Important Diploma Electrical Questions 3

    GURU TECHNICAL CLASSES KOTA RAJASTHAN

                     Contact : Ajay Gahlot 7733052211, 9672502497

          Important Diploma Electrical Questions 3

Q:1 What is effect of capitance in transmission line? 2. After raising the voltage at receiving end what will be happen? 3.how we nullify or control the raised voltage at receiving end?             

Answer: it is ferranti effect. the voltage at the receiving end is higher than the sending end. in order to control ferranti effect SHUNT REACTOR is place in the transmission line.

Q: 2 what is the importance of reactive power in power generation. if it is zero means wat will happen to system.                                                                                                                                                         Answer: Electrical machines work on the principle of conversion of  electromagnetic energy. A part of input energy is consumed  for creating and maintaining the magneticfield.This part of  the input energy cannot be converted into active energy and  is returned to the electrical network on removal of the  magnetic field. This power is known as “reactive” power Q. The Q Power flows back and forth, causing 90º Out of phase shift between the current and voltage waveform.This 

Reactive Power has one half of the Power In the positive area and the other half in the negative area.Unlike true power, reactive power is not useful power because it is stored in the circuit itself. This power is stored by
1)Inductors, Because they expand and collapse their magnetic fields in an attempt  to  keep  current  constant, 2) Capacitors,Because  they  charge and  discharge  in  an attempt  to  keep  voltage  constant. If it is zero than electromagnetic conversion  not possible.    

Q: 3  what is CRGO Transformers?                                                                                       

Answer: CRGO Transformers:- are the transfomrer in which the core material used is "Cold Rolled Grain Oriented " Steel. CRGO steel core is having less hysteresis losses therefore the  efficiency is high as compared to normal core transformer.

Q:4 why fuse is not used in neutral?                                                                                      

 Answer: Fuse is used to protect the equipment from abnormal  condition, equipment or load is always connectected before the nuetral point,flow of current is from phase to neutral,
so there will be no use to connect the fuse on the nuetral side. nuetral side current value is zero.

Q:5 Do you know the overhauling of a motor?                                                                       

Answer: overhauling of motor means just shutting down but the purpose is to do some maintenance and repairing of motor parts and  changing the parts if required to incresing the efficiency.

                                                                                                          Ajay Gahlot

                                                                   

Important Diploma Electrical Questions 2

Important Diploma Electrical Questions 2

Q: What is the permissible value of earth resistance.??
Answer: Earth resistance should be as small as possible . It depands on voltage level of the system to be grounded . As voltage level increases the earth resistance required to be nearer to zeero as far as possible....
For large power station = 0.5
for small substation = 2.0
for domestic wiring = 5.0

Q: whay we used silica gel in Transformer ?
Answer: it absorbs the moiosture content of the air and send dry air inside the transformer.....

Q: a 50hz motor to give 60hz whats happening in motor.what happen the motor?
Answer: If we increase only frequency of motor and keep voltage constant as a rated voltage then speed of motor will increase but maximum torque capacity of motor will reduce.....

Q: what is ferranti effect?
Answer: Under no-load or light load condition the receiving end voltage is grater than sending end voltage this effect is called ferranti effect. this is due to because of the capacitance effect in the long transmission lines only, this is not applicable for medium and short transmission lines...

Q: what is corona ?
Answer :corona is a one type of phenomenon, mainly occurs in transmission line, some electric charge act with surrounding air moisture. A violet glow mainly seems Also produce vibration in transmission line, produce ozone gas And odor....It calculating as loss of energy.

Q: what is bausbar?
Answer: it is metalic bar or hollow rod in which potential is same everywhere........ it receive electrical power to one or many incoming circuits and deliver this power to one or many outgoing circuits....

Q: what is the difference between ACTIVE POWER and REACTIVE POWER?
Answer: POWER SUPPLIED BY EXT. SOURCE IS CONSUMED IN 2 PARTS
1-ACTIVE POWER-which actually does the useful work in the machine and overcome losses.
2-REACTIVE POWER-which the system needs to produce magnetic field in the machine.
Understsnding of active power and reactive power is very 
much related to our life.What we eat gives power to us is
acive (power for doing any work) but power required to our mind to do a job is a reactive power......

Q: what r the types of transmission line?
Answer: Transmission lines are classified according to their span and working voltage.Usually, the following nomenclature is adopted to classify lies:
1. Short Lines: Less than 20kV and less than 80km
2. Medium Lines: Lengthe between 80-200km and Voltage between 20-100kV
3. Large Lines: More than 100kV voltage and more than 200km span.

Q: super position theorem is applicable to..........
answer: linear and lumped networks

Q: Current chopping mainly occurs in air blast circuit breaker.why?
Answer: In an air blast breaker a high velocity jet of air is made to flow through the arcing contacts that extinguishes the arc much before natural ac current 0 is reached , the air blast breaker retains the same extinguishing power irrespective of the nature of the fault , onsequently theblast of air sweeps out the ionised particles in between the contacts thereby buiding the rsistance and hence ultimately extnguishing the arc.

Q: what is main difference between electrical and electronics??
Answer: electrical is works on conductor materials and electronic works on semiconductor materials.

Q: What is meant by regenerative braking?
Answer: The Regerating braking is the speed of a motor is increased upto or above to the top speed. And suddenly disconnect the supply to motor. So, the motor is act as a generator and the generated supply opposing the main supply. So, the motor is tried to rotate in opposite direction. So it will
be stopped suddenly......
isme motor ko supply disconnect kiya jata h or motor apne inertia k karan lgtar run krta rhta h or field ko cut krke generator ki tarh behave krti h....

