Complete the sentences with words given in previous exercise and translate them into Russian.
1. A force _____ because it is carrying current and it is located in a magnetic field.
2. Because the shunt field is connected across the line, the flux in the machine_____, or will not change.
3. The torque developed by the motor is directly dependent upon the armature current.
4. The armature current depends directly upon _____connected to the motor.
5. This _____ reduces the counter-emf.
6. A load applied to the motor results in an increase in_____.
7. The series-field winding may also be connected differentially so that the series-field flux will oppose _____.
8. It is best _____when starting to prevent starting up in the wrong direction.
Give adequate Russian equivalents of the italicized words.
Available, availability - общий элемент смысла: наличие в момент надобности; то, чем можно
воспользоваться. Частотные русские эквиваленты: available - имеющийся в наличии, в распоряжении, доступный, годный и т.д.; availability - наличие, доступность и т.д.
1. Future observation of these comets will surely be possible if space vehicles are available to observe them. 2. Of these substances the first three are available to the plant: carbon dioxide, water and oxygen. 3. In what
follows an outline of the results available at the time of writing is given. 4. The availability of water-power makes it easy to have electricity. 5. The latter effect is due to the non-availability of free electrons to associate with the broken bonds.
Fail, failure - общий элемент смысла: невыполнение ожидаемого или должного. Частотные русские
эквиваленты: to fail - терпеть неудачу; переставать действовать, выходить из строя и т.д.; to fail to do smth. - не суметь, оказаться неспособным сделать, не сделать и т.д.; failure - неудача; недостаток, отсутствие; авария, отказ в работе и т.д.
1. In his book Prof. N. tried to succeed in what many scientists had failed before him. 2. All precautions failed to prevent the explosion. 3. Cells resulting from such division are often very small and fail to divide further. 4. Success came after many failures. 5. Planck was brought to the discovery of the quantum of energy by the failure of the classical laws to account for the properties of heat. 6. They could not complete the experiment in time because of the failure of the equipment.
Read and translate the text.
In the previous Unit we spoke about a dynamo and generators. A dynamo is a device that converts mechanical energy into electrical energy or electrical energy into mechanical energy. In the study of the generator we have seen how mechanical energy supplied to the generator in the form of armature rotation was converted into electrical energy. Now we shall apply electrical energy to the same dynamo and investigate the conversion of electrical energy into mechanical energy. In accordance with the foregoing definition, a generator can be used as a motor or a motor can be used as a generator.
Force on a conductor. If a conductor is placed in a magnetic field and current is allowed to flow through the conductor, the conductor will tend to move. A force is exerted on the conductor because it is carrying current and it is located in a magnetic field. The force exerted on the conductor is dependent upon three factors. First a magnetic field must exist, then a conductor must be located in the magnetic field, and finally current must flow in the conductor.
The force on the conductor is zero in the absence of a magnetic field. The greater (smaller) the magnetic flux density, the greater (smaller) the force exerted on the conductor.
The length of the conductor is also a factor that determines the magnitude of the force on the conductor; the smaller the conductor, the smaller the force: the longer the conductor, the greater the force exerted on the conductor. An important point should be noted at this time. Only that part of the conductor located within the magnetic field is effective in producing a force on the conductor.
The third factor required to produce a force on the conductor is the magnetic of the current through the conductor. With no current in the conductor, the force produced would be zero. The greater the current through the conductor, the greater the force exerted on the conductor.
Shunt motor. The shunt motor is physically the same as a shunt generator. The shunt-field coil consists of many turns of fine wire and is connected in series with a field rheostat. The shunt-field circuit is connected across the line in parallel with the armature.
Because the shunt field is connected across the line, the flux in the machine will remain essentially constant. The torque developed by the motor would therefore be directly dependent upon the armature current. Increasing the armature current would increase the torque. Decreasing the armature current would decrease the torque.
