ENGR_400_Module_1_Assignment

An industrial load of200KW has a powerfactor of 0.5 lagging. Agroup of synchronousmotors operating at apower factor of 0.8leading is installed andthe over-all power factorimproves to 0.75 lagging.Determine the KVArating of the synchronousmotors installed.Answer = 130.2354 KVA

A 3-phase overhead transmission line is being supported by three disc insulators. The potentials across top unit and middle unit are 9 kV and 11 kV respectively. Calculate: a. The ratio of capacitance between pin and earth to the self-capacitance of each unit. b. The line voltage. c. String efficiency. JAns: a. 0.22 b. 35.444 kV c. 76%]

COURSE: Electrical EngineeringSUBJECT: Electrical ApparatusINSTRUCTIONS:•    Write the GIVEN with their respective symbols and units.•    Do not skip the SOLUTIONS, do it step-by-step with their respective symbols and units•    Round up to 3 three decimal places the FINAL ANSWERS and BOX it.  PROBLEM:  A source delivers 50 kVA to a load with a power factor of 65 percent lagging. Find the load’s average and reactive powers.

Please answer quickly "In series-connected ac circuit, the total voltage across the circuit is always equal to the sum of the magnitude (only) of the individual voltage across each element."  True  False   The power factor is equal to cosine of the phase difference.  True  False   A leading power factor means that the circuit is predominantly capacitive in nature.  True  False   "Since most loads are resistive in nature (e.g. motors), improvement of power factor is done by connecting capacitor banks or a synchronous condenser "  True  False

Three loads connected in parallel across a 1000-V (RMS), 60-Hz single-phase source.Load 1: Inductive load, 125 kVA, 0.28PF laggingLoad 2: Capacitive load, 10 kW, 40 kVARLoad 3: Resistive load, 15 kWa)    Determine the total kW, kvar, kva, and supply power factor.b)    In order to improve the power factor to 0.8 lagging, a capacitor of negligible resistance isconnected in parallel with the above loads. Find the KVAR rating of that capacitor and thecapacitance in μf .c)    Comment on the magnitude of the supply current after adding the capacitor

Two equal voltages are out of phase with respect to each other by 90 electrical degrees. If the resultant is 311 Volts, what is RMS value of each one?-write legibly-show the complete solution

In a star connected system, the three phase currents are mutually displaced by 120 degree. Select one: True False

An 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 impedance, resistance and reactance of the circuit,              the r.m.s.-values of the voltage and current,              the true-, apparent- and reactive power in the circuit The time taken to reach -190 V for the second time.          Sketch the phasor diagram of this circuit

The length of a three-phase power transmission line with a nominal operating voltage of 69 kV is 16km. The impedance of the transmission line per unit length is 0.125 + j0.4375 ohm/ km. At the end of the line, a 70 MVA star connected load with a power factor of 0.8 back under 69 kV interphase voltage is fed. Capacitive circuit element with a capacitance of 19.14 mikro F / phase is placed as shunt at the end of the transmission line. According to these given; a) Line head voltage and current, b) Calculate the active and reactive power per line.

Circuit elements with an inductance of 200 mH, a capacity of 50 μF and a resistance of 10 Ω are connected in parallel. If the average value of 198 V sinusoidal AC voltage is applied to this system, find the line current, impedance and phase angle of the circuit. (Take the frequency as 60 Hz.)

Task A2 Power factor correction In an AC circuit, the current flowing through Load A is found to be 15<9.20 A. The voltage across the load is 240<620 V. 1) Calculate the apparent, real and reactive power, and the power factor of Load A. 2) A capacitor is connected in parallel with Load A to raise the load power factor to 0.98 lagging. Calculate the capacitance C of the capacitor to achieve the desired power factor. (< is the phase sign)

73. In phasor, the resistance has an angle of 90 degrees and the voltage and current are in phase." True False 74. The impedance (Z) of a circuit is the ratio of the phasor current to the phasor voltage. True False 75. Conductance is always expressed as a real number and comprised the real part of impedance equation. True False

A residential four-wire system supplies power at220 V rms to the following single-phase appliances:On the first phase, there are ten 75-W bulbs. On thesecond phase, there is a 750-W vacuum cleaner with apower factor of 0.87. On the third phase, there are ten40-W fluorescent lamps with power factor of 0.64.Finda. The current in the netural wire.b. The real, reactive, and apparent power for eachphase.

