A DC generator operates on the principle of Faraday’s laws of electromagnetic induction. According to Faraday’s law, whenever a conductor is placed in a fluctuating magnetic field (or when a conductor is moved in a magnetic field) an EMF is induced in the conductor.

Rule #1: For generation of DC voltage select a brushed DC motor or use a brushless EC (BLDC) motor with voltage rectifier. For the generation of AC voltage, select a brushless EC motor and connect 2 phases only. Hall sensors are not needed on brushless motors.

A direct-current (DC) generator is a rotating machine that supplies an electrical output with unidirectional voltage and current. The basic principles of operation are the same as those for synchronous generators.

Electric generator, also called dynamo, any machine that converts mechanical energy to electricity for transmission and distribution over power lines to domestic, commercial, and industrial customers. Generators also produce the electrical power required for automobiles, aircraft, ships, and trains.

Alternating current (A.C) is five times more dangerous than Direct current (D.C). The frequency of the alternating current is the main reason for this severe effect on the human body. The frequency of 60 cycles is in an extremely harmful range. At this frequency, even a small voltage of 25 volts can kill a person.

Applications of DC Generators They are used in DC motors where speed control is necessary. They are used as portable generators where low power supply is required. They are used in motorcycles as dynamos, in toys such as remote control cars and in appliances such as electric shavers.

Uses & Design Differences. AC and DC generators both use electromagnetic induction to generate electricity. An AC generator creates an alternating current that periodically reverses direction. But in a DC generator, a direct current flows in one direction.

A DC generator or direct current generator is one kind of electrical machine, and the main function of this machine is to convert mechanical energy into DC (direct current) electricity. The energy alteration process uses the principle of energetically induced electromotive force.

The most significant difference between DC motor and DC generator lies in the conversion mechanism….Difference between DC Motor and DC Generator.

DC machines are also used in applications where high starting torque and accurate speed control over a wide range are important. Major applications for DC motors are: elevators, steel mills, rolling mills, locomotives, and excavators. Like other rotating machines, DC motors result from the interaction of two magnets.

A DC Generator is an electrical device which converts mechanical energy into electrical energy. It mainly consists of three main parts, i.e. magnetic field system, armature and commutator and brush gear.

All dc generators have two parts, one part called the “stator”, as it is stationary, and the other part which moves or rotates called the “rotor”. Generally for a dc generator design, the magnetic field is on the stator and the power generating coil winding is on the rotor.

There are three methods of excitation, and thus three main types of DC generators: Permanent Magnet DC Generators – Field coils excited by permanent magnets. Separately Excited DC Generators – Field coils excited by some external source. Self Excited DC Generators – Field coils excited by the generator itself.

The DC generator converts mechanical power into electrical power. The magnetic flux in a DC machine is produced by the field coils carry current. The circulating current in the field windings produces a magnetic flux, and the phenomenon is known as Excitation.

As the armature rotates, a voltage is generated in its coils. In the case of a generator, the emf of rotation is called the Generated emf or Armature emf and is denoted as Er = Eg. In the case of a motor, the emf of rotation is known as Back emf or Counter emf and represented as Er = Eb.

Most of the shunt DC generators work on the principle of self-excitation. Following a positive feedback like action, the flux in a self-excited DC generator, builds up from a small amount of residual magnetism present in the field poles. In self-excited DC generators, the field winding is connected across the armature.

For DC shunt motor the field resistance is high and armature resistance is low so the variation of flux is very less when rated voltage is applied to the motor and motor speed does not exceeds rated speed at no load. So we can start the DC shunt motor with no load.

BRUSH HOLDERS ARE OFF ELECTRICAL NEUTRAL- even if the brush holders are equally spaced they may be out of their correct position and can cause sparking. OVERLOAD- excessive load on motor can cause sparking of brushes.

shunt field are parallel and hence have low current. Therefore it have more number of turns and core gets saturated due to which flux will be constant. Series generator have series winding and thus a high armature current is same as field current. Due to which resistance of field winding is low.

A DC shunt motor is a type of self-excited DC motor, and it is also known as a shunt wound DC motor. The field windings in this motor can be connected in parallel to the armature winding. This motor has a low starting torque and also runs at a constant speed.

A shunt generator is a type of direct current electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current.

Applications of Shunt Wound DC Generators They are used for general lighting. They are used to charge battery because they can be made to give constant output voltage. They are used for giving the excitation to the alternators. They are also used for small power supply (such as a portable generator).

