RSMSSB JE Electrical Mock Test - 3 - Electrical Engineering (EE) MCQ

Correct Answer is Both the statements are true.

Key Points

• Evidence of the fort and the lower town being surrounded by a defence wall has been found in Kalibanga.
• It was constructed using unbaked clay bricks.
• Kalibanga is currently located on the banks of the Ghaggar river in Hanumangarh district of Rajasthan.
• It was first discovered by Amalananda Ghosh in 1952 AD and subsequently excavation work was done by Shri B.B. Lal, Shri B.K. Thapar and Shri M.D. Khare between 1961 and 1964 AD.
• Excavation was done up to 05 levels here.
• Kalibanga was settled according to a well-organised town plan.
• Roads cutting at right angles and drains along the roads were indicative of development.
• Symbols of Eurotooth fields are found in Kalibanga.
• The oldest symbols of earthquakes are also found in Kalibanga.
• The script of Kalibanga was similar to the Indus script, which was written from right to left.

Additional Information

• Important ancient civilizations of Rajasthan -

Gangaur festival honors Parvati (Gauri), Lord Shiva's wife. The festival name itself derives from "Gana" (Shiva's followers) and "Gaur" (another name for Parvati).

Key points:

• Gaur/Gavar refers to Parvati
• Named after her connection to Lord Shiva
• Celebrated primarily in Rajasthan and some North Indian states
• Symbolizes marital happiness and devotion

The correct answer is option 4

Key PointsA total of about 12.2 billion cubic meter of natural gas proved reserves have been estimated by OIL, ONGC, Cairn India & Focus Energy in Jaisalmer Basin & Barmer-Sanchore Basin.

• Natural Gas is being produced by OIL from Tanot- Dandewala & by Focus Energy Ltd. from Shahgargh areas of Jaisalmer Basin for the supply to Ramgarh Power Plant.
• About 182 million barrel proved reserves have been assessed in 38 discovered fields of Barmer-Sanchore Basin.
• Production of Natural gas has also been commenced from Raageshwari Deep Gas Field and other Fields (Associated Gas) of Barmer Basin, and through national grid is being supplied to GNFC, GSPC & KRIBHCO etc.
• Bikaner-Nagaur Basin
• Commercial Production of crude oil has been commenced from Mangla Field on 29th August, 2009 and at present about 92,000-93,000 barrels of oil per day is being produced from Oil/Gas Fields namely Mangla, Bhagyam, Aishwariya, Saraswati, Raageshwari oil, Rageshwari-S1, ABH, Guda, NE, NI, NL, Raag Deep Gas, KW2.

Concept:

Dungarpur Railway Station:

• Dungarpur railway station is a small railway station in the Dungarpur district, Rajasthan.
• Its code is DNRP.
• It serves Dungarpur town.
• The station consists of a single platform.
• The platform is not well sheltered.
• It lacks many facilities including water and sanitation.

Explanation:

Ratlam Railway Station:

• Ratlam railway division is one of the six railway divisions under the Western Railway zone of Indian Railways.
• This railway division was formed on 1 April 1952 and its headquarter is located at Ratlam in the state of Madhya Pradesh of India.

Thus, Ratlam is a major railway station, a railway line starting from Dungarpur that will connect the southern part of Rajasthan.

The correct answer is Bundi style. Key Points

• Bundi school is an important school for the Rajasthani style of miniature paintings.
  • It lasted from the 17th to the 19th century.
  • This school of painting focused on hunting, festivals, a life of nobles, animals, birds, lovers, and scenes from Lord Krishna's life.
  • This school has a close association with the Mughal style.
  • The Chitrashala, which is also known as the Ummed Mahal, is a part of the Garh Palace. It was built in the 18th Century and forms a set of rooms on an elevated podium above the garden courtyard
  • The walls, ceiling of this palace are completely covered with paintings of the Bundi school which are still in very good condition.
  • One of the earliest examples of the Bundi Paintings is the Chunar Ragamala painted in 1561.

