Generator Isolated Operation

When a PLC is being used as a central power station control, one has to select one machine as a prime unit and allocate a suitable datum value to it, whenever the system load touches that datum value the PLC automatically gives start command to the next unit(s) and vice versa.

In your case with all three units running, I think that the datum value for the prime unit needs to be increased so that all units should take up the load in due proportion when the large motor starts.

the plc is working ok!!there is some other issue.

I did not say that the PLC is malfunctioning, only you should change the set parameters in the PLC.

clean/change the fuel filters on #3

1. Why generator 3 not sharing before 110 kW motor applied?
2. Is its governor droop same as other sets?
3. If Gen 3 is worn, its fuel pump at maximum stroke at 550 kW, then speed fall will reduce fuel flow in proportion to speed, with effect on possible power. Or could be maximum stroke stop is not same as others.
   

gen 3 was sharing load before!!

not confirmed about this

the gen 3 is old (10 years i guess)!!

can u just give an idea what could be the factors besides droop settings???

Thanx a lot buddy!! also if u can do me a favor and explain point # 2 in detail!! wat i get from this point is to redice load on gen 1 & 2 and simultaneously increase on gen 3???

also i didnt get the 90%-10%=80% case:S!!

hope u wud be a great help again!

About point 2 :-

1. Having adjusted set 3 governor speed setting for 10% load, do not adjust it again during droop test.
2. When you drop the speed settings on sets 1 & 2, set 3 is forced to take up load - by its droop-governor control.
3. Reason for starting at 10% is that governors can be more non-linear at say 0 -10%. If you find the droop specification, it may have a reduced performance at low loads.
4. Reason for ending at 90% is that according to your report, set 3 is giving less power. I am not familiar with set type mentioned and you did not state its kW rating. It is possible you cannot get 90% or even 80% of rating - you have to adjust to this by using a load less than the most you can get.
5. It is good idea to take up load in ~20% steps and take off load in same steps - unlikely you will get same in both directions! It helps to get as much info as possible when you do test. An expert may know how much difference is expected.

If you are able to measure fuel consumption of each set at similar loads, a comparison (having corrected each consumption to same load, in proportion to load) might reveal set 3 is much less efficient than others/maker's data. This would be a clear indication of wear or serious maladjustment (or both).

GA and look out for reverse power in/to G3 while you go down on the KW for the other two, really you will see reverse power on G2 & G1 and iF,,,,,,,,, well look out for it, meters will go the wrong way.

This may come as a stupid question, why is the thread called "Generator Isolated Operation"?

GA, called Island Mode too

I think there is difference between isolated and islanding operation. Isolated operation is that a hydropower plant auxiliary systems are energized and it is ready to take load condition, but not taking any load actually. But islanding means, a utility is taking particular load even when other load is out. Normally, in the even of a system failure, planned islanding is possible by using Diesel Generator.

sks

Do you have any fuel lift pumps in system? Engine driven? Problem with this could cause fuel starvation on set 3.