How an Alternator Operates
An alternator is probably the most essential part of every automobile and is most extensively used here. Its functioning can be better understood by studying the various stages involved inside a typical vehicle alternator.
Let’s walk through its different stages of operation:
To initiate the alternator, some amount of power is derived from the battery which is under charge and supplied to the rotor field winding via the voltage regulator. The rotor armature instantly develops a strong magnetic field around it and interacts with the stator assembly. The action forces the rotor to rotate. The rotating rotor’s magnetic field around the stator induces a strong AC current in the stator windings. This voltage is applied to the ignition chamber where it is converted into a high voltage spark. The spark ignites the present fuel mixture to create an explosion and start the engine. Since the engine is connected to the rotor of the alternator through a pulley and belt mechanism, it takes hold of the rotor rotation. The rotor now relieves the battery and starts rotating from engine power. After this, the alternator’s stator voltage is solely used to charge the battery and power other electrical equipment.
A voltage regulator is specifically included to strictly monitor the charging level of the battery by correcting the stator output current accordingly. The corrections are made by appropriately increasing or decreasing the rotor field current.
For example, as long as the connected battery is not fully charged, the regulator maintains a higher current level to the rotor field winding; this increases its electromagnetic effect over the stator winding, which in turn delivers a higher amount of current to the battery. This process starts reversing as the battery gradually gets fully charged.
Primarily, the stator may comprise of three sets of windings, each of these being positioned differently to each other.
Normally the above windings exists in two types of configurations, namely in Wye and delta designs as shown in the diagrams. The induced current from these windings result in a three phase output. Three phase output helps in generating more voltage even at lower speeds, thus making the functions more efficient.
When an alternator is intended to generate electricity from wind power, the pulley-belt assembly of the rotor may be simply integrated to the turbine mechanism and the above procedure replicated.
However, since the main idea here is to charge a connected battery most efficiently, any malfunction in the above explained procedure may drastically hamper the results. Also, since the entire operation involves many critical electronic and mechanical stages, pin-pointing a particular snag may be pretty difficult and can be properly located only with an oscilloscope.
The next section shows the various possible outcomes produced by an oscilloscope for different faults that may possibly occur inside an alternator.
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