Английский язык для судовых электромехаников - [57]

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/mm² in 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.

II

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.

prerequisite to verify

to contemplate on/off consent input

turning gear disengaged

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»

Material for Rendering and Discussion A Superconducting DC Motors for Marine Propulsion

I

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/mm² in 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.

II

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.