Т.Ю.Кущ, М.С.ВоловникАнглийский язык для судовых электромехаников. ENGLISH FOR MARINE ELECTRICAL ENGINEERS. 1986

propeller consequently starting logic attempt consumption to feed preset setting

first starting RPM

fuel oil lever to lapse response

to cut off

with the manoeuvring gradient

below 20% of minimum running speed

valve

return of the starting speed set-point

to set on a second higher level

a “Starting failure” alarm is activated

— ЦПУ

— передвигать, перемещать

— ручка, рычаг,' рейка

— логическая схема управления пуском двигателя

— аналоговая схема контроля оборотов двигателя (частота вращения)

— предварительное условие

— проверять

— следить за дискретным (вклю-чающим/отключающим) сигналом

— валоповоротное устройство отключено

— винт

— следовательно, поэтому

— логика пуска

— попытка

— расход

— подавать

— предустановочный

— установка

— первая величина пусковых оборотов

— топливный рычаг/рейка

— истекать (о времени)

— ответный сигнал (достижения оборотов)

— отключить

— со ступенью, соответствующей маневрированию

— более чем на 20% от минимально заданной рабочей скорости

— клапан

— возврат установленного значения пусковой скорости

— установить на второй более высокий уровень

— включается сигнал «Неудача пуска»

Electric propulsion power transmission is usually economical only for special vessels. However, superconducting motors with their greatly reduced weights and sizes indicate that this type of propulsion may become more widespread in the future.

The energy crisis of the early 1970s provided impetus for more sufficient energy conservation and for exploiting hitherto untapped resources.

The superconducting dc motor adds a potent new factor to this situation. It offers the best of these options in that it is lighter than the equivalent conventional ac motor and is a dc motor which may be operated from an ac generator via a simple diode-rectifier-convertor. It offers all the advantages of a dc propulsion system, together with high efficiency, and performance characteristics particularly suited to high efficiency propellers; with no practical power limit.

Superconductors are materials which, when cooled to below a critical temperature, exhibit zero electrical resistance and thus are able to sustain very high current densities. To qualify as an engineering material for electric machines, a superconductor must also tolerate a high magnetic field.

The superconductor is niobuim-titanium alloy which, when cooled to approximately 4.5°K, can carry a few thousand A/mm 2in a field of approximately 6 tesla with no resistive losses. It is thus possible to construct a lossless winding with several million ampere-turns producing correspondingly high flux output.

In practice this means a very much smaller and lighter motor than conventional types of the same output so that the economics of electrical propulsion merit re-examination.

Two magnetically opposed superconducting field windings are in closely fitting liquid-helium vessels, formed by partitions in a single structure designed to contain the electro-magnetic separating forces between the coils. This assembly is suspended in a vacuum vessel on the support cylinder.

The purpose of this system of vessels is to minimize the heat-flow from ambient to the liquid-helium vessels and coils at 4.5°I\.

The complete assembly is located within the rotor on a fixed support that passes through the bore of the large bearing at the non-drive end and is connected to a steady bearing on a stub extension of the output shaft.

The armature rotor group assembly comprises a drum carrying the slip rings, and rotor conductors interconnecting pairs of slip rings; a non-drive-end section; a drive-end section; and the output shaft.

The armature stator group consists of brushgear and stator conductors, mounted on a structure able to withstand the motor torque reaction on the stator conductors. The stator also includes the bearing and the base frame. For a propulsion application the drive-end bearing could include the main thrust block.

The torque of any motor is the product of the armature current and magnetic flux. In a superconducting motor the use of a pair of slip rings for each armature conductor permits a high armature current together with a high flux output, thus giving- high torque. With a constant field, speed varies linearly with voltage and torque varies linearly with current; thus for a propeller drive obeying the cube law, voltage varies with speed, current varies with speed squared and power varies with speed cubed.

The superconducting marine propulsion motors have the advantages of no practical upper power limit; very large torques; and excellent speed control.

A possible disadvantage is the need to provide a helium refrigeration system, but the main consequence of this is an economic cut-off below a certain rating, probably about 60 kW per rev/min.

An important feature of the motor design is the ability to operate the two halves of the field system independently so that, in the event of one half being inoperative, the motor can work at half voltage and full current, giving half power.

Other benefits are an integrated power plant with the use of more efficient propellers, manoeuvrability and better employment of space due to installation flexibility.

An integrated power plant means a “Central power station" concept with the minimum of auxiliary prime movers, which can lead to a significant reduction in the total installed power, together with general use of a single fuel-grade. It is also clear that a “Total energy” concept should be adopted, witli heal, recovery where possible.

The most efficient propeller combination can be used due to the freedom of choice of speed and torque.

Examples of ship types particularly suitable lor application of superconductive drive motors are icebreakers, large tugs and tankers.

By shifting the telegraph lever from FULL AHEAD to NAVIGATION, a gradual acceleration program is activated; the program is adjustable and enables the engine to reach navigation RPM’s in the desired lapse of time. If any fault occurs during gradual load take-over the engine load increase is interrupted; the engine stabilizes at the value reached at the moment in which the fault occurred and remains in that condition until the fault disappears.

Automatic resumption of power increase takes place according to the preset gradient.

If one of the stand-by causes persists beyond a given time the device automatically starts decreasing the load, beginning from stand-by position and persists until its determining cause disappears. The decrease may occur according to two adjustable speeds which are automatically selected by the programme as a function of the seriousness of the fault.

The following are some, of the anomalous conditions which determine the limiting and safety functions described above: fresh cooling water high temperature at ttie outlet of each cylinder; cylinder exhaust gas high temperature versus average value; cylinder exhaust gas mean temperature;