Additional Information

The correct answer is the Ramsnehi sect.

Key Points

• Ramsnehi sect was founded by Sant Ramcharan.
• The main centre of this sect was Shahpura (Bhilwara).
• Ramsnehi sect other centres -

1. Ren, Medta (Nagaur) - This centre was founded by Sant Daryaav
2. Sinhthal - Bikaner - This centre was founded by Sant Hariram das
3. Khedapa - Jodhpur - This centre was founded by Sant Ramdas.

Additional Information

1. The correct answer is Baran, Jhalawar, Kota

Key Points

• Black Soil is found in Baran, Jhalawar, Kota.
• Indian black soils are commonly known as Black Cotton Soils or "Regur".
• Black soil is known as Black Cotton Soil as cotton is an important crop that is grown in this type of soil.
• Black soil is good for producing cotton, oilseeds, wheat, linseed, millets, and tobacco.
• This soil is rich in calcium carbonate, potash, lime but has poor phosphorus content.
• Black soil can hold a lot of moisture.
• It is mostly found in the Peninsular Plateau of India.
• It is mostly found in areas such as Rajasthan, Gujarat, Madhya Pradesh, and Maharashtra.
• It is also found in states like Tamil Nadu, Andhra Pradesh, and Karnataka.

Important Points

• Mountain soils are formed due to the accumulation of organic matter which is derived from forest growth and is generally shallow in-depth and immature.
• This type of soil is rich in humus but has poor lime, potash, and phosphorus content.
• The desert soil is found in regions with low rainfall in an arid and semi-arid climate.
• The phosphate content in the soil is high, while the nitrogen content is low.
• Desert soil lacks humus and moisture.
• Laterite soils are found in those regions of the country which receive heavy rainfall with an alternate dry and wet period - mainly, near the coasts.

Additional Information

• Rajasthan is a state in northern India.
• It covers 342,239 square kilometers or 10.4 percent of India's total geographical area.
• It is the largest Indian state by area and the seventh-largest by population
• Area: 342,239 km²
• Governor: Kalraj Mishra
• Capital: Jaipur
• Population: 6.89 crores
• Chief minister: Ashok Gehlot
  

The correct answer is (i), (ii), and (iii).

Key Points

• The Khejarli massacre was an event in September 1730 in which 363 Bishnois were killed while trying to peacefully protect a grove of Khejri trees.
  • The soldiers were sent by the Maharaja of Marwar, Abhai Singh to cut the trees in the village of Khejarli to provide wood for a new palace.
  • The killings were carried out on the orders of his minister Giridhar Bhandari.
• Appiko Movement - In September 1983, women and youth of the region decided to launch a movement similar to Chipko, in South India.
• The Chipko movement or chipko Andolan was a forest conservation movement in India.
  • The movement originated in 1973 in the Himalayan region of Uttarakhand (then part of Uttar Pradesh) and went on to become a rallying point for many future environmental movements all over the world.​

Additional Information

• Appiko Movement
  • The movement was named Appiko which means “hug” in Kannada, symbolizing protection for the tree.
  • The movement was founded and led by environmental activist Panduranga Hegde.
  • The aim of the movement was to conserve the trees of the Kalse forests in Karnataka.
• Chipko movement
  • It was Sunderlal Bahuguna, a Gandhian activist, who gave the movement a proper direction and its success meant that the world immediately took notice of this non-violent movement, which was to inspire in time many similar eco-groups by helping to slow down the rapid deforestation, expose vested interests, increase social awareness and the need to save trees, increase ecological awareness, and demonstrate the viability of people power

The correct answer is A Dinner given by the groom side.

Key Points

• Jannotan in Rajasthani Culture means dinner given by the groom's side.
• The marriages in tribal culture are often different than what we usually see in our day-to-day lives.

