A three-phase overhead transmission line is being supported by three-disc suspension insulators; the potentials across the first and second insulator from the top are 8 kV and 11 kV respectively. Calcualte (i) the line voltage (ii) the ratio of capacitance between pin and earth to self capacitance of each unit (iii) the string efficiency
A three-phase overhead transmission line is being supported by three-disc suspension insulators; the potentials across the...
Q1. i). A 3 phase transmission line is supported by 3 suspension insulators. The capacitance of pin to earth is half of the capacitance of disc. Estimate: i Ratio of voltage across discs ii. String Efficiency [1.5] [0.5] For the same transmission line, if number of discs are increased to 4. Estimate: i. Ratio of voltage across discs ii. String Efficiency [1.5) [0.5] ill). What is the change observed in above cases (i & ii)? iv). What can be done...
In a string of three identical suspension insulators units supporting a transmission line conductor, if the self-capacitance of each unit is denoted as ‘C’ farads, the capacitance of each connector pin to ground can be taken as 0.1 C farads. Determine the voltage distribution across the string, if the maximum permissible voltage per unit is given as 20 kV. Determine the string efficiency. Derive the formula used to calculate the string efficiency with a neat sketch where ever required
A string of suspension insulators consists of three units. The capacitance between each link pin and earthis one-sixth of the self-capacitance of each unit. If the maximum voltage per unit is not to exceed 35 kV,determine the maximum voltage that the string can withstand. Also calculate the string efficiency.[84·7 kV; 80·67%]
A 3-phase, 50 Hz overhead transmission line has the following constants : Resistance/phase = 9·6 Ω Inductance/phase = 0·097 mH Capacitance/phase = 0·765 μF If the line is supplying a balanced load of 24,000 kVA 0·8 p.f. lagging at 66 kV, calculate : (i) sending end current (ii) line value of sending end voltage (iii) sending end power factor (iv) percentage regulation (v) transmission efficiency
3.8 A 275 kV three-phase transmission line of length 96 km is rated at 800 A. The values of resistance, inductance and capacitance per phase per kilometre are 0.078 12, 1.056 mH and 0.029 F, respectively. The receiving-end voltage is 275 kV when full load is transmitted at 0.9 power factor lagging. Calculate the sending-end voltage and current, and the transmission efficiency, and com- pare with the answer obtained by the short-line representation. Use the nomi- nal n and T...
THESE ARE THE QUESTIONS FROM THE SUBJECT POWER SYSTEM FUNDAMENTALS AND THE CHAPTER IS MECHANICAL DESIGN OF TRANSMISSION LINES . THE ANSWERS ARE GIVEN WITH THE QUESTION PLEASE DO ALL THE QUESTIONS PROPERLY ..DONOT SKIP ANY STEP AND DO YOUR BEST 5. A string of 4 insulators has self-capacitance equal to 4 times the pin-to-earth capacitance. Calculate (i) the voltage distribution across various units as a percentage of total voltage across the string and (ii) string efficiency. [(i) 14·5%, 18·1%,...
The answer = 14.49% ; 94.47% III. A three-phase overhead transmission line, 80 km long, delivers 24 MVA at 66 kV, 50 Hz, 0.8 power factor lagging. The line conductors have a diameter of 1.5 cm and are horizontally spaced at a distance of 2.5 m. Determine the voltage regulation and efficiency of the line. The line resistance is 8.72 ohm/phase.
A 3-phase, 50 Hz, long 300 Km transmission line delivers 60 MVA at 124 kV and 0-8 p.f. lagging. The total resistance 25.3 ohm and total reactance is 66.5 ohm and the admittance due to capacitance is 0.442*10-3 mho. Determine: (i) (ii) (iii) A,B, C and D constants of long T.L Sending end voltage, current and power factor Transmission efficiency, Voltage regulation
A 60 km-long three-phase 60-Hz transmission line has per phase line inductance of 1.554 mH/km and per phase line resistance of 10.33 mΩ/km. It supplies a three-phase Y connected 100 MW 0.9 lagging power factor load at 215 kV line-line voltage. Calculate the voltage regulation and efficiency of transmission.
Phase of a three-phase, 60 Hz, 300 km long power transmission line with a nominal operating line voltage of 500 kV. its inductance per 291 mH/phase, and its capacitance is 3.45uF/phase. Voltage between 500 kV phases from the end of the energy transmission line Under it, a load of 1000 MVA is fed with a power factor of 0.8 back. Power transmission line lossless assumption. This according to the operating conditions, a.) The line's phase constant (61), characteristic impedance (ZC)...