Marine Installation Manual
2021-08
2-11
2 Engine Power and Speed
2.6 Power range limits with a power take-off installation for a FPP
X72DF
With the addition of a constant nominal generator power across the engine
power range, the engine curve is changed, so no longer directly related to a pro
-
, the PTO is assumed to absorb 15 % of
nominal engine power. The CSR point includes the PTO power demand, this is
shown in the same figure between points B’ and B. The CMCR point is selected
from this propeller curve. This curve defines the nominal engine characteristic.
Method 1 allows for practical and flexible PTO operation, as limitations will
only occur in the engine’s lower speed range. At this lower speed range, the PTO
is limited by a minimum speed requirement (as defined by the PTO device sup
-
plier) and by the PTO layout limit Line 10 (only relevant if the PTO operation is
using a significant percentage of engine power).
Line 10
PTO Layout Limit
The PTO layout limit (Line 10 in
) defines the power limit for the re
-
sulting combination of the propeller and PTO. Defining Line 10 as the PTO
layout limit provides a margin for normal power load fluctuation and accelera
-
tion.
Figure 2
-
5 Power range limits for PTO operation — Method 1
The breakpoints of Line 10 are listed in
. Line 10 is a curve defined by
. The different components have a different coefficient,
forming the entire curve (see
for the individual coefficients).
Table 2
-
3
Line 10 coefficients
SM-0351
0
0
10
20
30
40
50
60
70
80
90
100
110
10
20
30
40
50
60
70
80
90
100
110
Engine speed [% Rx]
Engine power [% Rx]
B
8
6
5
4
2
1
9
13
3
3a
P12
P11
P10
P04
7
10
7a
7b
B
P04 (CMCR)
P10
P11
P12
100
40
60
96
100
13.2
28.8
92.2
Breakpoints
Engine
Speed [%Rx]
Engine
Power [%Rx]
PTO operation
range (Method 1)
Example of
PTO power
limitation
Line no.
Range (
n/n
CMCR
)
C2
C1
C0
Line 10
0.40 - 0.60
0.750
0.030
0.000
0.60 - 0.96
1.336
-0.321
0.000
0.96 - 1.00
0.000
1.941
-0.941