Additional Information

• For the Garasia tribe of northwestern Rajasthan, live-in relationships, rather than marriage, are the dominant mode of co-habitation.
• The primitive custom called 'nata pratha' (relationship) among tribal communities in Rajasthan allows men and women to live together without marriage as many times as they want.
  • A man - according to the custom - has to pay money to live with a woman to whom he is not married.
  • The amount is decided by the woman's parents and members of her community.
  • They negotiate a price in thousands of rupees, but the money does not go to the woman who is undergoing 'nata'.

The correct answer is Gauri.

Key Points

• The Gangaur festival is observed in Rajasthan as well as some regions of Gujarat, West Bengal, and Madhya Pradesh.
• The words "Gan" and "Gaur" make up the name "Gangaur," with the former referring to Shiva and the latter to Gauri.
• Gauri is worshipped and propitiated by women during the Gangaur festival.
• This festival takes place between March and April.
• This event honors the harvest, the coming of spring, having children, and marital faithfulness.
• The single women worship Gauri in order to ask for her blessings in finding a suitable husband.
• The married ladies pray to her for their husbands' longevity, happiness, and health.

Additional Information

• Lakshmi:
  • Lakshmi is hindu goddess of wealth and good fortune.
• Santoshi:
  • A Hindu deity known as "the Mother of Satisfaction," she is revered.
• Durga:
  • A significant Hindu deity known as Durga is revered as the primary manifestation of the mother goddess Mahadevi.

The correct answer is option 3):(SCR)

Concept:

• The power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics (for example in a switch-mode power supply). Such a device is also called a power device or, when used in an integrated circuit, a power
• SCR is used where high current and voltage ratings are involved. SCR is used as the load side for control of ac because the negative polarity of the voltage across SCR switched it off easily. Otherwise, a commutation circuit is needed to switch off the device. The typical switching frequency of SCR is 500 Hz

Power semiconductor device features

• Highest switching speed- MOSFET
• Highest voltage / current ratings- SCR
• Easy drive features -MOSFET
• Can be most effectively paralleled- MOSFET
• Can be protected against over-currents with a fuse- SCR
• Gate-turn off capability with regenerative features- GTO
• Easy drive and High power handling capability- SCR

Concept:
The damping ratio symbol is given by ζ and this specifies the frequency response of the 2nd order general differential equation.

Using the damping ratio, one can know the damping level of a system.

We have,

⇒

Characteristics Equation is given by:

1 + G(s) = 0

Comparing with C.E. of the second-order system:

Power electronic circuits can be classified as follows.

1. Diode rectifiers:

• A diode rectifier circuit converts ac input voltage into a fixed dc voltage.
• The input voltage may be single phase or three phase.
• They find use in electric traction, battery charging, electroplating, electrochemical processing, power supplies, welding and UPS systems.

2. AC to DC converters (Phase controlled rectifiers):

• These convert ac voltage to variable dc output voltage.
• They may be fed from single phase or three phase.
• These are used in dc drives, metallurgical and chemical industries, excitation systems for synchronous machines.

3. DC to DC converters (DC Choppers):

• A dc chopper converts dc input voltage to a controllable dc output voltage.
• For lower power circuits, thyristors are replaced by power transistors.
• Choppers find wide applications in dc drives, subway cars, trolley trucks, battery driven vehicles, etc.

4. DC to AC converters (Inverters):

• An inverter converts fixed dc voltage to a variable ac voltage. The output may be a variable voltage and variable frequency.
• In inverter circuits, we would like the inverter output to be sinusoidal with magnitude and frequency controllable. In order to produce a sinusoidal output voltage waveform at a desired frequency, a sinusoidal control signal at the desired frequency is compared with a triangular waveform.
• These find wide use in induction motor and synchronous motor drives, induction heating, UPS, HVDC transmission etc.

5. AC to AC converters: These convert fixed ac input voltage into variable ac output voltage. These are two types as given below.

i. AC voltage controllers:

• These converter circuits convert fixed ac voltage directly to a variable ac voltage at the same frequency.
• These are widely used for lighting control, speed control of fans, pumps, etc.

ii. Cycloconverters:

• These circuits convert input power at one frequency to output power at a different frequency through a one stage conversion.
• These are primarily used for slow speed large ac drives like rotary kiln etc.

