Stators star connected

Heat generated in a star-connected stator winding... 

In the event of single phasing, in star-connected windings, one of the phases of each positive and negative sequence components will counter-balance each other, to produce zero current in the open phase (Figure 12.8(a)). The magnitude of these components in the two healthy phases are equal, i.e. I, = 1, and the maximum heat of the stator as in equation (12.4)... 

Figure 12.8 Stator and line currents on single phasing for a star-connected winding...

High voltage supphes within a plant are invariably arranged as three-phase star-connected systems. The star point of the transformer secondary winding or the generator stator winding is... 

Consider a cross-section on a plane transversal to the machine s longitudinal axis of rotation o, as suggested in Fig. 8.3a. Because of the usual modeling assumptions, the magnetic phenomena are considered to be uniformly distributed along the longitudinal axis, hence they are analyzed with a 2D approach on the plane of the cross-section [9, chapter 10], In Fig. 8.3 some notation is fixed for further reference. The cartesian (jc, y)-coordinate system (axes at 90° electrical to each other) is fixed to the stator. The 3-phase (star- or Y-connected) stator winding shown in... 

In order to restrict the detection of earth faults to those within the stator winding, and those from the stator terminals to the switchgear current transformers, a sensitive relay (64) is used. Three current transformers are used in the stator live lines and one in the star to NER connection. All four current transformers are connected in parallel such that any unbalance in the currents due to an internal fault is detected by the restricted earth fault relay (64). A sensitive high impedance relay is used to achieve an instantaneous response. However, if a high impedance is connected across a current transformer it is possible that very high voltages will appear across the impedance. This is due to the action of... 

---