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Articles by Manish Kumar Saini
Page 54 of 80
Parallel RLC Circuit: Analysis and Example Problems
Consider a parallel RLC circuit shown in the figure, where the resistor R, inductor L and capacitor C are connected in parallel and I (RMS) being the total supply current. In a parallel circuit, the voltage V (RMS) across each of the three elements remain same. Hence, for convenience, the voltage may be taken as reference phasor.Here, $$\mathrm{\mathit{V}=\mathit{IZ}=\frac{\mathit{I}}{\mathit{Y}}}$$Where, Z= Total impedance of the parallel circuit, Y=1/Z= Admittance of the parallel circuit.The admittance of the parallel circuit is given by, $$\mathrm{\mathit{Y}=\frac{1}{\mathit{R}}+\frac{1}{\mathit{j\omega L}}+\mathit{j\omega C}=\frac{1}{\mathit{R}}+ {\mathit{j}}(\mathit{\omega C}-\frac{1}{\mathit{\omega L}})=\mathit{G}+\mathit{jB}}$$Where, G=1/R= Conductance of the circuit, B=1/X= Susceptance of the circuit, $$\mathrm{Magnitude\:of\:admittance, |\mathit{Y}|=\sqrt{(\frac{1}{\mathit{R}})^{2}+(\mathit{\omega C}-\frac{1}{\mathit{\omega L}})^{2}}}$$$$\mathrm{Phase\:angle\:of\:admittance, \:\varphi=\tan^{-1}(\frac{\mathit{\omega ...
Read MoreWhat is Street Lighting? – Objective, Principle, Advantages & Disadvantages
A source of light that is mounted on a lamp column or pole either on the side of the road or within the median to provide illumination is known as street lighting.Street lighting is required along the road to have safer, comfortable, convenient and efficient movement of vehicles at night.Objective of Street LightingThe primary objectives of street lighting are −Street lighting is required to increase or enhance the community value of the street.Street lighting is provided along the road sides to make traffic and obstructions on the road clearly visible in order promote safety and convenience.Street lights also make the ...
Read MoreWhat is Flood Lighting? – Definition, Purpose, Calculation and Applications
The flooding of large surfaces with light through powerful projectors, where the light sources are concentrated into narrow light beams using specific reflectors is known as flood lighting. Flood lighting is an artificial light with high-intensity, broad beam.Purpose of Flood LightingThe flood lighting may be employed for the following purposes −To enhance the beauty of the ancient monuments at night.To illuminate the railway yards, car parking, sport stadiums, construction sites, etc.To illuminate the advertising boards and show-cases, etc.Location and Mounting of ProjectorsIn practice, there are two possible locations of projectors for flood lighting, which are −For small buildings, uniform flood ...
Read MoreHow to select a site for a Steam Power Plant?
A thermal power station or steam power plant is a generating station which converts the heat energy of coal combustion into electrical energy.To achieve overall economy in power generation, the following factors should be considered while selecting a site for a thermal power plant −Supply of Fuel (Coal)The thermal plant should be located near the coal mines so that the transportation cost is minimum. Although, if the thermal power plant is to be installed at a place where coal is not available near the site, then care should be taken that adequate facilities exist for the transportation of coal.Water AvailabilitySince ...
Read MoreWhat are Welding Defects? – Types, Causes, and Remedies
The irregularities formed in the given weld metal due to wrong welding process or incorrect welding patterns, etc. are known as welding defects.The following table elaborates the different types of welding defects, their causes, and how to prevent these defects −The irregularities formed in the given weld metal due to wrong welding process or incorrect welding patterns, etc. are known as welding defects.The following table elaborates the different types of welding defects, their causes, and how to prevent these defects −Welding DefectCauses of Welding DefectRemediesBlow holeToo fast cooling rate.Wet, unclear or damaged electrode.Too thick base metal.Long or short arc length.Rusted ...