6. Static switches:

• The power semiconductor devices can operate as static switches or contactors.
• Depending upon the input supply, the static switches are called ac static switches or dc static switches.

Types of Distribution System

1) Radial Distribution System

• This system is used only when a substation or generating station is located at the center of the consumers.
• In this system, different feeders radiate from a substation or a generating station and feed the distributors at one end.
• Thus, the main characteristic of a radial distribution system is that the power flow is in only one direction.

2) Parallel Distribution System

• The above-mentioned disadvantage of a radial system can be minimized by introducing parallel feeders.
• The initial cost of this system is much more as the number of feeders is doubled. Such a system may be used where the reliability of the supply is important or for load sharing where the load is higher.

3) Ring Mains Distribution System

• Here, each distribution transformer is fed with two feeders but in different paths.
• The feeders in this system form a loop that starts from the substation bus bars, runs through the load area feeding distribution transformers, and returns to the substation bus-bars.

Calculation
Given, VR = 24 kV
Voltage drop = 0.25 × Receiving end voltage
Voltage drop = 0.25 × 24kV = 6 kV
Sending end voltage = Receiving end voltage + Voltage drop

Sending end voltage = 24 + 6 = 30 kV

Important formulas:

Calculation:

Concept:

The number of branches/loci of the root locus diagram is:

N = P if P ≥ Z

= Z, if P ≤ Z

1. Root locus diagram is symmetrical with respect to the real axis.

2. Number of asymptotes in a root locus diagram = |P – Z|

Analysis:

From the concept it is very much clear that, option 3 and option 4 can't be correct.

Because we are given the number of loci and not the number of asymptotes.

Now, option 2 says four poles or four zeros

If we have four poles but more than four zeros then the number of loci will not be four.

Similarly, if we have four zeros but more than four poles then also the number of loci will not be four.

Hence, option 1 is the most appropriate one.

The correct answer is option 1):(Partly demagnetizing and partly cross-magnetizing.)

Concept:

Armature reaction is defined as the effect of armature flux on field flux (ϕm)

Two undesirable effects will be produced on the main field flux by the armature reaction

(1) Decrease in the field flux per pole

(2) Distorted main field flux wave along the air gap.

Based on the power factor the Nature of the armature reaction is

1. Unity Power Factor Load: load is resistive. The nature of the armature reaction is cross magnetizing
2. Leading Power Factor Load: load is capacitive in nature. The nature of armature reaction is partly cross-magnetising and partly demagnetising
3. Lagging Power Factor Load: load is Inductive.The nature of armature reaction is partly cross-magnetising and partly magnetising

Modulation is a process of varying one or more properties of a carrier signal (High-frequency signal) with a modulating signal (Low-frequency signal). Hence, Modulation is the process of combining signal and radiofrequency.

Need for Modulation:

• It is needed in order to match the characteristics of the input signal to that of channel characteristics.
• Low-frequency signals can be multiplexed with high-frequency signals to travel long distances.
• Wireless transmission of low pass signal is made possible due to modulation.
• Practically realization of antenna size can be achieved.
• Some modulation technique reduces the effect of noise on the signal.

Important Point

The AM, FM, and PM output waveforms are as shown:

In Frequency modulation, the frequency of the carrier is varied according to the amplitude of the message signal and the amplitude of the carrier remains constant.

A transfer function can be described as

Where,

K is DC gain

z1 and z2 are zeros of transfer function

P1 and P2 are poles of transfer function

• Zeros are the roots of transfer function at which transfer function becomes zero.
• In a transfer function, the frequencies for which the value of numerator becomes zero are called Zeros.
• Poles are the roots of transfer function at which transfer function becomes infinity.
• In a transfer function, the frequencies for which the value of denominator becomes zero are called Poles.

