Why 50 Hz chosen?

Why 50 Hz chosen?  
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1 Answer

Answer :

Earlier 25 Hz generally used.

After developing of the high-speed turbine, 50/60 Hz standardized. 
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Related questions

A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Description : A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Last Answer : The number of poles in an induction motor can be calculated using the following formula: No. of poles = (120 * frequency) / speed In this case, the number of poles would be calculated as follows: No. of poles = ( ... ) - 50 Hz = 8.08 Hz So the motor has 6 poles and a slip frequency of 8.08 Hz.

Why we are using only 50 Hz for single and three phase electrical instruments?

Description : Why we are using only 50 Hz for single and three phase electrical instruments?

Last Answer : Synchronization condition: There are five conditions that must be met before the synchronization process takes place. The alternator must have equal line voltage, frequency, phase sequence, phase angle and waveform to that ... in the US and North America and 50 Hz in most of the rest of the world.

Can 60 Hz transformers be operated at 50 Hz?

Description : Can 60 Hz transformers be operated at 50 Hz?

Last Answer : The transformers rated below 1 KVA can be used on 50 Hz service. Transformers 1 KVA and larger, rated at 60 Hz, should not be used on 50 Hz service, due to the higher losses and resultant heat ... designs are required for this service. However, any 50 Hz transformer will operate on a 60 Hz service.

Why should be the frequency 50 Hz 60Hz only why not others like 45, 95 56 or anything , why should we maintain the frequency constant if so why it is only 50 Hz 60Hz?

Description : Why should be the frequency 50 Hz 60Hz only why not others like 45, 95 56 or anything , why should we maintain the frequency constant if so why it is only 50 Hz 60Hz?

Last Answer : We can have the frequency at any frequency you like, but than you must also make your own motors,high voltage transformers or any other equipment you want to use.We maintain the frequency at 50hz ... maintains a standard at 50 /60hz and the equipments are are made to operate at these frequency.

Why frequency is 50 hz only & why should we maintain the frequency constant?

Description : Why frequency is 50 hz only & why should we maintain the frequency constant?

Last Answer :  We can have the frequency at any frequency we like, but then we must also make our own motors, transformers or any other equipment we want to use.  We maintain the frequency at 50 Hz ... because the world maintains a standard at 50 /60hz and the equipments are made to operate at these frequency.

The line trap unit employed in carrier current relaying: (A) offers high impedance to 50 Hz power frequency signal (B) offers high impedance to carrier frequency signal (C) offers low impedance to carrier frequency signal (D) Both (A) & (C)

Description : The line trap unit employed in carrier current relaying: (A) offers high impedance to 50 Hz power frequency signal (B) offers high impedance to carrier frequency signal (C) offers low impedance to carrier frequency signal (D) Both (A) & (C)

Last Answer : Ans: B The line trap unit employed in carrier current relaying offers high impedance to carrier frequency signal. Because carrier frequency range is 35 km – 500 kHz XL = 2Π f l Where f increases XL will also increases

A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both eddy current and hysteresis losses increases. (C) Eddy current loss remains the same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Description : A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both ... same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Last Answer : (A) Both eddy current and hysteresis losses decreases.

A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Description : A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Last Answer : Ans: B N = NS (1-S) and NS =120 f / p =120 x 50 /4 = 1500 rpm ∴N= 1500 (1-0.02) =1470 rpm

The eddy current loss in an a-c electric motor is 100 watts at 50 Hz. Its loss at 100 Hz will be (A) 25 watts (B) 59 watts (C) 100 watts (D) 400 watts

Description : The eddy current loss in an a-c electric motor is 100 watts at 50 Hz. Its loss at 100 Hz will be (A) 25 watts (B) 59 watts (C) 100 watts (D) 400 watts

Last Answer : (D) 400 watts

Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Description : Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Last Answer : Ans: C Given : s = 0.02 ; f = 50 Hz Therefore, frequency of rotor induced emf = s f = 0.02 x 50 = 1.0 Hz

A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m.

Description : A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m.

Last Answer : (D) 75 r.p.m.

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : (C) 3.0 V.

The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about (A) 50 Hz. (B) 20 Hz. (C) 2 Hz. (D) Zero.

Description : The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about (A) 50 Hz. (B) 20 Hz. (C) 2 Hz. (D) Zero.

Last Answer : (C) 2 Hz.

Why 110V has been chosen in MCC cell?

Description : Why 110V has been chosen in MCC cell? 

Last Answer : To isolate control circuit from power circuit for Human safety at control circuit side.  

Why vector group of SUT is chosen as Yn-Yo-Yo?

Description : Why vector group of SUT is chosen as Yn-Yo-Yo?

Last Answer : To facilitate momentary paralleling of SUT with UT on 6.6kV buses.  

How 6.6 kV-bus supply was chosen?

