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[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]

Naam, on 2009-11-29 17:17:16, said:

genset, on 2009-11-29 03:32:02, said:

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 by genset, 2009-11-30 09:47:31.

[Naam]

genset, on 2009-11-30 06:51:05, said:

Naam, on 2009-11-29 17:17:16, said:

genset, on 2009-11-29 03:32:02, said:

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 by Naam, 2009-11-30 08:01:45.

[genset]

Hi Steve,

Quote

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.generator...rols/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.

Quote

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.generator...tion/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.

Quote

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 by genset, 2009-12-02 03:06:32.

[genset]

Quote

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 by genset, 2009-11-30 08:56:55.

[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...

Quote

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 by genset, 2009-12-02 16:45:34.

[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?  

[genset]

Quote

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?  

Hi Naam,

UPS systems and variable speed drives (previously discussed) are both types of SCR based, non-linear loads (rectifier loads).

The big 'hoo-ha' as you have accurately described it, began with post # 81, in which David96 offered the following explanation of the (apparent) low current drawn on startup by your air conditioning systems, raising the question of whether your ACs were non-linear loads:

        

Quote

'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.'

It was followed up (quite logically...) by Crossy in post # 85 in which he wrote:

        

Quote

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.

Based on the floor plan you posted showing the location and size of your AC units, the 'significant percentage' Crossy refers to, would have been way in excess of the 50% (percentage of rectifier load) mentioned in the Australian Defence Dept document (posted by David96).


                Although it became clear (following your subsequent post on the subject) that your AC units are not rectifier based loads, we disappeared down the rabbit hole somewhat on the question of non-linear loads from that point.

The degree to which the operation of UPS and other non-linear loads will affect the operation of a generator AVR needs to be observed on site, under working conditions. If a detrimental effect is observed, the previously discussed mitigation techniques should be employed.

Genset

[InterestedObserver]

Naam, on 2009-12-06 06:44:10, said:

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?  

Most on-line UPS have rectifiers (thyristors) in the input stage to charge the internal DC bus and power the inverter. The rectifiers are therefore required to carry 100% of the UPS load plus charge the backup batteries. Unless on bypass or batteries the on-line UPS will present significant harmonics to the power source. It is common practice to provide some form of power factor mitigation at the input stage.

[Naam]

InterestedObserver, on 2009-12-06 18:36:17, said:

Most on-line UPS have rectifiers (thyristors) in the input stage to charge the internal DC bus and power the inverter. The rectifiers are therefore required to carry 100% of the UPS load plus charge the backup batteries. Unless on bypass or batteries the on-line UPS will present significant harmonics to the power source. It is common practice to provide some form of power factor mitigation at the input stage.

assuming the inverters are not isolated from the generator the rectifiers do not carry any load as the power from the generator is routed directly (bypassing the rectifiers) to the consuming gadgets. that's the information i received from the manufacturer.

[Crossy]

Naam, on 2009-12-13 08:39:35, said:

assuming the inverters are not isolated from the generator the rectifiers do not carry any load as the power from the generator is routed directly (bypassing the rectifiers) to the consuming gadgets. that's the information i received from the manufacturer.

This is quite true in the case of off-line UPSs typically found in SOHO installations.

IO is specifically referring to the case of high-end on-line UPSs typically found in data centres which do not have a bypass, the inverter powers the load at all times even when mains is present and therefore the rectifiers do indeed carry the full load current of the load at all times.

That said, even with an off-line UPS (or no UPS) PC power supplies (particularly those with active power factor correction) present a non-linear load which could upset your genset if it forms a significant portion of the total load.

[InterestedObserver]

When evaluating off-line, the so called SOHO or standby, UPS be sure to get one with a sine wave output if you can. Most of the low end units have a square wave or pseudo sine wave output when running on batteries. Square wave outputs are not suitable for all loads. There will also be a finite delay (milliseconds) while switching to batteries.

