a) b) c) d) An 11 kV cable with impedance (0.1 + j0.7) 2/phase connects a...

 

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a) b) c) d) An 11 kV cable with impedance (0.1 + j0.7) 2/phase connects a small factory to the local 33 kV network by a 20 MVA, 11:33 kV step-up transformer with reactance of 4% to its own base. The fault level at 33 kV is high enough that the voltage there may be assumed constant and equal to 1 pu for all operating conditions. Loads within the factory operate at constant 0.95 lagging power factor. Draw the single line diagram of the network. Calculate: (i) The maximum factory load that can be connected without violating the statutory limit of ±6% of the nominal 11 kV voltage; A statically excited synchronous generator is to be connected at 11 kV main factory switchboard. If the generator is set to operate at fixed 0.95 lagging power factor, calculate the maximum power output of the generator and corresponding reverse power flow into the 33 kV network for the allowed ±6% voltage variation limit and peak loading conditions from a). (2) (ii) The phase angle difference (i.e. load angle) between the 11 kV and 33 kV network ends when the maximum load is connected. (4) What would be the voltage at the 11 kV main factory switchboard if the same generator is set to operate at 0.95 leading power factor during peak loading conditions? Briefly explain why this voltage value is obtained. (5) (4) (5) a) b) c) d) An 11 kV cable with impedance (0.1 + j0.7) 2/phase connects a small factory to the local 33 kV network by a 20 MVA, 11:33 kV step-up transformer with reactance of 4% to its own base. The fault level at 33 kV is high enough that the voltage there may be assumed constant and equal to 1 pu for all operating conditions. Loads within the factory operate at constant 0.95 lagging power factor. Draw the single line diagram of the network. Calculate: (i) The maximum factory load that can be connected without violating the statutory limit of ±6% of the nominal 11 kV voltage; A statically excited synchronous generator is to be connected at 11 kV main factory switchboard. If the generator is set to operate at fixed 0.95 lagging power factor, calculate the maximum power output of the generator and corresponding reverse power flow into the 33 kV network for the allowed ±6% voltage variation limit and peak loading conditions from a). (2) (ii) The phase angle difference (i.e. load angle) between the 11 kV and 33 kV network ends when the maximum load is connected. (4) What would be the voltage at the 11 kV main factory switchboard if the same generator is set to operate at 0.95 leading power factor during peak loading conditions? Briefly explain why this voltage value is obtained. (5) (4) (5)