AC and DC Electric Motors. Generators

Read the English words and their translation into Russian. Then cover the left column and translate the Russian words back into English.

magnet ['mxgnIt] магнит

magnetic field [mxg'netIk fJld] магнитное поле

armature ['RmqCq] якорь (электрической машины)

electromagnet [I"lektrou'mxgnIt] электромагнит

permanent ['pWmqnqnt] постоянный

pole [poul] полюс

to interact ["Intqr'xkt] взаимодействовать

force [fLs] сила

to rotate [rou'teIt] вращать, вращаться

torque [tLk] вращающий момент

commutator ['kOmjuteItq] коллектор (электродвигателя)

brush I [brAS] щётка (электродвигателя)

stator ['steItq] статор

rotor ['routq] ротор

fixed [fIkst] постоянный

winding ['waIndIN] обмотка

shunt-wound с параллельным возбуждением (об эл. машине)

series-wound с последовательным возбуждением, сериесный(об эл. машине)

compound-wound смешанного возбуждения (об эл. машине)

field coil катушка возбуждения; обмотка возбуждения

to reverse [rI'vLs] изменять на противоположное

rotation [rq'teISqn] вращение

hybrid ['haIbrId] гибрид

wear and tear [wFq] [tFq] износ

decreased уменьшенный

to occur [q'kL] происходить, иметь место

friction ['frIkSn] трение

emf (electromotive force) электродвижущая сила, эдс

arcing ['RkIN] искрение

brushless бесщеточный

key component базовая деталь

electronic circuitry электронные схемы

excite [Ik'saIt] возбуждать

sensor ['sensq] датчик

to chase [CeIs] догонять

hard drive дисковод жёсткого диска ПК

household appliances бытовая техника

graphite ['grxfaIt] графит

composition ["kOmpq'zISn] состав

conventional [kqn'venSqnql] обычный

Text 1

DC motor

DC motor is one of two basic types of motors: the other type is the alternating current (AC) motor.

A direct current (DC) motor converts electrical energy into mechanical energy. ­ DC motors are the simplest type of motor and are used in household appliances, such as electric razors, and electric windows and fans in cars.

Parts of DC electric motor.

In the above picture, you can see two magnets in the motor: The armature (or rotor) is an electromagnet and the field magnet is a permanent magnet.

DC motor has either permanent magnets or electromagnets (electromagnetic windings), which produce a magnetic field. When current passes through the armature (also known as the coil) placed between the north and south poles of the magnet, the field generated by the armature interacts with the field from the magnet and the armature rotates. The force rotating the armature is called torque. In a DC motor, the magnet forms the stator, the armature is placed on the rotor and a commutator switches the current flow from one coil to the other. The commutator connects the power source to the armature through the use of brushes. DC motors operate at a fixed speed for a fixed voltage.

DC Motor Types

Among DC motors, there are shunt-wound, series-wound, compound-wound motors. There are also permanent magnet motors.

A: shunt-wound
B: series-wound
C: compound-wound
f = field coil

The field coils and the armature in a shunt-wound motor are connected in parallel, also known as shunt, so the field coil current is proportional to the load on the motor.

In series-wound motors, the field coils and armature are connected in series and the current flows through the field coils and through the armature. The advantage of series-wound motors is that they have a large torque and they can be operated at low speed.

A compound-wound motor is hybrid of both the shunt-wound and series-wound types.It combines the characteristics of a series-wound motor and a shunt-wound motor. It has a greater torque than a shunt motor but a constant speed.

The function of the commutator is to transfer current to the rotating shaft. Brushes, electric contacts on the commutator, connect the power source to the armature. A brush is an electrical component which makes contact between a stationary and a moving electrical circuit. Brushes usually consist of a carbon/graphite composition.

At certain times during the rotation of a DC motor, the commutator must reverse the current. This can lead to decreased motor life because of the wear and tear that occurs through friction and arcing.

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