Difference between CFL and LED bulbs

In this article will knwo about the difference between LED and CFL bulbs . CFL and LED both is a lamp which is use to produce bright light . but due shortege of energy resorces its compulsary to use less energy consumption equipment, as like LED and CFL.
Difference between CFL and LED bulbs, CFL Vs LED
LED is more costly and longer life than CFL,  it is also most compact than LED.
we will show you difference between CFL and LED bulbs.

Difference between CFL and LED Bulbs

1. LEDs, or Light Emitting Diodes, have been in public use a lot longer than Compact 
Fluorescent Lamps or CFLs. These are the tiny diodes that light up to indicate that something is on, or blink to attract attention.
2. It is much and more efficient
It is low efficient
3. Led is the over long term are cheaper
It is the over long term are costly
4.  LEDs are substantially smaller compared to CFL.
CFL are substantially longer compared to LED.
5. Its efficiency is very high in comparison of CFL bulbs.
Its efficiency is less in comparison of LED bulbs. Its efficiency is less.
6. The electrical power used is LED 6-8 watts. It is equal to 60 watts bulbs.
In case of CFL electrical power used is approx. 13-15 watts. Which is also equal to 60 watts bulbs?
7. The energy saving in LED up to an 80% a year in energy costs.
The energy saving in CFL up to an 75% a year in energy costs.
8. LED life is 50000 hours. Which is very useful for essential cost?
CFL life is 80000 hours. Which is greater than LED bulbs, it is basic difference between CFL and LED.
9. Its cost is very high as compare to CFL.
Its cost is less as compare to LED
10. LED is high durable compare than CFL
CFL is less durable than LED
it is basic difference between LED and CFL bulbs
11. Its size is small and less maintenance
Its size is high and maintenance cost high
12. In case LED its remains cool in long time
In case of CFL it gets heated quickly
LEDs do not need extra components, like the ballasts that CFLs need.

CFL need extra component but in case of led there is does not need extra component.

Hence it is basic difference between LED and CFL bulbs, if you will find any incorect in above article please comment below in comment box.

if you want to know more about the difference between CFL and LED bulbs, you must watch this video.

Primary distribution system, Secondary distribution system

in this article we will know about the primary distribution system, we will also studied about the main primary distribuiton system . we will also know about the secondary distribution system.

Primary distribution system

primary distribution system, types of primary distribution system
Primary distribution system is of four types-
1. Radial feeder
2. Parallel feeder
3. Loop feeder
4. Primary network

1. Radial feeder

Radial feeder system is main types of primary distribution system
This feeder is used to supply small and medium residential, commercial loads. It radiates from the secondary substation and branches into sub feeder and laterals which extended into all parts of service area. The feeder and sub feeder are three phase three wire circuit. The distribution transformer is connected to primary   feeder, sub feeder and laterals through fused cutouts.

2. Parallel feeder

It consists of duplicate feed system having two radial feeders running in parallel. Each feeder supplies about half of total load of the area but has a capability to supply the entire load in the event of an outage on the other feeder. Failure of any feeder will result interruption of service until the load normally supplied by the faulted feeder is transferred to the other feeder by automatic control switch.

3. Loop feeder

A system of two or more radial feeders originating from the same or secondary different substation and separately routed through load area is known as loop feeder.it is also main types of primary distribution system.
If ends of two feeders are tied together through normally open switching device the resulting arrangement is known as open loop system and if ends are tied together by means of normally closed switching device the result is a ring loop feeder.

4. Primary Network

This system consists of a number of interconnected feeders. Two or more secondary transmission circuit supply two or more secondary substations from which the feeder takes off. Because the feeder is interconnected power is supplied to all the distribution transformers even though a part of network may be out of service. Each secondary substation consists of a transformer and the necessary switch gear to isolate the faulty feeder and to control feeder.
Secondary distribution system
The secondary distribution system consist of three phase four wire 400V distributors laid along road sides. The service connection are tapped off the off the distributors at convenient points. These connection may be 1 phase two wire circuit or 3 phase 4 wire circuit.These are basic types of primary distribution system.

