Construction and Application of D.C. Machines
Construction of D.C. Machines
A D.C. Machines is made up of two basic components:
—The stator which is the stationary part of the machine. It consists of the following elements: a yoke inside a frame; excitation poles and winding; commutating pole (compoles) and winding; end shield with ball or sliding bearing; brushes and brush holders; the terminal box.
—The rotor which is the moving part of the machine. It is made up of a core mounted on the machine shaft. This core has uniformly spaced slots into which the armature winding is fitted. A commutator, and often a fan, are also located on the machine shaft.
The frame is fixed to the floor by means of a bedplate and bolts. On low-power machine the frame and yoke are one and the same components, through which the magnetic flux produced by the excitation poles closes. The frame and the yoke are built of cast iron or cast steel or sometimes from welded steel plates.
In low-power and controlled rectifier-supplied machine the yoke is built up of (0.5~1mm) laminated iron sheets. The yoke is usually mounted inside a non-ferromagnetic frame(usually made of alumininum alloys, to keep down the weight). To either side of the frame there are bolted two end shields, which contain the ball or sliding bearing.
The (main) excitation poles are built from 0.5~1mm iron sheets held together by riveted bolts. The poles are fixed into the frame by means of bolts. They support the windings carrying the excitation current.
On the rotor side, at the end of the pole core is the so-called pole-shoe which is meant to facilitate a given distribution of the magnetic flux through the air gap. The winding is placed inside an insulated frame mounted on the core, and secured by the pole-shoe.
The excitation winding are made of insulated round or rectangular conductors, and are connected either in series or in parallel. The windings are linked in such a way that the magnetic flux of one pole crossing the air gap is directed from the pole-shoe towards the armature (north pole ) , which the flux of the next pole is directed from the armature to the pole-shoe (south pole) .
谢谢 这篇文章有三千多字呢 我用有道翻译了 但根本看不懂 您能帮帮忙吗?谢谢
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