In a Y -connected circuit, between each line -voltage and the nearest phase - voltage, there is a phase -angle of: 30°
Description : 4. A three-phase, four-wire system having \( 250 V \) line-to-neutral has the following loads connected between the respective lines and the neutral. Calculate the current in the neutral wire?\[Z_{R}=20 \angle 0^{\circ} ... Z_{Y}=20 \angle 35^{\circ} \Omega, Z_{B}=20 \angle-55^{\circ} \Omega\](10M)
Last Answer : 4. A three-phase, four-wire system having \( 250 V \) line-to-neutral has the following loads connected ... =20 \angle-55^{\circ} \Omega \] (10M)
Description : The product of apparent power and cosine of the phase angle between circuit voltage and current is?
Last Answer : In parllpar reasonans RLC circuit the current is
Description : A 500 MW, 3-phase, Y-connected synchronous generator has a rated voltage of 21.5 kV at 0.85 p.f. The line current when operating at full load rated conditions will be (A) 13.43 kA (B) 15.79 kA (C) 23.25 kA (D) 27.36 kA
Last Answer : A 500 MW, 3-phase, Y-connected synchronous generator has a rated voltage of 21.5 kV at 0.85 p.f. The line current when operating at full load rated conditions will be 15.79 kA
Description : In a three phase transformer, if the primary side is connected in star and secondary side is connected in delta, what is the angle difference between phase voltage in the two cases. (A) delta side lags by -30°. (B) star side lags by -30°. (C) delta side leads by 30°. (D) star side leads by -30°.
Last Answer : Ans: C This is vector group and has +30° displacement. Therefore, delta side leads by +30°.
Last Answer : Req= (1/1200 +1/560 + 1/2.1)^-1 = 2.1 ohms RT= 2.1 + 7.8 = 9.9 ohms IT = V/R = 24/9.9 = 2.4 A Veq= R I = 2.1 2 ... 7.8 = 12.096 w = 44.928 w _________________________________________ By: Ellis-Junior Kamatjipose [email protected]
Description : In a certain three -wire Y -connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages will be: A. 2,000 V B. 6,000 V C. 666 V D. 3,464 V
Last Answer : In a certain three -wire Y -connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages will be: 3,464 V
Description : In the illustrated circuit, what is the phase relationship of the amplifier output compared to the input? EL-0022 A. 0° in-phase B. 180° out of phase C. phase angle of the input divided by power factor D. unable to determine without the value of the bias voltage
Last Answer : Answer: B
Description : In a Y-connected circuit, the magnitude of each line current is? A.one-third the phase current B.three times the corresponding phase current C.equal to the corresponding phase current D.zero
Last Answer : In a Y-connected circuit, the magnitude of each line current is? A.one-third the phase current B.three times the corresponding phase current C.equal to the corresponding phase current D.zero
Description : A three-phase star -connected load is operating at a power factor angle ϕ with ϕ being the angle between
Last Answer : A three-phase star -connected load is operating at a power factor angle ϕ with ϕ being the angle between Phase voltage and phase current
Description : One important difference between wye-connected and delta-connected generators is that delta connections have ____________. A. line voltages equal to the vector sum of the phase voltages B. phase voltages 90° ... C. line current equal to the phase current D. line voltage equal to the phase voltage
Last Answer : Answer: D
Description : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is :
Last Answer : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is : 200 V
Description : A single-phase ac voltage source has 200 V rms and a system connected consumes an active power of 300 W. What is the reactive power consumed by the system if 2.5 A rms current is drawn ? (a) 100 VAR (b) 200 VAR (c) 300 VAR (d) 400 VAR
Last Answer : A single-phase ac voltage source has 200 V rms and a system connected consumes an active power of 300 W. What is the reactive power consumed by the system if 2.5 A rms current is drawn ? 400 VAR
Description : When shipboard electrical distribution circuits are connected in parallel, additional parallel circuits will cause the total circuit resistance to _____________. A. increase, causing a drop in the line current B ... an increase in the line voltage D. decrease, causing an increase in the line current
