1) What is Electrical Engineering?
Electrical engineering is the branch of engineering that studies and applies electricity, electronics, and electromagnetism.
2) What is electricity ?
Electricity is a broad phrase that encompasses all phenomena induced by electric charge, whether static or moving.
3) What are the types of electricity ?
There are two types,(1) Static Electricity and (2) Current Electricity.
4) What is static electricity ?
Static electricity is electricity at rest, as opposed to dynamic or current electricity, the effects of which are solely due to the charge's electrostatic field. It is also known as frictional electricity since it is created by rubbing two substances such as glass and silk together.
5) What is current electricity ?
Current electricity is defined as electricity in motion, the effects of which are caused by electron flow in a conductor.
6) What are the many types of current electricity?
There are two kinds of current: (1) direct current and (2) alternating current.
7)What are the many methods of generating electricity? Give some examples.
The methods are as follows:
i) Static electricity is produced by frictions.
ii) Through chemical reactions in cells and batteries.
iii) Through mechanical driving- A generator generates electricity in two distinct ways.
iv) Heat is used to generate thermal electricity.
v) Using the lighting effect - Electricity is generated in a photoelectric cell.
8) Explain the difference between direct and alternating current?
The movement of electric charge in only one direction is referred to as direct current (DC). It is the constant-voltage circuit's steady state.The flow of electric charge that alternately reverses direction is known as alternating current (AC). If the source varies on a regular basis, especially if it is sinusoidal, the circuit is known as an alternating current circuit.
9) Where is D.C. used ?
1)Battery charging
2)Electroplating
3)Electrolysis
4)Relays
5)Traction motors
10) Where is A.C. used ?
1)Home appliances
2)Fans
3)Refrigerators
4)Power driving motors.
5)Radio and television set
11) What is active, reactive, apparent & complex power?
1) Active power: This is the real power given to the load, such as a transformer, induction motor, generator, and so on, and dissipated in the circuit. It is indicated by the letter P, and its unit is watts W.
2) Reactive Power: Reactive power is the power that constantly bounces back and forth between the source and the load. It is represented by the letter Q, and its unit is VAR voltage-ampere reactive.
3) Apparent Power: It is the product of voltage and current without taking into account the phase difference. It is a hybrid of active and reactive power. It is represented by the letter S and its unit is the Volt-Ampere, or VA.
4) Complex power is the product of voltage and current with reference to their phase difference. It is the Vector or Complex sum of active and reactive power. It is represented by S and measured in VAR.
12) What is a leading & lagging power factor & how can you improve it? State the methods of power factor correction?
The cosine of the angle created by voltage and current is defined as the Power factor. A leading power factor occurs when the current exceeds the voltage. When current lags behind voltage, the power factor is lagging.Most loads are inductive, resulting in a trailing power factor. As a result, the following approaches are employed for p.f correction (to cancel out the lagging current):
1) Static Capacitor
The capacitor contributes to the provision of a leading current, which removes the trailing component of current and enhances the power factor.
2) Synchronous Condenser
It is a non-loaded over-excited synchronous motor with a leading power factor.
3) Phase Advancer
A phase advancer is a simple AC exciter that is linked to the main shaft of the motor and works with the motor's rotor circuit to boost power factor.
13) Why do we improve the power factor?
The following are the reasons for enhancing the power factors:
Large Line Losses (Copper Losses): Line losses (I2R) are current-dependent. When opposed to the high power factor, the low power factor draws a huge quantity of current.
Large kVA rating and equipment size: PF is inversely proportional to KVA. Low PF equipment with a high KVA rating takes up more space.
Large Conductor Size and Cost: Due to the poor power factor, we need large conductors to convey the heavy current required.
Poor Voltage Regulation and High Voltage Drop: The high current caused by low PF creates a high voltage drop that requires more frequent regulation than usual.
Low Efficiency : The losses due to the high current flow & voltage drop deteriorate the efficiency of the system. The efficiency is maximum at PF=1.
14) What is a unilateral & bilateral circuit?
A unilateral circuit is one whose attributes change depending on the direction of current flow or voltage. The parameters of a bilateral circuit do not alter when the current direction or supply voltage are changed.
15) What is a linear & non-linear circuit?
The relationship between current and voltage in a linear circuit is linear, i.e. directly proportional. With fluctuating current and voltage, circuit parameters like as frequency, resistance, inductance, capacitance, and so on stay constant.
