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The working principle of DC generator

When the DC generator is working, the action of the external mechanical force drives the conductor coil to rotate in the magnetic field, and continuously cut the magnetic lines of induction to generate induced electromotive force. Figure 1 shows a schematic diagram of the working principle of a typical DC generator

DC generator

 

Figure 2 shows the working process at the moment when the rotor winding of the DC generator starts to rotate. When the external mechanical force drives the winding to rotate, the coils ab and cd respectively do the action of cutting the magnetic induction line. According to the principle of electromagnetic induction, a current is generated inside the winding. The direction of the current can be determined by the right hand. It can be judged as: induced current through the coil dc→cb→ ba, commutator 1, brush A, ammeter, brush B, and commutator 2 form a loop.

GC generator 01

Figure 3 shows the working process after the rotor winding of the DC generator has been rotated through 90°. When the winding turns 90°, the two winding sides are in the physical neutral plane of the magnetic field, and the brushes are not in contact with the commutator segments, no current flows in the windings, F=0, and the torque disappears.

DC generator 2

Figure 4 shows the working process of the DC generator rotor winding after 90° rotation. Under the action of external mechanical force, the rotor winding continues to rotate. At this time, the winding continues to cut the magnetic induction line, and an induced current can be generated in the winding. The induced current flows through the winding ab→bc→cd, commutator 2, brush A, The ammeter, brush B, and commutator 1 form a loop.

DC gneerator 3

It can be seen from Figure 5 that the induced electromotive force in the rotor winding is an alternating electromotive force, while the electromotive force at the AB end of the brush is a DC electromotive force, that is, through the commutator and the brush, the current output by the rotor winding is always One direction is the working principle of a DC generator.

It is worth noting that in the actual DC generator, the rotor winding is not a single coil, but composed of many coils. These coils in the winding are evenly distributed in the slots of the rotor core, and the end of the coil is connected to the commutation On the corresponding slide of the device. The commutator is actually composed of many arc-shaped conductive sliding sheets, which are insulated from each other by mica sheets. The greater the number of coils and commutator slides, the smaller the DC pulsation generated by the generator. Generally, the output voltage of small and medium DC generators is 115V, 230V, 460V, and the output voltage of large DC generators is about 800V.


Post time: Aug-07-2020