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Q29. Following measurements are made for a test specimen with a 7 kV rms supply at a frequency of 6 kHz: The air capacitance of the electrode system - 30 nF with negligible loss angle. The capacitance and loss angle of the electrodes with specimen are 130 nF and 0.0066 respectively. Assuming there is no additional stray capacitance, determine the dielectric loss factor A) 0.975 pEin B) 0.253 pF/m C) 0.624 pF/m D) 0.080 pF/m Q.30. A solid dielectric exposed to high voltage in a laboratory to determine its mechanical breakdown strength. The dielectric has 0.97 GPa Young's modulus and relative permittivity 2.2. If the breakdown occurs when the applied voltage reaches 13 MV, determine the initial thickness of the dielectric A) 3.07 mm B) 3.32 mm C) 2.57 mm D) 2.82 mm

Q29. Following measurements are made for a test specimen with a 7 kV rms supply at a frequency of 6 kHz: The air capacitance of the electrode system - 30 nF with negligible loss angle. The capacitance and loss angle of the electrodes with specimen are 130 nF and 0.0066 respectively. Assuming there is no additional stray capacitance, determine the dielectric loss factor A) 0.975 pEin B) 0.253 pF/m C) 0.624 pF/m D) 0.080 pF/m Q.30. A solid dielectric exposed to high voltage in a laboratory to determine its mechanical breakdown strength. The dielectric has 0.97 GPa Young's modulus and relative permittivity 2.2. If the breakdown occurs when the applied voltage reaches 13 MV, determine the initial thickness of the dielectric A) 3.07 mm B) 3.32 mm C) 2.57 mm D) 2.82 mm

Introductory Circuit Analysis (13th Edition)
Introductory Circuit Analysis (13th Edition)
13th Edition
ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:Robert L. Boylestad
Chapter1: Introduction
Section: Chapter Questions
Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...
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please solve parts 29  and 30

An experiment in a certain gas to find Townsend's coefficients resulted in the curve shown in the fig. 2 where d is the distance between the plates, and I is the current. the field value was kept fixed throughout the experiment. Answer questions Q21 & Q22. Q. 21. If the labeled slope is 9/cm, the steady-state current is 0.5 nA at d-0.2 cm. The critical threshold distance for sustained discharge is 0.8 cm. Find the current when d-0.75 cm noting that at this distance the curve is out of the linear range. A) 192.65 NA B) 190.65 nA C) 188.65 nA (D) 194.65 NA Q. 22. If the critical threshold distance for sustained discharge is d-0.77 cm, the value of Townsend's second ionization coefficient is 0.102%, and the steady-state current is 0.57 nA at d-0.4 cm. And if the current after increasing the distance is 1.22 nA, find the percentage of the supply voltage increment assuming you are working in the linear range. A) 17.3% B) 23.3% D 21.3% Slope d1 d C) 19.3% C', Ra w EN, Rp 1(t) 0 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Q. 23. For the transformer ratio arm bridge shown in Fig. 3, C's-200 nF, Ra-137.5 M2, Rp 10 G, and Cp-20 nF. What of the following could be the ratio Na: Nb to balance the bridge. (A) 110: 690 C) 100: 680 B) 140: 670 D) 150: 680 vo(t) Q. 24. A 4 kV, 110 Hz Schering bridge with a grounded detector as shown in fig. 4 has Cs-100 pF. In a test on an insulator, the balance was obtained with C4-0.2 μF, R4-210 52, and R3= 140 2. By removing the insulator from the measuring system, the balance will be reached at R3=700 £2 and C4-0.004 µF. Consider the system stray capacitance and leakage and find the insulator parallel resistance Rp.: Α) 306.62 ΜΩ Β) 316.62 ΜΩ C) 326.62 ΜΩ D) 336.62 ΜΩ Q. 25. A Rogowski coil is required to measure a 2 A current at a frequency of 4 kHz. The voltmeter is connected across the integrating circuit shown in the Fig. 5. For proper integration, the circuit time constant RC is selected to be 10 times less than the period of the wave. If the coil has an effective area of 103 m², an axial length of 0.3 m, and 100 turns, find the reading of the voltmeter: A) 41.9 mV B) 52.38 mV C) 26.82 mV D) 33.52 mV Q. 26. A solid dielectric of 1 cm thickness and relative permittivity &, 3.3 has an internal void filled with air which breaks down at 30kV/cm. If internal discharge occurs when the applied voltage reaches 8.3 kV rms, determine the thickness of the void. A) 1.07 mm B) 0.67 mm C) 1.27 mm (D) 0.87 mm Q. 27. A specimen is tested for insulation resistance by the loss of charge method. The specimen capacitance is 2.8 nF. It is observed that after charging, the voltage falls to half the initial value in one minute. If the voltmeter used is assumed with infinite resistance, determine the insulator resistance. A) 44.14 G B) 27.08 G C) 30.91 GN D) 90.48 GN
