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An alternator coupled to a hydraulic turbine runs at slow speed, as compared to others.

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Description : In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

Answer : In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.

Description : Synchronous motor always runs at which speed?

Answer : Synchronous motor always runs at synchronous speed.

Description : Is the speed of alternator is directly proportional to frequency?

Answer : Yes, speed of alternator is directly proportional to frequency.

Answer : In main line service as compared to urban and suburban service distance between the stops is more, maximum speed reached is high, acceleration and retardation rates are low.

Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.

Answer : When a conductor carries more current on the surface as compared to core, it is due to skin effect.

Answer : H.R.C. fuse, as compared to a rewirable fuse, has no ageing effect, high speed of operation, high rupturing capacity.

Description : Define armature reaction in an alternator. Explain the effect of armature reaction at various P.F. of loads of alternator.

Answer : Armature Reaction: The effect of armature flux on main flux is called as armature reaction.  Armature Reaction at Various Power Factors: When armature is loaded, the armature flux modifies ... lagging p.f. For capacitive loads the effect of flux is partly distorting and partly strengthening.

Description : In an AC. circuit, a low value of kVAR compared with kW indicates?

Answer : In an AC. circuit, a low value of kVAR compared with kW indicates high power factor.

Description : At which power factor alternator is said to be overexcited?

Answer : At leading power factor alternator is said to be overexcited.

Description :  applications of RC coupled amplifier

Answer : Applications of RC coupled amplifier: (i) Widely used as Voltage amplifiers. (ii) They are used in Public Address System. (iii) In Tape recorders. (iv) In stereo amplifiers (v) In T.V. V.C.R. and C.D. Players.

Description : advantages and disadvantages of direct coupled amplifier over RC coupled amplifier. 

Answer : Advantages:  Due to absence of coupling capacitors, the gain does not reduce on the lower frequency side.  This amplifier can amplify dc signals. Reduced cost and complexity due to absence of ...   The output waveform has a dc shift.  Poor frequency response at a higher frequency.

Description :  transformer coupled amplifier

Answer :  transformer coupled amplifier

Description : State the need of multistage amplifier. Draw frequency response of R-C coupled amplifier.

Answer : The need of multistage amplifier The voltage (or power) gain, obtained from a single stage small signal amplifier, is limited. Therefore, it is not sufficient for all practical applications. Therefore, in ... to use a MULTISTAGE AMPLIFIER .  Frequency response of R-C coupled amplifier.

Description : State the need of cascade amplifier and draw circuit diagram of 2-stage direct coupled amplifier.

Answer : Need:- The voltage (or power) gain, obtained from a single stage small signal amplifier, is limited. Therefore, it is not sufficient for all practical applications. Therefore, in order to obtain greater voltage and power gain, cascade amplifiers are used.

Description : Compare RC coupled, transformer coupled and direct coupled amplifier based on four points.

Answer : Parameter RC coupled Transformer coupled Direct coupled  Coupling element Resistor and capacitor Transformer No element Impedance matching Poor Excellent good Frequency ... Low frequency amplifier,opamp Size and cost small Large and bulky least

Description : List the advantages of RC coupled amplifier.

Answer : Advantages: 1. The frequency response is excellent 2. The circuit is very compact and extremely light 3. Cost is low because it employ resistors and capacitors which are cheap 

Description : Explain DC coupled drive circuit with unipolar output.

Answer : DC coupled drive circuit with unipolar output: The figure shows the circuit and waveforms

Description : What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these

Answer : What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these

Description : While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then (A) It would over-run the other alternator (B) Its rotor ... (C) Its portion of share in load will increase (D) Its power factor would be decreased.

Answer : While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then Its portion of share in load will increase

Description : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7

Answer : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is 6/7

Description : The power factor of an alternator depends on?

Answer : The power factor of an alternator depends on load.

Description : The magnitude of various voltage drops that occur in an alternator depends on?

Answer : The magnitude of various voltage drops that occur in an alternator depends on load current.

Description : What causes diodes to fail in alternator?

Description : State working principle of alternator. State the meaning self and separate excitation. 

Answer : Working principle of alternator: When a conductor is moved in magnetic field or a magnetic field moved with respect to conductor, according to Faraday's law of electromagnetic induction, the conductor ... like battery or shaft-mounted exciter, then the excitation is said to be separate excitation.

Description : Draw equivalent circuit of alternator.

Answer : Equivalent circuit of alternator

Description : Explain the construction of alternator with neat diagram.

Answer : Diagram: Construction of three phase alternator: Construction wise, an alternator generally consists of field poles placed on the rotating fixture of the machine i.e. rotor as shown in the ... of rotor used in construction of alternator, 1. Salient pole type. 2. Cylindrical rotor type. 

Description : Alternator

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Description : In alternator where the voltage drop occurs?

Answer : In alternator voltage drop occurs in armature resistance, leakage reactance, and armature reactance.

Answer : If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in damage to the starting winding.

Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

Description : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α

Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ

Answer : Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.

Description : What speed does electricity travel at?

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Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.

Answer : The speed/load characteristics of a universal motor is same as that of D.C. series motor.

Description : In an adjustable speed ac drive which quantity gets reduced above rated speed ? (A) developed torque (B) stator frequency (C) reduced starting torque (D) stator current

Answer : In an adjustable speed ac drive which quantity gets reduced above rated speed ? (A) developed torque (B) stator frequency (C) reduced starting torque (D) stator current

Description : An electric motor in which both stator field and rotor rotates with same speed is called?

Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.

Description : What is the speed of an electromagnetic wave in water?

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Answer : Ns         equals        f/pair pole 50/4      - 12.5

Description :  An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: A) 1000 rpm B) 920 rpm C) 950 rpm D) 970 rpm

Answer : An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: 970 rpm

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Answer : It   can  be  corrected  by  increasing  the  input  to  the  prime  mover.

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Answer : The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.

Description : Define Feed and speed in shaping machine

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Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases 

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