Description : How 6.6 kV-bus supply was chosen?

Last Answer : 11 kV was rejected in view of the high insulation cost with 11 kV motors. 3.3 kV was rejected, since max motor size with 3.3 kV bus is limited to 2 MW. But we are having the motors having rating more than 2 MW, which cannot suit to 3.3 kV bus. 6.6 kV bus we can start upto 5 mw size motor. 

Why all 415V transformers are chosen Dyn 11? What are the protections provided for the 415V transformers?

Description : Why all 415V transformers are chosen Dyn 11? What are the protections provided for the 415V transformers?

Last Answer : a) To facilitate interchange. b) To have momentary parallel during changeover. Protections a) Door interlock to trip HT and LT breakers. b) LT breaker can on only after HT breaker is in on position. c) ... and restricted E/F (51N + 64). f) Winding temp high trip (140°C trip and 130°C alarm) 

Why SET is chosen as Dyn 11?

Description : Why SET is chosen as Dyn 11? 

Last Answer : To have smooth commutation in generation in between stator and rotor.  

Why off load tap changer was chosen for GT?

Description : Why off load tap changer was chosen for GT?

Last Answer : Because our plant works on base load always.  

Why bi-directional flow is chosen for PHT system?

Description : Why bi-directional flow is chosen for PHT system?

Last Answer : Bi-directional flow is chosen for PHT system because, a. Uniform temperature gradient is facilitated so there will be no differential thermal expansion. b. It facilitates fuelling even when the ... , which facilitates uniform neutron flux and this intern gives rise to maximum fuel burns up. 

If the supply voltage is 220 volts 60 Hz, what is the operating voltage of the motor controller circuitry illustrated? EL-0011 A. 110 volts DC B. 110 volts AC C. 220 volts DC D. 220 volts AC

Description : If the supply voltage is 220 volts 60 Hz, what is the operating voltage of the motor controller circuitry illustrated? EL-0011 A. 110 volts DC B. 110 volts AC C. 220 volts DC D. 220 volts AC

Last Answer : Answer: D

In a 60 Hz AC system, the current will pass through one complete cycle in _____________. A. 60 seconds B. 6 seconds C. 1 second D. .016 of a second

Description : In a 60 Hz AC system, the current will pass through one complete cycle in _____________. A. 60 seconds B. 6 seconds C. 1 second D. .016 of a second

Last Answer : Answer: D

A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Description : A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Last Answer : Answer: A

An AC generator produces 60 Hz at 1800 RPM. If the generator speed is increased to 1830 RPM, the cycles will _____________. A. remain at 60 Hz B. increase to 61 Hz C. decrease to 59 Hz D. increase to 63 Hz

Description : An AC generator produces 60 Hz at 1800 RPM. If the generator speed is increased to 1830 RPM, the cycles will _____________. A. remain at 60 Hz B. increase to 61 Hz C. decrease to 59 Hz D. increase to 63 Hz

Last Answer : Answer: B

If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Description : If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Last Answer : Answer: C

If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration turned opposite of those in the transmitter by design, what corrective action should be taken? EL-0092 A. Reverse the 60 Hz supply connections to 'S1' and 'S2'. B. No action is needed. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Description : If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration turned opposite of those in the transmitter by design, what corrective action should be taken? EL-0092 A. Reverse the 60 Hz supply ... is needed. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Last Answer : Answer: B

If the electricity represented by the wave form in 'B' were applied to the left side of the illustrated circuit, the output on the right side would be ____________. EL-0064 A. direct current with the top lead positive with repect to the lower lead B. direct current, half wave rectified with a ripple frequency of 60 hz C. direct current with the top lead negative with repect to the lower lead D. clipped to a value equal to the square root of 3 times the input voltage value

Description : If the electricity represented by the wave form in 'B' were applied to the left side of the illustrated circuit, the output on the right side would be ____________. EL-0064 A. direct current with the ... lower lead D. clipped to a value equal to the square root of 3 times the input voltage value

Last Answer : Answer: C

When shore power is being connected to a ship in dry dock, _____________. A. the ship's generators are paralleled with the shore power to provide continuous power B. proper phase sequence must be established C. exactly 450 volts must be supplied from the shore D. exactly 60 Hz must be provided by the terminal

Description : When shore power is being connected to a ship in dry dock, _____________. A. the ship's generators are paralleled with the shore power to provide continuous power B. proper phase sequence must be ... 450 volts must be supplied from the shore D. exactly 60 Hz must be provided by the terminal

Last Answer : Answer: B

A handheld digital tachometer could give a bad reading if ___________________. A. aimed directly at the shaft B. partially aimed at a 60 Hz. fluorescent light C. positioned 5-10 inches from the shaft D. the tape is too shiny

