Основы английского языка для судовых электриков - страница 42

3. Inductive reactance: Reactance in ac circuit caused by its inductance.

4. Inductance/inductance coil/reactance coil, choking coil: A piece of apparatus used in an electric circuit because of the fact that it possesses inductance.

5. Mutual inductance: It is the term used to describe the relationship that exists when a current change in one circuit induces an emf in another circuit. It depends upon the coefficient of coupling & the relative value of the two inductances. The coefficient of coupling is unity when all the flux lines of one coil cut across the turns of the other. In short, mutual inductance is the property of two circuits by virtue of which mutual induction occurs between them.

6. Variable inductor: An inductance coil whose self-inductance is continuously variable between wide limits.

39. / 5 мин./ Переведите словосочетания. Пользуйтесь словарем. Приведите несколько примеров с данными словосочетаниями.

То raise the potential of the positive-terminal end; to carry a current; to connect a light bulb to the source; to be at a higher potential; to apply a potential difference to the external circuit; the conventional direction of curent flow; to move through a conductor; the field exerts a force upon the charge; the charges are given energy through chemical action; to/dis/charge a battery.

40. / 5 мин./ Ознакомьтесь со смыслом следующих утверждений. Отметьте буквой R истинные, буквой W ложные утверждения.

1. The application of brushes & commutators eliminates many problems of maintenance, wear & dangerous sparking. 2. The induced emf voltage causes rotor current to flow. 3. Majority of motors for

marine installation are high in first cost & in maintenance cost, complicated & unreliable. 4. There is some difference in construction between a DC generator & a DC motor. 5. The starting characteristics define the operation of starting from the moment the motor begins running to the moment when steady-state operation is established. 6. To rectify the current in the external circuit, the machine is furnished with a special device called the conductor.

41. /2 мин./ Учитывая общий смысл и начальные буквы пропущенных слов, заполните пропуски.

Fig. 8. Electromagnetic relays, а/ With a clapper-type armature.Ь/ With a>pull-in armature.

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1. The dc machine consists of two main parts: a) the stationary part & b) the r... p... 2. The stationary part comprises the m... p..., the commutating poles, the frame. 3. The armature comprises a slotted armature core, a winding inserted in the armature slot, the

c... & the brush gear.

42. / 10 мин./ Прочитав текст, объясните по-русски, что изображено на Рис. 8 $

Automation Means of Control & Inspection Relays

The most common relay types are ther’elapper-armature & the pull-in armature dc relays shown in Fig.8.Th the former the contacts are closed in the energized position when a current energizes a coil.

1. The magnetic flux generated by the coil closes on the magnetic circuit consisting of a core 2, a yoke 3, an armature 6, & an air gap in the overcoming the action of spring 4, to press against the core

2, closing contacts 8, allowing a current to flow through the output circuit. Reset of contacts in the de-energized position of the relay may, however, be prevented or delayed due to hysteresis^>4effect. This difficulty is overcome with the aid of a nonmagnetic spacer 7 inserted between the armature 6 & the core 2 to ensure an easy separation. In the pull-in armature dc relay /Fig.8b/ the contacts are closed also in the energized position when a core 2 /which is also the armature/ pulls in due to magnetic forces & thus closes contacts. 4. These reset in the de-energized position of the relay by the action of a spring or pull of gravity. The relays used for the switching of high current circuits are called contactors. The above-mentioned relays are also known as neutral because they do not'depend for their operation on the polarity of the energizing current, those which do are called polarized or polar relays, a permanent providing the magnetic bias. The polarized relays may be of two types: biased & unbiased, these last are often called the center-adjusted devices.