Electrical Engineering Q/A 41 to 50

 41: What are power systems?

Process of transferring electricity from generation end to consumer is called power system. It has three stages:

Generation, transmission and distribution 

42: What are the advantages of star-delta starter with induction motor?

(1). The main advantage of using the star delta starter is reduction of current during the starting of the motor. Starting current is reduced to 3-4 times of current of Direct online starting. (2). Hence the starting current is reduced, the voltage drops during the starting of motor in systems are reduced.

43: How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil?

It's possible by means of Electronic chokes,otherwise it's not possible to ionize the particles in tube light with normal voltage.

44: Why Human body feel Electric shock ?? n in an Electric train during running, We did nt feel any Shock? why?

Unfortunately our body is a pretty good conductor of electricity, The golden rule is Current takes the lowest resistant path if you have insulation to our feet as the circuit is not complete (wearing rubber footwear which doing some repairs is advisable as our footwear is a high resistance path not much current flows through our body). The electric train is well insulated from its electrical system.

 45: What is encoder, how it function?

An encoder is a device used to change a signal (such as a bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another. This is usually done by means of a programmed algorithm,especially if any part is digital, while most analog encoding is done with analog circuitry.

46: How tube light circuit is connected and how it works?

A choke is connected in one end of the tube light and a starter is in series with the circuit. When supply is provided,the starter will interrupt the supply cycle of AC. Due to the sudden change of supply the chock will generate around 1000volts. This volt will capable of to break the electrons inside the tube to make electron flow. once the current passes through the tube the starter circuit will be out of part. now there is no change of supply causes choke voltage normalized and act as minimize the current.

47: Why use the VCB at High Transmission System? Why can't use ACB?

Actually the thing is vacuum has high arc quenching property compare to air because in VCB,the die electric strengths equal to 8 times of air. That y always vacuum used as in HT breaker and air used as in LT.

48: What is an exciter and how does it work?

There are two types of exciters, static exciter and rotory exciter.purpose of excitor is to supply the excitation dc voltage to the fixed poles of generator. Rotory excitor is an additional small generator mounted on the shaft of main generator. if it is dc generator, it will supply dc to the rotory poles through slip ring and brushes(conventional alternator). if it is an ac excitor, out put of ac excitor is rectified by rotating diodes and supply dc to main fixed poles.ac excitor is the ac generator whose field winding are stationary and armature rotates. initial voltage is built up by residual magnetism.It gives the starting torque to the generator.

49: What is the difference between resistance, reactance and impedance?

Resistance is the opposition to electric current by a material. It is inherent(Inbuilt) property of material. Denoted by R.

Whereas reactance is the opposition to electric current by inductor and capacitor. Denoted by X.

Impedance is the combination of both reactance and resistance. It is denoted by Z

50: How does a human body conducts electrical current?

We humans are best conductors of electricity. Our body is made up of 70% water and water is a good conductor of electricity. Secondly our body contains electrolytes which have electrical properties to maintain osmotic pressure and acidity in your body. Nerves in your body are basically conductors in a way.