In Plugging or Reverse Current Braking the armature terminals or the supply polarity of a separately excited or shunt motor when running are reversed. Therefore, in plugging the supply voltage V and the induced voltage Eb which is also called back EMF will act in the same direction. Thus, during plugging the effective voltage across …
In Dynamic Braking, a braking resistor Rb is connected across the armature as soon as the DC motor is disconnected from the supply mains. The motor now works as a generator, producing the braking torque. For the braking operation in Dynamic Braking, the motor is connected in two ways. Firstly the separately excited or shunt …
Dynamic Braking or Rheostatic Braking of DC Motor Read More »
The dc motor converts mechanical power into dc electrical power. One of the most important features of the dc motor is that their speed can easily be control according to the requirement by using simple methods. Such type of control is impossible in an AC motor. The concept of speed regulation is different from the …
Speed Control of DC Motor: Armature Resistance Control and Field Flux Control Read More »
Swinburne’s Test is an indirect method of testing of DC machines. In this method, the losses are measured separately and the efficiency at any desired load is predetermined. Machines are tested for finding out losses, efficiency and temperature rise. For small machines direct loading test is performed. For large shunt machines, indirect methods are used …
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 the no-load speed with a constant excitation. Contents: Applications …
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 …
Ward Leonard Method Of Speed Control Or Armature Voltage Control Read More »
Efficiency is simply defined as the ratio of output power to the input power. Let R be the total resistance of the armature circuit (including the brush contact resistance, at series winding resistance, inter-pole winding resistance and compensating winding resistance). The efficiency of the DC generator is explained below in the line diagram: I is …
In the present day world, 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 Machines are in Electrolytic Processes, Welding …
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 …
Characteristic is the graph between the two dependent quantities. It shows the steady-state characteristic of DC generators. The characteristic of the DC generators explains the relations between the loads, excitation and terminals voltage through the graph. Following are the three important characteristics of a DC Generator. Magnetization Characteristic This characteristic gives the variation of generating …
Characteristic of DC Generators – Separately Excited Self Excited And Compound Generator Read More »