[Naam]

InterestedObserver, on 2009-12-13 11:15:39, said:

When evaluating off-line, the so called SOHO or standby, UPS be sure to get one with a sine wave output if you can. Most of the low end units have a square wave or pseudo sine wave output when running on batteries. Square wave outputs are not suitable for all loads. There will also be a finite delay (milliseconds) while switching to batteries.

i have no idea on what waves my three UPS are surfing    what i know is that the computers don't wink an eye, don't realise anything watching TV but one of my former modems (now replaced) minded the switch and started connecting again.

[Deke]

For some reason I can't quote from Genset's first post.  Also, apologies for getting into this thread late; it is a good one.

I'd like to point out one thing which is of little practical importance but probably worth noting if you are specifying new equipment.

Since 2007, the standard voltage at the delivery point (low voltage side of the PEA/MEA transformer) is 230/400 V (-10% / +6%).

If you are ordering new equipment, you should take this into account.  Particularly if you are buying your own transformer, it should be 22 kV/400 V.

[genset]

Deke, on 2009-12-23 21:45:40, said:

For some reason I can't quote from Genset's first post.  Also, apologies for getting into this thread late; it is a good one.

I'd like to point out one thing which is of little practical importance but probably worth noting if you are specifying new equipment.

Since 2007, the standard voltage at the delivery point (low voltage side of the PEA/MEA transformer) is 230/400 V (-10% / +6%).

If you are ordering new equipment, you should take this into account.  Particularly if you are buying your own transformer, it should be 22 kV/400 V.

Hi Deke,

Welcome to the thread, new blood is welcome it'll prevent us from becoming inbred... I'm hoping the thread will serve as a hub (long term), for questions or comments related to generator installation and operation as they arise, so readers should feel free to pitch in whenever they need feedback or would like to comment. I've been very busy for the past few weeks, but always keep one eye on the thread.

The generators I am promoting (and most AVRs fitted to contemporary generators) feature a potentiometer to enable adjustment of the reference voltage for the alternator. This will allow you to accurately match the voltage requirement of your equipment (+/- 10% of 230/400v) if necessary.

I mentioned in an earlier post, that I would discuss automatic transfer switch systems in more depth and I will do that when time permits; but I would like to briefly address a misconception that seems to exist (based on a number of email enquiries), regarding the role of an automatic transfer switch.

Installing an automatic transfer switch system to control the transfer of power from primary (utility) to secondary (generator) source and back WILL NOT prevent an interruption of electrical supply to your home. An open transition (break, before make) automatic transfer switch system will monitor your utility supply and when needed, automatically start the generator; it will then transfer the supply and carry out the reverse process when the utility supply is restored and stable.

As the system cannot see a power outage coming, there will ALWAYS be an interruption in power during which time the utility contactor is de-energized, the generator is started and self tests are carried out; once a stable supply is being generated, the generator contactor is energized and the power (generator) restored to your home. When the utility supply is restored, the interruption will be much shorter (as both supplies are live), the transfer back to utility power (once the supply is stable) is relatively quick (1 second or so).

If you have critical circuits which you do not want interrupted, you will need to support them with a UPS system of some sort to prevent supply problems, an automatic transfer switch system alone will not prevent an interruption in your supply.

Genset

Edited by genset, 2009-12-24 05:26:26.

[david96]

Deke, on 2009-12-23 22:45:40, said:

For some reason I can't quote from Genset's first post.  Also, apologies for getting into this thread late; it is a good one.

I'd like to point out one thing which is of little practical importance but probably worth noting if you are specifying new equipment.

Since 2007, the standard voltage at the delivery point (low voltage side of the PEA/MEA transformer) is 230/400 V (-10% / +6%).

If you are ordering new equipment, you should take this into account.  Particularly if you are buying your own transformer, it should be 22 kV/400 V.

System Voltage. Australia, AS60038 230/400V supply range -6% to +10%.
IEC 60038:1983 (moving from 220/380V) supply range -10% to +6%

The initial introduction of the 230V system has only created an iilusion of a world standard as it has been introduced by tinkering with tolerances. The initial effect in Australia is virtually no change of voltage at the device.
Source NHP Technical News issue 28.

I think you will find that the voltage at the device in Thailand will not change if it adopts
IEC60038. 220 volts falls in between the tolerances of IEC60038.
Calculations should be made on the basis of 230/400V.