Description : A 100 kVA, 415 V(line), star-connected synchronous machine generates rated open circuit voltage of 415 V at a field current of 15 A. The short circuit armature current at a field current of 10 A is equal to the ... unit saturated synchronous reactance is (A) 1.731 (B) 1.5 (C) 0.666 (D) 0.577
Last Answer : 0.6
Description : Two wattmeters connected to measure the power input to a balanced three-phase circuit indicate 4.5 KW and 3 KW respectively. Find the power factor of the circuit. A. 0.7 B. 0.8 C. 0.95 D. 0
Last Answer : Two wattmeters connected to measure the power input to a balanced three-phase circuit indicate 4.5 KW and 3 KW respectively. Find the power factor of the circuit. 0.95
Description : Consider a circuit with four resistors in series connected to a voltage source. What happens to the voltage across each resistor, if the value of each of the resistors is doubled? A) It will double B) It will remain the same C) It will be halved D) It will become zero
Last Answer : Consider a circuit with four resistors in series connected to a voltage source. What happens to the voltage across each resistor, if the value of each of the resistors is doubled? A) It will double B) It will remain the same C) It will be halved D) It will become zero
Description : A series R-L circuit is suddenly connected to d.c. voltage source of V volts. The current in this series circuit, just after the switch is closed, is equal to (1) Zero (2) V/L (3) V/C (4) V.L/C
Last Answer : When is a series RLC circuit is over damped
Description : Two 100 watt light bulbs are connected in parallel across a 100 volt power supply. The total power developed in the circuit is _______________. A. 200 watts B. 100 watts C. 50 watts D. equal to the product of the amperes times the voltage in each branch
Last Answer : Answer: A
Description : In the illustration circuit, A, B, C, and D are each 12 volts. What is the voltage of the lead connected to C and D with respect to the lead connected to A and B? EL-0039 A. (+) 48 volts B. (-) 24 volts C. (-) 48 volts D. (+) 24 volts
Description : In the illustration circuit, A, B, C, and D are each 12 volts. What is the voltage at the output lead connected to 'A' and 'B' with respect to the output lead connected to 'C' and 'D'? EL-0039 A. (+) 48 volts B. (-) 24 volts C. (-) 48 volts D. (+) 24 volts
Description : 9 leds each of 1 volt drop is series with 9 volt battery , do we need a resistor?(SMD leds) I have seen some smd leds without resistor !
Last Answer : We connect resistor to limit the current. So, it depends upon the current rating of the LED, which is provided by manufacturer.
Description : When testing for blown fuses in a three-phase supply circuit to a motor, you should first ___________________. A. apply the megger across the tops of the line fuses B. apply an ammeter diagonally across ... of the line fuses D. ensure the circuit is de-energized, and then use a continuity tester
Description : In the illustrated motor controller circuit, which statment is true? EL-0023 A. The high and low speed lights operate at less than line voltage with a resistor in series. B. This controller can be ... . The wattage of the high speed light must be greater than the wattage of the low speed light.
Description : Which of the following actions must be carried out before a voltage tester can be used to test the three line fuses to a three-phase motor? A. The fuses must be removed from the circuit. B. The ... disconnected and tagged. D. Nothing need be done as long as the motor is running under a light load.
Description : The power consumed in a circuit element will be least when the phase difference between the current and voltage is?
Last Answer : The power consumed in a circuit element will be least when the phase difference between the current and voltage is 90°.
Description : In testing a three-phase delta winding for an open circuit using a megohmmeter, you must ______________. A. test each phase with all connections intact B. measure the voltage across the open ... groups to avoid short circuiting D. open the delta-connections to avoid shunting the phase being tested
Description : What is the phase angle of an ohm inductor in series with an ohm resistor connected to a 5 KHz source?
Last Answer : You need to provide values of resistor and inductor etc to find the phase angle.
