Two-phase motors are like three-phase motors in all respects except for the number of groups & the connections of the groups. As in the three-phase motor, the number of groups is equal to the number of phases multiplied by the number of poles.
The phase A connection is similar to that of the running winding, & the phase В connection is similar to the starting-winding connection. However, there is no centrifugal switch in a two-phase motor, & both windings have voltage applied to them all the time.
Two-phase motors have windings connected in series or in parallel, depending on the design of the motor.
20. /3 мин./ Прочтите 22 интернациональных слова из основного текста и переведите их.
21. / 3 Мин./ Найдите в основном тексте английские эквиваленты следующих русских словосочетаний: поврежденный во время транспортировки, при заказе запчастей, подать всё необходимые данные, схемы возможных подсоединений, соответствовать техническим условиям, рассматриваемый привод, тип конструкции, серийный номер машины, плата с указанием номинальной мощности отсутствует, отштампованный на конце вала.
22. / 3 мин./ Дайте русские эквиваленты следующих словосочетаний из основного текста:
when ordering; the rating plate is missing; during transport; the starting time; operating conditions; mounting instructions; stamped on the shaft end; unless otherwise agreed; the machine will be rated; necessary data have been supplied; it is furnished with instructions.
23. /6 мин./ Переведите определения следующих терминов . При необходимости используйте словарь.
Electrical machines are machines for converting mechanical energy into electric energy, i.e., generators, or machines for converting electric energy into mechanical energy, i.e., motors. Loss is a part of the energy consumed by the machine which cannot be effectively utilized in the machine proper since, practically, it is dispersed in the form of heat into air. An apparatus is usually a complicated mechanism or asembly of many different pieces used for scientific experiments or, tests, or for practical purposes. A telephone apparatus consists in .general of a microphone & a telephone receiver. An installation is 1) the action of placing something in position for uie or 2) the complete apparatus or equipment, e.g. for the production of electrical energy.
>1 24. /50 мин./ Прочтите три отрывка из инструкции. .
1. Выпишите существительные, необходимые для описания защиты от перегрузок /А/.
2. Укажите в письменном виде условия, которые необходимы для установки двигателя /В/.
3. Выпишите действия, необходимые для выполнения первого пуска /С/.
4. Перечитайте отрывки из инструкции и свои записи. Напишите на их основе 10 практических советов по работе с машиной.
A. Overload Protection
The machine must be protected with thermial relays against too high temperature rise caused by overcurrent. The best protection is achieved when the thermal relays control each phase. Except
! overcurrent, too high temperature rise may be due to risen ambient temperature, poor ventilation & in some cases to starting or brakings. In these cases the thermal relay does not protect the machine.
The temperature of the machine windings can be waJcHed by resistance elements. These must in general be installed when the machine is being manufactured, i.e. they must be ordered as additional equipment before the manufacture.
B. Erection
The machine must be placed on a solid & even foundation to prevent vibration & especially resonances.
The open machine /except weather protected/ must be mounted in rooms where the air is clean & dry.
The maximum permitted ambient temperature on sites is +40°C, unless otherwise agreed.
The combination of letter & figure after the machine type designation indicates the ratings on the name plate.
The machines must be mounted so that the fan covers are not too near the wall or other similar obstacle. The distance from the fan cover to the wall is stated in the dimension drawings.
The half-coupling & the pulley must be mounted on the shaft so that the bearings are not damaged. Suitable methods & tools must be used for the mounting, especially blows must be avoided.
