I’m not an expert on brushless alternators, but when I acquired a damaged Dunlite wind turbine, I became seriously interested in how they work. Basic Theory. The synchronous electrical generator (also called alternator) belongs to the comprehend the physical principles governing the operation of electric rotating. The brushless alternator consists of 3 phase AC winding and DC field winding on the stator. The magnetic amplifier works on the principle of saturation of magnetic core. It has . Automatic alternator paralleling operation facility available.
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It can be shown that if T r is the mechanical torque princi;le by a turbine to the rotor of the induction generator, the generated electrical stator power transferred across the air gap is given by T r N s. At this point, the torque delivered by the wind turbine is sufficient to accelerate the unit further, the speed exceeds the synchronous speed and the induction machine becomes a generator.
There are two main ways to produce the magnetic field used in the alternators, by using worjing magnets which create their own persistent magnetic field or by using field coils.
Star connection which is generally used requires four slip rings. An automatic voltage control device controls the field current to keep output voltage constant. The voltage generated is not steady and its often difficult to control the excitation.
The process also produces an inherent AVR action, since any load current in the output brushoess winding induces more rotor current to offset the armature reaction effect. Leave a comment Cancel reply Your email address will not be published. The first diesel electric locomotives, and many of those still in service, lrinciple DC generators as, before silicon power electronics, it was easier to control the speed of DC traction motors.
The field current is supplied with the help of low voltage DC generator also known as an exciter.
Before going to the explanation part you should know about stator,rotor,field windings and armature. In case, the alternator is connected to main engine or propeller shaft, then there will be too much variations in the speed.
Many alternators are cooled by ambient air, forced alternattor the enclosure by an attached fan on the same shaft that drives the alternator.
The poles produce a stationary field which induces a voltage in the exciter rotor winding as it turns. The main alternator uses the opposite configuration with a rotating field and stationary armature.
The rotor contains no windings and has double the tooth-pitch of the stator. The other pole had an open end to receive the stator winding.
The stationary part of an alternator is called the stator and the rotating part is called the rotor. Anonymous 16 March at Larger marine diesels may have two or more alternators to cope with the heavy electrical demand of a modern yacht. Three-phase alternators are the most common, but polyphase alternators can be two phase, six phase, or more. Either configuration works equally well and both are used separately or in principlf depending on mechanical, electrical and other objectives.
The sliprings can be eliminated in generators using two mechanically coupled stators and wound rotors with the bruzhless stator supplied from the frequency converter.
Of course the entire system is the complete generation set consisting of the generator and only the marked part is the alternator. Bijoy chandrasekhar 20 July at The brushless high speed alternators also doesn’t use any DC exciters. This is great one to see your blog last time I see same design to my friend constraction building in chennai. Archived from the original on 11 February This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC supplies the rotating field of the main alternator and hence alternator output.
The outer cover also held the three-phase stator windings. The larger of the two sections is the main alternator and the smaller one is the exciter. Retrieved from ” https: A simple form of wind turbine generator uses an induction machine driven by the wind turbine. Newer Post Older Post Home. Working Principle of Alternators Do you know how do alternators work?
How Does Brushless Alternator Works? In small sizes, the induction generator can provide a low-cost alternative to the syn- chronous generator, but nrushless has a relatively poor performance when supplying a low power factor aletrnator. Faraday developed the “rotating rectangle”, whose operation was heteropolar — each active conductor passed successively through regions where the magnetic field was in opposite directions.
How Does Brushless Alternator Works? (With Diagram) | Marinesite
Bijoy chandrasekhar 19 January at Most of these had two generators: With a simple squirrel cage rotor therefore the slip must be bruahless to avoid high rotor loss with a resultant low efficiency.
In other projects Wikimedia Commons. The even numbered teeth experience a low flux level. As shown in the figure, the rotor is located in between the stator.