MECHANICAL vs. ELECTRICAL OUTPUT
MECHANICAL vs. ELECTRICAL OUTPUT
(OP)
During the load test of a recently refurbished Genset the engine output data parameters does not match the measured electrical output.
The test was conducted sharing the available load of 3.3MW between three Gensets of identical characteristics in parallel.
Engine type: MaK 12M 282 AK
Output: 1990 kW
Speed: 1000 rpm
At full load the mechanical parameters (Fuel rack position and Charge air pressure after air cooler, according to the Engine Diagram) indicated that the engine under test (Gen 4) was delivering 101% of rated power (2017 kW)
kV A A A MW HZ KVA Cos fi
Gen 4 10.87 81 83 85 1.5 49.6 1586 0.95
Gen 6 10.87 56 58 55 0.9 49.6 1053 0.85
Gen 1 10.87 61 62 61 0.9 49.6 1153 0.78
How to solve this conflict when both parties seems to be right.
The test was conducted sharing the available load of 3.3MW between three Gensets of identical characteristics in parallel.
Engine type: MaK 12M 282 AK
Output: 1990 kW
Speed: 1000 rpm
At full load the mechanical parameters (Fuel rack position and Charge air pressure after air cooler, according to the Engine Diagram) indicated that the engine under test (Gen 4) was delivering 101% of rated power (2017 kW)
kV A A A MW HZ KVA Cos fi
Gen 4 10.87 81 83 85 1.5 49.6 1586 0.95
Gen 6 10.87 56 58 55 0.9 49.6 1053 0.85
Gen 1 10.87 61 62 61 0.9 49.6 1153 0.78
How to solve this conflict when both parties seems to be right.






RE: MECHANICAL vs. ELECTRICAL OUTPUT
During the load test of a recently refurbished Genset the engine output data parameters does not match the measured electrical output.
The test was conducted sharing the available load of 3.3MW between three Gensets of identical characteristics in parallel.
Engine type: MaK 12M 282 AK
Output: 1990 kW
Speed: 1000 rpm
At full load the mechanical parameters (Fuel rack position and Charge air pressure after air cooler, according to the Engine Diagram) indicated that the engine under test (Gen 4) was delivering 101% of rated power (2017 kW).
On the electrical side the readings were as follow:
kV A A A MW HZ KVA Cos fi
Gen 4 10.87 81 83 85 1.5 49.6 1586 0.95
Gen 6 10.87 56 58 55 0.9 49.6 1053 0.85
Gen 1 10.87 61 62 61 0.9 49.6 1153 0.78
How to solve this conflict when both parties seems to be right.
RE: MECHANICAL vs. ELECTRICAL OUTPUT
Did you factor in losses? In addition to the electrical output, the engine has to overcome friction, windage, perhaps drive the lubricating oil pump, fuel lift pump, cooling water pump and radiator fan.
Blacksmith
RE: MECHANICAL vs. ELECTRICAL OUTPUT
RE: MECHANICAL vs. ELECTRICAL OUTPUT
I don’t have accurate data regarding the fuel BTU, but let me try to clarify the situation.
During the load test with the three identical generator in parallel we alternatively transfer 1.8MW load to Gen 1 and Gen 6 while Gen 4 only accept a maximum of 1.5MW.
In this case we can assume that the de-rating due to local conditions and the fuel BTU equally affect the three Generators.
RE: MECHANICAL vs. ELECTRICAL OUTPUT
Are all the cylinders firing?
What are the compression readings of all cylinders?
What is the firing pressure of all cylinders? (If applicable)
What is the fuel pressure? (Fuel filter clogged, pump weak?)
What is the jacket water temperature? (Running cold?)
These may appear to be silly, but the engine is down on power and it’s easy to overlook one misfiring cylinder or a gradual degradation of all cylinders.
Blacksmith
RE: MECHANICAL vs. ELECTRICAL OUTPUT
RE: MECHANICAL vs. ELECTRICAL OUTPUT
1 2 3 4 5 6 7 8 9 10 11 12
Firing Pressure (bar)
103 98 98 97 101 97 103 102 99 101 103 99
Exhaust gas Temperature (°C)
360 375 365 360 395 370 370 390 360 375 380 360
Jacket water Temperature 79 °C
Fuel Pressure 2 bar
Obviously there are thermocuples on each exhaust port.
We did not measure the compression pressure, only the firing pressure on each cylinder as above
RE: MECHANICAL vs. ELECTRICAL OUTPUT
You say the fuel is the same, do they all draw from a common tank or could #4 being using old or contaminated fuel?
Are you measuring the electrical load with the same meter, or could there be a gauge calibration error?
I'm not seeing anything obvious, but there has to be something!
Blacksmith
RE: MECHANICAL vs. ELECTRICAL OUTPUT
Cylinder
1 2 3 4 5 6 7 8 9 10 11 12
Firing Pressure diff. (bar)
7 2 2 1 5 1 6 5 2 4 6 2
Exhaust gas Temperature diff. (C)
-29 -34 1 -35 -5 11 -6 -15 -19 1 -34 -29
Charge air pressure after charge air cooler diff. (bar)
Bank A –0.138 Bank B –0.13
Regarding the fuel, The Bulk Storage and Intermediate tanks are common.
The daily tank is individual but during the refurbishment was totally emptied and cleaned. All filters renovated.
Regarding the electrical instruments each generator has its individual Control Panel and meters. The instrument panel readings have been compared with Fluke 87 III Multimeter.
Electrical readings are OK.
Nawao
RE: MECHANICAL vs. ELECTRICAL OUTPUT
Blacksmith
RE: MECHANICAL vs. ELECTRICAL OUTPUT
Precisely, the conflict is with him.
Nawao
RE: MECHANICAL vs. ELECTRICAL OUTPUT
RE: MECHANICAL vs. ELECTRICAL OUTPUT
If you are scratching your head for ideas, this may be of some consideration. (My experience of fault finding is that you cannot rule out the refurbishment work as a route cause, just because the work has been done. Pepole do make mistakes and the work is worth double checking!)
On the generator excitation system fine tuning point, looking at your load figures, it would appear that your reactive component load sharing ( quadrature droop setting) is miss-matched between gensets,[Provided of course that your instrumentation is accurate]
For a final balanced system, each machine should be set at manufacturers rated power factor, and would be normally expected to maintain a drooping charactoristic, say from 10% load upwards to full load at rated power factor, such that reactive load sharing between gensets at their respective per unit loads is maintained.