The alternator in a car (i.e., the DC generator which recharges the battery) is a common example of a DC generator of the type discussed above. Of course, in an alternator, the external torque needed to rotate the coil is provided by the engine of the car. Figure 42: Emf generated in a steadily rotating DC generator.

From what you read above, we can say that the main advantages of DC generators include simple design, simple parallel operation, and fewer problems of system stability. You also read about different types of DC generators and their working principle.

Advantages of Dc shunt motor:

• The power supply of the DC motor is any way cheap.
• Shunt would motor able to runs at a predetermined speed.
• The speed of a dc shunt motor is sufficiently constant.
• Direct current machines can use for heavy industrial applications where the torque and speed wider range.

Characteristics of a DC Shunt Motor:

• Speed-Armature Current Characteristic:
• Torque-Armature Current Characteristic:
• Speed-Torque Characteristic:
• Break in Field Circuit of a DC Motor:

AC motors are generally considered to be more powerful than DC motors because they can generate higher torque by using a more powerful current. However, DC motors are typically more efficient and make better use of their input energy.

Disadvantages of DC motors

• High initial cost.
• Increased operation and maintenance cost due to the presence of commutator and brush gear.
• Cannot operate in explosive and hazard conditions due to sparking occur at brush (risk in commutation failure)

Thus, the speed of a DC motor can control in three ways:

1. By varying the flux, and by varying the current through field winding.
2. By varying the armature voltage, and the armature resistance.
3. Through the supply voltage.

DC can be generated in a number of ways: An AC generator equipped with a device called a “commutator” can produce direct current. Use of a device called a “rectifier” that converts AC to DC. Batteries provide DC, which is generated from a chemical reaction inside of the battery.

Application of DC Series motor

• Cranes.
• Air compressor.
• Lifts.
• Elevators.
• Winching system.
• Electric traction.
• Hair drier.
• Vacuum cleaner and in speed regulation application.

Below are some of the most prominent advantages of DC motors:

• They are suitable for low-speed torque.
• They have adjustable speed.
• They offer a wide range of speed control both below and above the rated speed.
• They have a very high and strong starting torque.

Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.

So, a DC motor is started by using a starter. There are various types of dc motor starters, such as 3 point starter, 4 point starter, no-load release coil starter, thyristor controller starter etc. The basic concept behind every DC motor starter is adding external resistance to the armature winding during starting.

Difference Between Dynamo and DC Motor – definition

The input of a brushless DC motor is current/voltage and its output is torque. Understanding the operation of the DC motor is very simple from a basic diagram is shown below. DC motor basically consists of two main parts. The rotating part is called the rotor and the stationary part is also called the stator.

Torque or moment or moment of force is the tendency of a force to rotate or move an object about an axis. A force is a push or pull, likewise, torque is a twist to an object. Mathematically, torque, T = F × r.

A practical way to calculate the magnitude of the torque is to first determine the lever arm and then multiply it times the applied force. The lever arm is the perpendicular distance from the axis of rotation to the line of action of the force. and the magnitude of the torque is τ = N m.

DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.

Nominal voltage: 12VDC. Voltage range: 12 – 24VDC. Current @ maximum efficiency: 0.063A. Speed @ maximum efficiency: 8600 RPM.

conductors in armature. Hence, speed of a DC motor is directly proportional to emf of rotation (E) and inversely proportional to flux per pole (φ). N=120f/P.

Thus, the speed of a DC motor can be controlled in three ways:

1. By varying the supply voltage.
2. By varying the flux, and by varying the current through the field winding.
3. By varying the armature voltage, and by varying the armature resistance.

The correct answer is use a bigger fan of same 12V rating which draws more current. However, if fan can not be changed but a slightly higher cooling is desired then you can try feeding 13 V power supply to a 12 V fan. Mostly it would run at a slightly higher speed.

If you want to adjust the output torque within the rated torque range, you can usually adjust the input voltage or the amount of excitation current. If the DC motor has been set, the torque can only be increased by the speed reducer, which can be multiplied or even increased by a thousand times.

Increasing the speed can be achieved by increasing the supply frequency as the speed and frequency are directly proportional; however, there are two constraints. The first is the saturation of the magnetic circuit, but this issue can be significantly avoided by keeping the V/f ratio constant.