Transcribed Image Text:An experiment in a certain gas to find Townsend's coefficients resulted in the curve shown in the fig. 2 where d is the distance between the plates, and I is the current. the field value was kept fixed throughout the experiment. Answer questions Q21 & Q22. Q. 21. If the labeled slope is 9/cm, the steady-state current is 0.5 nA at d-0.2 cm. The critical threshold distance for sustained discharge is 0.8 cm. Find the current when d-0.75 cm noting that at this distance the curve is out of the linear range. A) 192.65 NA B) 190.65 nA C) 188.65 nA (D) 194.65 NA Q. 22. If the critical threshold distance for sustained discharge is d-0.77 cm, the value of Townsend's second ionization coefficient is 0.102%, and the steady-state current is 0.57 nA at d-0.4 cm. And if the current after increasing the distance is 1.22 nA, find the percentage of the supply voltage increment assuming you are working in the linear range. A) 17.3% B) 23.3% D 21.3% Slope d1 d C) 19.3% C', Ra w EN, Rp 1(t) 0 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Q. 23. For the transformer ratio arm bridge shown in Fig. 3, C's-200 nF, Ra-137.5 M2, Rp 10 G, and Cp-20 nF. What of the following could be the ratio Na: Nb to balance the bridge. (A) 110: 690 C) 100: 680 B) 140: 670 D) 150: 680 vo(t) Q. 24. A 4 kV, 110 Hz Schering bridge with a grounded detector as shown in fig. 4 has Cs-100 pF. In a test on an insulator, the balance was obtained with C4-0.2 μF, R4-210 52, and R3= 140 2. By removing the insulator from the measuring system, the balance will be reached at R3=700 £2 and C4-0.004 µF. Consider the system stray capacitance and leakage and find the insulator parallel resistance Rp.: Α) 306.62 ΜΩ Β) 316.62 ΜΩ C) 326.62 ΜΩ D) 336.62 ΜΩ Q. 25. A Rogowski coil is required to measure a 2 A current at a frequency of 4 kHz. The voltmeter is connected across the integrating circuit shown in the Fig. 5. For proper integration, the circuit time constant RC is selected to be 10 times less than the period of the wave. If the coil has an effective area of 103 m², an axial length of 0.3 m, and 100 turns, find the reading of the voltmeter: A) 41.9 mV B) 52.38 mV C) 26.82 mV D) 33.52 mV Q. 26. A solid dielectric of 1 cm thickness and relative permittivity &, 3.3 has an internal void filled with air which breaks down at 30kV/cm. If internal discharge occurs when the applied voltage reaches 8.3 kV rms, determine the thickness of the void. A) 1.07 mm B) 0.67 mm C) 1.27 mm (D) 0.87 mm Q. 27. A specimen is tested for insulation resistance by the loss of charge method. The specimen capacitance is 2.8 nF. It is observed that after charging, the voltage falls to half the initial value in one minute. If the voltmeter used is assumed with infinite resistance, determine the insulator resistance. A) 44.14 G B) 27.08 G C) 30.91 GN D) 90.48 GN
Q28. A coaxial cable with a conductor surrounded by two dielectric layers. The radius of the conductor is 0.9 cm. The first dielectric layer has a 1.3 relative permittivity and 4.7 mm thickness. If the second layer has a 3.5 mm thickness and was selected to maintain the same maximum electric field value, find the field value at the middle of the second layer if the applied voltage is 29 kV. A) 2.09 kV/mm B) 2.79 kV/mm D) 3,19 kV/mm C) 3.39 kV/mm Q29. Following measurements are made for a test specimen with a 7 kV rms supply at a frequency of 6 kHz: The air capacitance of the electrode system-30 nF with negligible loss angle. The capacitance and loss angle of the electrodes with specimen are 130 nF and 0.0066 respectively. Assuming there is no additional stray capacitance, determine the dielectric loss factor A) 0.975 pm (B) 0.253 pF/m C) 0.624 pF/m D) 0.080 pF/m Q.30. A solid dielectric exposed to high voltage in a laboratory to determine its mechanical breakdown strength. The dielectric has 0.97 GPa Young's modulus and relative permittivity & 2.2. If the breakdown occurs when the applied voltage reaches 13 MV, determine the initial thickness of the dielectric. A) 3.07 mm B) 3.32 mm C) 2.57 mm D) 2.82 mm Assuming a fixed distance between parallel plates with a uniform field, and assuming unchanged Townsend's coefficients, the pressure is changed, and the breakdown voltage is measured with the following results: At a pressure 650 torr the breakdown voltage is found to be 320 V. At