Secondary distribution system

The secondary system used are-

1. Radial
2. Open loop
3. Network distribution

1. Radial system

It takes off from the distribution transformer and runs through the area to be served by it.

2. Open loop system

This system consist of two distributors taking off from the same distribution transformer and running in different directions and supplying different areas at time of fault one of distributors, power can supplied through partially, from the other distributor.

3. Network distribution

A network grid system consist of a number of inter connected distributors. Two or more distribution transformers feed the distribution network and operate continuously in parallel. This system is suitable for serving high load density metropolitan areas. Which are shows in secondary distribution system.


 Hence these are primary distribution system. if you will find any incorect above article please comment below in comment box.

Difference between mosfet and IGBT

In this article we will learn about the main difference between MOSFET and IGBT. We know about the main working of MOSFET and IGBT.

Working of MOSFET

They have generally a planner structure. The silicon oxide layer acts as insulating layer to allow source and drain connections to the n-regions.                      
Difference between MOSFET and IGBT , basic difference between mosfet and igbt, working of igbt
When gate is made positive with respect to source then electric field draws free electrons to P-substrate to from n-channel. It is a voltage-controlled device and the conduction is entirely due to movement of electrons and in p-channel MOSFET conduction is entirely due to movement of holes. 


Overview of IGBT

IGBT is the insulated gate bipolar junction transistor. It is a three terminal device namely gate(G), collector( C), and emitter (E) it is a voltage controlled device . IGBT has the advantage of both BJT and MOSFET, it has high input impedance and low conduction losses. IGBT have low switching speed then MOSFET.

Other meaning of IGBT

1. Conductivity modulated field effect transistor (COMFET)
2. Insulated gate conductor
3. Bipolar mode MOSFET
4. Bipolar mode transistor

Difference between mosfet and IGBT

Difference between MOSFET and IGBT , basic difference between mosfet and igbt, working of igbt

           MOSFET                                                    IGBT

1. In the power MOSFET the decreased in the electron mobility with increasing temperature result in a rapid increased in the on state resistance of the channel and hence the on state drop.
In IGBTs, this increase in voltage drop is very small.
2. The on stage voltage drop increases by a factor of 3 between room temperature and 200 degree sallies.
Here with the identical conditions, the increment in the on state voltage drop is very small.
3. All highest temperature, maximum current rating goes down to 1/3 value.
At high ambient temperature: IGBT is extraordinary well suited.
4. Current sharing in multiple paralleled MOSFETs is comparatively poor than IGBTs.
Current sharing in multiple parallel IGBTs is far better than power MOSFET.
5. The turn on transients is to MOSFETs
Turn on transients is identical identical to IGBTs..
6. Power MOSFET is suited for applications that require low blocking voltages and high operating.
IGBT is the preferred device for applications that require high blocking voltages and lower operating frequencies.
7. it is less better in power handling
It is better in power handling than MOSFET.
8. MOSFET have not PN junctions.
IGBT have PN junction

Hence these are some difference between MOSFET and IGBT. if you will find any incorect in above article please  comment in comment box.

If you want to know more about the basic difference between IGBT and MOSFET. you must watch this video.

Working and Construction of Repulsion Motor

In this article we will learn about the working of repulsion motor. We will also know about the construction of repulsion motor.

Working and construction of repulsion motor

Repulsion is similar to an AC series motor except that:

working and construction of repulsion motor, priciple of repulsion motor
1. Brushes are not connected to supply but are short circuited. Consequently, current are induce in the armature conductors by transformer action.

2. The field structure has non-salient pole construction.
For developed starting torque by adjusting position of sort circuited brushes on the commutator.

