WinGD X72DF, Installation Manual

Page: 52 / 237

Marine Installation Manual 2021-08 2-14
2 Engine Power and Speed
2.7 Prohibited operation area
X72DF
As seen in Figure 2 - 7,  2-13 , the prohibited operation area of an engine is de -
fined by an engine tuned to an R1
—
R2 speed. At this speed rating the restriction
exists between 70 % and 100% speed, with a required minimum engine power at
these points of 5.8 % and 17%, respectively. These values are governed by the
Formula 2 - 6 for Line 11.
If the CMCR speed rating of the engine is less than the R1
—
R2 speed, the re -
quired minimum power at this point is also calculated by the Line 11 equation.
Line 11 The lowest operational power limit, between 70% of R1
—
R2 speed and 100 %
CMCR speed, is defined by the following equation:
Formula 2 - 6
As calculated by this equation and shown in Figure 2 - 7,  2-13 , at 70% of
R1
—
R2 speed the minimum engine power equals approximately 5.8 % of the
CMCR power (point E). The minimum power requirement at 100 % CMCR
speed (point F) must be calculated depending on the engine rating. Examples of
this calculation are shown further on.
Line 12
While operating at 100 % CMCR speed, the allowed engine power can range be -
tween the minimum required power (point F) and 100 % CMCR power.
Field A
The available design range of the engine is defined by Line 7, Line 11 and Line
12.
3
1 2
11 0.17
R R
n
Line
n
-
æ ö÷
ç
÷
ç
=
÷
ç
÷÷
çè
ø
´
NOTE
For test purposes, the engine may run within the prohibited operation
area for a maximum of 30 minutes during testing and sea trials. This
operation is only permissible at low load and in the presence of author -
ised representatives of the engine builder. Further requests must be
agreed upon by WinGD.
NOTE
The operational design range must respect the Barred Speed Range
(BSR) limits from torsional vibration.