a pressure 850 torr, the breakdown voltage is found to be 370V. Answer Q31 & Q32 Q.31. Find the value of the pressure for minimum breakdown voltage according to Paschen's law. A) 227.88 torr B) 229.88 torr C) 223.88 torr D) 225.88 torr Q. 32. Find the value of the minimum breakdown voltage according to Paschen's A) 231.77 V B) 227.77 V C) 233.77 V D) 229.77 V Q. 33. A cable is tested for partial discharge using the traveling wave technique. If the cable length is 119 km and the velocity of signal propagation in the cable is 0.26 km/us. And the time difference between the pulses measured at the detector at the end of the cable is 220 us. Find the location of the partial discharge point from the receiving end. A) 88.4 km B) 84.4 km C) 90.4 km D) 86.4 km A 3-phase transmission line has conductors 1.4 cm in diameter spaced 1 m apart in an equilateral formation. If a current wave of 9 A travels along the line, and the line is connected at the end to a second transmission line with a surge impedance of 470 22, answer Q34 & Q35: Q. 34. If the resistance and leakance are negligible, calculate the reflected phase voltage value (V): A) 626.6 V B) 576.6 V C) 651.6 V D) 601.6 V Q. 35. If the second transmission line has a resistance of 5 per km and a leakance of 0.9 μ S per km, and if the line is 50 km long and is terminated at the end of the line by a 900 2 star connected load. Find the value of the reflected current wave at the end of the line. A) 2.6 A B)-2.08 A C) -1.66 A D)-3.24 A
Transcribed Image Text:Q28. A coaxial cable with a conductor surrounded by two dielectric layers. The radius of the conductor is 0.9 cm. The first dielectric layer has a 1.3 relative permittivity and 4.7 mm thickness. If the second layer has a 3.5 mm thickness and was selected to maintain the same maximum electric field value, find the field value at the middle of the second layer if the applied voltage is 29 kV. A) 2.09 kV/mm B) 2.79 kV/mm D) 3,19 kV/mm C) 3.39 kV/mm Q29. Following measurements are made for a test specimen with a 7 kV rms supply at a frequency of 6 kHz: The air capacitance of the electrode system-30 nF with negligible loss angle. The capacitance and loss angle of the electrodes with specimen are 130 nF and 0.0066 respectively. Assuming there is no additional stray capacitance, determine the dielectric loss factor A) 0.975 pm (B) 0.253 pF/m C) 0.624 pF/m D) 0.080 pF/m Q.30. A solid dielectric exposed to high voltage in a laboratory to determine its mechanical breakdown strength. The dielectric has 0.97 GPa Young's modulus and relative permittivity & 2.2. If the breakdown occurs when the applied voltage reaches 13 MV, determine the initial thickness of the dielectric. A) 3.07 mm B) 3.32 mm C) 2.57 mm D) 2.82 mm Assuming a fixed distance between parallel plates with a uniform field, and assuming unchanged Townsend's coefficients, the pressure is changed, and the breakdown voltage is measured with the following results: At a pressure 650 torr the breakdown voltage is found to be 320 V. At a pressure 850 torr, the breakdown voltage is found to be 370V. Answer Q31 & Q32 Q.31. Find the value of the pressure for minimum breakdown voltage according to Paschen's law. A) 227.88 torr B) 229.88 torr C) 223.88 torr D) 225.88 torr Q. 32. Find the value of the minimum breakdown voltage according to Paschen's A) 231.77 V B) 227.77 V C) 233.77 V D) 229.77 V Q. 33. A cable is tested for partial discharge using the traveling wave technique. If the cable length is 119 km and the velocity of signal propagation in the cable is 0.26 km/us. And the time difference between the pulses measured at the detector at the end of the cable is 220 us. Find the location of the partial discharge point from the receiving end. A) 88.4 km B) 84.4 km C) 90.4 km D) 86.4 km A 3-phase transmission line has conductors 1.4 cm in diameter spaced 1 m apart in an equilateral formation. If a current wave of 9 A travels along the line, and the line is connected at the end to a second transmission line with a surge impedance of 470 22, answer Q34 & Q35: Q. 34. If the resistance and leakance are negligible, calculate the reflected phase voltage value (V): A) 626.6 V B) 576.6 V C) 651.6 V D) 601.6 V Q. 35. If the second transmission line has a resistance of 5 per km and a leakance of 0.9 μ S per km, and if the line is 50 km long and is terminated at the end of the line by a 900 2 star connected load. Find the value of the reflected current wave at the end of the line. A) 2.6 A B)-2.08 A C) -1.66 A D)-3.24 A
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