Electrical Eng.

who are this idiot guys....posting none sense question..grade 1 level.

WHICH LEVEL DO YOU BELONG?

Ask the wife or girlfriend! She will explain in a clear and concise manner giving details on exactly what it is!

Droop is the difference between no-load voltage and load voltage.

Correct, but you should also include the sentence:-

Without any voltage correction......

In the RN we had a droop characteristic of 45% from no to full. load....

It is possible to design the rotor/stator and the air gap to give a greater or lesser "Droop"......

CWARNER 7 11

Thanks for your GA. That's something I didn't know and I am glad I read your answer as I'm sure the person who asked the question is.

Some people's answers sure says a lot about them.

Randy

Droop setting is a parameter in the governing system of a generating unit. There are two types of droop setting. Permanent droop setting and temporary droop setting. Temporary droop setting is the I factor in the PID setting (Proportional, Integral, Derevative). Permanent speed droop is the rate at which the generating unit accepts or rejects the load. It is a very vast subject. I've tried to put it into a nutshell. Hope you get the hang of it

Samuel Chelliah

Never mind all the rhetorics....

Droop refers to the dropping of the speed of the prime mover with the load. It is also used for the dropping of the voltage of the alternator with the load. All are related somehow.

Here, when referred to the droop setting on the Mechanical governor of an engine driving an alternator, it means to set the amount of speed drop allowed from no load (say 1500 rpm) to full load (say 1548). WHEN referring to the Automatic Voltage regulator, it means setting of the amount of drop in voltage allowed from no load to full load.

Finally, DROOP settings are usefull ONLY when parallelling Generators together, this allows for proper load sharing between them.

NOW, since you are asking, It means you need more to learn and maybe read more carefully any instructions accompagning your genset.

Good luck

You wrote:-

Droop refers to the dropping of the speed of the prime mover with the load.

I totally disagree.

The prime mover is set up to hold a specific speed (frequency), this does not change no matter what the load. This used to be mechanical, its probably a combination of mechanical/electrical/electronic today.....it holds the speed stable throughout all load changes.

If an alternator slowed down, the frequency would slow down. If it was running in parallele, it would be thrown off, because the speed drop would increase the load on the other alternator and reverse current would flow and the alternator world drop off.

Low frequency could damage other equipment too....

The droop only refers to the voltage drop from no load to full load WITHOUT AVR.

Andy,

You are right about keeping the frequency steady as being the objective. But this used to be difficult on engines using mechanical governors like WOODWARD etc. Therefore, there is a slight drop in frequency from no load to full load on these engines, and for the record, some models did have a droop setting (Woodward Hydraulic Governors circa 1980's..) They also had setting for the load sharing and load limits etc really sophisticate governors.

With the advent of electronic and digital electronics, you can hope for more accurate control on the frequency.

Therefore, when Synchronising two units, you needed to set the droop on each unit so that the curve characteristic of both engines were similar and deviated equally with the load... I thing this covers your side of your response.

From the OP side: He seems lost about the subject and needed to know the meaning of "DROOP" as an english word and a jargon used in the power generation sector. Therefore, I meant to explain that it means "Bending, Curving down" of a characteristic curve whether it was speed variation or voltage variation.

VOLTAGE: When two engines are parallelled, the drrop in voltage is necessary even if you do not see it or realise it. The Voltage regulator on each unit actually varies the field current to match the load and try to keep the voltage steady. But there will be a droop with the load. this droop varies (curve) from unit to unit and the droop setting actually tries to match both units characteristics so that they keep sharing the load correctly (Load sharing if available can be of different precision...)

Finally, I did not pretend to cover all the details and complications of this side of the topic. it will require more theory and will be out of the scope... Just explaining what droop means. The OP can then search for more...

OK.

It would appear that my 60's experiences were more modern than even I thought!!