Recently, in order to save fuel oil at reduced ship's speed, there is a case to introduce a diesel generator relatively small capacity with parallel operation to make up for shortage of electric generating power of the turbine generator driven by exhaust gas economizer steam.
It is necessary to keep KW and KVA load of each machine within their limits even in sudden change of ship's electric load for the purpose of satisfactory make up function by the diesel generator.
A dynamic mathematical model, with an example of analysis, expressing time base variables of each machine with parallel operation upon sudden change of ship's electric load, is hereby shown.

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For the purpose of energy saving, the exhaust gas turbo-generator utilizing exhaust gas of main engine is adopted in many of recent generating plants. On the other hand, due to installation of various energy saving plants, reduction of ship speed, etc. there is a tendency to increase in the number of ships where output of exhaust gas turbo-generator is unsufficient compared with the required electric power of ships. Accordingly, there arises a need for auxiliary generating means to supply this insufficiency.
This report describes comparison in features and payability of various auxiliary means to exhaust gas turbo-generator, such as means by auxiliary diesel generator, shaft generator and auxiliary boiler.

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Recent ships have been tended to apply thyristor shaft generator for saving fuel and thyristor shaft motor to return the excess energy of exhaust gas turbo-generator to the main shaft for saving fuel. Regarding those typical system constructions, as shown in Fig.1 and Fig.5, the analysis was performed in accordance with the brief theoretical formula to obtain electric power, electric current and power factor on each part.
Further, the calculated value due to the formula and the observed value taken in an actual operation were compared where nearly same results were obtained. On voltage, however, the values were given slightly different as a reason was assumed that the formula did not deal with the voltage drop of DC-reactor while the actual operation included AC-reactor for wave form improvement.

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Automation of shipboard generating plants, that started in 1960's, was primarily to satisfy the requirements for unattended machinery spaces. However, recent demands for “super-rationalized ships” that can be operated with a minimum crew and for “energy-saving ships” to cope with sky-rocketing fuel costs have necessitated more careful, get-to-the-point monitoring and control of shipboard generating plants and loads. This has led to the development of a power management system (PMS) . In general, this PMS performs the following functions:
1) Automatic start and stop control of generators according to changing power demands,
2) Optimum load sharing control of the running generators including exhaust-gas turbine driven generator and shaft driven generator, and
3) Start blocking of large motors.
The recent advancement of applied electronics, particularly in the microcomputer application technology, is tremendous and the use of microcomputers and related technology is now seen in almost all shipboard automation. This paper presents an outline of the power management system and microcomputer used in it.

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Recently, thyristor motors are applied on board.
The plants, which applied, are electric propulsion motor, shaft generator and trawl winch motor.
Thyristor motor is brushless and commutatorless type machine.
And so, the strong points of this, are maintenance-free and high reliability against bad environment (moisture and oil mist) .
On this point, this motor is suited to marine use, and will be applied widely in future.

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Recently, use of computer, especially micro-computer system has been necessary and important for super-rationalized-ships.
A variety of function and a raise of data quantity make a great rapid advance more than our prospect at using computer system specification.
The following explain WE6 Data link system as distributed multi-computer system, SDLC protocal, system operation, reliability and hardware etc.

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