The OR Operation is also one of the functions in a digital logic circuit. It is represented by a plus (+) sign. For example: x + y = z which is read as “x or y is equal to z”. The truth table for the OR operation is shown in the table below: The truth …
The three Binary Operations are AND Operation, OR and NOT Operation. A binary logic deals with variables having distinct values like true or false, yes or no, hot or cold, high or low, etc. In a digital system design, assigning the values 1 or 0 to these two values of the variables because digital algebraic …
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 …
