Digital Computer Integrated Automation Systems

Digital Computer Applications

There are such applications of minicomputers as: Supervision of plant operating data with alarm recording, data logging and process monitoring of the process.

Automation and control systems can be conveniently integrated with minicomputer digital processors. Interface units apt to handle all inputs and outputs problems from the process to the computer (Fig. 1) are available, depending on the type of solution contemplated.

Fig. 1. Process of the computer

On demand digital display of plant variables. Event recording: print out of the various plant variables on occurrence of an event, with the chronological history of groups of events in their exact sequence.

Recording of the value of the various plant variables in the time intervals preceeding the occurrence of a fault condition.

Trend recording: recording of the tendency of a variable to exceed set-point value over a short and medium term.

Recording of the maximum off-normal drift of a variable from threshold value.

Sequence control: for groups of variables.

Optimization of complex automation systems with set-point value correction by the computer.

Plant efficiency and performance calculations.

Operator guide: processing of the data collected by comparison with the optimum memorized operating program in order to furnish guidance to the operator.

Information storage: collection of data relating to plant operation. Formulation of consents and locks based on complex programs including non-linear functions of plant parameters.

Data communication: local processing of the variables by the peripheral microcomputers with data transmission to the central microcomputer. Microcomputer. The microcomputer is a control unit with extremely flexible program; modern electronic technology has made this facility available for application in the solution of control problems which heretofore had to be handled by wired logic or relay logic.

Easily expandable high speed programs include complex arithmetic and logic operations.

The microcomputer itself comes as a conventional electronic unit mounted on standard racks apt to contain several plug-in type modules. The following modules are fitted in the standard rack:

1. Central Processor Unit (CPU). CPU performs arithmetical and logical calculations at high speed with 8 bit words: it performs all the processing functions and is capable of addressing itself up to 64 memory bits.
2. Electronic type programmable memory (PROM) or fixed memory (ROM).
3. Memory module for electronic type data.
4. Input module connecting the CPU with the process.
5. Output module, to dispatch the microcomputer information toward the process.
6. Interface module, to adapt the input signals and input/output card capacity to the multiplexing and demultiplexing units and for A/D to D/A conversion.

Computer Hardware

The heart of the system is the Central Processing Unit (CPU), which holds both program and data, an Arithmetic-Logic Unit (ALU), which contains processing circuitry such as an adder, shifter, and a few fast registers for holding the operands, and the instruction currently being processed (Fig. 2). The program counter would also be included in the ALU.

One part of the CPU is a set of routing circuits which provide path between storage and the ALU and input/output controllers or channels. Many storage or input devices may be wired to one channel; but only one device per channel can be transmitting information from or to main storage at any one time.

Fig. 2. General organization of a computer system

In general, large computers may be thought of as having four distinct parts: a high-speed calculating unit, a memory unit, an input device and an output device.

Micro-Electronics — its Effect on Future Ship Operation

Ship operation could change considerably in the future as a result of the increasing introduction of micro-processor controlled machinery and equipment. Working practices, training, bridge and machinery space layouts will alter.

Although few problems remain to be solved at the present state of development, as automation increases, the relationship between controls, machinery and ship design will be more closely linked, resulting in the need for a much more integrated approach to ship design.

Over the past five years a comprehensive programme of research and development aimed at introducing micro-electronics into merchant ship operation has been carried out.

Initially, the work consisted of a design study for a highly-automated petroleum products tanker together with a preliminary attempt to evaluate micro-processor technology in a range of marine applications.

Following this, further evaluation of micro-electronics technology resulted in the design and construction of an advanced cargo control station for a liquid bulk carrier. This incorporates a wide range of microelectronics hardware systems which will be increasingly used for the surveillance and control of machinery and of cargo operations.

Microcomputers are currently undergoing shipboard trials and there is continuous feedback on their performance and reliability.

A Code of Practice has now been prepared which will form the basis for the installation of future micro-electronics equipment on board merchant ships.

Safe Operation of Nuclear Ships

Experience. The first stage was difficult because of lack of experience in the technical operation of marine nuclear reactors as such, and even more of nuclear-powered ships.

Major conclusions drawn after the first period of trial operation were that nuclear power plant is reliable in operation, provides for easy
passing through transient conditions from any power range and gives ice-breakers good manoeuvrability.

The system of a nuclear power guarantees safe charging of power output when energy reactor protection is activated, or when pieces of equipment are out of order.
Biological shielding and other design elements are reliable guards for personnel and environment.

Endurance of 210 days with one charge of fuel was confirmed. At the same time, several shortcomings of the first nuclear steam-generating plant were revealed.

Major equipment had a short service life.

Certain elements of equipment had poor maintainability in the central compartment which was imperfectly designed for radioactive decontamination.

The great number of steeled joints in the primary coolant circuit reduced its reliability, caused temporary reactor shutdowns and contributed to the formation of liquid radioactive wastes.

The systems of electric power supply, control and automation also required improvement.

The short service life of major equipment, such as steam generators, the primary circuit gate valve, etc., a high cost of dismantling/mounting of radioactive equipment were major handicaps to the success of nuclear power.

Solutions included the design of special equipment for the repair and reloading of reactors; and the collection and utilization of radioactive wastes.

Automation

To the layman, largely guided by the popular press, "automation" appears as a startling modern invention which will lead to the wholesale establishment of automatic factories and the building of automatic ships.

To the engineer automation is merely a contemporary phase in the process of technical evolution that has gone on continuously since the first crude machine. The engineer's aim has always been to make the best use of machines, materials and money.

The answer, of course, does not lie in the mass installation of "black boxes", electronic or otherwise. It lies in the ingenuity and breadth of vision of the people involved in designing the control system.

The primary aims of control are to reduce the inefficiencies inevitably associated with human machine minding. A complete elimination of human judgement is quite impracticable. However highly developed an automatic system may become the skill and experience of the trained operator will still be essential.