Technical Specification of Generators

Make it simple. Just talk to your local area Generator supplier or vendor , they will suggest you the model,type, characteristics, performance, compatibility with local conditions etc...(Ofcourse ambient temperature has a role in any type of equipments)

You have to take care of kVA, p.f, kW, Voltage, Frequencey and derating factor.

Derating factor for altitude is very important. Mostly in a lot of generator catalog till 1000 meter see level, the derating factor is zero and above the 1000 m there are some factors which must be considered.

Please can you provide me with more details regarding derating factor for altitude preferbly with an example.

while quoting for generator the supplier mention 150 kWe.what does e indicate in case it refer to electric than what is the advantage of mentioning e.please answer in detail as you normally try your best to satisfy the problemers

Derating factors are vary depending on the manufaturer,size and the operation mode (standby/prime/continuous) of the genset. For example CUMMINS DQLB 50Hz genset has 2660kWe output at 1030m @ 40C. Above these conditions Genset to be derated for 4.2% per 305m increase of altitude and 11.6% per 10C increase of temp.

If the same genset operating in continuous mode, derating factors are: 5.2% for 305m altitude; 25.8% per 10C temperature.

The best way to get away from derating factors is by giving the required power you need at genset terminals and ambient conditions for the supplier and ask him to calculate the net output and to select the appropriate size from his catelogues for you.

e- is electrical output from the generetor terminal. This is less than the engine output.(e.g: engine output: 6000kW, genset electrical output:5820kW).

Thanks a lot for providing me the technical details required on my side regarding generators.

Prime generators can be run for 24hrs continuously. how safe it is to run for how many continuous hours a standby generator.

Is there any thumb rule to calculate unit per liter for a generator. What will be UPL for 150KVA generator at 40 to 50C temperature (Summer) will winter have any effect on UPL for the generator.

The rated output of a machine is reduced in ambient temperatures exceeding 40 C and at altitudes above sea level exceeding 1000m. The latter is because the air density is decreased, and its ability to cool the machine is reduced. Derating factors are applied for these conditions and typical values are as below

If you need any more information please let me know.

Thanks for your informative data. What is the advantage / disadvantage of using electronic governor over mechanical governor in Diesel Generators.

Dear Mr. Salahuddin zia,

The Time lag for Mechanical or Electro-Mechanical governor is very high. This High Time Lag combined with SLACKNESS of linkage mechanism will aggravate the problem of precise governing, some times few milliseconds or several mill seconds.

Electronic governors are VERY VERY QUICK in sensing variation, few micro seconds only.

SDR710

In addition to the points referred by Mr.Hameedullah Ekhlass, the DROOP CHARACTER of the Generator Engines and DROOP CHARACTER of the VOLTAGE of the Generators to be checked and assessed for adoptability.

If not proper, then LOAD-SHARING by the Generators will pose a problem

sdr710

Can you please further specify technical details regarding DROOP CHARACTER of the Generator Engines and DROOP CHARACTER of the VOLTAGE of the Generators. With special emphasis on how to check and asses for their adoptability.

Dear Mr.Salahuddin zia,

You have referred that one Generator is 150 kVA, and the other is 320 kVA, to be put into parallel operation.

Assume the Speed Drop for 320 kVA is 5% from No-Load Frequency of 50 cycles to 49.5 cycles to full load, and for the 150 kVA set the Speed Drop is 4.0%, for the same level of Frequency Drop from 50 cycles to 49.5 cycles, then the 150 kVA D.G.Set will BE FORCED TO SHARE MORE LOAD IN THE COMBINED PARALLEL OPERATION, than the 320 kVA set even though it is bigger in Capacity.

Suppose your total combined Load for PARALLEL OPERATION is is 420 kVA, individually none of these 2 sets can handle this 420 kVA load. If you put these 2 sets in parallel, then, by virtue of the SPEED DROOP CHARACTER, 150 kVA DG Set will try to share and take a load of 186.66 kVA and the 320 kVA set will take ONLY 420-186.66 = 233.33 kVA only even though the Set capacity is 320 kVA.

In the above speed droop character, for 150 kVA set is small or shallow, and 320 kVA set has, relatively STEEP Speed Droop Character, and due to this it can not share load proportionately. If proportionate load is to be shared, for a combined Load of 420 kVA, the 320 kVA set should share A LOAD OF 272.34 kVA, AND 150 kVA set should share a load of 127.65 kVA ONLY.

In this case or example, the droop is good for 150 kVA set, GOOD,because it is 4% and the 320 kVA is not that good when compared to the other set BAD,which has 5% character.

The GOOD SET is forced to share a load of 186.66 kVA, MORE THAN IT'S CAPACITY (GOOD CHARACTER OR BEHAVIOUR IS PUNISHED BY FORCED OVER-LOAD) which will be OVER-LOAD for 150 kVASet , as against a proportional Load of 127.65 kVA, a difference of 59.01 kVA. MORE, and 320 kVA set will refuse to take proportionate load OF 272.34 kVA and will take a Load of 233.33 kVA ONLY, 39.01 kVA LESS - COURTESY-SPEED DROOP CHARACTER.

NATURE and LAW HAS SPECIAL CHARACTER TO PUNISH WHO ARE VERY GOOD and LAW ABIDING, and allow those who defy the LAW or BAD GO SCOT FREE. The above DROOP CHARACTER is one example for this.

A similar logic applies for VOLTAGE DROOP CHARACTER of the 2 ALTERNATORS to be operated in PARALLEL. Instead of the speed droop (for the Engine) it will be the VOLTAGE DROOP for the ALTERNATORS TO BE OPERATED IN PARALLEL.

These 2 characters to be UNDERSTOOD PROPERLY and matched.

THANKS.

SDR710

I am greatly thankful to you for the detail explanation.i hope you will not mind if i ask you a similar question for explanation.

in case the 2 generators to be run in parallel are of same rating say 150 kVa, each.than the same pattern of your explanation follows or than the explanation will change.if it changes can i have the answer thanks

regards

s.zia

Dear Mr.Salahuddin zia,

Logic is the SAME and NO EXCEPTION.

You are the 1st person to respond with in 15minutes of my posting to the CR4 Link.

Thanks,

SDR710

once again thank you for your answer.i tell you your technical support is helping lot of personal like me.please keep it up and make the way straight for us with your valuable points.

i am still waiting for my answer for the question which was .thumb rule for calculating Unit per liter for diesel generator say 150kva .thanks

regards

s.zia

Dear Mr.Salahuddin zia,

A value of 3.18 to 3.2 KW.Hr per litre of Diesel consumption for the Diesel engine of Generator set is a GOOD PERFORMANCE. Some time back there was a thread about SPECIFIC FUEL CONSUMPTION OF DIESEL GEN. SET.

Pl. search the thread and you will find the answer where I have also responded to the thread. You can find the search link to right side 2nd from the top" SEARCH THIS FORUM" and you can get any topic by searching.

thanks,

sdr710

i think it was way back in March2010.i am reproducing the solution but i need few clarification hope some one will help me out.

Q.how to calculate units per litre (UPL) for DG (62.5 kva).

A.specific fuel consumption=164 gm/bhp-hr=219.84 gm/kwh

density of diesel fuel =850 gm/l

219.84gm=0.2586 litre

therefore one litre of diesel fuel can produce 3.87 kwh (1/0.2586).in other words UPL for this engine is 3.87 units/litre of fuel.

my questions are

1)how do we calculate 164 gm/bhp-hr=219.84 gm/kwh.

2)and is 850 gm/l density of fuel constant for all rating of DG

regards

s.zia