A three-phase 400V, star-connected motor has an output of 50kW, with an efficiency of 90 per...
A three-phase 400V, star-connected motor has an output of 50kW, with an efficiency of 90 per cent and a power factor of 0.85. Calculate the line current. Sketch a phasor diagram showing the voltages and the currents. If the motor windings were connected in mesh (delta), What would be the correct voltage of a three-phase supply suitable for the motor?
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A three-phase 400V, star-connected motor has an output of 50kW,
with an efficiency of 90 per...
A three-phase generator connected in a star generates a phase voltage of Vθ = 2500 Vrms...
A three-phase generator connected in a star generates a phase voltage of Vθ = 2500 Vrms and supplies a delta-connected three-phase load. The three phases of the generator feed 3 equal charges each composed of R = 10 Ω, XC = 4Ω and XL = 10Ω. a) Calculate the phase, line and load currents b) Calculate the phase, line and load voltages c) Calculate the powers of Apparent (S), Real (P) and Reactive (Q) delivered by the generator d) Calculate...
5 Three inductive coils each of inductance 45mH are connected in star to a 3 phase...
5 Three inductive coils each of inductance 45mH are connected in star to a 3 phase 400V, 50 Hz supply. Calculate the inductance of each coil, which when connected in delta to take the same supply voltage and line current, also find the power delivered at unity power factor for both star and delta connected load. (6 Marks)
A three-phase generator connected in a star generates a phase voltage of Vθ = 24 KVrms and supplies a three-phase transformer connected in star. The transformation ratio is 115: 1. Each of the three c...
A three-phase generator connected in a star generates a phase voltage of Vθ = 24 KVrms and supplies a three-phase transformer connected in star. The transformation ratio is 115: 1. Each of the three coils of the secondary transformer feed 3 equal charges each composed of them by R = 18Ω, XC = 2Ω and XL = 20Ω. a) Calculate the phase, line and charge currents after the b) Calculate the phase, line and load voltages c) Calculate the Apparent...
Q3 (3 marks) (4 marks) Two wattmeters are connected in the a and b phases, with...
Q3 (3 marks) (4 marks) Two wattmeters are connected in the a and b phases, with the ends of the voltage coils connected in the c phase, of a balanced three phase star- connected lagging load. Draw a circuit diagram showing the three phases, the wattmeters and the load. Draw a phasor diagram of the phase voltages and currents, the voltages across the wattmeter voltage coils, and the angles between the wattmeter voltages and currents. Show that the sum of...
b) The load connected to a three-phase supply comprises three similar coils connected in star. If...
b) The load connected to a three-phase supply comprises three similar coils connected in star. If the phase currents are 10A and the total active power and power factor absorb by the loads are 3kW and 0.8 lagging, respectively. Find: i. The magnitude of phase and line voltages (4 marks) ii. Total apparent power (1 mark) iii. The impedance of each coil. (2 marks) c) If the coil in Q3(b) are now connected in delta to the same three-phase supply,...
Problem 2 A 15 HP, 96% efficient, three-phase Wye-connected synchronous motor is connected to a 4...
Problem 2 A 15 HP, 96% efficient, three-phase Wye-connected synchronous motor is connected to a 480 VAC, 60 Hz power supply. The field excitation is set such that the power factor is 0.97 leading. The machine draws 9 kW from the supplv. The per-phase armature reactance is 9500. Find the internally generated voltage, E, Calculate the motor torque angle, δ. Draw the phasor diagram, showing Vn E, XsL, IA ,Θ and δ. a. b. c.
Problem 2 A 15 HP,...
A three-phase electrical heater dissipates 50kW when connected to a 4160V, 3-phase line. (a) Draw the...
A three-phase electrical heater dissipates 50kW when connected to a 4160V, 3-phase line. (a) Draw the circuit diagram and indicate system parameters (line to line voltage, currents, fuses, etc.) if the loads (resistors) are connected in WYE. (b) What is the LINE current if the resistors are all connected in WYE? (c) Draw the circuit diagram and calculate the LINE current if the resistors are all connected in DELTA? (d) While the delta connected load resistors are working fine, and...
A three-phase generator connected in star generates a phase voltage of Vθ = 220 Vrms and supplies a three-phase load also connected in star. The three phases of the generator are connected to the thre...
A three-phase generator connected in star generates a phase
voltage of Vθ = 220 Vrms and supplies a three-phase load also
connected in star. The three phases of the generator are connected
to the three loads shown Remember that the return of the current of
each charge is through the Neutral.
a) Calculate the phase, line, load and neutral currents
b) Calculate the phase, line and load voltages
c) Calculate the powers of Apparent (S), Real (P) and Reactive (Q)...
A three-phase delta-connected synchronous induction motor is connected to a 415 volt, 50 Hz supply. The...
A three-phase delta-connected synchronous induction motor is connected to a 415 volt, 50 Hz supply. The winding resistance is negligible and the synchronous reactance per phase is 5 ohms. The input power is 20 kW and the motor has a leading power factor of 0.8. Draw the phasor diagram for this machine: ii) use the IXs phasor and the V phasor to construct the phasor for E. iii) measure or calculate the magnitude of E iv) By construction and/or by...
The parameters of a 400V, 50Hz, three phase star connected induction motor are: Stator impedance ?1...
The parameters of a 400V, 50Hz, three phase star connected induction motor are: Stator impedance ?1 = 1.7 + ?4 ohm/phase Referred rotor impedance ?2 ′ = 1.2 + ?2.6 ohm/phase Magnetizing impedance ?0 = 5 + ?60 ohm/phase Determine the torque at a slip of 5% using : a) The exact equivalent circuit b) The approximate equivalent circuit
5 Three inductive coils each of inductance 45mH are connected in star to a 3 phase 400V, 50 Hz supply. Calculate the inductance of each coil, which when connected in delta to take the same supply voltage and line current, also find the power delivered at unity power factor for both star and delta connected load. (6 Marks)
Q3 (3 marks) (4 marks) Two wattmeters are connected in the a and b phases, with the ends of the voltage coils connected in the c phase, of a balanced three phase star- connected lagging load. Draw a circuit diagram showing the three phases, the wattmeters and the load. Draw a phasor diagram of the phase voltages and currents, the voltages across the wattmeter voltage coils, and the angles between the wattmeter voltages and currents. Show that the sum of...
b) The load connected to a three-phase supply comprises three similar coils connected in star. If the phase currents are 10A and the total active power and power factor absorb by the loads are 3kW and 0.8 lagging, respectively. Find: i. The magnitude of phase and line voltages (4 marks) ii. Total apparent power (1 mark) iii. The impedance of each coil. (2 marks) c) If the coil in Q3(b) are now connected in delta to the same three-phase supply,...
Problem 2 A 15 HP, 96% efficient, three-phase Wye-connected synchronous motor is connected to a 480 VAC, 60 Hz power supply. The field excitation is set such that the power factor is 0.97 leading. The machine draws 9 kW from the supplv. The per-phase armature reactance is 9500. Find the internally generated voltage, E, Calculate the motor torque angle, δ. Draw the phasor diagram, showing Vn E, XsL, IA ,Θ and δ. a. b. c.
Problem 2 A 15 HP,...
A three-phase generator connected in star generates a phase
voltage of Vθ = 220 Vrms and supplies a three-phase load also
connected in star. The three phases of the generator are connected
to the three loads shown Remember that the return of the current of
each charge is through the Neutral.
a) Calculate the phase, line, load and neutral currents
b) Calculate the phase, line and load voltages
c) Calculate the powers of Apparent (S), Real (P) and Reactive (Q)...
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