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Chapter 2 Solutions
Power System Analysis and Design (MindTap Course List)
- The load on a 120-V, 60 Hz supply is 5KW (resistive), 8 KVAR (inductive), and 2 KVAR (capacitive). Find the following: a) total kilovolt-amperes, b)power factor of the combined loads, c) current drawn from the supply, d) capacitance needed to establish unity power factor, e) capacitive reactance needed to establish unity power factor, f) the current drawn from the supply at unity p.f.arrow_forwardA 3-phase, 50 Hz, 440 V motor develops 100 H.P. (74·6 kW), which works for 3000 hours per annum, the power factor being 0·75 lagging and efficiency 93%. A bank of capacitors is connected in delta across the supply terminals and power factor raised to 0·95 lagging. The tariff is Rs 100 per kVA plus 20 paise per kWh. If the power factor is improved to 0·95 lagging by means of loss-free capacitors costing Rs 60 per kVAR, Compute the annual saving effected. Allow 12% per annum for interest and depreciation on capacitors.arrow_forwardA 3-phase, 50 Hz overhead transmission line, 100 km long, 110 kV between the lines at the receiving end has the following constants : Resistance per km per phase = 0·153 Ω Inductance per km per phase = 1·21 mH Capacitance per km per phase = 0·00958 μF The line supplies a load of 20,000 kW at 0·9 power factor lagging. Calculate using nominal π representation, the sending end voltage, current, power factor, regulation and the efficiency of the linearrow_forward
- An e.m.f. whose instantaneous value at time t is given by v(t) = 283 sin (314t + π/4) volts is applied to an inductive circuit and the current in the circuit is i(t) = 5.66 sin (314t - π/6) amperes. Determine: (iii) the active power absorbed (in W)arrow_forwardAn alternating single-phase circuit describes the instantaneous values of the applied voltage and the corresponding current as: v = 360 sin (201,69 t + π/6) and i = 36 sin (201,69 t - π/9) Calculate: the frequency (1) the phase angle, in degrees, (1) the power factor of the circuit (1) the value of the voltage and current 10 ms after zero, (2) the impedance, resistance and reactance of the circuit, (3) the r.m.s.-values of the voltage and current, (2) the true-, apparent- and reactive power in the circuit (3) The time taken to reach -190 V for the second time. (3) Sketch the phasor diagram of this circuit (2)arrow_forwardA 3-phase, 50 Hz, 440 V motor develops 100 H.P, which works for 3000 hours per annum, the power factor being 0·75 lagging and efficiency 93%. A bank of capacitors is connected in delta across the supply terminals and power factor raised to 0·95 lagging. The tariff is Rs 100 per kVA plus 20 paise per kWh. If the power factor is improved to 0·95 lagging by capacitors costing Rs 60 per kVAR and having a power loss of 100 W per kVA. Compute the annual saving effected. Allow 12% per annum for interest and depreciation on capacitorsarrow_forward
- A 50 Hz, 250 V single phase power line has the following loads placed across it in parallel; 4 kW ata pf of 0. 8 lagging; 6 kVA at a pf of 0.6 lagging; 5 kVA which includes 1.2 kVAR leading. Determinethe overall pf of the system and the capacitance of the capacitor which, if connected across themains restore the power factor to unity.arrow_forwardf. A residential air conditioning unit with an SEER of 14 serves a single-detached family residence in Quezon City, Philippines having an annual cooling load hours of 6,116 hours. The total cooling load is 36,000 Btu/hr. Calculate the annual operating cost for the A/C unit if the energy cost is Php 7.96/kW-hr.arrow_forwardA 3-phase transmission line is being supported by three-disc insulators. The potentials across top unit (i.e. near to the tower) and middle unit are 8 KV and 11 KV respectively. Calculate: 1) The ratio of capacitance between pin and earth to the self-capacitance of each unit 2) The line voltage 3) String efficiency Subject Power Transmission And Distributionarrow_forward
- An e.m.f. whose instantaneous value at time t is given by v(t) = 283 sin (314t + π/4) volts is applied to an inductive circuit and the current in the circuit is i(t) = 5.66 sin (314t - π/6) amperes. Determine: (iii) the active power absorbed (in W)the answer is not 207.286arrow_forward. A 46KV 0.8 lagging power factor load is connected to the end of a short transmission line wherethe voltage is 230. If the line resistance and reactance are 0.06 and 0.08 ohm, respectively,calculate the voltage at the sending end.arrow_forward3. The voltage v(t) = 359.3 cos(wt) volts is applied to a load consisting of a 14ohm resistor in parallel with a capacitive reactance Xc = 28 ohm. Calculate (a) the instantaneous power absorbed by the resistor, (b) the instantaneous power absorbed by the capacitor, (c) the real power absorbed by the resistor, (d) the reactive power delivered by the capacitor, and (e) the load power factor.arrow_forward
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