Electrical drives and control pdf
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ELECTRICAL DRIVES & CONTROL-100 TWO MARKS WITH ANSWER
Define Drives A particular system employed for motion control is called drive. Transportation systems, fans, etc. Define electric Drives A system employed for motion control by using electric motor as a primemover is called electric drive. Write all basic elements of electric drives Electric drives consist of following basic elements. Write the functions of power modulators.
It modulates the power flow from source to load through motor. It converts D. C according to the needs. What are the types of electric drives It consist of three types such as a.
Individual drive b. Group drive c. Multi motor drive 6. Define individual drive. A single motor is used to drive a single load is called individual drive. Define group drive.
A single motor is drive a several machines is called group drive. Define multi motor drive. In this type of drive system separate motors are used for operating different parts of the same load is called multi motor drive.
What is heating curve? The curve is drawn between temperature rise Vs time, when drive is loaded called heating curve. Mention the different types of classes of duty. Continuous duty b. Short time duty c.
Intermittent duty d. Intermittent duty with starting e. What are the main factors influencing to select the electric drives for particular applications? Any motor select as a electric drive for particular application it should depend on the following factors a.
Transient operation c. Related with source. Need of cost e. Life period f. Reliability g. Location and environment What are the applications of electrical drives? Paper mills b. Electric traction c. Cement mills d. Steel mills What are the types of enclosures? Screen protected type b. Drip proof type c. Totally enclosed type d. Flame proof type What is meant by overload current capacity of motor.
It is generally greater than the full load current capacity of the motor. During the short time period, the motor can withstand by applying overload. Define continuous rating of a motor.
Continuous rating of a motor is denotes operation at constant load of sufficient duration. Centrifugal pumps, fans, compressors and conveyors are some examples of equipment which run continuously with constant load.
Compare AC and DC drives. DC drives: a. The power circuit and control circuit is simple and in expensive b. It require frequent maintenance c. What is meant by intermittent duty? There are certain loads which require motors to be run for a certain period of time and them switched off for a small period.
This type duty is called intermittent duty. Define heating time constant. Heating time constant is defined as the time taken by the machine to attain 0. The heating time constant of the machine is the index of the time taken by the machine to attain its final steady temperature rise Write the best choice of electric motors for the following application: a Pump load, b Elevator a Pump load- single phase or three phase cage induction motor b Elevator DC series motor, Slip ring induction motor.
What are the advantages of the group drive? A single large motor can be used instead of a number of small motors. The rating of the single large motor may be approximately reduced.
What is meant by braking? Stopping of motor by producing load torque opposite to the torque produced by the electric motors. Write the types of braking used for DC motor a. Dynamic or rheostatic braking b. Plugging or reverse voltage braking c. Regenerative braking. What is meant by dynamic braking? In this method the armature of shunt motor is disconnected from the supply and is connected across a variable resistance R.
The braking torque is controlled by the resistance R. What is meant by plugging in DC motor? In this method, connections of the armature terminals are reversed so that motor tends to run in the opposite direction therefore the braking torque is produced. What is meant by regenerative braking in DC motor? In regenerative braking , generated energy is supplied to the source.
What is a mechanical characteristic of a motor? Speed torque characteristics of a motor are called mechanical characteristics of motor. Why motor characteristics are important? To select the electric motor for a particular application it is necessary to know the characteristics of electric motors.
Only the performance of DC motor can be judged from its characteristics curve. State the different modes of operation of three phase induction motor. Motoring mode b. Braking mode c. Generating mode 9. Give the application of DC motors a. DC shunt motor- Over head cranes b.
DC series motor-Traction c. DC compound motor-Pressing machine What are the operating characteristics of DC series motor? High starting torque b. Low speed at high loads and dangerously high speed at low loads. What are the operating characteristics of DC shunt motor? Medium starting torque b. Approximately constant speed. What is the relation between speed and flux of a dc motor?
The speed of a dc motor is inversely proportional to field flux. Name the types of braking used in shunt motors. Dynamic braking b.
Define Drives A particular system employed for motion control is called drive. Transportation systems, fans, etc. Define electric Drives A system employed for motion control by using electric motor as a primemover is called electric drive. Write all basic elements of electric drives Electric drives consist of following basic elements. Write the functions of power modulators. It modulates the power flow from source to load through motor. It converts D.
Premium Membership. Learn from experienced power engineers. DC motors are widely used in many speed-control drives. Open-loop operation of DC motors may be satisfactory in many applications. When the load increases the speed of the motor drops and the new operating point of speed is obtained after the transient.
Definition : The system which is used for controlling the motion of an electrical machine, such type of system is called an electrical drive. In other words, the drive which uses the electric motor is called electrical drive. The electrical drive uses any of the prime movers like diesel or a petrol engine, gas or steam turbines, steam engines, hydraulic motors and electrical motors as a primary source of energy. This prime mover supplies the mechanical energy to the drive for motion control. The block diagram of the electrical drive is shown in the figure below. The electrical load like fans, pumps, trains, etc.
Free Electric Drives books
A basic study of electrical drives is fundamental to an electrical engineering curriculum, and, today, gaining a better academic understanding of the theory and application of controlledvelocity electrical drive technologies is increasingly important. Electrical drives provide superior control properties for a wide variety of processes, and the number of applications for precision-controlled motor drives is increasing. A modern electrical drive accurately controls motor torque and speed with relatively high electromechanical conversion efficiencies, making it possible to considerably reduce energy consumption. Because of the present pervasive use of electric machinery and the associated large energy flows, the introduction of more effective and efficient electrical drives promises significant environmental benefit,. And electrical engineers are responding by introducing new and more efficient electrical drives to a myriad of industrial processes.
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