Posts

Showing posts with the label INDUCTION

#20 Explain the application of storage batteries.

Explain the application of storage batteries. Storage batteries are used for various purposes, some of the applications are mentioned below: • For the operation of protective devices and for emergency lighting at generating stations and substations. • For starting, ignition and lighting of automobiles, aircrafts etc. • For lighting on steam and diesel railways trains. • As a supply power source in telephone exchange, laboratories and broad casting stations. • For emergency lighting at hospitals, banks, rural areas where electricity supplies are not possible.

#19 What is slip in an induction motor?

What is slip in an induction motor? Slip can be defined as the difference between the flux speed (Ns) and the rotor speed (N). Speed of the rotor of an induction motor is always less than its synchronous speed. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol ‘S’.

#18 Why back emf used for a dc motor? highlight its significance?

Why back emf used for a dc motor? highlight its significance. The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back emf. Its value depends upon the speed of rotation of the armature conductors. In starting, the value of back emf is zero.

#17 What are the various kind of cables used for transmission?

What are the various kind of cables used for transmission? Cables, which are used for transmitting power, can be categorized in three forms: • Low-tension cables, which can transmit voltage upto 1000 volts. • High-tension cables can transmit voltage upto 23000 volts. • Super tension cables can transmit voltage 66 kV to 132 kV.

#16 How can you relate power engineering with electrical engineering?

How can you relate power engineering with electrical engineering? Power engineering is a sub division of electrical engineering. It deals with generation, transmission and distribution of energy in electrical form. Design of all power equipments also comes under power engineering. Power engineers may work on the design and maintenance of the power grid i.e. called on grid systems and they might work on off grid systems that are not connected to the system.

#15 Why AC systems are preferred over DC systems?

Why AC systems are preferred over DC systems? Due to following reasons, AC systems are preferred over DC systems: a. It is easy to maintain and change the voltage of AC electricity for transmission and distribution. b. Plant cost for AC transmission (circuit breakers, transformers etc) is much lower than the equivalent DC transmission c. From power stations, AC is produced so it is better to use AC then DC instead of converting it. d. When a large fault occurs in a network, it is easier to interrupt in an AC system, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt. Due to following reasons, AC systems are preferred over DC systems: a. It is easy to maintain and change the voltage of AC electricity for transmission and distribution. b. Plant cost for AC transmission (circuit breakers, transformers etc) is much lower than the equivalent DC transmission c. From power stations, AC is produced so it is be...

#14 State the difference between generator and alternator?

State the difference between generator and alternator Generator and alternator are two devices, which converts mechanical energy into electrical energy. Both have the same principle of electromagnetic induction, the only difference is that their construction. Generator persists stationary magnetic field and rotating conductor which rolls on the armature with slip rings and brushes riding against each other, hence it converts the induced emf into dc current for external load whereas an alternator has a stationary armature and rotating magnetic field for high voltages but for low voltage output rotating armature and stationary magnetic field is used.

#13 Why star delta starter is preferred with induction motor?

Why star delta starter is preferred with induction motor? Star delta starter is preferred with induction motor due to following reasons: • Starting current is reduced 3-4 times of the direct current due to which voltage drops and hence it causes less losses. • Star delta starter circuit comes in circuit first during starting of motor, which reduces voltage 3 times, that is why current also reduces up to 3 times and hence less motor burning is caused. • In addition, starting torque is increased and it prevents the damage of motor winding.

#10 a book of protection and switch gear by badriram

a book of protection and switch gear by badriram CLICK HERE  TO DOWNLOAD THE BOOK . . . . . . ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓ . . . . . https://drive.google.com/open?id=0B-xPXNqqPzIITnhpUzk1M25teUk . . . . . . . . If you want more book, slide, ppts and notes online you can request in the comment section , Visit this site for more books, slide, ppts, notes and share this site link with the needy one. Thank You

#8 TRANSDUCERS

      INTRODUCTION OF TRANSDUCERS  A transducer is a device that convert one form of energy to other form. It converts the measurand to a usable electrical signal.   In other word it is a device that is capable of converting the physical quantity into a proportional electrical quantity such as voltage or current. BLOCK DIAGRAM OF TRANSDUCERS • Transducer contains two parts that are closely related to each other i.e. the sensing element and transduction element.  • The sensing element is called as the sensor. It is device producing measurable response to change in physical conditions.  • The transduction element convert the sensor output to suitable electrical form. CHARACTERISTICS OF TRANSDUCERS 1. Ruggedness  2. Linearity  3. Repeatability  4. Accuracy  5. High stabilityand reliability  6. Speed of response  7. Sensitivity  8. Small size TRANSDUCERS SELECTION FACT...

#6 Moving Iron Instrument

                                        MOVING IRON  • Moving-iron instruments are generally used to measure alternating voltages and currents.  • In moving-iron instruments the movable system consists of one or more pieces of soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil. Components  • Moving element: a small piece of soft iron in the form of a vane or rod.  • Coil: to produce the magnetic field due to current flowing through it and also to magnetize the iron pieces.  • In repulsion type, a fixed vane or rod is also used and magnetized with the same polarity.  • Control torque is provided by spring or weight (gravity).  • Damping torque: the damping device consisting of an air chamber and a moving vane attached to the instrument spindle.  • Deflecting...

#4 INDUCTION MOTOR

Image
Induction Motor | Working Principle | Types of Induction Motor One of the most common electrical motor used in most applications which is known as  induction motor . This motor is also called as asynchronous motor because it runs at a speed less than its synchronous speed. Here we need to define what is synchronous speed. Synchronous speed is the speed of rotation of the magnetic field in a rotary machine and it depends upon the frequency and number poles of the machine. An  induction motor  always runs at a speed less than synchronous speed because the rotating magnetic field which is produced in the stator will generate flux in the rotor which will make the rotor to rotate, but due to the lagging of flux current in the rotor with flux current in the stator, the rotor will never reach to its rotating magnetic field speed i.e. the synchronous speed. There are basically two  types of induction motor ...