Read MoreMechanics of Train Movement and Derivation for Tractive Effort
Mechanism of Train MovementThe essential mechanism of an electric locomotive is shown in the figure below.Here, the armature of the driving motor has a pinion of the diameter d1 attached to it. The tractive effort at the edge of the pinion is transferred to the driving wheel by means of a gearwheel.Let, T = Torque exterted by the motor in NmF1 = Tractive effort at the pinionFt = Tractive effort at the wheel$\gamma $ = Gear ratiod1 = Diameter of piniond2 = Diameter of gear wheelD = Diameter of driving wheel$\eta $ = Efficiency of power transmission from motor to ...
Read MoreSystems of Track Electrification: AC Electrification System
There are two types of AC system of track electrification −Single-Phase Low-Frequency AC System (15 kV to 25 kV at 16$\frac{2}{3}$ Hz, 25 Hz and 50 Hz)Three-Phase AC System (3.3 kV to 3.6 kV at 16$\frac{2}{3}$ Hz)Single-Phase Low-Frequency AC SystemIn a single-phase low-frequency system of track electrification, an AC voltage of 15 kV at a frequency of 16$\frac{2}{3}$ to 25 Hz is used.The use of high voltage AC in the system reduces the current flowing through the overhead transmission line resulting in the reduced voltage drops and it helps in installing the substations at larger distances, about 50 to 80 ...
Read MoreElectric Traction: Trapezoidal Speed Time Curve
The speed-time curve of a main line service is best and most easily replaced by trapezoid. The figure shows the simplified trapezoidal speed-time curve for the main line service.Let, $\mathit{V_{m}}$ = Crest speed in kmph$\alpha$ = Acceleration in kmphps$\beta$ = Retardation in kmphpsT = Total time of run in seconds$\mathit{t_{\mathrm{1}}}$ = Acceleration time in seconds$\mathit{t_{\mathrm{2}}}$ = Free running time in seconds$\mathit{t_{\mathrm{3}}}$ = Retardation time in secondsD = Total distance of run in kmTherefore, the time of acceleration in seconds is given by, $$\mathrm{\mathit{t_{\mathrm{1}}}\:=\:\frac{\mathit{V_{m}}}{\alpha }}$$And the time for retardation in seconds is, $$\mathrm{\mathit{t_{\mathrm{3}}}\:=\:\frac{\mathit{V_{m}}}{\beta }}$$Hence, the time for free running in seconds is, ...
Read MoreElectric Traction: Quadrilateral Speed Time Curve
For urban and suburban services, the simplified quadrilateral speed-time curve of electric traction is shown in the figure.Let, $\alpha$ = Acceleration in kmphps$\beta$ = Braking retardation in kmphps$\beta_{c}$ = Coasting retardation in kmphpsV1 = Maximum speed at the end of acceleration in kmphV2 = Speed at the end of coasting in kmphT = Total time of run in secondst1 = Acceleration time in secondst2 = Coasting time in secondst3 = Braking time in secondsD = Total distance travell in kmTherefore, the time of acceleration is given by, $$\mathrm{\mathit{t_{\mathrm{1}}}\:=\:\frac{\mathit{V_{\mathrm{1}}}}{\alpha } }$$The time of coasting is given by, $$\mathrm{\mathit{t_{\mathrm{2}}}\:=\:\frac{\mathit{V_{\mathrm{1}}}-\mathit{V_{\mathrm{2}}}}{\beta_{c} } \:\:\:\cdot \cdot ...
Read MoreCrest Speed, Average Speed & Schedule Speed of an Electric Train
Crest Speed of Electric TrainThe maximum speed attained by an electric train during running is termed as its "crest speed". It is denoted by Vm.Average Speed of Electric TrainAverage speed is defined as the mean of the speeds attained by the electric train from start to stop. In other words, average speed is defined as the ratio of the distance covered by the train between two stops to the actual time of run. The average speed of train is denoted by Va and is given by, $$\mathrm{\mathrm{Average\: speed, }V_{a}\:=\:\frac{\mathrm{Distance\: between \:two\: stops\: (\mathit{D})}}{\mathrm{Actual\: time\: of\: run (\mathit{T_{\mathrm{run}}})}}\:\mathrm{kmph}}$$Schedule Speed of Electric ...
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