Description : A handheld digital tachometer could give a bad reading if ___________________. A. aimed directly at the shaft B. partially aimed at a 60 Hz. fluorescent light C. positioned 5-10 inches from the shaft D. the tape is too shiny

Last Answer : Answer: B

The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator

Description : The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator

Last Answer : Answer: C

If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration were in 180 degree error with those of the transmitter, what corrective action should be taken? EL-0092 A. Reverse the 60 Hz connections to 'S1' and 'S2'. B. No action is needed as this is proper operation. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Description : If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration were in 180 degree error with those of the transmitter, what corrective action should be taken? EL-0092 A. Reverse the 60 Hz ... is proper operation. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Last Answer : Answer: A

If coil 'R1-R2' at the receiver of figure 'A' shown in the illustration were in 180 degree error with respect to that of the transmitter, what corrective action should be taken? EL-0092 A. No action is necessary as this is proper operation. B. Reverse the 60 Hz supply connections at 'R1' and 'R2'. C. Interchange connections 'S1' and 'S2'. D. Interchange connections 'S1' and 'S3'.

Description : If coil 'R1-R2' at the receiver of figure 'A' shown in the illustration were in 180 degree error with respect to that of the transmitter, what corrective action should be taken? EL-0092 A. No action is ... and 'R2'. C. Interchange connections 'S1' and 'S2'. D. Interchange connections 'S1' and 'S3'.

Last Answer : Answer: B

If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration turned opposite of those in the transmitter, what corrective action should be taken to have both turn in the same direction? EL-0092 A. Reverse the 60 Hz supply connections to 'S1' and 'S2'. B. No action is needed. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Description : If coils 'R1-R2-R3' at the receiver of figure 'B' shown in the illustration turned opposite of those in the transmitter, what corrective action should be taken to have both turn in the same direction? EL-0092 A ... is needed. C. Interchange leads 'R1' and 'R3'. D. Interchange leads 'R2' and 'R3'.

Last Answer : Answer: C

If coil 'R1-R2' at the receiver of figure 'A' shown in the illustration turned opposite of that in the transmitter, what corrective action should be taken? EL-0092 A. No action is necessary as this is normal operation. B. Reverse 60 Hz supply connections to 'R1' and 'R2'. C. Interchange connections to 'S1' and 'S2'. D. Interchange connections to 'S1' and 'S3'.

Description : If coil 'R1-R2' at the receiver of figure 'A' shown in the illustration turned opposite of that in the transmitter, what corrective action should be taken? EL-0092 A. No action is necessary as this is ... . C. Interchange connections to 'S1' and 'S2'. D. Interchange connections to 'S1' and 'S3'.

Last Answer : Answer: D

The output voltage of a 440 volt, 60 Hz AC generator is controlled by the ______________. A. load on the alternator B. load on the prime mover C. speed of the prime mover D. exciter output voltage

Description : The output voltage of a 440 volt, 60 Hz AC generator is controlled by the ______________. A. load on the alternator B. load on the prime mover C. speed of the prime mover D. exciter output voltage

Last Answer : Answer: D

Assuming a standard 60 Hz. input to the circuit shown in the illustration, the ripple frequency would be ____________. EL-0085 A. 30 Hz B. 60 Hz C. 90 Hz D. 120 Hz

Description : Assuming a standard 60 Hz. input to the circuit shown in the illustration, the ripple frequency would be ____________. EL-0085 A. 30 Hz B. 60 Hz C. 90 Hz D. 120 Hz

Last Answer : Answer: D

If the clock frequency to the circuit shown in the illustration were 2 kHz, what would be indicated at the output of 'FF-C'? EL-0087 A. 250 Hz B. 666 Hz C. 6 kHz D. 16 kHz

Description : If the clock frequency to the circuit shown in the illustration were 2 kHz, what would be indicated at the output of 'FF-C'? EL-0087 A. 250 Hz B. 666 Hz C. 6 kHz D. 16 kHz

Last Answer : Answer: A

What will happen if Transformer is operated at 100 HZ Frequency?

Description : What will happen if Transformer is operated at 100 HZ Frequency?

Last Answer : 1. As per EMF equation of the transformer frequency is directly proportional to winding voltage. If we double the frequency the sinusoidal root mean winf=ding voltage also doubled. E=4.44 * f*b*n* ... core 5) This is followed by heating up of the oil and thus cooling temperature goes down sharply.

Can 60 Hz Transformers be Used at Higher Frequencies?

Description : Can 60 Hz Transformers be Used at Higher Frequencies?

Last Answer : A: Transformers can be used at fre¬quencies above 50 Hz up through 400 Hz with no limitations provided nameplate voltages are not exceeded. However, 50 Hz transformers will have less voltage ... Where better regulation and smaller physical size are required, contact us for special 400 Hz designs.