Skin effect:

• Skin effect is the tendency of an alternating electric current to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases with greater depths in the conductor.
• The phenomenon arising due to unequal distribution of current over the entire cross-section of the conductor is referred to as the skin effect.
• Such a phenomenon does not have much role to play in the case of a very short transmission line, but with an increase in the effective length of the conductors, skin effect increases considerably.
• The distribution of current over the entire cross-section of the conductor is quite uniform in the case of a DC system.
• But in the alternating current system, current tends to flow with higher density through the surface of the conductors (i.e., the skin of the conductor), leaving the core deprived of current.
  

Hence due to the skin effect effective area of the conductor of the line decreases, so that the resistance of the line increases.

Factors affecting skin effect in transmission lines are:

• Frequency – The skin effect increases with the increase in frequency.
• Diameter – It increases with the increase in the diameter of the conductor.
• The shape of the conductor – Skin effect is more in the solid conductor and less in the stranded conductor because the surface area of the solid conductor is more.
• Type of material – Skin effect increase with the increase in the permeability of the material (Permeability is the ability of the material to support the formation of the magnetic field).

Important Points:

• The Skin effect is negligible if the frequency is less than the 50Hz and the diameter of the conductor is less than the 1cm.
• In the stranded conductors like ACSR (Aluminium Conductor Steel Reinforced) the current flows mostly in the outer layer made of aluminum, while the steel near the center carries no current and gives high tensile strength to the conductor.
• The concentration of current near the surface enabled the use of an ACSR conductor.

TRIAC:
TRIAC stands for Triode for Alternate Current
Unlike SCR, TRIAC is bi-directional.
It is ideal for operation utilizing AC power for switching purposes (operated at power frequency)
It can control current flow for both halves in an alternating current cycle.

The TRIAC symbol is shown below.

The V-I characteristics are shown below.

Applications:

• Lighting control - especially domestic dimmers.
• Control of fans and small motors.
• Electronic switches for general AC switching and control

Classification of buses:

Load Buses:

• In these buses, no generators are connected and hence the generated real power PGi and reactive power QGi are taken as zero.
• The load drawn by these buses is defined by real power -PLi and reactive power -QLi in which the negative sign accommodates for the power flowing out of the bus.
• These buses are sometimes referred to as P-Q bus. The objective of the load flow is to find the bus voltage magnitude |Vi| and its angle δi.

Voltage Controlled Buses:

• These are the buses where generators or voltage-controlled equipments are connected. Therefore the power generation in such buses is controlled through a prime mover while the terminal voltage is controlled through the generator excitation.
• Keeping the input power constant through turbine-governor control and keeping the bus voltage constant using an automatic voltage regulator, we can specify constant PGi and |Vi| for these buses.
• These buses are also referred to as P-V buses. The reactive power supplied by the generator QGi depends on the system configuration and cannot be specified in advance.

Slack or Swing Bus:

• This bus sets the angular reference for all the other buses. Since it is the angle difference between two voltage sources that dictates the real and reactive power flow between them, the particular angle of the slack bus is not important.
• It sets the reference against which angles of all the other bus voltages are measured. For this reason, the angle of this bus is usually chosen as 0°. Furthermore, it is assumed that the magnitude of the voltage of this bus is known.

Important Points:

Bus types for power flow analysis are shown in the table given below:

Where | Vi | = Magnitude of the voltage
δi = Load angle
Pi = Active power
Qi = Reactive power

The rotor speed of the alternator is given by
N = 120f/P   ....(1)

Where,
N = Speed of rotor in rpm
f = Frequency of generated emf
P = Number of Poles
From equation (1)
f = NP/120
f ∝ NP
So the output frequency of an alternator depends on both the number of poles and rotational speed.

Absolute error (ε):

The difference between the indicated or measured value and the true or actual value is called absolute error. Also known as a static error.

