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DC GENERATORS


A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. This principle is explained as follows; Whenever a conductor is moved within a magnetic field in such a way that the conductor cuts across magnetic lines of flux, voltage is generated in the conductor. The AMOUNT of voltage generated depends on (1) the strength of the magnetic field, (2) the angle at which the conductor cuts the magnetic field, (3) the speed at which the conductor is moved, and (4) the length of the conductor within the magnetic field.continue..


Simple direct current (DC) generators contain an armature (or rotor), a commutator, brushes, and a field winding. The interactive tutorial presented below examines the operation of a simple DC or direct current generator.
A variety of sources can supply mechanical energy to the DC generator to turn its armatures in order for its coils to cut through the lines of force in a magnetic field. These sources include steam, wind, a waterfall, or even an electric motor.
In a direct current generator, the commutator's job is to change the alternating current (AC), which flows into its armature, into direct current. To put it another way, commutators keep the current flowing in one direction instead of back and forth. They accomplish this task by keeping the polarity of the brushes stationed on the outside of the generator positive. The commutator is made up of copper segments, with a pair (of segments) for every armature coil being insulated from all the others.continue..


A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. This principle is explained as follows: Whenever a conductor is moved within a magnetic field in such a way that the conductor cuts across magnetic lines of flux, voltage is generated in the conductor. The AMOUNT of voltage generated depends on (1) the strength of the magnetic field, (2) the angle at which the conductor cuts the magnetic field, (3) the speed at which the conductor is moved, and (4) the length of the conductor within the magnetic field.The POLARITY of the voltage depends on the direction of the magnetic lines of flux and the direction of movement of the conductor. To determine the direction of current in a given situation, the RIGHT-HAND RULE FOR GENERATORS is used. This rule is explained in the following manner. .continue..


Separately excited D.C. Generator are those whose field magnets are energized from an independent source of D.C. Current. Separately excited generators are often used in feedback control systems when control of the armature voltage over a wide range is required. 
Self excited D.C. Generators are those whose field magnets are energized by the currents produced by the generators themselves.
Shunt wound D.C. Generator have field windings and armature windings connected in parallel (shunt). The output varies inversely with load current. It contains many turns of fine wires. When a generator is in operation, whether or not it is delivering load current, the shunt field is always excited.


Generators used in battery-charging systems must be regulated so as to not overcharge the battery(ies) they are connected to. Here is a crude, relay-based voltage regulator for a DC generator: Simple electro-mechanical relay circuits such as this one were very common in automotive electrical systems during the 1950's, 1960's, and 1970's. The fundamental principle upon which their operation is based is called negative feedback: where a system takes action to oppose any change in a certain variable. In this case, the variable is generator output voltage. Explain how the relay works to prevent the generator from overcharging the battery with excessive voltage. .continue..

The speed of a d.c. machine operated as a generator is fixed by the prime mover. For general-purpose operation, the prime mover is equipped with a speed governor so that the speed of the generator is practically constant. Under such condition, the generator performance deals primarily with the relation between excitation, terminal voltage and load. These relations can be best exhibited graphically by means of curves known as generator characteristics. These characteristics show at a glance the behaviour of the generator under different load conditions.
D.C. Generator Characteristics The following are the three most important characteristics of a d.c. generator:.continue..

Power generators are mechanical equipment that provide power by turning mechanical energy into electricity. These power generating machines are mostly used to provide much needed power during power disruptions. These machines are also sometimes used to provide power on locations that has no utility power. Some power generators are used to provide electrical power on vehicles such as RVs, automobiles, trains, airplanes, boats, etc.
There are numerous types of power generators today. And one of the many types is the Direct Current generator or the DC generator types. Most of the power generator types that are in use nowadays are AC types. However, there several circumstances that favour DC generators over AC generators..continue..

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