Q: Why frequency fix in 50 Hz?

Answer: We know that syn speed=120f/p The turbines are designed such that they will give max efficiency at 3000rpm. for good performence a generator should have 2field poles. hence giving f=50hz

Q:what is name of transformer oil ?
answer: The chemical name of transformer oil name is "Dicloro di-floro ethyle benzene" and brand name is Askarel, pyroclor (naphtheline base), etc

Q: why the generating voltage in India is 11kV or why is it be transmitted as multiples of 11..???

Answer: In India the generating voltage is 11kv.b,coz we,all know the formfactor value is 1.11.due to this the power is generated in 11kv & transmitted as multiples of 1.11

Important Diploma Electrical Questions 1

                          GURU TECHNICAL CLASSES 

                                                               KOTA RAJASTHAN

                                          Contact : Ajay Gahlot 7733052211, 9672502497

  

                          Important Diploma Electrical Questions

Q: what happen if we give 220 volts dc supply to d bulb and tube light?
Answer: tubelight will not work because it's chalk will be burned because of not induction created in it but lamp will be worked cause filament is only need supply,eighter d.c or a.c.

Q: What type of motor is used inside computer CPU.....??
Answer: stepper motor or servo motor in stabilizer....................

Q: why we can't use more then 50 hz in india ? Is it possible ? or why some contraries use 50Hz and some use 60Hz supply..???
Answer: 50 Hz frequency is the britis system and every component is  manufacturing since that time it self to work by this  frequency. 60Hz Frequency is american system....
We know that Ns=120f/P or f=Ns*P/120, P=2,4,6,8 etc. & Ns  we can adjust by adjusting the speed of Engine which coupled with alternator so that f comes to 60 or other
frequency.Hence it is possible to generate the frequeny other than 50 Hz.
Now if f = 60 or others, then loss will be vary accordingly, insulation / dielectric loss,dimension of the
all equipment, all machines which is using for manufacture of electrical component has to change. In other words all the existing M/Cs has to modified from root it self , which is not possible for a single day. Hence excisting m/cs are using at 50Hz........

Q: Why the capacitor are connected in Delta(Three Phase) for power factor improvement ?
Answer: The effective capacitance more in delta as compared with star connection provided that same capacitors are used....

Q: what is the CT of protection and CT of metering ?
Answer: there are two type of ct.
one is metering CT another one is Protection CT
the metering ct has very less error, so we can measure current and actual power by accuratly,
the protecton ct has more error but that has more saturaion level, so during fault condition this ct will not saturate. but Metering ct will saturate when fault condition and that time we can't measure the current value.

Q: what phase and neutral..???
Answer: In AC power system(single/three phase) in which the current flow is known as phase and the return path is neutral. In three phase star system the common point where the three phase are joined together is known as neutral.When there is any unbalance occurs there is a flow of current in neutral also(which is connected to earth). ....

Q: why neutral is required in electrical system..?
Answer: The neutral works as a return path for the current flowing through any equipment.In single phase system it is necessary to close the circuit through neutral wire... and also used for unbalanced 3 phase supply...................

Q: what is effect of temperature rise on sag ans tension of conductor wire..?
Answer: sag is proportional to temp and tension is inversely proportional to temp............ if temp rise than sag increase but tension decrease...........

Q: why we are using the ac supply in domestic purpose, why don't use dc supply.??
Answer: In india the geration and transmission voltage is AC.. 
1.DC generation also available but we could not going to generate as much as our require because it has somelimitation for commutator & Brush in DC generator and also transmission of DC supply is so complicated in 
compared with AC.
2. dc supply is more dangerous compare to ac because dc frequency is zero.
3. dc is transmitted in a same voltage but in ac supply voltage is step up or step down "which we want to use" with the help of transformer.. for decease current.

Q: Whether the LIGHTNING is AC or DC???
Answer: Its neither dc nor ac.. its just a high magnitude pulse... more powerful pulse..

SSC JUNIOR ENGINEER ELECTRICAL 2012 2nd PAPER GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI LEVEL COMPETITION CONTACT: 09672502497, 7733052211

SSC JUNIOR ENGINEER ELECTRICAL 2012 2nd PAPER
GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI LEVEL COMPETITION CONTACT: 09672502497, 7733052211

SSC JUNIOR ENGINEER ELECTRICAL 2013 2ND PAPER GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI LEVEL COMPETITION CONTACT: 09672502497, 773305221

SSC JUNIOR ENGINEER ELECTRICAL 2013 2ND PAPER

GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI LEVEL COMPETITION CONTACT: 09672502497, 773305221

SSC JUNIOR ENGINEER ELECTRICAL 2012 OBJECTIVE PAPER GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI LEVEL COMPETITION CONTACT: 09672502497, 7733052211

SSC JUNIOR ENGINEER ELECTRICAL 2012 OBJECTIVE PAPER 

GURU TECHNICAL CLASSES KOTA FOR ELECTRICAL DIPLOMA AND ITI

LEVEL COMPETITION 

CONTACT: 09672502497, 7733052211

SS

"Direction of current" best technical classes in kota GTC kota 7733052211

Q: Why direction of current take opposite of direction of flow of electrons ??

Ans: because  I= q/t

where "I" is current "q" is charge "t" is timenow in the above equation,if the "q" charge positive hoga to, the "I" current bhi positive hogi.but if the "q" is negative, then "I" will also carry negative sign jo ye btata ki current opposite direction me flow hogi... or electron pe -ve charge hota h or ye -ve termnl se +ve trmnl ki or bhte h or current -ve hone k karn opposite flow hoti h...