A single phase system is supplying power at 220 V to an inductive and capacitive load of 30 A each, Inductive load is lagging the voltage by 30 degrees and capacitive load leading the voltage by 45 degrees. Compute the real and apparent power for both the loads (Question from subject introduction to power engineering)

Two buses are interconnected by a transmission line of impedance (0.03 +j0.011) pu. The voltage on one bus is 1/0°pu, and the load on the other bus is (1.2 + j0.5) pu. Estimate the following: i) receiving end voltage after two iterations ii) load current iii) sending end apparent power PLEASE SHOW WORKING STEP BY STEP

A three-phase 150 kVA, 4160 V, 0.8 lagging pf load is to be supplied by three single-phase transformers having a turns ratio of 2. Calculate the current that flows in the primary windings if the transformers are connected delta-delta.    Subject: Electrical Apparatus and Divices BOX THE FINAL ANSWER

Vab = 300&angle;300°, Vbc = 300&angle;180°, Vca = 300&angle;420°" A   POSITIVE PHASE SEQUENCE B   NEGATIVE PHASE SEQUENCE

From the following circuit, which is fed by an alternating voltage source, do as indicated. A. Calculate the equivalent total impedance (describe both complex impedance and phasor impedance). B. Calculate the total rms phasor current of the circuit. NOTE: THE VALUES CORRESPOND TO THE EVEN OR ODD TERMINATION OF YOUR TICKET NUMBER. VALUES FOR TICKET TERMINATION IN EVEN NUMBER: v (t) = 24cos (250t + 45) V R = 1 kΩ L = 300 mH C = 1000 pF VALUES FOR TICKET TERMINATION IN ODD NUMBER: V (t) = 32cos (420t + 35) V R = 2.7 kΩ L = 450 mH C = 100 μF

An impedance (inductive) ZL = (11.5 + j10) ohms is connected in parallel with an impedance (capacitive) ZC = (8 – j20) ohms. Calculate (a) the conductance and susceptance of each branch; (b) the total conductance, susceptance, andadmittance of the circuit; (c) the current in each branch, and the total current and power factor, if the impressed emf is 120 volts. draw the circuit diagram

An 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)

The following diagram shows a three-wire single-phase circuit of a house. Consider that the refrigerator consumes 8.5 A, with an inductive angle of 45°. TV and kitchen loads are 200W and 8kW respectively. Calculate: a) Current line 1, line 2 and neutral. b) Total power of the circuit....

The phase a voltage of an abc phase sequence balanced Y-connected power source is Van=120∠90° V rms. Calculate the line voltage of this power source. Answer : Vab=208∠120° V rms, Vbc=208∠0° V rms, Vca=208∠(-120°) V rms,

A 3-phase, 50-Hz overhead transmission line 100 km long has the following constants : Resistance/km/phase = 0.1 Q Inductive reactance/km/phase = 0-2 N Capacitive susceptance/km/phase = 0-04 × 10- 4 siemenS Determine sending end voltage when supplying a balanced load 10,000 kW at 66 kV, p.f. 0-8 lagging. Use nominal T method . Select one: a. 330 kV b. None of the above c. 52 kV d. 69.5 kV

A ower system is operating at 1000Mw, 132kV, 50Hz, with 0.8 p.f. laging in parallelwith another line at 750OMW, 132kV, 50Hz with 0.707 p.f. lagging. Both are interconnectedat the station and when the compensating device is on, the overall power factor isimproved to 0.9 lagging. Suggest suitable capacitors, shunt and series. Individual loadsand combined load are to improve power factor to 0.9 in all cases.

PLS USE 4 DECIMAL PLACES FOR THE FINAL ANSWERS   An inductive reactance of 10 ohms is connected in parallel with the capacitive reactance of 30 ohms. If the combination is connected in series with a 10 ohm resistance. The given voltage is 200V.   *What is the total real power of the system in magnitude with unit of kW?    *What is the total real power of the system in magnitude with unit of kVAR?   *What is the total impedance in polar form in ohms?   *What is the total real power of the system in magnitude with unit of kVA?    *What is the total current in polar form in A?

In 132 kV transmission system, the phase to ground capacitance is 0.01micro F. The inductance being 4 H. Calculate the voltage appearing across the pole of a circuit breaker if a magnetizing current of 9 A is interrupted. Find the value of resistance to be used across contact space to eliminate the striking voltage transient.

The total kVA rating of capacitors required to raise the full-load power factor of a 3-phase,  440 V, 50 Hz induction motor  from 0.75 to 0.85 lagging is Qc = 15 KVAR. Capacitors are delta connected. (i) Determine the line current drawn by the capacitor bank  (ii) Determine the phase current of the capacitor bank  (iii) Determine the capacitive reactance per phase Xc (iv) What will be the capacitance per phase if the capacitors are delta connected ?

A factory is supplied by a three phase, 3 wire system with the following characteristics: Vab= 230<0 Vbc=n230<240 Ia= 110<-36.87 Ic=125<53.13 Find the current Ib.

The impedance of an electrical circuit is (30 − j50) ohms. Determine (a) the resistance, (b) the capacitance, (c) the modulus of the impedance, and (d) the current flowing and its phase angle, when the circuit is connected to a 240V, 50 Hz supply.

The sending-end voltage in the circuit seen is adjusted so that the load voltage is always 13,800 V(rms). The variable capacitor is adjusted until the average power dissipated in the line resistance is minimum. 1. a) If the frequency of the sinusoidal source is 60 Hz, what is thevalue of the capacitance in microfarads?2. b) If the capacitor is removed from the circuit, what percentageincrease in the magnitude of Vs is necessary to maintain 13,800V(rms) at the load?3. c) If the capacitor is removed from the circuit, what is thepercentage increase in line loss?