1. 0.868, weakly non-uniform. 2. 19.04 mm, 51.79 mm 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.

2- Draw and explain the phasor diagram for two transformers in parallel.

NEAT EXPLAIN NEEDED( CORRECT ANSWER NO GPT PLEASE)

A 10 MVA three phase load is to be served by a three phase transformer at aline voltage of 13.8 kV. The supply side voltage(line-line) is 138 kV. Varioussingle phase transformers are available in the warehouse but all havewindings with voltage ratings under 100 kV and current ratings under 250 A.Is it possible to serve the load using only three single phase transformers? Ifso, specify the three phase connections and the low and high voltage ratingsof the single phase transformers.

Define all the losses in the transformer with the diagram and then define the hysterisis loss with thw graph.

Problem 1 - Series en Parallel AC networks [19] Look at the circuit in Figure 1 and determine the following: (a) Total Admittance. (b) Total Impedance. (c) Total Current (l:). (d) Current (I1) through impedance Z2. (e) Current (12) through impedance Z3. (f) Current (I3) through impedance Z4. (g) Is this an inductive or capacitive circuit? A. B Zs 220V;50HZ Figure 1 (h) Voltage across Z1. (i) Voltage across A and B. G) Voltage across Zs. Z1 = 3 + j5 ohm Z2 = 10 + jo ohm Z3 = 5 + j15 ohm Z4 = 10 – j30 ohm Zs = 20 – j30 ohm Admittance and Impedance in rectangular notation. All currents and voltage in polar notation. Take voltage as reference.

Consider the three single-phase two-winding transformers shown in Figure. 3. The high-voltage windings are connected in Y. (a) For the low-voltage side, connect the windings in A, and label the terminals a, b, and c in accordance with the American standard. (b) Relabel the terminals a', b', and c' such that VAN is 90° out of phase with V₂'b' for positive sequence. DI H₂ Figure. 3: Three-Winding Transformer

Three single-phase transformers, each rated 10 MVA , 66.4/12.5 kV, 60 Hz , with an equivalent series reactance of 0.1 per unit divided equally between primary and secondary, are connected in a three-phase bank. The high-voltage windings are Y-connected and their terminals are directly connected to a 115-kV three-phase bus. The secondary terminals are all shorted together. Find the currents entering the high-voltage terminals and leaving the low-voltage terminals if the low-voltage windings are (a) Y-connected and (b) Δ- connected.

Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit leakage reactance, are connected as a three-phase extended autotransformer bank, as shown in Figure 3.36(c). The low-voltage winding has a 110 volt rating. (a) Draw the positive-sequence phasor diagram and show that the high-voltage winding has a 479.5 volt rating. (b) A three-phase load connected to the low-voltage terminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Draw the per-unit impedance diagram and calculate the voltage and current at the high-voltage terminals. Assume positive-sequence operation.

A bank of three single-phase transformers, each rated 30MVA,38.1/3.81kV, are connected in Y- with a balanced load of three 1, Y-connected resistors. Choosing a base of 90MVA,66kV for the high-voltage side of the three-phase transformer. spify the base for the low-voltage side. Compute the per-unit resistance of the load on the base for the low-voltage side. Also, determine the load resistance in ohms referred to the high-voltage side and the per-unit value on the chosen base.