Regenerative Braking

In Regenerative Braking, the power or energy of the driven machinery which is in kinetic form is returned back to the power supply mains. This type of braking is possible when the driven load or machinery forces the motor to run at a speed higher than no load speed with a constant excitation. Contents: Applications…

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Ward Leonard Method Of Speed Control Or Armature Voltage Control

Ward Leonard Method of speed control is achieved by varying the applied voltage to the armature. This method was introduced in 1891. The connection diagram of the Ward Leonard method of speed control of a DC shunt motor is shown in the figure below. Contents Torque and Power Characteristic Advantages of Ward Leonard Drives Drawbacks…

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Efficiency of DC Generator

Efficiency is simply defined as the ratio of output power to the input power. Let R = total resistance of the armature circuit (including the brush contact resistance, at series winding resistance, interpole winding resistance and compensating winding resistance). I is the output current Ish is the current through the shunt field Ia is the…

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Applications of DC Machines

In the present day world, the electrical energy is generated in bulk in the form of an alternating current. Hence, the use of DC machines, i.e., DC generators and motors are very limited. They are mainly used in supplying excitation of small and medium range alternators. The Industrial Applications of DC are in Electrolytic Processes,…

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Losses in DC Machine

The losses that occur in a DC Machine is divided into five basic categories. The various losses are Electrical or Copper losses (I2R losses), Core losses or Iron losses, Brush losses, Mechanical losses, Stray load losses. These losses are explained below in detail. Contents: Electrical or Copper losses Magnetic Losses or Core Losses or Iron…

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Characteristic of DC Generators – Separately Excited Self Excited And Compound Generator

Characteristic is the graph between the two dependent quantities. Following are the three important characteristics of a DC Generator. Magnetization Characteristic This characteristic gives the variation of generating voltage or no load voltage with field current at a constant speed. It is also called no-load or open circuit characteristic. Internal Characteristic Internal characteristic of DC…

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Starting of DC Motors

A starter is a device to start and accelerate a motor. A controller is a device to start the motor, control and reverse the speed of the DC motor and stop the motor. It also protects the motor from any damage. Need of Starters for DC Motors The armature current of a motor is given…

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Power Flow Diagram of DC Generator and DC Motor

The Power Flow Diagram is used to determine the efficiency of a generator or motor. The power flow diagram of DC Generator is shown below. In the above figure of power flow diagram of DC Generator, it is shown that initially the mechanical power is given as an input which is converted into electrical power,…

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Methods of Improving Commutation

There are three main methods of Improving Commutation or obtaining sparkles Commutation is Resistance and Voltage Commutation and Compensating Winding. Further, the voltage commutation consists of another two methods which are used to produce the injected voltage, named as Commutating poles or Interpoles and Brush Shift. The following methods of Improving Commutation are explained below…

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Speed Regulation of DC Motor

If the load is applied to the DC motor or machine, the speed of the motor decreases automatically. Thus to maintain the constant speed, the difference between no load and full load speed called as Speed Regulation should be maintained very less. The motor is said to at good regulation if they maintian the constant…

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