1. Four relations have been given. Select the correct relation ?
Flux = MMF/Reluctance.
and Reluctance = 1/Permeance
2. In Boolean algebra - 
Basic formula of boolean algebra
(A. Ā) + A = A + A = A
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3. Both main winding and auxiliary winding of a single phase induction motor is
placed on the ?
Both main winding and auxiliary winding of a single phase induction motor is placed on the stator.
# -The stator winding in the Single phase induction motor has two parts: Main Winding and Auxiliary Winding.
#- Single-phase capacitor-run induction motor. A typical .... The split-phase motor has a main winding and an auxiliary winding that are situated 90° apart
# -Main windings will be large in diameter and have less number turns in order to have less resistance and more inductance, where as auxillary windings will be smaller in diameter comparing the main winding and have large number of turns to have large resistance and less inductance.
4. Which of the following power plants employs the Rankine cycle ?
The Rankine cycle is a model used to predict the performance of steam turbine systems.
It was also used to study the performance of reciprocating steam engines.
The Rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work while undergoing phase change.
#This gives a theoretical maximum Carnot efficiency for the steam turbine alone of about 63.8% compared with an actual overall thermal efficiency of up to 42% for a modern coal-fired power station.
5. The torque angle of a 3-phase synchronous motor depends on its ?
Torque angle δ is the angle between Rotor flux and Stator fluxes, both are rotating at synchronous speed.
It is noted that for synchronous motors the rotor flux axis lags the stator flux axis by the angle δ
The stator of the synchronous motor consists of three phase armature windings.
if the load on a synchronous motor is increased the following points are considered which are given below.
#-The motor continues to run at synchronous speed.
#-The torque angle δ increases.
#-The excitation voltage Ef remains constant.
#-The armature current Ia drawn from the supply increases.
#-The phase angle ϕ increases in the lagging direction.
#-There is a limit to the mechanical load that can be applied to a synchronous motor.
As the load is increased, the torque angle δ also increases until the condition arises when the rotor is pulled out of synchronism and the motor is stopped.
#-Pull-out torque is defined as the maximum value of the torque which a synchronous motor can develop at rated voltage and frequency without losing synchronism.
It values varies from 1.5 to 3.5 times the full load torque.
6. Permeance is analogous to .. in an electrical circuit ?
In a magnetic circuit, permeance is a measure of the quantity of magnetic flux for a number of current-turns.
This concept is analogous to electrical conductance in the electric circuit.
7. 1 kcal is approximately equal to ?
1 kilocalorie (1000 calories or 1 kcal) means the energy it takes to raise the temperature of 1kg of water by 1°C.
Watt = Joule/S
joule = watt/sec
1 kilocalorie equals 4.184 kilo joules = approximately 4200 Joules = 4200 Watt-second
8. lamps are used to light up sports stadiums ?
#-Most sports stadiums and indoor arenas use high intensity discharge (HID) lamps for almost all of their overhead lighting needs. On average, stadium lights have much higher wattage than other outdoor lighting applications such as billboards, roadways, and parking lots
#-High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube.
#-The most common examples of high intensity discharge lamps are metal halide lamps, sodium vapor lamps, mercury vapor lamps and xenon arc lamps. Now lets look specifically at high intensity discharge or HID lights
#- LEDs are ideal as they are brighter but do not produce the same glare that HIDs are responsible for. LEDs are compact and energy efficient. Unlike the HID, LED headlights provide instant light when turned on. ... Like the HID headlight, they shine very brightly and are often mistaken as hi-beams as well.
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9. The type of insulator used on lines upto 33 kV is ?
1- Pin insulator
2- Reel insulator
3- Post insulator
4- Strain insulator
1- Pin insulator
2- Reel insulator
3- Post insulator
4- Strain insulator
Pin insulator
The pin insulator is used in power distribution for the voltage up to 33kV.
It is placed on the cross arm of the supporting tower.
The pin insulator has grooves on the upper end for keeping the conductor.
Strain insulator
A strain insulator is an electrical insulator that is designed to work in mechanical tension (strain), to withstand the pull of a suspended electrical wire or cable.
They are used in overhead electrical wiring, to support radio antennas and overhead power lines.
These insulators are, therefore, known as tension or strain insulators.
For low voltage lines (less than 11 kV), shackle insulators are used as strain insulators.
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10. Water hammer effect is expected in a ?
Water hammer or hydraulic shock phenomenon and can be understood as abrupt collision of fast moving solid slug with in the piping system with any obstruction that may be bend, valve etc.
Thus a water hammer is defined as a sudden increase in pressure on account of hindrance to fluid motion or direction-change.
Hydraulic shock is a pressure surge or wave caused when a fluid, usually a liquid but sometimes also a gas, in motion is forced to stop or change direction suddenly; a momentum change.
This phenomenon commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe.
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