Construction of Repulsion motor

working and construction of repulsion motor, priciple of repulsion motor
The field of stator winding is wound like the main winding of a split phase motor and is connected directly to a single phase source. The armature or rotor is similar to a DC motor armature with drum type winding connected to a commutator (not shown in fig.) However, the brushes are not connected to supply but are connected to each other or short circuited. Short circuited the brushes effectively make the rotor into a type of squirrel cage.

Principle of repulsion motor

working and construction of repulsion motor, priciple of repulsion motor
The principle of operation is illustrated in fig. which shows a two-pole repulsion motor with its two short-circuited brushes. The two drawings of fig. represent a time at which the field current is increasing in the direction shown so that the left hand pole is N-pole and the right hand pole is S-pole at the instant shown.

A) in fig. the brush axis is parallel to the stator field. When the stator winding is energized from single-phase supply EMF is induced in the armature conductors (rotor) by induction. By lenzs law, the direction of the EMF is such that the magnetic effect of the resulting armature currents will oppose the increase in flux. The direction of current in armature conductors will be as shown in fig. current flow from brush B to brush A where it enters the armature and flows back to brush B through the two paths ACB and ADB. With brushes set in this position, half of the armature conductors under the N-pole carry current inward and half carry current outward. The same is true under S-pole. Therefore, as much torque is developed in one direction as in the other and the armature remains stationary. The armature will also remain stationary if the brush axis is perpendicular to the stator field axis. It is because even then net torque is zero.

B. If the brush axis is at some angle other than 0 degree or 90 degree to the axis of the stator field, a net torque is developed on the rotor and the rotor accelerated to its final speed. fig. represents the motor at the same instant as that in fig. but the brushes have been shifted clock wise through some angle from the stator field axis. Now EMF is still induced in the direction indicated in fig and current flows through the two paths of the armature winding from brush A to brush B. however because of the new brush positions, the greater part of the conductors under the N-pole the opposite direction. With brushes in the position shown in fig. torque is developed in the clockwise direction and the rotor quickly attains the final speed.

Thus, repulsion motor may be made to rotate in either direction depending upon the direction in which the brushes are shifted.

Hence these are working and construction of repulsion motor . 

For knowing more about the construction and working of repulsion motor.

Difference between CT and PT, Current Transformer and Potential Transformer

In this article we will know about what is difference between CT and PT . we will also know short description of CT and PT. So these are some difference between PT and CT.

Difference between CT and PT , ct and pt difference

Difference between CT and PT

       CT (Current Transformer)
    PT  (Potential Transformer)
1. The primary winding current in CT is independent of the secondary winding circuit condition.
The primary winding current is PT depends on secondary circuit burden.
2. In case of CT , it is connected in series with one line and a small voltage exist across its terminals, however CT carries the full line current.
In |PTs full line voltage is impressed upon its terminals.
3. The primary winding current and excitation of a CT vary over wide limits in normal operation.

In case of PT , it is under normal operation the line voltage is nearly constant and therefore the flux density and exciting current of a PT varies only over a restricted range .
4. The CT may be through as a series transformer under virtual short circuit conditions.
The PT may be considering as parallel transformer with its secondary winding operating under open circuit conditions.
6. The secondary of a C.T cannot be open during maintenance.
The secondary of  a P.T can be open circuited maintenance or during testing.
7. In case of CT primary current is independent of the secondary circuit condition.
In case of PT , its primary current is depend on secondary circuit condition.
8. It can be consider as a series transformer
It can be consider as a parallel transformer.
9. By the help of CT , a 5A ammeter can be measured higher current.  As like 400A.
With the help of PT , A 230 Voltmeter can be measured thousand volt. As like 11KV.
10.  CT is used for current measurement
PT is used for Voltage measurement


Hence these are some difference between CT and PT if you will find any incorrect in above article you must comment in comment box.

Basic Electrical Question and Answer

In this article we will study of basic electrical question and which is mostly asked in interview. We will know all basic electrical question and answer.

Basic Electrical questions and answer

Basic electrical question and answer, electrical interview question and answer

1.  DC basics and networks questions and answer

1. What is drifting current?

The steady flow of electrons in one direction caused by the applied electric field constitutes electric current, called the drift current.

