Man B&W S80ME-C7, Project Manual

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MAN B&W 4.03
Page 6 of 6
MAN Diesel
198 43 156.2 MAN B&W K108ME-C6, K98MC/MC-C/ME/ME-C6/7,
S90MC-C/ME-C7/8, K90ME/ME-C9, K90MC-C/ME-C6, S80MC6,
S80MC-C7/8, S80ME-C7/8/9, K80ME-C9, K80MC-C/ME-C6,
S70MCC/ME-C/ME-GI7/8, S70MC6, L70MCC/ME-C7/8,
S65ME-C/ME-GI8, S60MC6, S60MC-C/ME-C/ME-GI7/8,
L60MC-C/ME-C7/8, S50MC-C7/8, S50MC6, S50ME-B8/9
In such a case, the problem is solved by installing
a small, elastically supported bearing in front of
the stator housing, as shown in Fig. 4.03.05.
As the DMG type is directly connected to the
crankshaft, it has a very low rotational speed and,
consequently, the electric output current has a
low frequency – normally of the order of 5 Hz.
Therefore, it is necessary to use a static fre-
quency converter between the DMG and the main
switchboard. The DMG/CFE is, as standard, laid
out for operation with full output between 00%
and 70% and with reduced output between 70%
and 50% of the engine speed at specified MCR.
Static converter
The static frequency converter system (see Fig.
4.03.06) consists of a static part, i.e. thyristors and
control equipment, and a rotary electric machine.
The DMG produces a threephase alternating
current with a low frequency, which varies in ac-
cordance with the main engine speed. This alter-
nating current is rectified and led to a thyristor in-
verter producing a threephase alternating current
with constant frequency.
Since the frequency converter system uses a DC
intermediate link, no reactive power can be sup-
plied to the electric mains. To supply this reactive
power, a synchronous condenser is used. The
synchronous condenser consists of an ordinary
synchronous generator coupled to the electric
mains.
Extent of delivery for DMG/CFE units
The delivery extent is a generator fully builton
to the main engine including the synchronous
condenser unit and the static converter cubicles
which are to be installed in the engine room.
The DMG/CFE can, with a small modification,
be operated both as a generator and as a motor
(PTI).
Yard deliveries are:
. Installation, i.e. seating in the ship for the syn-
chronous condenser unit and for the static
converter cubicles
. Cooling water pipes to the generator if water
cooling is applied
3. Cabling.
The necessary preparations to be made on
the engine are specified in Figs. 4.03.0a and
4.03.0b.
SMG/CFE Generators
The PTO SMG/CFE (see Fig. 4.0.0 alternative 6)
has the same working principle as the PTO DMG/
CFE, but instead of being located on the front end
of the engine, the alternator is installed aft of the
engine, with the rotor integrated on the intermedi-
ate shaft.
In addition to the yard deliveries mentioned for the
PTO DMG/CFE, the shipyard must also provide
the foundation for the stator housing in the case
of the PTO SMG/CFE.
The engine needs no preparation for the installa-
tion of this PTO system.