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MAN B&W Diesel A/S S60MC-C Project Guide

In such a case, the problem is solved by installing a smali, elastically supported bearing in front of the stator housing, as shown in Fig. 4.09.

As the DMG type is directly connected to the crank-shaft, it has a very Iow rotational speed and, consequently, the electric output current has a Iow frequency - normally in order of 15 Hz.

Therefore, it is necessary to use a static frequency converter between the DMG and the main switch-board. The DMG/CFE is, as standard, laid out for operation with fuli output between 100% and 70% and with reduced output between 70% and 50% of the engine speed at specified MCR.

Yard deliveries are:

1 • Installation, i.e. seating in the ship for the synchronous condenser unit, and for the static con-verter cubicles

2.    Cooling water pipes to the generator if water cooling is applied

3.    Cabling.

The necessary preparations to be madę on the engine are specified in Figs. 4.05a and 4.05b.

Static converter

The static converter (see Fig. 4.10) consists of a static part, i.e. thyristors and control equipment, and a rotary electric machinę.

The DMG produces a three-phase alternating current with a Iow frequency, which varies in accor-dance with the main engine speed. This alternating current is rectified and led to a thyristor inverter pro-ducing a three-phase alternating current with eon-stant frequency.

Since the frequency converter system uses a DC in-termediate link, no reactive power can be supplied 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 generatorfuliy built-on to the main engine inclusive of the synchronous condenser unit, and the static converter cubicles which are to be installed in the engine room.

The DMG/CFE can, with a smali modification, be operated both as a generator and as a motor (PTI).

198 1S 59

485 600 100

4.14