An ideal choke takes a current of 8A when connectd to an AC source of 100V and 50 Hz. A pure resistor under the same condition strikes a current of 10

Description : An ideal choke takes a current of 8A when connectd to an AC source of 100V and 50 Hz. A pure resistor under the same condition strikes a current of 10

Last Answer : An ideal choke takes a current of 8A when connectd to an AC source of 100V and 50 Hz. A pure ... resistor and inductor `sqrt(10x)`A. Find value of x

The frequency of direct current is __. (1) Zero (2) 50 HZ (3) 60 HZ (4) 100 HZ

Description : The frequency of direct current is __. (1) Zero (2) 50 HZ (3) 60 HZ (4) 100 HZ

Last Answer : (1) Zero Explanation: Direct Current (DC) refers to power systems that use only one polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current.

What volume of the chamber is required to measure absorption coefficient at 100 Hz? A. 125 m3 B. 50 m3 C. 150 m3 D. 352 m3

Description : What volume of the chamber is required to measure absorption coefficient at 100 Hz? A. 125 m3 B. 50 m3 C. 150 m3 D. 352 m3

Last Answer : D. 352 m3

The agreed standard for measuring loudness is the loudness sensation produced by a 1000 Hz sine wave _____ dB above the listener’s threshold of hearing. A. 80 B. 50 C. 30 D. 40

Description : The agreed standard for measuring loudness is the loudness sensation produced by a 1000 Hz sine wave _____ dB above the listener’s threshold of hearing. A. 80 B. 50 C. 30 D. 40

Last Answer : D. 40

A loudspeaker cabinet has an internal volume of 5,184 in3 (84,950 cm3 ). It has a port area on the baffle of 50 in2 (322.58cm2 ) and a thickness of 0.70 in (18 mm). What is the Helmholtz resonance, in hertz, of this loudspeaker enclosure? A. 250 Hz B. 245 Hz C. 240 Hz D. 255 Hz

Description : A loudspeaker cabinet has an internal volume of 5,184 in3 (84,950 cm3 ). It has a port area on the baffle of 50 in2 (322.58cm2 ) and a thickness of 0.70 in (18 mm). What is the Helmholtz resonance, in hertz, of this loudspeaker enclosure? A. 250 Hz B. 245 Hz C. 240 Hz D. 255 Hz

Last Answer : C. 240 Hz

A cantilever shaft having 50 mm diameter and length of 300 mm has a disc of mass 100 kg at its free enD. The Young’s modulus for the shaft material is 200 GN/m 2 . Calculate the natural longitudinal frequency in Hz. A. 575B. 625 C. 525 D. 550

Description : A cantilever shaft having 50 mm diameter and length of 300 mm has a disc of mass 100 kg at its free enD. The Young’s modulus for the shaft material is 200 GN/m 2 . Calculate the natural longitudinal frequency in Hz. A. 575B. 625 C. 525 D. 550

Last Answer : A. 575

A weight of 50 N is suspended from a spring of stiffness 4000N/m and subjected to a harmonic force of magnitude 60N and frequency 60 Hz. what will be the static displacement of the spring due to maximum applied force A. 0.015m B. 0.15 m C. 15 m D. 150m

Description : A weight of 50 N is suspended from a spring of stiffness 4000N/m and subjected to a harmonic force of magnitude 60N and frequency 60 Hz. what will be the static displacement of the spring due to maximum applied force A. 0.015m B. 0.15 m C. 15 m D. 150m

Last Answer : B. 0.15 m

A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural frequency (f n ), respectively, are a) 0.471 and 1.19 Hz b) 0.471 and 7.48 Hz c) 0.666 and 1.35 Hz

Description : A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural ... , are a) 0.471 and 1.19 Hz b) 0.471 and 7.48 Hz c) 0.666 and 1.35 Hz

Last Answer : a) 0.471 and 1.19 Hz

A cantilever shaft having 50 mm diameter and length of 300 mm has a disc of mass 100 kg at its free end. The Young’s modulus for the shaft material is 200 GN/m 2 . Calculate the natural longitudinal frequency in Hz. a) 575 b) 625 c) 525 d) 550

Description : A cantilever shaft having 50 mm diameter and length of 300 mm has a disc of mass 100 kg at its free end. The Young’s modulus for the shaft material is 200 GN/m 2 . Calculate the natural longitudinal frequency in Hz. a) 575 b) 625 c) 525 d) 550

Last Answer : a) 575

A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural frequency (f n ), respectively, are a) 0.471 and 1.19 Hz b) 0.471 and 7.48 Hz c) 0.666 and 1.35 Hz d) 0.666 and 8.50 Hz

Description : A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural ... .19 Hz b) 0.471 and 7.48 Hz c) 0.666 and 1.35 Hz d) 0.666 and 8.50 Hz

Last Answer : a) 0.471 and 1.19 Hz