2. What are limitations in ohms law?

Ohms law cannot be applied to the circuits consisting of electronic tubes or transistors (because such element are not bilateral) and 2. Nonlinear elements such as powdered iron, electric arc etc.

3. What is meant by potential divider?

The potential divider is a high resistance connected across the supply mains and is used to provide a variable voltage from a constant supply voltage.

4. What is the principle of duality?

Two physical systems or phenomena are called dual if they are described by equations of the same mathematical form. The principle of duality holds goods for series and parallel circuits.

5. What is mean by node?

A junction or node is a point in a network where two or more branches meet.

6. Distinguish between mesh and loop of networks.

A loop is a closed path in a network formed by a number of connected braches. Mesh is a loop that contains no other loop within it.

7. State the super position theorem

In a network of linear impedances containing more than one source, the current which flows at any point is algebraic/ phasor sum of all currents which would flow at that point if each source was considered separately and all other sources are replaced by their internal impedances. In basic electrical question and anshwer mostyly asked about the super position theorem.

8. what is utility of thevnin theorem

The venin‘s theorem is advantageous when we are to determine the current in a particular element of linear bilateral network particularly when it is desired to find out the current which flows through a resister for its different values. It makes the solution of the complicated networks ( particularly electronic networks) quite simple.

9. why terminal potential of a cell ( or a battery) is alwys less than its emf?.

Terminal potential of a cell (or a battery) is always less than its emf because some of the emf developed is used in overcoming the internal resistance of the cell (or a battery) itself. 

10. What is polarization vector?

The some of dipole moments per unit volume in a dielectric material is called the polarization vector or dielectric polarization, P.

11. What do you mean by solenoid and rotational fields?

A vector field that has a zero divergence is called the solenoid field and a vector field having a zero rotational everywhere is called an rotational field.

12. Define capacitance between two conductors. ?

Capacitance between any two conductors is the charge required to be added to increase potential by unit. Mathematically   , C = Q/V.

13. What is Fleming’s right hand rule?

According to Fleming’s right hand rule if the thumb, fore-finger and middle finger of the right hand are held mutually perpendicular to each other, forefinger pointing into the direction of the field and thumb in the direction of motion of conductor then middle finger will point in the direction of the induced emf. It is basic electrical question in electrical field.

14. What is hysteresis loss?

The energy expended in taking a specimen through a magnetic cycle is known as hysteresis loss. Hysteresis loss is very basic electrical question in case of transformer.

15. What is the effect of self-induction in a dc circuit?

The self-induction opposes the change of current in a dc circuit.

16. How can eddy current and hysteresis losses be minimized?

Hysteresis loss can be minimized by choosing a core material with low hysteresis coefficient such as low carbon steel, silicon alloys, and alloy steel. so these are basic electrical question and answer post basic electrical question. 

17. What is see beck effect?

The absorption or evolution of heat energy, if a current is allowed to flow in a conductor having its different parts at different temperatures is known as Thomson effect.

2. Ac basics electrical question

Here we will know about some AC basic question and answer.

1. Why the RMS value of an alternating current or voltage is used to denote its amplitude?

RMS value of an alternating current or voltage is used to denote its amplitude because it is related to the power developed in a resistance by the alternating current or voltage.

2. What is armature value of an alternating or voltage?

The effective or RMS value of an alternating current is given by that steady current which when flows through a given resistance alternating current is flowing through the same résistance for the same time duration.

3. What is significance of form factor?

Form factor is a means of relating the mean value with the effective or RMS value of alternating quantity and it is useful in determination of effective or RMS values of the alternating quantities whose mean or average values over half a period can be determined conveniently.

4. What is the significance of peak factor?

Knowledge of peak factor  of an alternating voltage is very essential in connection with determining the dielectric strength since the dielectric stress developed in an insulating material is proportional the peak value of the voltage applied to it.

