Concept explainers
Consider a load impedance of
(a) Develop an expression for the reactive power Q in terms of
(b) Let the instantaneous current be
(c) Comment on the average real power P supplied to the inductor and the instantaneous power supplied.
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Power System Analysis and Design (MindTap Course List)
- S1) The serial impedance per unit length of a three-phase 140 km power transmission line is 0.09 + j0.88 ohm/ km and its admittance is j4.1x10-6 S / km. Power factor under 210 kV interphase voltage from the end of this energy transmission line A power of 150 MVA, which is 0.85 back, is drawn. Using this transmission line data and the T equivalent circuit model, the line Calculate the head voltage (V1), current (I1) and load angle.arrow_forwardA three-phase system includes a 346.4 V line-to-line supplying a three-phase motor rated 15KVA 0.8pf lag plus additional balanced constant impedance loads. The single-phase representation of the system is shown below. Assume that sources and loads are Y-connected. 1. What is the RMS value of the line current, I in A? 2. If this set of loads will be supplied through a service transformer. What should the minimum size of the transformer in kVA? 3. What should be the size of three-phase capacitor(that will be added to the load mix) to improve power factor to almost 0.95 lag?arrow_forwardA (medium) single phase transmission line 100 km long has the following constants : Resistance/km = 0·25 Ω ; Reactance/km = 0·8 Ω Susceptance/km = 14 × 10−6 siemens ; Receiving end line voltage = 66,000 V The line is delivering 15 000 kW at 0 8 power factor lagging. Assuming that the total capacitance of the line is localised at the receiving end alone, determine the sending end current Select one: a. 50 A b. 320 A c. 240 A d. None of The abovearrow_forward
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