Absolute error (ε) = Am - At

Where

Am = measured or indicated value

At = true or actual value

Gross error:

• Gross errors are the observational errors that happen due to the lack of observation of the observer.
• These errors vary from observer to observer.
• The gross errors may also occur due to improper selection of the instrument.

Relative error:

The relative error is the absolute error over the true or actual value.

Relative static error R.S.E = ε / At =

% R.S.E = × 100

Probable error is a quantity formerly used as a measure of variability which is equal to 0.6745 times the standard deviation.

Concept:

Electrical resistivity is the reciprocal of electrical conductivity.

• Diamond is a good electrical insulator, having a resistivity of 100 GΩ·m to 1 EΩ·m (10¹¹ to 10¹⁸ Ω·m)
• Silicon and Germanium are semiconductor material with standard resistivity’s at room temperature is as shown
  • Silicon - 2.3 x 10⁷ Ω·m
  • Germanium – 4.7× 10³ Ω·m
  • The resistivity of silicon is more than the germanium, also when germanium is dopped its resistivity further decreases, as the dopant atoms increase the conductivity of the material.
• Gold is a good conductor with high electrical conductivity and low electrical resistivity (0.022 micro-ohm m)

The sequence of increasing order of electrical resistivity:

Gold < Doped Germanium < Silicon < Diamond

Energy

⇒ t = τ loge(2)

Ripple Counter

• A ripple counter is an asynchronous counter where only the first flip-flop is clocked by an external clock.
• All subsequent flip-flops are clocked by the output of the preceding flip-flop.
• Asynchronous counters are also called ripple-counters because of the way the clock pulse ripples its way through the flip-flops.
• Only one flip-flop is applied with an external clock pulse and another flip-flop clock is obtained from the output of the previous flip-flop.
• The flip-flop applied with external clock pulse act as LSB (Least Significant Bit) in the counting sequence.
• An n-bit ripple counter can count up to 2n states. It is also known as MOD n counter.

A 3-bit Ripple counter using JK flip-flop –

In the above ripple counter, we can see the external clock is provided only to D₀ FF for D₁ FF, the clock is obtained from Q̅₀ (output of D₀ FF), and for D₂ FF clock pulse is obtained from Q̅₁ (output of D1 FF)

Rise time (tr): It is specified as the transition time for an input signal to rise from 0.1 to 0.9 times of signal's max output value.

Additional Information

Bandwidth(B.W.): It is defined as the range of frequencies over which the majority of the signal passes.

tr × B.W. = 0.35

The correct answer is option 2):(Impulse relay)

Concept:

• An impulse relay is a switching device designed to control electricity consumers. It works as follows: every time the switch is pressed, the built-in terminal of the relay changes its state – e.g., from switch on to switch off, etc.
• Impulse relays are a form of latching relay that transfers the contacts with each pulse. Many impulse relays are made up of a magnetic latch relay and a solid-state steering circuit that, upon application of power, determines which position the relay is in and energizes the opposite coil.
• The contacts transfer and hold that position when power is removed. When reenergized, the contacts transfer again and hold that position, and so on. In order to transfer the contacts, one simply provides a single unidirectional pulse.
• There is no need to redirect the control pulse or reverse the polarity. Impulse relays can be used as wear equalizers.
• They are well suited for applications such as turning a single device on or off from one or more locations with a single momentary switch or push button at each station.
• For example, a conveyor could be started and/or stopped from multiple locations by means of a single button at each position.
• Impulse relay is the relay which can be operated on both AC and DC.

Concept:

• In star connection: I_L = I_P
• In delta connection: IL = I_P
• The turn ratio of the 3ϕ transformer is always expressed in terms of phase current.
• The turn ratio is given by:

Calculation:

Let the line current on the primary side of delta connected transformer be I_L.

Then, the phase current on the primary side of delta connected transformer is given by:

The phase current on the secondary side of the star-connected transformer is given by:

∵ I_p1 = I_p

In star connection: IL = I_P​

IL2 = I_P2

IL2 =