5. Why is the inductor usually iron cored?

Inductors or choke coils are made of iron core because large valued flux densities can be produced in iron cores and so inductance of large value can be had. Air-cored inductors become too much bulky to provide an inductance of required value.

6. What is skin effect?

The phenomenon of concentration of an electric current near the surface of the conductor is known as skin effect.

7. What is the active and reactive power?

The power which is actually consumed or utilized in an ac circuit is called the true or active power of the circuit power is consumed only in resistance. It is given by the product of the circuit voltage current and power factor.
A pure inductor and a pure capacitor do not consume any power, as in a quarter cycles whatsoever is drawn from the supply source by these components, the same is returned to the supply source in the other quarter cycle. This power which flow back and forth (in both direction in the circuit) or reacts itself is called reactive e power. This is also known as wattles power. The reactive power of an ac circuit is given by the product of voltage current sine wave angle.

3. DC machines electrical questions

Here we will study about some basic dc machine question and answer.

1. Why energy storing capacity of magnetic field is much larger than that of electric field

Because the value of permittivity of free space is very small compared to permeability of free space.

2. What is the main factor which governs the size and rating of electric machine?

“Temperature rise” is the main factor which governs the size and rating of an electric machine.

3. What information’s should the rating of a machine give?

The rating of an electrical rotating machine should include the output, voltage, speed and any other information that may be necessary for the proper operation of machine.

4. In which terms are dc machines rated?

The dc machines are rated in terms of KW output at a given speed and voltage.

5. Why the coils used in commercial generator do consist of several turn in series?

It is done so as to increase the magnitude of generated EMF, being in direct proportion to the number of turns in the coil.

6. Why is the armature core of a dc machine laminated?

To reduce the eddy current loss.

4. Electrical power generation interview question and answer

Here we will know about some basic power generation electrical question and answer.

1. What are the reasons of power crises in India?

The causes, which are responsible for power crises in India, are sharp increase in demand, poor utilization of electrical equipment, high transmission losses, the delay in commissioning of power high transmission losses, the delay in commissioning of power projects, erratic monsoons, shortage of coal, faulty planning and plant outages.

2. What is meant by catchment area?

The catchment area is the area, bounded by water sheds, which drains into a stream or river across 3. which the dam has been built at a suitable place.

3. What is hydro graph?

A hydro graph is a graphical representation between discharge or flow with time.

4. What is the use of mass curve?

Mass curve is used in determination of the capacity of the storage reservoir in hydro-projects.

5. Why thermal power stations are always situated by the side of a river or lake?

The thermal power stations are always situated by the side of a river or lake so as to meet large quantity water requirement. Water is required in a steam power station to raise the steam in boilers.


5. What for surge tank is provided?


Surge tank is provided to absorb sudden changes in water requirements and reduce water hammer and negative pressure in pen stock.

5. Industrial and power electronic question and answer

1. What is power electronic?

Power electronics is a subject that concerns the application of electronic principles into situations that are rated at power level rather than signal level. Alternatively, it may also be defined as a subject that deals with the apparatus and equipment operating on the principle of electronics but rated at power level rather than signal level.

2. How is current limited in conducting state of an SCR?

 The current in conducting state of an SCR is controlled by external impedance.

3. What is false triggering?

False triggering is unintended turn-on of an SCR either through gate due to noise pick-up or excessive anode voltage.

Hence these are some basic electrical question and answer if you will find any incorrect in above please comment below in comment box.

If you want to know more electrical question and answer you must watch this video.

Control System Interview Questions

In this article we will study of control system interview question and answer. we will also learn in detail of various type interview question and answer.

Control System Interview Questions

control system interview questions, interview question and anshwer of control system

1. What is control system?

control system interview questions, interview question and anshwer of control system


A control system is an arrangement of physical components connected or related in such a manner as to command, direct or regulate in such a manner as to command, direct or regulate itself or another system.
Control system can be of two viz. open-loop control system and closed-loop control system.

