website http://www.generatorsolutions.org/#/installation/4534128487 I recommend building an enclosure whether a generator is enclosed in a canopy or not. This improves the asthetic appearance of the generator installation and further reduces the noise signature; most importantlyly however, it reduces the possibility of overheating as a direct result of thermal radiation on the canopy exterior and protects the alternator from moisture penetration (very important, the alternator should be kept dry at all costs).

Not only should generator exhaust fumes be vented whether the generator runs on gasoline or diesel, but some thought should be given to the prevailing wind and in which direction (towards whom/what) the exhaust fumes will travel. Again, as time progresses, I will add a more detailed post to the thread focusing specifically on generator installation.

It might also be an idea of giving the prices of manual and automatic switches and of the appropriate cabling, or even selling both.

As I mentioned in my original post, I will not be offering a fully comprehensive service in Thailand until 2011. I do build transfer switch systems and will indeed (at some point...) sell them with generators or as a separate item to be retro-fitted to an existing (electric start) generator with remote start facility (I will also sell genset controllers with remote start facility for those without). All of these items will be available on my website, together with prices. I will address the cost of automatic transfer switch panels, when I post the consolidated transfer switch information in the next week or so.

Genset

Edited December 1, 2009 by genset

[genset]

but i doubt that the same ISO Norm applies to "whether occurred during... or...". if that is the case i say as an experienced physicist and engineer who was for years in charge of building industrial plants AND running them "ISO = bullshit²!"

Hi Naam,

You're correct. I should have simply stressed that the 500 hours ISO recommendation is for time accrued during periods of 'limited time running'. Standby generators should not be considered for applications requiring periods of extended use (previous post amended).

Genset

Edited November 30, 2009 by genset

[Naam]

ElKangorito: "Doc, the 500 hours is a standard maintenance period. It is considered that equipment, such as generators, that have not accrued 500 hours of operation within a 12 month period, have this maintenance carried out regardless."

Genset: "The ISO 8528-1:2005 rating for limited time running power (standby operation), cites a recommended period of annual use (500hrs)"

can you gentlemen perhaps find a common denominator? i will add my two Satangs later.

[genset]

Hi Naam

Ok... lets see if we can clear this up...

ElKangorito: "Doc, the 500 hours is a standard maintenance period. It is considered that equipment, such as generators, that have not accrued 500 hours of operation within a 12 month period, have this maintenance carried out regardless."

Elkangorito is correct in his assumption that generators rated for standby use (and prime power use) should be serviced every 500 hrs or annually (whichever comes first), also, he is correct to raise the importance of regular maintenance, particularly where a standby generator is installed in a critical support role (we want a standby generator to start first time, every time if possible, regular maintenace and exercising will keep the generator in peak condition); however... this 500 hr maintenance period is NOT the reason for the ISO 8528-1:2005 recommended period of annual use for 'limited time running power' (standby) generators.

The alternator windings of a generator used in a standby power role, may operate at up to 25 degrees C hotter than the alternator windings of a generator used in a prime power role (both featuring the same NEMA insulation grade). The more heat in the alternator windings, the greater the chance of insulation failure. A standby generator may operate in this manner because the ISO standby generator rating specifies 'limited time running' (that is an ISO definition of a standby machine, not mine...), hence the recommended period of annual use of 500 hrs, accrued over short periods of time to avoid insulation failure as the alternator operates at its maximum rated capacity (the issue of ratings was covered in some detail in post #75 please revisit that post for more info).

I hope this clears up any confusion, kicked off by me I should add... I should really stick with my own advice and only contribute to the thread at weekends and not late at night when I'm half asleep, cant resist jumping into the fray however... my apologies for the confusion Naam.

Genset

Edited December 2, 2009 by genset

[david96]

Transfer Switches. General.

1. Manual rotary type 1-0-2 or 1-2 mutlipole in sizes 16A/20/32/63 etc.

2. Contactors switched manually using a 2P control switch 1-0-2, position 1 in the mains supply and position 2 is the generator supply. Contactors are interlocked electrically.

Generally used where the generator supply is less than 63A. Normally be made to operate automatically with additional control module or circuitry.

3. Motor operated transfer switches. These consist of 2 x 3 pole switches or (1 x3 pole

and 1 x 4pole) They have 2 motor operators and are designed for auto operation.

The motor(s) opens the switch(es) and charges a spring for closing of the switch(es).

These ATS have a high fault current rating and are normally used in commercial and industrial

environments. 125A to 1600A 50kA typical.

Note than the contactor option is cost effective under 63A and if manual operation is all that is required and only requires 3 components, consisting of 2 suitable sized and rated contactors and a 48x48mm 2 pole c/o switch 1-0-2 plus 2 DIN 6A 1 pole MCBs for control wiring protection.

The advantage of the contactor option is that contactors and switches may be available "off the shelf" locally.

[Naam]

taking my time and going through all expert opinions again i found:

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.

i assume that "rectifier load" is the current drawn by the UPS's battery charger. if that is the case why the eff did we make a big hoo-ha about it? wasn't it clear from the beginning that aforesaid load is only a tiny percentage of the total demand?