We discussed the basics of dc generators in one of our previous articles. This article emphasizes the dc generator working.
Before understanding the dc generator working in detail. Let’s know the basic principle first. DC generator works on the principle of faraday’s law of electromagnetic induction. Which states that whenever a conductor is placed in a varying magnetic field, it induces an e.m.f. And if the circuit is closed the generated emf induces a current in the circuit.
As a conductor/coil is placed between magnetic fields a current is induced in the coil. Every time the conductor rotates is cuts the field lines and an emf is generated. The magnetic field moves from the north pole to the south pole of the magnet.
Note** The color coding applied for coil and split-ring in this article is used only for a better understanding of the direction of induced current and dc generator working.
So we know the direction of the magnetic field. Let’s consider, the coil placed in the field rotates in a clockwise direction. Now we can find out the direction of induced current in the coil by fleming’s right-hand rule.
Fleming’s right-hand rule states that hold the right-hand forefinger, middle finger, and thumb perpendicular to each other. Where the forefinger denotes the direction of the magnetic field, the thumb denotes the direction of motion of the conductor and the middle finger will denote the direction of induced current in the conductor.
So according to fleming’s right-hand rule direction of the induced current is shown in the fig. given below.
In fig 1. The magnetic field moves from the north pole to the south pole and the rotation of the conductor is clockwise the red line moves upward. So the direction of the current on the red line is inside the plane and in fig 2. The magnetic field moves from the same north pole to the south pole and the rotation of the conductor is clockwise then the blue line moves downwards and the direction of the induced current for a blue line is outside the plane.
As the coil starts to rotate further, it comes at 90 degrees with the field lines. And the rotation of the coil is parallel to the field line so the coil was not able to cut the flux of the field line to generate emf. Therefore no current will be flowing at this time.
Now as the coil rotates further clockwise and the red line moves toward the south pole the current generated reverses its direction and similarly the blue line. That how the current flows continuously in the loop.
As in the above figs. The loop is open it will not generate electricity. But when the loop forms the closed-loop structure it will convert mechanical energy into electricity (electrical energy) and acts as a generator.
As we know generators are of two types AC and DC generators. AC generator produced AC power and DC generator produces DC power. So let’s see how DC generator works?
Read more: Types of DC generator
DC generator working
In the above section, we discussed how current is flowing in the coil. So in the dc generator, a split ring is connected to the coil to make it a closed loop. The split ring is the conducting cylinder divided into two parts that are insulated from each other. Two brushes are placed on the split ring and the external load is connected to the brushes.
Now when the coil is placed in field lines the blue side of the coil is connected to the pink side of the split ring and the red side of the wire is connected to the yellow side of the split ring. As the coil starts rotating clockwise, the blue side of the coil rotates towards the south pole with the respective side of the split ring connected and similarly for the red part of the coil.
During the continuous rotation of the coil, the split ring is always connected to the coil. This makes the circuit a closed loop which results in the continuous supply of electrical energy to the load.