The current and voltage do not have a linear relationship in a non-linear circuit. The electrical characteristics of such circuits change as the voltage and current vary.
16) What may cause the current in a linear circuit to double?
The current should be increased for two reasons:
1) Either half the total resistance of the circuit is lowered.
2) Alternatively, the circuit's supply voltage is doubled.
17) Why is Battery Rating in Ah (Ampere hour) and not in VA or Watts?
The charge contained inside the compounds is converted into electrical energy by a battery. The amount of current it can deliver is for a specific amount of time, hence the unit for its rating is Ampere-hour Ah. While batteries provide direct current with no phase or frequency, there is no idea of P.F or reactive power, therefore there is no need to describe it in VA and it is rated in Ah.
18) What is a primary & secondary cell?
The primary cell is a non-rechargeable battery that can never be recharged. They are disposable and cannot be utilized once completely charged. They are typically found in toys, handheld devices, and remote controls, among other things.
The secondary cell is a rechargeable battery that can be recharged hundreds of times (depending on the life cycle of the battery). Their initial cost is higher than that of the primary cell. They are mostly found in cell phones, autos, generators, and other similar devices.
19) What are the limitations of ohm’s law?
Ohm law does not apply to a unilateral or non-linear circuit. The criteria for ohm's law is that the resistance must be constant and temperature dependent. A non-linear or unilateral circuit's resistance varies with voltage and current. As a result, it is inapplicable not such a circuit. The temperature must also remain steady.
20) Does current lead or lag the voltage in an inductive or capacitive circuit?
In an inductive circuit, current lags behind voltage, whereas current leads voltage in a capacitive circuit.
21) Define the term Capacitance and Inductance?
Capacitance is a component's ability to store charge between two plates when a potential difference is applied. It is symbolized by the letter C and is measured in Farads F.
Inductance is the ability of a conductor to resist or oppose changes in current. The current creates a magnetic field, the strength of which changes with the current. It is represented by the letter L and is measured in Henry H.
22) Why the Capacitors works on AC only?
In general, a capacitor provides infinite resistance to dc components (that is, it blocks the dc components). It enables ac components to pass through.
23) What is the maximum power transfer theorem?
It defines the specifications for maximum power transfer from source to load. It asserts that the maximum power will be transferred from source to load in a linear, bilateral network when the exterior load resistance matches the internal resistance of the source or the circuit's Thevenin's resistance.
24) Explain Thevenin’s Theorem in a single sentence.
Thevenin’s theorem states that any linear electrically complex circuit is reduced into a simple electric circuit with one voltage and resistance connected in series.
25) Explain Norton’s Theorem in a single sentence.
According to Norton's Theorem, any linear circuit, no matter how complex, can be simplified to an equivalent circuit with only a single current source and parallel resistance coupled to a load.
26) Explain Network Theorem.
Any element of a network's current or voltage is equal to the algebraic sum of the currents or voltages produced separately by each source. In other words, this theorem permits us to solve a current or voltage problem utilizing only one source at a time.
27) What is the working principle of a circuit breaker?
A circuit breaker is a device that either makes or breaks a circuit. It features two types of contacts: fixed and movable. Under typical conditions, the moving contact makes contact with the stationary contact, providing a closed contact for current flow. An arc forms between the fixed and movable contacts during abnormal and faulty conditions (when current exceeds the rated value), resulting in an open circuit. Arc Quenching media such as air, oil, vacuum, and so on extinguish the arc.
28) What Is a Vacuum Circuit Breaker?
By opening the contact terminals, a circuit breaker cuts the circuit. During the opening, an arc is formed between the terminals, which can be quenched using a variety of media. The medium for arc quenching in VCB is a vacuum. When opposed to air, vacuum has a higher voltage arc quenching ability and is employed in high voltage circuits.
29) What is the difference between MCB & MCCB?
The MCB stands for "miniature circuit breaker" and is used for current ratings of less than 100 amps and interrupting rates of less than 18k Amps. Its tripping properties are not adjustable, and it is employed for home reasons.
The MCCB is an abbreviation for "Molded case circuit breaker." It has a high current rating of roughly 2500 Amps and interrupting ratings ranging from 10K to 200K Amps. Its tripping properties can also be changed. They are widely utilized in industry.
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