MAIN STRUCTURAL ELEMENTS OF A D. C. MACHINE
(ГЕНЕРАТОР ПОСТІЙНОГО СТРУМУ)

   

 A direct-current machine consists of two main parts, a stationary part, usually called the stator, designed mainly for producing a magnetic flux, and a rotating part, called the armature or the rotor. The stationary and rotating parts should be separated from each other by an air-gap. The stationary part of a d.c. machine consists of main poles, designed to create the main magnetic flux; commutating poles interposed between the main poles; and a frame. It should be noted here that sparkless operation of the machine would be impossible without the commutating poles. Thus, they should ensure sparkless operation of the brushes at the commutator.

      The main pole consists of a laminated core the end of which facing the armature carries a pole shoe and a field coil through which direct current passes. The armature is a cylindrical body rotating in the space between the poles and comprising a slotted armature core, a winding inserted in the armature slots, a commutator, and a brush gear.

      The frame is the stationary part of the machine to which are fixed the main and commutating poles and by means of which the machine is bolted to its bedplate. The ringshaped portion which serves as the path for the main and commutating pole fluxes is called the yoke. End-shields or frame-heads which carry the bearings are also attached to the frame.

      Of these main structural elements of the machine the yoke, the pole cores, the armature core and the air-gap between the armature core and the pole core are known to form the magnetic circuit while the pole coils, the armature windings, the commutator and brushes should form the electric circuit of the machine.

II. Translate the following phrases, using the given variants of translation:

      to consist – складатися : to consist of a stationary part and a rotating part;

      separated – окремий, відокремлений: the stationary and rotating parts should be separated from each other by an air gap;

     to serve – служити: the ringshaped portion or yoke serves as a path for the main and commutating pole fluxes.

III. Join the beginnings and the ends

           Beginnings                                                                           Ends

The stationary parts of a d. c machine are ....                a laminated core the end of which carries a pole shoe and a field coil.

The two main parts of a direct current machine are ....        main poles , commutating poles and a frame

The main pole consists of ....                                           а stationary part or stator and a rotating part, called the armature or the rotor.

IV. Arrange synonyms in pairs and memorize them:

     a) to consist of; to be separated from; to create; to be interposed between; to pass; to rotate;

     в) to be divided with; to produce; to introduce into; to permeate; to roll; to revolve; to comprise.

V. Write out the names of the machine parts and describe their operational characteristics