2. What is feedback in control system? What are its characteristics?

Feedback is that property of a closed loop control system which allows the output or some other controlled variable of the system, to be compared with the input to the system, so that the appropriate control action may be formed as some function of the output and input.
A feedback is said to exist in a system if the cause and effect between variables is interrelated.

The characteristics of feedback are: increased bandwidth, increased accuracy, reduced distortion and non linearity and tendency towards oscillations or instability.this control system interview questions maximum ask in interviews.

3. What is system error?

The system error is the ideal value of the controlled variable minus the value of the final controlled variable.

4. What are control system components?

Various components employed in control systems are servo-motors, amplidynes, synchros, stepper motors, tachometers, gyroscopes etc.

5. Which types of servomotors generally lend themselves to small horse power requirements?

Two phase and shaded pole type induction motor are used.

6. Give one advantage of the two phase servomotor over the shaded pole type.

Better response to very small controls signals

7. Why are drag-cup-construction used in rotors of certain fhp machines for control purposes?

In drag-cup-construction all heavy iron lamination remain stationary and only a light cup rotates, so the inertia is quite small.

8. Why is series compensating winding employed in the amplidynes?

Compensating winding is connected in series with the power output brush terminals of the amplidyne to neutralize the armature reaction mmf set up by the load current and increase amplification factor.

9. Why area commutating poles required in amplidynes?

Com mutating poles are required in amplidynes to give satisfactory commutation

10. Why amplidynes are not extremely over-compensated

In case of extreme over-compensation, undesirable self-excitation of the amplidyne that is spontaneous rise in voltage and load current at constant control current (or with the control circuit open) can occur. Self-excitation can caus3e considerable over-loading of the amplidyne and totally disrupt operation of system containing the amplidynes. it most important control system interview question.

11. Why Amplidynes are provided with split-poles?

Amplidynes are provided with split-poles to provide space for inter poles.

12. What is stepper motor?

A motor in which the rotor turns in discrete movements is called a stepper motor.

13. What are the two types of stepper motors?

Permanent –magnet type and variable reluctance type motor are stepper motor.

14. For the same number of poles which stepper motor produces?

1. Largest stepping angle
2. Smallest stepping angle?
1. Permanent magnet type- largest stepping angle
2. Variable reluctance type-smallest stepping angle.

15. Where is stepper motor used?

Super motors are used in industrial situations which call for precise positioning of an object or precise control of speed without having to resort to closed-loop feedback. ,, it is most important question of control system.

16. How an ac tachometer is superior to dc tachometer.

AC tachometer does not cause any maintenance problem of commentators and brushes.

17. What is transfer function?

It is the mathematical expression that relates the system output to the system input and so describes the behavior of a system. It is expressed as ratio of the Laplace transform of the output variable to the lap lace transform of the input variable with the assumption that all the initial conditions are zero.

18. What is linear system?

A linear system is a system that follows the law of superposition and homogeneity.

19. What is analogous system?

Systems which are governed by the same types of equations are called analogous systems. Analogous systems may have entirely different physical appearances. For example, a given electrical circuit consisting of resistances, inductance and capacitance may be analogous to a mechanical system consisting of a suitable combination of dash pots, weights and springs or it may be analogous to an acoustical device consisting of an appropriate arrangement of fine mesh screens, tubes and cavities.

20. What is signal flow graph?

A signal flow graph is pictorial representation of the simultaneous equations describing a system. It graphically displays the transmission of signals through the system, as does the block diagram.
21. What is meant by overshoot?
Over shoot is maximum difference between the transient and steady-state solutions for a unit step function input.

22. Enlist the applications of sampled data systems.

Sampled data system finds applications in
1. High speed tin plate rolling mills using quantized data for control.
2. Numerically controlled machine tool operations.
3. Pulse controlled or digital controlled electric drives.
4. Large complex systems using telemetry links based on pulse modulation (PM) translation of data.


 Hence these are some control system interview question if you will find any incorrect in above article ou must comment below in comment box.