Description : A alternator is delivering power to a balanced load at unit power factor. The phase angle between the line voltage and the line current is? (A) 90° (B) 60° (C) 30° (D) 0°
Last Answer : A alternator is delivering power to a balanced load at unit power factor. The phase angle between the line voltage and the line current is 30°
Description : A two-phase generator is connected to two 90Ω load resistors. Each coil generates 120 V ac. The value of current flowing through the common neutral line will be: A. 1.33 A B. 1.88 A C. 2.66 A D. 1.77 A
Last Answer : A two-phase generator is connected to two 90Ω load resistors. Each coil generates 120 V ac. The value of current flowing through the common neutral line will be: 1.77 A
Description : A ________network is made of a set of switches connected by physical links, in which each link is divided into nchannels. A) line-switched B) frame-switched C) circuit-switched D) none of the above
Last Answer : circuit-switched
Description : At a particular instant, the R-phase voltage of a balanced 3-phase system is + 30 V, and the Y-phase voltage is – 90 V. The voltage of B-phase at that instant is (A) + 120 V (B) – 120 V (C) – 60 V (D) + 60 V
Last Answer : At a particular instant, the R-phase voltage of a balanced 3-phase system is + 30 V, and the Y-phase voltage is – 90 V. The voltage of B-phase at that instant is + 60 V
Description : The circuit illustrated represents a single phase AC ground detecting system. If a ground occurs on line 'B', which of the lamps will burn the brightest? EL-0008 A. X B. Y C. Both will be equal brightness. D. both will go out.
Description : Figure 'D' of the diagram shown in the illustration has a turns ratio of four to one. If a three-phase 440 volt supply is connected to terminals 'A-B-C', what voltage should develop across terminals 'a-b-c'? EL-0084 A. 64 volts B. 110 volts C. 190 volts D. 762 volts
Description : Figure 'C' of the diagram shown in the illustration has a turns ratio of four to one. If a three-phase 440 volt supply is connected to terminals 'A-B-C', what voltage should develop across terminals 'a-b-c'? EL-0084 A. 64 volts B. 110 volts C. 190 volts D. 762 volts
Last Answer : Answer: C
Description : Figure 'B' of the diagram shown in the illustration has a turns ratio of four to one. If a three-phase 440 volt supply is connected to terminals 'A-B-C', what voltage should develop across terminals 'a-b-c'? EL-0084 A. 64 volts B. 110 volts C. 190 volts D. 762 volts
Description : Figure 'A' of the diagram shown in the illustration has a turns ratio of four to one. If a three-phase 440 volt supply is connected to terminals 'A-B-C', what voltage should develop across terminals 'a-b-c'? EL-0084 A. 64 volts B. 110 volts C. 190 volts D. 762 volts
Description : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay
Description : The line voltage EL in a star connection is equal to.... (Ep = phase voltage)
Last Answer : The line voltage EL in a star connection is equal to √3 .Ep (Ep = phase voltage)
Description : A three phase induction motor is driving full -load torque which is independent of speed. If the line voltage drops to 90% of the rated value, % increase in motor copper losses (a) 23% (b) -18% (c) 123% (d) None of these
Last Answer : A three phase induction motor is driving full -load torque which is independent of speed. If the line voltage drops to 90% of the rated value, % increase in motor copper losses (a) 23% (b) -18% (c) 123% (d) None of these
Description : At what phase angle is the voltage momentarily constant in a sine wave?
Last Answer : We often see the peak and trough (maximum positive and maximumnegative excursions) of the sine wave considered as points ofmomentarily constant voltage. Those points are at phase angles of90 degrees and at 270 degrees.
Description : Diffecult questions
Last Answer : No. Please send me
Description : The number of cycles per second occurring in AC voltage is known as the _____________. A. phase angle B. frequency C. wave form D. half mode
Description : The voltage of a particular bus can be controlled by controlling the a) Active power of the bus b) Reactive power of the bus c) Phase angle d) All of the above
Last Answer : b) Reactive power of the bus
Description : In power system, if a voltage controlled bus is treated as a load bus then which one of the following limits would be violated? a) Voltage b) Active power c) reactive power d) Phase angle
Last Answer : a) Voltage
Description : In load flow studies of a power system, a voltage control bus is specified by a) Real power and reactive power b) Reactive power and voltage magnitude c) Voltage and voltage phase angle d) Real power and voltage magnitude
Last Answer : d) Real power and voltage magnitude
Description : If the phase -angle of the voltage coil of a directional relay is 50°, the maximum torque angle of the relay is: (A) 130° (B) 100° (C) 50° (D) 25°
Last Answer : If the phase -angle of the voltage coil of a directional relay is 50°, the maximum torque angle of the relay is: 50°
Description : If you obtain a low resistance reading with a megohmmeter connected between terminals 'A' and 'C' of the three-phase, wye-connected winding shown in the illustration, there is __________. EL-0074 A. no open circuit ... 'B' C. an open circuit between 'A' and 'C' D. an open circuit in both windings
Description : The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit