Electricity Production; Power Take Off - Man B&W S80ME-C7 Project Manual

MAN B&W

Electricity Production

Introduction
Next to power for propulsion, electricity produc-
tion is the largest fuel consumer on board. The
electricity is produced by using one or more of the
following types of machinery, either running alone
or in parrallel:
• Auxiliary diesel generating sets
• Main engine driven generators
• Exhaust gas- or steam driven turbo generator
utilising exhaust gas waste heat (Thermo Effi-
ciency System)
• Emergency diesel generating sets.
The machinery installed should be selected on the
basis of an economic evaluation of first cost, ope-
rating costs, and the demand for man-hours for
maintenance.
In the following, technical information is given re-
garding main engine driven generators (PTO), dif-
ferent configurations with exhaust gas and steam
driven turbo generators, and the auxiliary diesel
generating sets produced by MAN Diesel.

Power Take Off

With a generator coupled to a Power Take Off
(PTO) from the main engine, electrical power
can be produced based on the main engine's
low SFOC and the use of heavy fuel oil. Several
standardised PTO systems are available, see Fig.
4.0.0 and the designations in Fig. 4.0.02:
• PTO/RCF
(Power Take Off/Renk Constant Frequency):
Generator giving constant frequency, based on
mechanicalhydraulical speed control.
• PTO/CFE
(Power Take Off/Constant Frequency Electrical):
Generator giving constant frequency, based on
electrical frequency control.
MAN B&W K108ME-C6, K98MC/MC-C/ME/ME-C6/7,
S90MC-C/ME/ME-C7/8, K90ME/ME-C9, K90MC-C/ME-C6, S80MC6,
S80MC-C7/8, S80ME-C7/8/9, K80ME-C9, K80MC-C/ME-C6
The DMG/CFE (Direct Mounted Generator/Con-
stant Frequency Electrical) and the SMG/CFE
(Shaft Mounted Generator/Constant Frequency
Electrical) are special designs within the PTO/CFE
group in which the generator is coupled directly to
the main engine crankshaft and the intermediate
shaft, respectively, without a gear. The electrical
output of the generator is controlled by electrical
frequency control.
Within each PTO system, several designs are
available, depending on the positioning of the
gear:
• BW I:
Gear with a vertical generator mounted onto the
fore end of the diesel engine, without any con-
nections to the ship structure.
• BW II:
A freestanding gear mounted on the tank top
and connected to the fore end of the diesel en-
gine, with a vertical or horizontal generator.
• BW III:
A crankshaft gear mounted onto the fore end of
the diesel engine, with a sidemounted genera-
tor without any connections to the ship struc-
ture.
• BW IV:
A freestanding stepup gear connected to the
intermediate shaft, with a horizontal generator.
The most popular of the gear based alternatives
are the BW III/RCF type for plants with a fixed
pitch propeller (FPP). The BW III/RCF requires no
separate seating in the ship and only little atten-
tion from the shipyard with respect to alignment.
MAN Diesel
4.01
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