Engine Load Diagram; Operating Curves And Limits For Continuous Operation - Man B&W S80ME-C7 Project Manual

MAN B&W

Engine Load Diagram

Definitions
The engine's load diagram defines the power and
speed limits for continuous as well as overload
operation of an installed engine having a specified
MCR point M that confirms the ship's specification.
Point A is a 00% speed and power reference
point of the load diagram, and is defined as the
point on the propeller curve (line ),  the layout
curve of the engine  through the matching point
O, having the specified MCR power. Normally,
point M is equal to point A, but in special cases,
for example if a shaft generator is installed, point
M may be placed to the right of point A on line 7.
However, MAN Diesel may always consider point
A as the engine's MCR for shop test.
In most cases, the points M and A are identical.
The service points of the installed engine incorpo-
rate the engine power required for ship propulsion
and shaft generator, if installed.
Engine shaft power, % of A
110
105
7
100
5
95
90
4
1 2 6
85
80
75
70
65
60
55
8 4
50
45
40
60 65 70
75
Regarding 'i' in the power function P = c x n
A 00% reference point
M Specified MCR
O Matching point
Fig. 2.04.02: Standard engine load diagram
MAN B&W ME/ME-C/ME-GI engines
A=M
7
5
O
6
1
2
80 85 90 95 100 105 110
Engine speed, % of A
i , see page 2.0
178 05 427.3
Operating curves and limits for continuous
operation
The continuous service range is limited by four
lines:
4, 5, 7 and 3 (9), see Fig. 2.04.02. The propeller
curves, line , 2 and 6 in the load diagram are also
described below.
Line 1:
Propeller curve through specified MCR (M), en-
gine layout curve (i = 3).
Line 2:
Propeller curve, fouled hull and heavy weather
– heavy running (i = 3).
Line 3 and line 9:
Line 3 represents the maximum acceptable speed
for continuous operation, i.e. 05% of A.
During trial conditions the maximum speed may
be extended to 07% of A, see line 9.
The above limits may in general be extended to
05% and during trial conditions to 07% of the
nominal L

sional vibration conditions permit.
The overspeed setpoint is 09% of the speed
in A, however, it may be moved to 09% of the
nominal speed in L
tion conditions permit.
Running at low load above 00% of the nominal L
speed of the engine is, however, to be avoided for
extended periods. Only plants with controllable
3
pitch propellers can reach this light running area.
9
Line 4:
Represents the limit at which an ample air supply
is available for combustion and imposes a limita-
tion on the maximum combination of torque and
speed (i = 2).
Line 5:
Represents the maximum mean effective pressure
level (mep), which can be accepted for continuous
operation (i = ).
MAN Diesel
speed of the engine, provided the tor-
, provided that torsional vibra-

2.04
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