1. In a coaxial power cable the radius of the conductor is 25 mm and the thickness of insulation is 8 mm. Calculate the Schwaiger factor n in this field configuration. Comment on uniformity of electric field. 2. What will be the most economical (optimum) conductor diameter of a single core power cable to be used on 132 kV power systems? Also find the diameter over the insulation provided to the conductor if the maximum permissible stress is not to exceed 8 kV/mm. 3. Two parallel plates which are oppositely charged are placed 5 cm apart. The potential difference, in volts, between the plates is 100 kV. Find the electric field intensity between them. 4. In a 220 kV rated voltage coaxial spherical system of a GIS the radius of the inner HV electrode is 10.0 cm and the SF6 gas insula- tion thickness of 18.0 cm is provided around. Find 1. 0.868, weakly non-uniform. 2. 19.04 mm, 51.79 mm 3. 2 kV/mm 4. (a) 19.75 kV/cm, 2.52 kV/cm, 0.357 (a) The max and min electric field intensities and the Schwaiger factor in the system. (b) For the given system voltage and fixed outer radius of the coaxial system, what changes in the configuration will be needed to optimise the max field inten- sity in this system? What will be its value then? 5. If a potential of 5 kV is applied across gap distance d' of 5 cm in air between (a) the uniform, (b) weakly nonuniform and (c) extremely nonuniform field electrode systems shown in Fig. 2.1, find the maximum field intensities, Emax at the high-voltage electrode in each case? 6. In which case is the dielectric properties of air utilized least? (b) Radius of HV conductor 14 cm, 18.14 kV/cm 5. 1 kV/cm, 4 kV/cm, 100 kV/cm 6. Extremely non-uniform field Field lines Equipotential lines Field lines Equipotential lines (a) (b) Figure 2.1 ■Typical electrostatic field configurations: (a) Field between sphere or cylinder and plane; (b) field on a bundle of four conductors carrying the same potential as used in transmission lines.

1. In a coaxial power cable the radius of the conductor is 25 mm and the thickness of insulation is 8 mm. Calculate the Schwaiger factor n in this field configuration. Comment on uniformity of electric field. 2. What will be the most economical (optimum) conductor diameter of a single core power cable to be used on 132 kV power systems? Also find the diameter over the insulation provided to the conductor if the maximum permissible stress is not to exceed 8 kV/mm. 3. Two parallel plates which are oppositely charged are placed 5 cm apart. The potential difference, in volts, between the plates is 100 kV. Find the electric field intensity between them. 4. In a 220 kV rated voltage coaxial spherical system of a GIS the radius of the inner HV electrode is 10.0 cm and the SF6 gas insula- tion thickness of 18.0 cm is provided around. Find 1. 0.868, weakly non-uniform. 2. 19.04 mm, 51.79 mm 3. 2 kV/mm 4. (a) 19.75 kV/cm, 2.52 kV/cm, 0.357 (a) The max and min electric field intensities and the Schwaiger factor in the system. (b) For the given system voltage and fixed outer radius of the coaxial system, what changes in the configuration will be needed to optimise the max field inten- sity in this system? What will be its value then? 5. If a potential of 5 kV is applied across gap distance d' of 5 cm in air between (a) the uniform, (b) weakly nonuniform and (c) extremely nonuniform field electrode systems shown in Fig. 2.1, find the maximum field intensities, Emax at the high-voltage electrode in each case? 6. In which case is the dielectric properties of air utilized least? (b) Radius of HV conductor 14 cm, 18.14 kV/cm 5. 1 kV/cm, 4 kV/cm, 100 kV/cm 6. Extremely non-uniform field Field lines Equipotential lines Field lines Equipotential lines (a) (b) Figure 2.1 ■Typical electrostatic field configurations: (a) Field between sphere or cylinder and plane; (b) field on a bundle of four conductors carrying the same potential as used in transmission lines.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.34P: Three single-phase, two-winding transformers, each rated 450MVA,20kV/288.7kV, with leakage reactance...

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