Resistance Series Generator:
- Independently Excited:
This generator has two field windings. One called the different excitation field, delivers a consistent attractive motion, ɸm, and is invigorated with alternating current through a ferro-thunderous voltage controller and a silicon rectifier, both mounted on the generator outline. The other called the resistance series field, is set in series with the welding circuit. At no heap, there is no ongoing moving through the series field winding and the e.m.f. of the generator is exclusively because of the attractive motion, ɸm.
While the welding circuit is finished and a curve is struck, the series winding produces a changing attractive transition, ɸo, which goes against the fundamental field motion, ɸm. With the expansion in welding current, the impact of resistance series field additionally increments, so the absolute attractive motion is diminished, and the terminal voltage of the welding generator is cut down.
At the point when there is a short out, the two attractive motions become almost equivalent in greatness, the all out attractive transition breakdowns, and the terminal voltage of the generator drops to nothing. Hence, the impact of the resistance series field is one of creating hanging volt-ampere trademark. Welding current can be adjusted persistently by fluctuating the primary transition, ɸm, with a rheostat, Rh.
Self Excited:
A circuit chart of a self-energized series generator is displayed in Fig. 4.21 (b). As seen from the chart, the field winding is stimulated from one-half of the armature twisting of the actual generator. For this reason there is a third brush c, set between the principal brushes an and b. Therefore it is otherwise called THIRD BRUSH GENERATOR. Under load, the voltage between brushes an and c remaining parts for all intents and purposes steady and the self excitation field twisting connected across the two brushes delivers a steady attractive field, ɸm
At the point when the circular segment is started, the welding current streams in the series field winding associated so that its attractive transition, ɸ0, goes against the attractive field, ɸm, of the exciter. The bigger the ongoing in the welding circuit, the more grounded the kicking activity of the series winding, and lower the generator voltage, as the e. m. f. actuated in the armature twisting of the generator relies upon the resultant attractive field. At the hour of short out the upsides of ɸm and ɸ0 are almost equivalent and inverse in real life consequently the resultant transition is practically immaterial and the terminal voltage drops to nothing. In this way, the series twisting assists in accomplishing a hanging volt-ampere normal for the power with obtaining.
Part Pole D.C. Welding Generator:
In a split-shaft welding generator a hanging volt-ampere trademark is gotten inferable from the impact of armature response. This generator is likewise called a BIPOLAR WELDING GENERATOR and is utilized mostly for manual welding.
This generator has four fundamental shafts and three arrangements of brushes riding the analyst, as displayed in Fig. 4.22. As unmistakable from the traditional dc generator in which north and south poles are put on the other hand, in a bipolar generator the like poles are put next to each other (S1 S2 and N1N2). Two contiguous like posts might be respected, attractively, as a solitary shaft split into two sections, subsequently the name split-post generator.
Bipolar Welding Generator
The attractive motion connecting the shafts might be isolated into two sections. One section moves from N1 to S1and the other from N2 to S2. The greatness of the e. m. e armature relies upon the densities o two transitions denser the motion cut across by the armature guides, the more prominent the e. m. f. of the armature. The welding circuit is associated with the brushes An and B, and the field loops twisted upon the attractive shafts are associated with the brushes An and E.
At the point when the curve is begun, the ongoing coursing through the armature winding sets up an attractive field around it. The attractive motion rises out of the armature center and ranges the air space between the armature and the shafts. A piece of the motion enters S1 has its way through the edge, S2, and the air hole in the armature center. The other piece of the transition has its way through N1, the casing, N2, and crosses the air space to enter the armature center. In Fig. 4.22, the way of the attractive motion in the armature is shown by the dabbed lines.
The bigger the ongoing in the armature winding, the more grounded the magnetic transition.
Alluding to the chart, it tends to be seen that the attractive transition in the armature twisting moves with the attractive motion in the posts N1 and S1(as shown by thick bolts) and against the attractive motion in the shafts N2 and S2. At the end of the day the armature attractive motion will in general development attractive transition in the posts on the one side, and to kill it on the other.
The attractive posts N1 and are built to such an extent that they work in states of attractive immersion, and the expansion of armature attractive motion can’t increment it any longer, much as a soaked saline arrangement can’t break up any longer salt.
The attractive transition of the armature, which goes against the attractive motion in the shafts N2 and S2, lessens this motion and truth be told nearly kills it. The substituting activity of the super attractive motion increments as the ongoing in the welding circuit increments. A more vulnerable attractive motion in the shafts creates a lower generator voltage.
