armature windings of generator

There are two types of armature windings most commonly used for a three phase generator.

i)Single layer winding.
ii) Double layer winding.

Conductors Construction :

Each bar consists of a large number of separately insulated strands to reduce the skin effect losses. In the straight slot portion the strands are transposed by 360` .The transposition provides for a mutual neutralisation of the voltage induced in the individual strands due to the slot cross filled and ensures that no or only small circulating current exists in the bra interior. The current flowing through the bar is thus uniformly distributed over the entire cross section and losses will be reduced.


Insulation of Bars :

The high voltage insulation is provided ,with thermosetting system. This system is void free and has excellent electrical ,mechanical and thermal Properties .All bars are provided with an end corona protection from the slots to the end winding portion and to prevent the formation of the crepage sparks.


Corona Protection :

To prevent potential difference and possible corona discharges between the insulation and the slot wall ,the slot section of the bars are provided with the outer corona protection .This corona protection consists of a wear resistance, highly flexible coating of alkyd varnish containing graphite.

Electrical Connection of Bars & Phase Connectors :


Electrical Connection of Bars :

Electrical connection between the top and bottom bar is made by brazing, one top bar being brazed to the associated bottom bar. The coil connections are wrapped with tapes applied half over lap. The thickness of the wrapper depends upon machine voltage. After taping, an insulating gap between the individual coil connections being sufficiently large, no additional insulation is required.


Phase Connectors :

The phase connectors consist of flat copper sections, the cross section of which results in the low specific current loading. The connections to the stator winding are or riveted and soldered type. The phase connectors are wrapped with mica resin tape applied half overlap, which contain the full quantity of synthetic resin having good quantity of penetrating properties .Then a wrapper of shrinking tape is applied .


Output Lead :

The beginning and end of the 3-phase winding is solidly bolted to the output leads with flexible. The output leads consists of fat copper sections with mica insulation. To prevent eddy current losses and unwarranted temperature rise , the output leads are brought through insulating plates.